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47th US Rock MechanicS/GeoMechanicS SyMpoSiUM 1

Welcome from the chair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

acknoWledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

sponsors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

exhibitors' floor plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

exhibitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

general information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

hotel floor plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

symposium program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

invited plenary presentations . . . . . . . . . . . . . . . . . . . . . . . . . 19

monday technical program . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

tuesday technical program . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Wednesday technical program . . . . . . . . . . . . . . . . . . . . . . . . 30

technical tours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

special activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

abstracts table of contents . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

author index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

table of contentS

2 47th US Rock MechanicS/GeoMechanicS SyMpoSiUM

WelcoMe to San francisco, california, USaon behalf of the organizing committee, i would like to welcome you to the 47th us rock mechanics / geomechanics symposium and the city of san francisco, california . We have one of the most successful symposia to date, with more than 350 papers, four keynote speakers, 44 technical sessions,

two poster sessions, four short courses, three Workshops, 15 exhibitors, three technical tours and a large number of exciting special activities .

this multidisciplinary international annual meeting is the focal event for the rock mechanics and geomechanics community, bringing together professionals and students from civil, geological, mining, geophysical and petroleum engineering . the symposium focuses on new and exciting advances in rock mechanics and geomechanics that cut across disciplines and span the globe with more than half of the papers from countries outside the us . presentations at the symposium encompass all aspects of rock mechanics, rock engineering and geomechanics from the nano-scale to the scale of reservoirs and mines addressing many of societies pressing concerns such as geothermal energy, hydraulic fracturing, oil & gas production, carbon dioxide sequestration, civilian infrastructure and mine integrity .

We are fortunate to hold the symposium in san francisco, a city that blends mexican, asian and american cultures, skyscrapers with early spanish missions, and a climate controlled by the cool currents of the pacific ocean . rated one of the top ten most walkable cities, it has many interesting neighbourhoods, from nob hill to historic chinatown, the mission district to the financial district, and north beach, that provide food and ambience for a range of appetites . san francisco is home to world class museums, architectural landmarks like the golden gate bridge, major league sports teams, theatres, a range of music genres, a beautiful waterfront, aquarium, parks and night clubs . as William saroyan once said “if you’re alive, you can’t be bored in san francisco . if you’re not alive, san francisco will bring you to life .”

the symposium could not have happened without the effort and dedication of many people who worked tirelessly throughout the year . i am very grateful for their assistance, commitment, dedication and the hard work of the technical chairs, the organizing committee, and also of kathryn greco, hill montague, Wayne gibson, and peter smeallie .

thank you for participating in the symposium . please enjoy the conference, learn as much as you can, meet and make friends, and take advantage of the many things that san francisco has to offer .

“san francisco has only one drawback . ‘tis hard to leave .” (rudyard kipling)

laura J . pyrak-nolte Chair of the 47th US Rock Mechanics/Geomechanics Symposium Professor of PhysicsProfessor of Civil EngineeringProfessor of Earth, Atmospheric and Planetary SciencesPurdue University


acknoWleDGeMentS

Organizing COmmittee Laura J. Pyrak-NolteChairpurdue universityAlvin ChanTechnical Committee: PetroleumshellWilliam DershowitzTechnical Committee: Civilgolder associatesErik EberhardtCanadian Liaison university of british columbiaRussell EwyTechnical Tours Chairchevron energy technology co .

Peter SmeallieExecutive Directoramerican rock mechanics

associationSarah WilsonVenue Committee Jacobs associates Joseph MorrisTechnical Committee: Interdisciplinaryschlumberger-doll researchSeiji NakagawaNational Laboratories Liaison lawrence berkeley national

laboratoryMaria-Katerina NikolinakouPaper Awards Committeethe university of texas at austin

Marisela Sanchez-NagelPoster Awards Committeeitasca houstonJamal RostamiTechnical Committee: Mining pennsylvania state university

SeSSiOn ChairS/DevelOperSJonathan Ajo-FranklinSherif AklFlorian AmannTarabay AntounEwerton AraujoJose ArguelloStephen BauerDoug BlankenshipBrian BonnerTom BrattonTrevor CarterLaura ChiaramonteAlexander ChudnovskyPeter ConnollyBrian CrawfordBill DershowitzDave DewhurstRuss DetwilerMark DiederichsJohn DudleyHerbert EinsteinDerek ElsworthEssie EsterhuizenRuss EwySouheil EzzedineJonathan FriedmanMikhail GeilikmanLeslie GertschSteve GlaserYonggui Guo

Marte GutierezNicolas GuyPaul HaginGang HanJohn HanningFrank HansenJohn HarrisonZara HosseiniAmie HowsHaiying HuangGerg HusenfusGhazal IzadiScott JohnsonJohn KemenyEunhye Kim Dan KingPaul La Pointe Don LeeYi LouHamid MalekiKim McCarterMary McLaughlinHani MitriDan MoosAntony MossopMichael MurphyNeal NagelMaria NikolinakouCortney PalleskeRomain PrioulLangsten RadfordMileva Radonjic

Azadeh RiahiLance RobertsJonny RutqvistDavid Scarpato Nick SitarSergey StanchitsGreg StillmanRoberto Suarez-RiveraDoug TesarikNicholas ThompsonFulvio TononAzra TutuncuStuart WalshDale WaltersErik WestmanSarah Wilson Hong YangKarim ZakiFengshou Zhang

pOSter SeSSiOnS COOrDinatOrTeri Nichols conocophillips

paper awarDS COmmitteeMaria-Katerina NikolinakouChairthe university of texas at austin


pOSter awarDS COmmitteeMarisela Sanchez-Nagel, ChairAnita AiChloé ArsonChandong ChangPaul HaginJustin HustoftGang LiMichael MurphyNeal NagelTerri NicholsAzadeh RiahiLance A. RobertsDavid J. ScarpatoJosh TaronDale WaltersLiangyang Zhang

Career Center/StuDent trivia COnteStOrganized by the Future Leaders of ARMA

Alvin ChanAmie L. HowsHaiying HuangThierry LavoieMichael MurphyMarisela Sanchez-NagelMaria-Katerina NikolinakouAzadeh RiahiDavid J. ScarpatoKarim Zaki

wOrkShOp OrganizerSTony AddisMark DiederichsJohn DudleyMaurice DusseaultAxel MakuratAzra Tutuncu

teChniCal tOur leaDerSJulio GarciaRichard GoodmanCasey MooreMark Walters

arma BOarD Of DireCtOrSPresident Mark D. Zoback stanford universityVice President Antonio Bobet purdue universityTreasurer Bill Dershowitz golder associates, inc .Secretary Anthony Iannacchione university of pittsburghImmediate Past President Azra N. Tutuncu colorado school of minesDon Banks vicksburg, ms

John Curran rocscienceRussell T. Ewychevron energy technology co .Michael Hardy agapito associates, inc .Mary MacLaughlin montana techJohn McLennan university of utah Gangerico Ramos conocophillipsErik Westman virginia tech

SympOSium StaffPeter Smeallie Executive Director, ARMA

Katy Greco Registrar

Hill Montague, Sr. Symposium Communications

Jim Roberts Registrar Staff


SpOnSOrSthe 47th u .s . rock mechanics / geomechanics symposium is sponsored by the american rock mechanics association, a professional society that serves as the direct link in the united states to the professionals, firms, teachers, and students in the fields of rock mechanics and rock engineering .

the following companies have generously provided support for the 47th symposium:

Agapito Associates Inc. Sponsor of the 25 June Symposium Awards Banquet

Calpine Corporation Contributed in-kind support for the 27 June Geysers Technical Tour

Chevron Sponsor of Student Scholarships for Discounted Symposium Registration

ConocoPhillips Sponsor of the 24-25 June Poster Presentations

Golder Associates, Inc. Sponsor of the three Coffee Breaks

Itasca International Inc. Sponsor of the Symposium Delegate Bag

MetaRock Laboratories, Inc. Sponsor of the 24 June Morning Coffee Break

MTS Systems Corp. Sponsor of the 23 June MTS Lecture, and Opening Reception

Rocscience Donated Registration Lanyards

TerraTek / a Schlumberger Co. Sponsor of Future Leaders Luncheon on 25 June

Special thanks to Derek Elsworth and Sidney Green for support of the ARMA Fellows activities at the symposium.

TerraTekSalt Lake City, Utah


eXhiBitOrS flOOr plan


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Booth 11AEG: Association of Environmental and Engineering Geologists PO Box 460518 Denver, CO 80246 www.aegweb.org

aeg is the acknowledged international leader in environmental and engineering geology, and is greatly respected for its stewardship of the profession . aeg offers information on environmental and engineering geology useful to practitioners, scientists, students, and the public . stop by for information on our annual meeting in seattle, 8-15 september 2013 .

Booth 15Engineering Seismology Group 20 Hyperion Court Kingston, Ontario K7K 7G3 Canada www.esg.ca

esg solutions, celebrating its 20th anniversary, is a leading provider of passive microseismic monitoring solutions to oil, gas and mining . esg gives clients insight into the location and nature of microseismic events . esg has a full suite of solutions that enable clients to mitigate risk, opti-mize production and reduce costs .

booth 5GCTS Testing Systems 6103 S. Maple Avenue, #1 Tempe, AZ 85283 www.gcts.com

gcts provides a full line of computer servo- controlled testing systems for rocks, soils, pave-ments, and construction materials . advanced systems for triaxial, direct shear, point load, indi-rect tension, hydraulic fracture, polyaxial, hollow cylinder, ultrasonic, and other specialized equipment including high-pressure/high temperature triaxial cells . for more information about our testing equipment, please visit our web site at www .gcts .com .

booth 12 Golder Associates, Inc. 18300 NE Union Hill Road Redmond, WA 98052 www.golder.com

golder associates provides consulting, design, and construction services in the areas of earth, environment, and energy . operating as an employee-owned group since its formation in 1960, golder now has more than 9,000 dedicated professionals operating in local companies across africa, asia, australia, europe, north america, and south america .


booth 14Intelligent Resources Inc.Suite 142, 757 West Hasting StreetVancouver, BC V6C1A1Canadawww.rayfract.comour rayfract® refraction tomography software allows reliable imaging of subsurface velocity structure including faults, strong lateral velocity variation and other velocity anomalies . our smooth inversion tomographic method is based on physically meaningful modeling of first break propagation, for p-wave and s-wave surveys . We forward model refraction, transmission and diffraction and back-project travel time residuals along wave paths, also known as fresnel volumes instead of conventional rays .

booths 7 & 8Itasca Consulting Group 111 Third Avenue South Minneapolis, MN 55401 www.itascacg.com

itasca is a global, employee-owned, engineering consulting and software firm, working primarily with the geomechanics, hydrogeological and microseismics communities . We solve problems in many industries including mining, civil engineering, oil & gas, manufacturing and power genera-tion . itasca works directly with mining companies, industrial companies, government agen-cies, and as a specialist consultant to other consulting firms . the dynamic interchange between consulting and software, complemented with hands-on field experience, forms the core of itasca’s unique, expert services to its customers

booth 16MTS Systems Corp. 14000 Technology Drive Eden Prairie, MN 55344 www.mts.com

mts is a leading supplier of rock mechanic test systems . offering extensive expertise in support-ing today’s most critical geological material evaluation application like ultrasonic velocity, fracture toughness, polyaxial testing and many more . mts delivers a full range of high-performance hardware, software, and accessories required to meet challenging rock testing requirements .

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booth 2MALA GeoScience USA, Inc. 465 Deanna Lane Charleston, SC 29492 www.malags.com

mala geoscience usa, inc . is the north american representative for reutech min-ing’s movement and surveying radar (msr) . the msr provides highly accurate, real-time, all weather surveying and slope movement measurements in open pit mines . state-of-the-art radar technology allows the integration of data with the mapping tools of the mine .

booth 1MetaRock Laboratories, Inc. 6723F Stella Link Road Houston, TX 70005 www.metarocklab.com

metarock laboratories, inc . is a unique and diversely skilled geo-mechanics and special core analysis laboratory . We are able to provide high quality testing and consulting services (i .e ., triaxial, uniaxial, ucs, scal, etc .) on rock samples . We have extensive experience in designing and developing testing apparatus/vessels and pumps . additionally, we have experience and capa-bilities related to elevated temperature testing and equipment, custom software and integration, and acoustic velocity and anisotropy measurements as a function of stress .

booth 17Rocscience Inc. 31 Balsam Avenue Toronto, Ontario M4E 3B5 Canada www.rocscience.com

rocscience develops geotechnical software used worldwide by over 5,000 users in over 100 countries . our suite of programs includes slope stability, settlement and consolidation, and stress analysis, support design and underground modeling . created by experienced engineer-developers, our high-quality programs enable users to save time and money when designing solutions in both soil and rock .

software tools for rock and soil


booth 6Simpleware Ltd Bradninch Hall Castle Street Exeter EX4 3PL United Kingdomwww.simpleware.com

simpleware provides and develops world-leading mesh generation software which converts 3d scan data (e .g . ct, microct, xmt, etc .) into high-quality computational models . it is being used by researchers across all material engineering sectors, including geosciences and oil and gas .

booths 3 & 4TerraTek / a Schlumberger Company Schlumberger Reservoir Laboratories Salt Lake City, Utah USA Schlumberger Innovation CenterSalt Lake City, Utah USA

terratek, a schlumberger company, is the ‘flagship’ of the schlumberger reservoir laboratories, located in salt lake city, utah usa; with other schlumberger reservoir laboratories located in houston, texas, calgary, canada, and in argentina, australia, brazil, china, malaysia, poland, russia, and venezuela .

the schlumberger innovation center is located in salt lake city, utah usa and serves as a bridge between research and commercialization; and focuses on the concept “rocks matter” considering rock-fluid interaction and applying rock mechanics / geomechanics aimed at complex reservoir oil and gas recovery .

booth 13Weatherford Laboratories 8845 Fallbrook Drive Houston, TX 77064 www.weatherfordlabs.com

Weatherford laboratories provides a single source with the industry’s most comprehensive, integrated rock and fluid analysis worldwide .

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TerraTekSalt Lake City, Utah


general infOrmatiOn

Mapslocal maps are available from the hotel .

transportation, parking, Restaurantsthere are two bart/muni subway stations within a few blocks on market street . bus route maps are available from the hotel . parking is available for a fee within the hotel and in neighboring garages . san francisco has no shortage of world-class restaurants and quick and easy lunch shops . the concierge desk has a list of nearby restaurants .

Registration and Speaker Ready Roomon-site registration is available on the second floor pre-function lobby during the following hours:

friday, 21 June . . . . . . . . . . . . . . . . 8:00 am – 10:00 amsaturday, 22 June . . . . . . . . . . . . 7:30 am – 10:00 am sunday, 23 June . . . . . . . . . . . . . . 7:30 am – 9:00 pmmonday, 24 June . . . . . . . . . . . . . 7:00 am – 6:45 pmtuesday, 25 June . . . . . . . . . . . . . 7:00 am – 6:30 pmWednesday, 26 June . . . . . . . . 7:00 am – 2:00 pm

the speaker ready room is located just off the pre-function lobby on the second floor of the hotel . a laptop and lcd will be available . the speaker ready room will be available during the same hours as the registration desk . please see the registration desk for access to this room .

exhibit hallthe exhibit hall is located in metropolitan ballroom iii . the hours are:

sunday, 23 June . . . . . . . . . . . . . 7:00 pm – 9:00 pmmonday, 24 June . . . . . . . . . . . . 9:30 am – 4:30 pmtuesday, 25 June . . . . . . . . . . . . 9:30 am – 4:30 pmWednesday, 26 June . . . . . . . 9:30 am – 12:00 noon

Speakers breakfastspeakers and session chairs are required to attend the speaker’s breakfast on the day of your presentation . please bring the appropriate ticket . the breakfasts begin at 7:00 am in the third floor city, commonwealth, and cornell rooms . rooms and tables will be identified by session, and you will load presentations via a portable usb storage device to the session laptop . in addition to uploading your presentation, you will be able to meet your session chair(s) . it will be helpful if you bring along 2 or 3 written sentences about yourself so that the session chair can prepare an introduction .

if you wish to review your presentation prior to loading it onto the session laptop, you will be able to do so in the speaker ready room .


career cornera career corner with bulletin boards will be set up for students to post resumes and employers to post career opportunities . the event, conceived as an informal gathering, serves as the first step to connect students and potential employers . volunteers from the future leaders group will be available during the two poster session times and on monday, 24 June, from 6:00 to 6:30 pm . to facilitate the communication, advise on resume writing and discuss career outlook .

students participating in the career corner should bring hard copies of their resumes . all students who post their resumes will be automatically entered into a drawing for a raffle prize . employers interested in advertising openings, simply bring hard copy material to post at the symposium .

Student trivia contesta student trivia contest will be held on monday, 24 June starting at 6:30 pm . students are encouraged to form an interdisciplinary team with up to three members . the questions will cover a diverse range of technical areas, including civil, petroleum and mining engineering . the winners of the event will be announced at the banquet on tuesday and could earn a cash prize of over $100 .

Short coursesthree of the four short courses offered have been confirmed:

Saturday, 22 June – Short Course 1: reliability engineering for tunnel construction, $190 (commonwealth room)

Saturday, 22 June – Short Course 2: geomechanical considerations for unconventional hydrocarbon developments: evaluating the role of natural fractures and microseismicity, $190 (city room)

Sunday, 23 June – Short Course 4: numerical modeling of cave mining, $190 (city room)

technical toursthere are three technical tours offered:

Saturday, 22 June – Technical Tour 1: santa cruz geology, $110

Sunday, 23 June – Technical Tour 2: san francisco bay geologic engineering tour with richard goodman, $90

Thursday, 27 June – Technical Tour 3: the geysers/napa valley, sold out


Workshops Friday, 21 June – Workshop 1: 3rd geomechanics solutions for environmental and technical challenges in unconventional resources, $125 (metropolitan i)

Saturday, 22 June – Workshop 2: isrm-arma Workshop on petroleum geomechanics testing, $125 (metropolitan i)

Thursday, 27 June – Workshop 3: spall prediction, $100 (stanford)

Special activitiesthere are four special activities offered:

Sunday, 23 June – Special Activity 1: alcatraz: “the rock,” $69

Monday, 24 June – Special Activity 2: lunch at m .y . china, $95

Tuesday, 25 June – Special Activity 3: san francisco highlights, $58

Wednesday, 26 June – Special Activity 4: an evening at “beach blanket babylon,” $80

other Scheduled eventsSunday, 23 June – arma board of directors meeting (victorian room, Westin st . francis on union square)

Sunday, 23 June – asce rock mechanics committee meeting (boardroom)

Monday, 24 June – lunch meeting of the arma publications committee (boardroom)

Monday, 24 June – career corner trivia contest (2nd floor prefunction lobby)

Monday, 24 June – itasca 3dec reception (metropolitan iii, by invitation)

Monday, 24 June – arma fellows dinner and meeting (farallon restaurant, 450 post street)

Tuesday, 25 June – lunch meeting of the arma future leaders (commonwealth room)

Wednesday, 26 June – lunch meeting of the organizing committee for minneapolis 2014 (boardroom)


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Concordia

Olympic

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MetropolitanBallroom

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hOtel meeting rOOmS

The Westin San Francisco Market Street50 Third Street, San Francisco, CA 94103Telephone: 415-974-6400


47th u.S. rOCk meChaniCS / geOmeChaniCS SympOSium teChniCal prOgram anD timetaBlefriday, 21 June 2013Registration - 8:00 am - 10:00 am, 2nd floor marble registration desk

Workshop 1 - 8:30 am - 5:00 pm, metropolitan i 3rd Workshop on geomechanics solutions for environmental and technical challenges in unconventional resources

Saturday, 22 June 2013Registration - 7:30 am - 10:00 am, 2nd floor marble registration desk

Workshop 2 - 8:00 am - 5:00 pm, metropolitan i isrm-arma Workshop on petroleum geomechanics testing

Short Course 1 - 8:30 am - 4:30 pm, commonwealth reliability engineering for tunnel construction

Short Course 2 - 8:30 am - 5:00 pm, city room geomechanical considerations for unconventional hydrocarbon develop-ments: evaluating the role of natural fractures and microseismicity

Technical Tour 1 - 9:30 am - 6:30 pm, assemble in 1st floor hotel lobby santa cruz geology

Sunday, 23 June 2013Registration -7:30 am - 9:00 pm, 2nd floor marble registration desk

Technical Tour 2 - 8:00 am - 5:00 pm, assemble in 1st floor hotel lobby san francisco bay geological engineering tour

Short Course 4 - 9:00 am - 4:00 pm, city room numerical modeling of cave mining

Special Activity 1 - 11:30 am - 3:30 pm, assemble in 1st floor hotel lobby tour of alcatraz

Opening Session - 6:00 pm - 6:20 pm, metropolitan i & ii

MTS Lecture - 6:20 pm - 7:00 pm, metropolitan i & ii peter flemings, “the science of pore pressure prediction in the deepwater”

Opening Reception and Exhibits - 7:00 pm - 9:00 pm, metropolitan iii Sponsored by MTS Systems Corporation


Monday, 24 June 2013Registration - 7:00 am - 6:45 pm, 2nd floor marble registration desk

Speaker’s Breakfast - 7:00 am - 7:50 am, city, commonwealth, cornell

Technical Sessions - 8:00 am - 9:30 amsession 1: experimental rock mechanics i - shale and mudrocks, metropolitan i session 2: mine seismicity, stanfordsession 3: co2 sequestration and utilization, metropolitan iisession 4: rock slopes i, franciscan

Coffee Break, Exhibits Open - 9:30 am - 10:00 am, metropolitan iii Sponsored by Metarock Laboratories, Inc.

Plenary Address - 10:00 am - 10:50 am, metropolitan i & ii larry myer, “geological carbon sequestration”

Technical Sessions - 11:00 am-12:30 pmsession 5: reservoir geomechanics i, -metropolitan isession 6: deep mine rock mechanics, stanfordsession 7: transport and coupled processes in fractures, metropolitan iisession 8: rock slopes ii, franciscan

Lunch - on your own, 12:30 pm-2:00 pm

Special Activity 2 - 12:30 pm - 2:00 pm, assemble in 1st floor hotel lobby multi-course lunch at m .y . china

Technical Sessions - 2:00 pm - 3:30 pmsession 9: Wellbore stability, metropolitan isession 10: numerical modeling in coal mines, stanfordsession 11: thermal, hydrological, mechanical, chemical and biological influences

upon rock, metropolitan iisession 12: constitutive models, francican

First Poster Session - 3:30 pm - 4:30 pm, metropolitan iii and olympic, concordia career corner, exhibits, coffee and light refreshments Coffee Break Sponsored by Golder Associates Tunnel and Grouting Group Poster Session Sponsored by ConocoPhillips

Technical Sessions - 4:30 pm - 6:00 pmsession 13: coupled process models i, metropolitan isession 14: geomechanical challenges associated with geothermal drilling, stimulation

and production i, stanfordsession 15: geologic repository issues for nuclear Waste disposal, metropolitan ii session 16: laboratory-scale rock mechanics, franciscan

Career Corner - 6:00 pm - 6:30 pm, 2nd floor prefunction lobby

Student Trivia Contest - 6:30 pm - 7:30 pm, 2nd floor prefunction lobby


tuesday, 25 June 2013Registration - 7:00 am - 6:30 pm, 2nd floor marble registration desk


Technical Sessions - 8:00 am - 9:30 amsession 17: unconventionals i, metropolitan isession 18: ground control i, stanfordsession 19: rock physics and geophysics, metropolitan iisession 20: discrete geomechanics i, franciscan

Special Activity 3 - 9:00 am - 1:00 pm, assemble in 1st floor hotel lobby san francisco highlights

Coffee Break, Exhibits Open - 9:30 am - 10:00 am, metropolitan iii Sponsored by Golder Associates Mining Services

Plenary Address - 10:00 am - 10:50 am, metropolitan i & ii chris breeds, “history of the mediterranean sea to dead sea canal project and current concepts for restoration of the dead sea and lower Jordan river”

Technical Sessions - 11:00 am - 12:30 pmsession 21: fracture mechanics i, metropolitan i session 22: ground control ii, stanfordsession 23: rock heterogeneity and scaling, metropolitan iisession 24: discrete geomechanics ii, franciscan

Lunch - on your own, 12:30 pm - 2:00 pm

Technical Sessions - 2:00 pm - 3:30 pmsession 25: pore pressure and stress, metropolitan i session 26: coal mine rock mechanics, stanfordsession 27: acoustic emissions, metropolitan iisession 28: rock mass characterization and ground improvement, franciscan

Second Poster Session - 3:30 pm - 4:30 pm, metropolitan iii and olympic, concordia career corner, exhibits, coffee and light refreshments Sponsored by ConocoPhillips

Technical Sessions - 4:30 pm - 6:00 pmsession 29: experimental rock mechanics ii - sand, metropolitan i session 30: coupled process ii, stanfordsession 31: geomechanical challenges associated with geothermal drilling, stimulation

and production ii, metropolitan iisession 32: tunnels and caverns i, franciscan

ARMA Awards Banquet - 7:15 pm - 9:30 pm san francisco marriott marquis hotel, 780 mission street (one block from the Westin) Sponsored by Agapito Associates, Inc.


Wednesday, 26 June 2013Registration - 7:00 am - 2:00 pm, 2nd floor marble registration desk


Technical Sessions - 8:00 am - 9:30 amsession 33: fracture mechanics ii, metropolitan isession 34: production in Weak rock, evaporites and caving, stanfordsession 35: new developments in computational rock mechanics, metropolitan iisession 36: dams and foundations, franciscan

Coffee Break, Exhibits Open - 9:30 am - 10:00 am, metropolitan iii Sponsored by Golder Associates FracMan Technology Group

Plenary Address - 10:00 am - 10:50 am, metropolitan i & ii erik eberhardt, “large slope failures; monitoring failures over time”

Technical Sessions - 11:00 am - 12:30 pmsession 37: reservoir geomechanics ii, metropolitan i session 38: tunnels and caverns ii, stanfordsession 39: high performance computing: the challenge of harnessing hpc for rock

mechanics, metropolitan iisession 40: fracture statistics and rock mass measures, franciscan

Technical Sessions - 12:30 pm - 2:00 pmsession 41: unconventionals ii, metropolitan i session 42: experimental rock mechanics iii - novel rocks and testing methods, stanfordsession 43: uncertainty Quantification and parameter estimation in geomechanics,

metropolitan iisession 44: rock mass strength and deformability, franciscan

Closing Session - 2:00 pm - 2:15 pm, metropolitan i

Special Activity 4 - 7:00 pm – 10:00 pm, assemble in 1st floor hotel lobby beach blanket babylon

thursday, 27 June 2013Technical Tour 3 - 7:30 am – 6:00 pm, assemble in 1st floor hotel lobby

the geysers / napa valley Workshop 3 - 8:30 am - 5:00 pm, stanford

Workshop on spall prediction


inviteD plenary preSentatiOnSSunday, 23 June, 6:20 pm - 7:00 pm, Metropolitan I & II

MtS lecture - the Science of pore pressure prediction in the Deepwater

Peter B. Flemings, The University of Texas

the 2011 gulf of mexico deepwater macondo blowout exposed the public to the extreme environment of deepwater drilling . Water depths of 10,000 feet are common, pore pressures routinely converge on the lithostatic pressure, and stress states are complex . drilling in this environment is expensive and difficult . a new generation of studies combines geomechanics, petroleum engineering, geotechnics, and geoscience to study the coupled behavior and evolution of basin systems . i will link observations of pressure and basin-scale fluid flow with coupled models to

provide insight into the dynamic nature of pore pressure and flow in deepwater systems . i will show how pressure and stress couple to trap and release hydrocarbons and create conditions for unstable drilling . i will show how both large scale geological evolution and micro-scale understanding of rock behavior are critical to understanding these systems . scientists and engineers trained in these skills will lead the next generation of energy exploration .

Dr. Peter B. Flemings is a professor with the Jackson school of geosciences at the university of texas, where he holds the Jackson chair in geosystems . he studies pore pressure, stress, and fluid flow in sedimentary basins around the world . his research group specializes in applying geotechnical approaches to understand the evolution of pressure, stress, and material properties over geological time- and length-scales . he served as an informal advisor to the u .s . energy secretary’s macondo Well integrity team and he consults internationally on pore pressure prediction . he is deeply involved in scientific drilling: he was co-chief scientist for iodp expedition 308, an expedition focused on the development of excess pore pressure and he developed a pore pressure penetrometer for ocean drilling . he has published over 80 technical papers and has been a distinguished speaker for the american association of petroleum geologists and for the integrated ocean drilling program .

Monday, 24 June, 10:00 am - 10:50 am, Metropolitan I & II

Geologic co2 Storage: current Status and future DirectionsLarry Myer, Lawrence Berkeley National Laboratory (Ret.)

during the past decade, carbon capture and sequestration (ccs) has gained recognition amongst the broader global scientific community, as well as policymakers, as an important means of mitigating the effects of greenhouse gas (ghg) emissions on climate change . accompanying this has been rapid development of the underlying subsurface science and technology needed to make ccs a commercial reality . since the mid-1990’s, a number of storage research and development projects, both commercial and small scale, have been undertaken worldwide . in the united states,

led by the department of energy’s (doe) office of fossil energy and the national energy technology laboratory (netl), a network of seven regional carbon sequestration partnerships (rcsps) was put in place to help develop the technology, infrastructure, and regulations needed to implement large-scale co2 storage in different regions and geologic formations . the overall experience represented by global field projects and other research shows that geologic storage of co2 is technologically feasible in a number


of different geologic environments; powerful tools have been developed to predict the behavior of co2 in the reservoir, and a portfolio of tools with the potential for monitoring all aspects of storage projects has developed . accompanying technological advances has been the resolution of many legal and regulatory issues surrounding geologic storage . in the u . s ., regulations are now in place for the injection of co2 for purposes of storage, and for accounting of co2 emissions . even though advances have been great, challenges remain . further work is needed to assess the technical feasibility of co2 storage across the spectrum of depositional environments, and other research needs include improved methods to manage pressure and detect and mitigate potential leakage . technology advances alone are insufficient to enable broad global deployment of ccs . of equal, if not greater, importance, are the legal, regulatory, and public acceptance challenges that must continue to be resolved .

Dr. Larry Myer is a retired staff scientist at lawrence berkeley national laboratory (lbnl), where he conducted research in the earth sciences division (esd) from 1981 until 2010 . currently, he consults and is a member of the geologic sequestration team at leonardo technologies, inc . dr . myer has been leading research activities in geologic sequestration since 1999 . he co-directed the doe funded Qeo-seQ project, through which he led the development of the monitoring program for the frio co2 injection pilot, the first saline formation co2 pilot in the united states . he was the geologic sequestration program head for lbnl, which has carried out research in support of many of the major sequestration field demonstrations throughout the world . from 2003 until 2010, he held a joint position at the california energy commission and was technical director of the West coast regional carbon sequestration partnership, which is evaluating carbon dioxide sequestration options and opportunities, for the west coast of north america . dr . myer received a phd in geological engineering from the university of california, berkeley . his disciplinary research was in geomechanics and geophysics with a focus on deformation and failure of rock, seismic wave propagation, and fluid flow in fractured and porous rock .

Tuesday, 25 June, 10:00 am - 10:50 am, Metropolitan I & II

history of the Mediterranean Sea to Dead Sea canal project and current concepts for Restoration of the Dead

Sea and lower Jordan RiverChris D. Breeds, Subterra, Inc.

the demise of the dead sea presents a unique opportunity for environmental restoration, as well as economic prosperity . since the 1970’s the dead sea has lost a third of its surface area, and it continues to drop in depth by over a meter on average every year . this is a man-made problem due primarily to upstream water diversion and evaporation . the Jordanian, israeli and palestinian authority governments have all identified “saving the dead sea” as an issue of national priority and a recently

completed regional poll shows extensive, widespread public support for restoring the lower Jordan river . the mediterranean sea to dead sea project will benefit the region by providing: • restoration of the historic seawater levels in the dead sea;• Water and infrastructure that can be used to begin restoration of the lower Jordan river watershed;• a new water supply for both drinking and irrigation in the east and West banks of the Jordan river;• a new electrical power supply for israel, Jordan and the palestinian authority;• infrastructure (roads, dams, water distribution, and wastewater disposal);• new job opportunities for all participants; and• natural resource protection .

the project will provide mutual long term benefits for israelis, palestinians and Jordanians, with increased eco-tourism, cultural heritage site preservation and water and power for households, industry


and agriculture . the mediterranean sea to dead sea project is currently proposed as an alternate to the red-dead project that has been under study since the mid 1980’s . this paper will present the historic development of the med-dead project, current concepts for water transmission, desalination, and lower Jordan river restoration and a comparison of the med-dead and red-dead projects .

Dr. Chris Breeds graduated from the university of nottingham, uk with an honors degree in mining engineering and a phd in mining rock mechanics in 1976 . he is a registered professional civil engineer in the us and a chartered engineer–mining in the uk . his broad experience includes: subsurface rock mechanics and geotechnical engineering; subsidence engineering; underground and surface blasting; shotcrete and concrete technology; feasibility studies and conceptual design for tunnel and mine facilities; mine and tunnel systems analysis; preparation of construction cost estimates, bid documents, and specifications; and project management for both private and government projects . this broad technical expertise is complimented by management experience which includes incorporating and managing companies in the us, uk and germany as well as managing large multidisciplinary groups involved in project work .

Wednesday, 26 June, 10:00 am - 10:50 am, Metropolitan I & II

improving our Understanding and assessment of Deep-Seated Rock Slope hazards through an

integrated Mapping, Monitoring and Modelling approach

Erik Eberhardt, University of British Columbia

globally, mountain regions are experiencing accelerated economic development in response to population growth, rising living standards and associated demands for increased mining and energy production . in the civil engineering sector, the importance of rock slope hazard assessments has intensified in response to the heightened risk profiles associated with hydroelectric dam reservoir safety, energy development (e .g .,

pipelines), and urban expansion . in the mining sector, the depletion of shallower resources are pushing surface mine designs to consider pit slope heights in excess of 1000 m, challenging the industry’s collective experience . together, the associated engineering challenges and economic/safety risks will require a transition in the state-of-the- art toward a more detailed accounting of the 3-d spatial and temporal complexity in ground conditions, responses and interactions that can adversely impact rock slope stability . this presentation will summarize results from recent research involving a number of rock slope hazard investigations in which field mapping (aided by lidar), monitoring (including insar), and state-of-the-art numerical modeling were integrated to minimize geological uncertainty and enable a more reliable interpretation of rock slope behavior to be incorporated into the engineering decision-making process .

Dr. Erik Eberhardt is a professor of rock engineering and director of the geological engineering program at the university of british columbia in vancouver, canada . he is a registered professional engineer in the province of british columbia . his early career included working for a number of open pit and underground mines in canada followed by a 6 year period working in switzerland at the eth Zurich on a variety of rock slope and tunneling projects . he took up his current position at ubc in 2004 where he manages a large research group specializing in rock mass characterization, geotechnical monitoring and numerical modeling applied to mining, petroleum, tunneling, and rock slope engineering . he also continues to practice as a consulting engineer on international projects in north and south america, europe and asia . he has published over 125 technical papers and was named the canadian geotechnical society’s 29th colloquium speaker .


mOnDay teChniCal prOgramSe

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258

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255

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Mon

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11:0

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234

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echa

nism

s of

be

achr

ocks

in O

kina

wa

and

Ishi

kaw

a, J

apan

407

- M

.A. P

erra

sQ

ueen

ston

For

mat

ion:

Tun

nel b

ack

anal

ysis

and

forw

ard

shaf

t pr

edic

tion

2:30

-2:4

5pm

132

- X

inpu

She

nC

ase

Stu

dies

on

Wel

lbor

e S

tabi

lity

of

Tig

ht S

and

For

mat

ions

in W

est

Chi

na

201

- Ani

l K. R

ayN

umer

ical

Mod

elin

g of

the

Per

form

ance

of A

ctiv

e an

d P

assi

ve

Bol

ts in

stal

led

at a

n Ill

inoi

s B

asin

C

oal M

ine

650

- Ta

ha H

usai

nIn

fluen

ce o

f inf

usio

n ra

te a

nd m

agm

a rh

eolo

gy o

n th

e gr

owth

of l

ava

dom

es

350

- P.

H.S

.W. K

ulat

ilake

Dev

elop

men

t of a

n or

thot

ropi

c co

nstit

utiv

e m

odel

for

a jo

inte

d ro

ck

mas

s

2:45

-3:0

0pm

346

- O

.-M

. Nes

Bor

ehol

e S

hale

Sta

bilit

y A

naly

sis

to

Fac

ilita

te S

ucce

ssfu

l Dril

ling

of a

H

oriz

onta

l Wel

l in

the

Nor

th S

ea

174

- E

.M.C

. Kia

sM

odel

ing

unst

able

failu

re o

f coa

l pi

llars

in u

nder

grou

nd m

inin

g us

ing

the

disc

rete

ele

men

t met

hod

253

- V

. Vila

rras

aIm

pact

s of

col

d C

O2

inje

ctio

n in

de

ep s

alin

e aq

uife

rs o

n th

e ro

ck

mec

hani

cal i

nteg

rity

524

- P.

Kan

tiaN

on-d

estr

uctiv

e te

stin

g of

roc

k m

ass

defo

rmat

ion

in s

pent

nuc

lear

fuel

di

spos

al r

esea

rch

faci

litie

s

3:00

-3:1

5pm

490

- B. P

ark

Dis

cret

e E

lem

ent M

odel

ing

of

Tra

nsve

rsel

y Is

otro

pic

Roc

k

165

- R. G

uD

istin

ct E

lem

ent A

naly

sis

of

Dis

cont

inui

ty S

tabl

e an

d U

nsta

ble

She

ar F

ailu

re

621

- L.

Bla

nco

Mar

tínT

herm

al-H

ydra

ulic

-Mec

hani

cal

Pro

cess

es M

odel

ing

to E

valu

ate

Sal

t-ba

sed

Rep

osito

ries

in th

e Lo

ng-T

erm

394

- M

orte

za N

ejat

iT

heor

etic

al a

nd N

umer

ical

Mod

elin

g of

Roc

k H

yste

resi

s B

ased

on

Slid

ing

of M

icro

crac

ks

3:15

-3:3

0pm

411

- J.

L. A

vila

Impa

ct o

f Dril

ling

Mec

hani

cs o

n th

e G

eom

echa

nica

l Mod

el: A

n E

xam

ple

from

Gor

gon

Dev

elop

men

t Dril

ling

Cam

paig

n, o

ffsho

re A

ustr

alia

198

- Rag

hwen

dra

Sin

ghE

stim

atio

n of

par

ting

stab

ility

and

su

ppor

t req

uire

men

ts d

urin

g de

pilla

ring

in tw

o co

ntig

uous

coa

l se

ams

241

- A.K

.M. B

. Ala

mE

ffect

of c

onfin

ing

pres

sure

on

perm

eabi

lity

durin

g de

form

atio

n an

d fa

ilure

of s

ever

al r

ocks

und

er

com

pres

sion

348

- E

. Bak

htia

ryTo

war

ds a

The

rmod

ynam

ic

Fra

mew

ork

to M

odel

Par

ticle

C

rush

ing

and

Sie

ving

Mon

day,

24

June

201

3


Sess

ion

13Se

ssio

n 14

Sess

ion

15Se

ssio

n 16

Met

ropo

litan

ISt

anfo

rdM

etro

polit

an II

Fran

cisc

an

Tim

eC

oupl

ed P

roce

ss M

odel

s I

(pp

88-9

1)G

eom

echa

nica

l Cha

lleng

es A

ssoc

iate

d w

ith

Geo

ther

mal

Dril

ling,

Stim

ulat

ion

&

Prod

uctio

n I (

pp 9

1-93

)

Geo

logi

c R

epos

itory

Issu

es fo

r N

ucle

ar W

aste

Dis

posa

l(p

p 94

-96)

Labo

rato

ry-S

cale

Roc

k M

echa

nics

(pp

97-9

9)

4:30

-4:4

5pm

368

- M

ark

W. M

cClu

reC

ompu

tatio

nal I

nves

tigat

ion

of

Tre

nds

in In

itial

Shu

t-in

Pre

ssur

e du

ring

Mul

ti-st

age

Hyd

raul

ic

Stim

ulat

ion

in th

e B

arne

tt S

hale

533

- L.

Urp

iC

oulo

mb

stre

ss c

hang

e du

ring

and

afte

r te

nsile

frac

ture

ope

ning

in a

ge

othe

rmal

res

ervo

ir

456

- A. H

ampe

lB

ench

mar

k C

alcu

latio

ns o

f the

T

herm

o-M

echa

nica

l Beh

avio

r of

R

ock

Sal

t – R

esul

ts fr

om a

US

-G

erm

an J

oint

Pro

ject

240

- M

.D. S

herp

aT

he E

ffect

of J

oint

Fre

quen

cy o

n a

Dis

cont

inuo

us R

ock

Mas

s un

der

Exp

erim

enta

l Com

pres

sive

Tes

ting

Con

ditio

ns

4:45

-5:0

0pm

556

- S

. Hol

Cre

ep b

ehav

ior

of c

oal a

nd s

hale

re

late

d to

ads

orpt

ion

of r

eser

voir

fluid

s

166

- L.

P. F

rash

Exp

erim

enta

tion

with

Hyd

raul

ic

Impu

lse

Stim

ulat

ion

in a

Sca

led

Enh

ance

d G

eoth

erm

al S

yste

ms

Res

ervo

ir

370

- J.

Gua

dalu

pe A

rgüe

lloR

evis

iting

the

1980

’s W

IPP

Roo

m D

an

d B

In-S

itu E

xper

imen

ts:

Per

form

ing

The

rmo-

Mec

hani

cal

Sim

ulat

ions

of R

ock

Sal

t Usi

ng a

S

tate

-of-

the-

Art

Cod

e S

uite

265

- A. F

erra

riV

olum

etric

beh

avio

r an

d co

nsol

idat

ion

of s

hale

s at

hig

h co

nfin

ing

stre

sses

5:00

-5:1

5pm

404

- M

.H. T

ran

Inco

rpor

atin

g th

e E

lect

roki

netic

E

ffect

s in

to th

e P

oroe

last

ic W

ellb

ore

and

Cyl

inde

r P

robl

em fo

r A

pplic

atio

ns in

Sha

le D

rillin

g an

d C

hara

cter

izat

ion

222

- F.

H. C

orne

tS

eism

ic a

nd a

seis

mic

mot

ions

ge

nera

ted

by la

rge

scal

e flu

id

inje

ctio

ns in

a d

eep

gran

ite m

assi

f

303

- K

.D. M

elle

gard

Hig

h-te

mpe

ratu

re c

hara

cter

izat

ion

of

bedd

ed P

erm

ian

salt

296

- Y

i Che

ngE

volu

tion

of E

n-ec

helo

n F

law

s to

a

She

ar R

uptu

re in

Mou

lded

Gyp

sum

un

der

Uni

axia

l Com

pres

sion

5:15

-5:3

0pm

575

- J.

Hw

ang

A 3

-Dim

ensi

onal

Fra

ctur

e P

ropa

gatio

n M

odel

for

Long

-Ter

m

Wat

er In

ject

ion

249

- Y.

Pol

sky

Dev

elop

men

t of a

Neu

tron

Diff

ract

ion-

Bas

ed S

trai

n M

easu

rem

ent

Cap

abili

ty fo

r T

riaxi

al L

oadi

ng

Con

ditio

ns

327

- C

. Mis

sal

Und

ergr

ound

Infr

astr

uctu

re R

oom

s in

Squ

eezi

ng R

ock

– G

eote

chni

cal

Con

ditio

ns in

the

Kon

rad

Min

e du

ring

the

Con

vers

ion

to a

Rep

osito

ry fo

r R

adio

activ

e W

aste

503

- E

. Gha

zvin

ian

The

effe

ct o

f ani

sotr

opy

on c

rack

da

mag

e th

resh

olds

in b

rittle

roc

ks

5:30

-5:4

5pm

436

- G

haza

l Iza

diT

he In

fluen

ce o

f The

rmal

- H

ydra

ulic

- M

echa

nica

l- an

d C

hem

ical

Effe

cts

on th

e E

volu

tion

of P

erm

eabi

lity,

S

eism

icity

and

Hea

t Pro

duct

ion

in

Geo

ther

mal

Res

ervo

irs

608

- D

. Dem

psey

Mod

elin

g S

hear

Stim

ulat

ion

of th

e E

GS

Wel

l Des

ert P

eak

27-

15 U

sing

a

Cou

pled

The

rmal

-Hyd

rolo

gica

l-M

echa

nica

l Sim

ulat

or

483

- M

. Sán

chez

Cou

pled

TH

M a

naly

sis

of a

nuc

lear

w

aste

rep

osito

ry in

cry

stal

line

rock

580

- A. A

ydin

Str

ess

indu

ced

elec

tric

fiel

d m

easu

rem

ents

of d

iffer

ent r

ock

litho

logy

usi

ng th

e E

lect

ric P

oten

tial

Sen

sor

5:45

-6:0

0pm

466

- S

.A.B

. Fon

tour

aA

pplic

atio

ns o

f Par

tial F

luid

-m

echa

nica

l Cou

plin

g in

the

Res

ervo

ir G

eom

echa

nics

Sco

pe

279

- S

. Gen

tier

A fl

ow m

odel

of t

he d

eep

geot

herm

al

rese

rvoi

r of

Sou

ltz-s

ous-

For

êts

(Fra

nce)

280

- F

abric

e D

upra

yS

igni

fican

ce o

f roc

k T

HM

par

amet

ers

in g

eolo

gica

l nuc

lear

was

te s

tora

ge

sim

ulat

ion

336

- W

ei L

iuA

naly

sis

of p

hysi

cal a

nd m

echa

nica

l pr

oper

ties

of im

pure

sal

t roc

k

Mon

day,

24

June

201

3


Sess

ion

17Se

ssio

n 18

Sess

ion

19Se

ssio

n 20

Met

ropo

litan

ISt

anfo

rdM

etro

polit

an II

Fran

cisc

an

Tim

eU

ncon

vent

iona

ls I

(pp

100-

102)

Gro

und

Con

trol

I(p

p 10

2-10

5)R

ock

Phys

ics

and

Geo

phys

ics

(pp

105-

107)

Dis

cret

e G

eom

echa

nics

I(p

p 10

8-11

0)

8:00

-8:1

5am

666

- R

. Sua

rez-

Riv

era

Geo

mec

hani

cs C

onsi

dera

tions

for

Hyd

raul

ic F

ract

ure

Pro

duct

ivity

477

- Y.

Luo

Iden

tifyi

ng R

oot C

ause

s fo

r S

ubsi

denc

e ov

er A

band

oned

Coa

l M

ine

– A

Cas

e S

tudy

151

- D

.N. D

ewhu

rst

Mec

hani

cs, P

hysi

cs, C

hem

istr

y an

d S

hale

Roc

k P

rope

rtie

s

320

- G

. Yag

oda-

Bira

nR

espo

nse

spec

tra

of s

lend

er

colu

mns

as

obta

ined

with

2D

-DD

A

and

geop

hysi

cal s

ite r

espo

nse

test

s

8:15

-8:3

0am

200

- A.M

. Rio

sS

tres

s S

hado

w E

valu

atio

ns F

or

Chi

cont

epec

– E

valu

atin

g N

ew

Com

plet

ion

Opt

ions

448

- C

.J. S

chm

idS

tabi

lity

eval

uatio

n of

sto

pes

and

pilla

rs a

t MA

X M

ine

and

deve

lopm

ent o

f a S

urpa

c-F

LAC

3D

mod

el-b

uild

ing

tech

niqu

e

343

- S

. Nak

agaw

aLo

w-f

requ

ency

(<

100

Hz)

Dyn

amic

F

ract

ure

Com

plia

nce

Mea

sure

men

t in

the

Labo

rato

ry

362

- R

. Has

him

oto

Sta

bilit

y an

alys

is o

f mas

onry

st

ruct

ures

in A

ngko

r T

hom

,Cam

bodi

a us

ing

elas

to-p

last

ic N

MM

-DD

A w

ith

subl

oadi

ng C

am-c

lay

mod

el

8:30

-8:4

5am

289

- A. C

uiC

ontr

ols

of A

niso

trop

ic In

-situ

Str

ess

and

Per

mea

bilit

y in

Opt

imiz

atio

n of

W

ells

and

Hyd

raul

ic F

ract

ures

for

Unc

onve

ntio

nal R

eser

voirs

: E

xam

ples

from

the

Wes

tern

Can

ada

134

- A.R

. Rai

QA

/QC

and

lear

ning

cur

ve fo

r ce

men

ted

rock

fill

at th

e T

urqu

oise

R

idge

Joi

nt V

entu

re, N

evad

a

405

- M

.K. C

hoi

Rel

atio

nshi

p be

twee

n S

hear

and

N

orm

al S

tiffn

ess

for

a F

ract

ure

Sub

ject

ed to

Mix

ed-M

ode

Load

ing

416

- R

oozb

eh G

erai

li M

ikol

aE

xplic

it T

hree

Dim

ensi

onal

D

isco

ntin

uous

Def

orm

atio

n A

naly

sis

for

Blo

cky

Sys

tem

8:45

-9:0

0am

140

- L.

A. M

atza

rU

nder

stan

ding

Sha

le F

ailu

re fr

om

Labo

rato

ry A

naly

sis

to F

ield

O

pera

tions

138

- P.

B. H

ughe

sC

emen

ted

past

e ba

ckfil

l at

Stil

lwat

er

Min

e, M

onta

na

541

- M

. Pet

ružá

lek

The

ani

sotr

opy

of u

ltras

onic

wav

es

velo

city

and

atte

nuat

ion

of m

igm

atite

sa

mpl

es u

nder

uni

axia

l loa

ding

489

- T.

Sas

aki

Num

eric

al s

tabi

lity

on r

ock

fall

prob

lem

s by

3-D

DD

A

9:00

-9:1

5am

312

- M

ehdi

Mok

htar

iF

ailu

re B

ehav

ior

of A

niso

trop

ic

Sha

les

118

- N

. Mav

ong

Slo

pe M

onito

ring

of L

arge

Sca

le

Exp

erim

ent o

f Und

ercu

t Slo

pe a

t M

ae M

oh M

ine,

Tha

iland

614

- C

.S. S

herm

anE

last

odyn

amic

Sim

ulat

ion

of T

unne

l D

etec

tion

Exp

erim

ents

in

Het

erog

eneo

us G

eolo

gica

l Med

ia

492

- S

. Mik

iA

pplic

atio

n of

NM

M-D

DA

to

eart

hqua

ke in

duce

d sl

ope

failu

re a

nd

land

slid

e

9:15

-9:3

0am

578

- P

riyav

rat S

hukl

aN

anoi

nden

tatio

n S

tudi

es o

n S

hale

s13

0 -

Sae

edeh

Rez

aei

App

licat

ion

of C

lose

Ran

ge

Pho

togr

amm

etry

to M

onito

r D

ispl

acem

ents

in O

pen

Pit

Min

es

676

- N

. Guy

Influ

ence

of S

AG

D p

roce

ss o

n se

ism

ic v

eloc

ities

498

- Y

uan

Wan

gE

nerg

y-W

ork-

Bas

ed C

onfin

ed-

Unc

onfin

ed S

eepa

ge M

odel

ing

Usi

ng

Num

eric

al M

anifo

ld M

etho

d

Tues

day,

25

June

201

3tueSDay teChniCal prOgram


Sess

ion

21Se

ssio

n 22

Sess

ion

23Se

ssio

n 24

Met

ropo

litan

ISt

anfo

rdM

etro

polit

an II

Fran

cisc

an

Tim

eFr

actu

re M

echa

nics

I(p

p 11

1-11

3)G

roun

d C

ontr

ol II

(pp

114-

115)

Roc

k H

eter

ogen

eity

and

Sca

ling

(pp

116-

118)

Dis

cret

e G

eom

echa

nics

II(p

p 11

9-12

1)

11:0

0-11

:15a

m

252

- D

. Chu

prak

ovIn

ject

ion-

sens

itive

mec

hani

cs o

f hy

drau

lic fr

actu

re in

tera

ctio

n w

ith

disc

ontin

uitie

s

642

- A.G

. Tho

mps

onC

ase

stud

ies

of r

ock

rein

forc

emen

t co

mpo

nent

s an

d sy

stem

s te

stin

g

678

- A.E

. Rod

rigue

z-H

erre

raF

ield

-sca

le g

eom

echa

nica

l ch

arac

teriz

atio

n of

the

Hay

nesv

ille

Sha

le

269

- G

en-h

ua S

hiB

asic

Equ

atio

ns o

f Tw

o D

imen

sion

al

and

Thr

ee D

imen

sion

al C

onta

cts

11:1

5-11

:30a

m

700

- Q

. Gan

Bre

akdo

wn

pres

sure

s du

e to

in

filtr

atio

n an

d ex

clus

ion

in fi

nite

le

ngth

bor

ehol

es

689

- S

. Bal

lant

yne

Dev

elop

men

ts in

Em

piric

al

App

roac

hes

to M

inin

g in

Fro

zen

Roc

k M

ass

261

- M

. Che

rtov

On

the

Lim

itatio

ns o

f Effe

ctiv

e M

ediu

m A

ppro

ache

s fo

r E

stim

atin

g F

ract

ure

Wid

th in

Ani

sotr

opic

Roc

ks

168

- A. T

arok

hR

elat

ions

hip

betw

een

grai

n si

ze a

nd

frac

ture

pro

pert

ies

of r

ock

11:3

0-11

:45a

m

153

- N

. Ray

soni

Und

erst

andi

ng G

eoch

emic

al

Inte

ract

ion

of P

ropp

ant-

For

mat

ion

for

Impr

oved

Con

duct

ivity

of H

ydra

ulic

F

ract

ures

135

- L.

A. S

andb

akS

hotc

rete

Str

engt

h Te

stin

g at

the

Tur

quoi

se R

idge

Joi

nt V

entu

re,

Nev

ada

366

- J.

Sch

iebe

rTe

xtur

al a

nd C

ompo

sitio

nal

Het

erog

enei

ty o

f Tig

ht S

hale

s at

the

Mic

ro-S

cale

388

- W

. Min

kley

Dis

cont

inuu

m-m

echa

nica

l beh

avio

ur

of s

alt r

ocks

and

the

prac

tical

re

leva

nce

for

the

inte

grity

of s

alin

ar

barr

iers

11:4

5-12

:00p

m

403

- Y

i Yan

gC

ompa

rison

of B

rittle

ness

Indi

ces

in

Org

anic

-ric

h S

hale

For

mat

ions

563

- S

.A.R

. Ken

eti

Dev

elop

ing

an A

ppro

ach

for

Rel

iabi

lity

Ana

lysi

s of

Ben

ch F

ace

Ang

le D

esig

n in

Ope

n P

its w

ith

Str

uctu

rally

Con

trol

led

Slid

ing

Fai

lure

656

- J.

W. C

olov

osR

educ

tion

of m

acro

scal

e ca

libra

tion

expe

rimen

ts th

roug

h co

nstr

aint

s on

an

isot

ropi

c el

astic

stif

fnes

ses

583

- P.

Ham

diN

umer

ical

sim

ulat

ion

of d

amag

e du

ring

labo

rato

ry te

stin

g on

roc

k us

ing

a 3D

-FE

M/D

EM

app

roac

h

12:0

0-12

:15p

m

659

- M

ichi

haru

Hiy

ama

Dis

tinct

ele

men

t ana

lysi

s fo

r hy

drau

lic fr

actu

ring

in s

hale

- E

ffect

of

brit

tlene

ss o

n th

e fr

actu

re

prop

agat

ion

653

- S. H

olM

icro

frac

turin

g of

coa

l rel

ated

to

adso

rptio

n-in

duce

d sw

ellin

g an

d m

atrix

-sca

le h

eter

ogen

eity

673

- W

.C. L

iuN

umer

ical

inve

stig

atio

n of

cra

ck

prop

agat

ion

and

failu

re m

echa

nism

of

laye

red

rock

s

12:1

5-12

:30p

m

254

- G

. Hoc

king

Com

paris

ons

of P

lane

Pro

paga

tion

from

Dila

ting

Cas

ing

and

Con

vent

iona

l Per

fora

tions

whe

n S

timul

atin

g th

e M

ilk R

iver

For

mat

ion

630

- S

.M. E

zzed

ine

Enh

anci

ng H

eat E

xtra

ctio

n an

d M

inim

izin

g W

ater

Los

ses

by

Dep

loyi

ng S

ilica

Gel

in E

nhan

ced

Geo

ther

mal

Sys

tem

s

600

- M

.F. G

eorg

eB

lock

The

ory

App

licat

ion

to U

nlin

ed

Roc

k S

pillw

ay E

rodi

bilit

y A

sses

smen

t

Tues

day,

25

June

201

3


Sess

ion

25Se

ssio

n 26

Sess

ion

27Se

ssio

n 28

Met

ropo

litan

ISt

anfo

rdM

etro

polit

an II

Fran

cisc

an

Tim

ePo

re P

ress

ure

and

Stre

ss(p

p 12

2-12

4)C

oal M

ine

Roc

k M

echa

nics

(pp

125-

127)

Aco

ustic

Em

issi

ons

(pp

128-

130)

Roc

k M

ass

Cha

ract

eriz

atio

n an

d G

roun

d Im

prov

emen

t(p

p 13

1-13

2)

2:00

-2:1

5pm

527

- Z.R

. Nag

yIte

rativ

e 3D

geo

mec

hani

cal m

odel

ing

to d

eter

min

e di

strib

utio

n an

d im

pact

of

str

esse

s in

dee

pwat

er G

ulf o

f M

exic

o su

bsal

t and

nea

r-sa

lt en

viro

nmen

ts

183

- K

. Han

naG

eote

chni

cal-G

eoph

ysic

al V

oid

Map

ping

and

Foa

med

-San

d B

ackf

illin

g of

the

Rap

son

Coa

l Min

e,

Col

orad

o S

prin

gs, C

olor

ado

- C

ase

Stu

dy

295

- K

. Mas

uda

Ultr

ason

ic T

rans

mis

sion

and

A

cous

tic E

mis

sion

Mon

itorin

g of

In

ject

ion-

Indu

ced

Fra

ctur

e P

roce

sses

in R

ock

Sam

ples

284

- Ja

lale

ddin

Yag

hoob

i Raf

iT

heor

etic

al A

ppro

ache

s in

Gro

utin

g F

ract

ures

of t

he R

ock

Mas

s:

The

orie

s an

d A

pplic

atio

ns

2:15

-2:3

0pm

729

- J.

M. R

ance

Pre

dict

ing

the

Pal

eo E

volu

tion

of

Ove

rpre

ssur

ed G

eolo

gica

l Str

uctu

res

154

- G

.S. E

ster

huiz

enP

ract

ical

est

imat

ion

of r

ock

prop

ertie

s fo

r m

odel

ing

bedd

ed c

oal

min

e st

rata

usi

ng th

e C

oal M

ine

Roo

f R

atin

g

400

- S

.D. G

oodf

ello

wA

naly

sis

of c

ontin

uous

Aco

ustic

E

mis

sion

wav

efor

m r

ecor

ds fr

om

rock

frac

turin

g ex

perim

ents

449

- M

ashu

qur

Rah

man

In-li

ne u

ltras

ound

bas

ed r

heol

ogy

- A

new

tool

for

the

mea

sure

men

t of

flow

and

rhe

olog

ical

pro

pert

ies

of

cem

ent b

ased

gro

ut

2:30

-2:4

5pm

302

- A.W

. Cha

nA

n A

ltern

ativ

e In

terp

reta

tion

of

Leak

off a

nd L

ost C

ircul

atio

n P

ress

ure

Mea

sure

men

ts

443

- B

. Qiu

App

licat

ions

of S

ubsu

rfac

e S

ubsi

denc

e T

heor

ies

to G

roun

d C

ontr

ol in

Coa

l Min

es

664

- S

. Sta

nchi

tsM

onito

ring

the

Ear

ly O

nset

of

Hyd

raul

ic F

ract

ure

Initi

atio

n by

A

cous

tic E

mis

sion

and

Vol

umet

ric

Def

orm

atio

n M

easu

rem

ents

514

- I.

Olo

fsso

nH

ydra

ulic

cha

ract

eriz

atio

n an

d gr

outin

g of

twin

par

alle

l tun

nels

at

Äsp

ö H

ard

Roc

k La

bora

tory

, Sw

eden

2:45

-3:0

0pm

545

- P.

Bau

tman

sW

irelin

e st

ress

test

ing

in r

eser

voir

sand

s -

som

e ge

omec

hani

cal

cons

ider

atio

ns a

nd a

cas

e fr

om th

e N

orw

egia

n co

ntin

enta

l she

lf

734

- J.

L. P

orat

hur

Ext

ract

ion

Des

ign

for

Mul

tiple

Sea

ms

Hig

hwal

l Min

ing

in In

dia

– A

Cas

e E

xam

ple

586

- A. D

aman

iA

cous

tic M

appi

ng a

nd M

icro

scop

ic

Ana

lysi

s of

Lab

orat

ory

Indu

ced

Hyd

raul

ic F

ract

ures

und

er T

riaxi

al

Str

ess

Con

ditio

ns

672

- E

. Hoe

kQ

uant

ifica

tion

of th

e G

eolo

gica

l S

tren

gth

Inde

x ch

art

3:00

-3:1

5pm

308

- T.

P. M

anno

nR

evis

iting

Wel

l Des

ign

and

For

mat

ion

Pre

ssur

e P

redi

ctio

n: C

ase

Stu

dy fr

om G

ulf o

f Mex

ico

105

- V

.K. S

ingh

Geo

tech

nica

l Stu

dy o

f Coa

l Rib

F

ailu

re a

t Ana

nta

Coa

l Min

e, O

rissa

, In

dia

298

- A. H

eday

atM

ulti-

mod

al m

onito

ring

of s

lip a

long

fr

ictio

nal

disc

ontin

uitie

s

597

- D

avid

L. K

nott

Som

e In

tere

stin

g M

ine

Sta

biliz

atio

n P

roje

cts

in A

ustr

alia

3:15

-3:3

0pm

121

- V

. Dok

hani

The

Effe

ct o

f Bed

ding

Pla

ne

Orie

ntat

ion

on P

ore

Pre

ssur

e in

S

hale

For

mat

ions

: Lab

orat

ory

Test

ing

and

Mat

hem

atic

al M

odel

ing

605

- A. M

ajdi

App

licat

ion

of a

rtifi

cial

neu

ral

netw

orks

for

pred

ictin

g th

e he

ight

of

dest

ress

ed z

one

abov

e th

e m

ined

pa

nel i

n lo

ngw

all c

oal m

inin

g

639

- P.

A. S

elva

dura

iE

xper

imen

tal e

vide

nce

of

mic

rom

echa

nica

l pro

cess

es th

at

cont

rol l

ocal

izat

ion

of s

hear

rup

ture

nu

clea

tion

186

- N

umer

ical

mod

elin

g of

str

ain

tran

sfer

from

roc

k m

ass

to a

fibr

e op

tic s

enso

r in

stal

led

insi

de a

gr

oute

d bo

reho

le

Tues

day,

25

June

201

3


Sess

ion

29Se

ssio

n 30

Sess

ion

31Se

ssio

n 32

Met

ropo

litan

ISt

anfo

rdM

etro

polit

an II

Fran

cisc

an

Tim

eEx

perim

enta

lR

ock

Mec

hani

cs II

- Sa

nd(p

p 15

8-16

0)

Cou

pled

Pro

cess

II(p

p 16

0-16

2)G

eom

echa

nica

l Cha

lleng

es A

ssoc

iate

d w

ith

Geo

ther

mal

Dril

ling,

Stim

ulat

ion

&

Prod

uctio

n II

(pp

163-

165)

Tunn

els

and

Cav

erns

I(p

p 16

5-16

7)

4:30

-4:4

5pm

473

- A. T

orab

iE

ffect

of i

nitia

l gra

in s

ize

and

pack

ing

on th

e ev

olut

ion

of e

last

ic p

rope

rtie

s of

poo

rly li

thifi

ed s

ands

tone

s

631

- K

oohm

areh

Hos

sein

iIn

clus

ion

of G

eom

echa

nics

in

Str

eam

line

Sim

ulat

ion

for

H

ydro

mec

hani

cal M

odel

ing

of

Und

ergr

ound

CO

2 S

tora

ge

307

- J.

Rut

qvis

tM

odel

ing

and

Mon

itorin

g of

Dee

p In

ject

ion

at th

e N

orth

wes

t Gey

sers

E

GS

Dem

onst

ratio

n, C

alifo

rnia

732

- S

. Kar

ekal

Osc

illat

ing

Dis

c C

uttin

g Te

chni

que

for

Har

d R

ock

Exc

avat

ion

4:45

-5:0

0pm

521

- R

.M. H

olt

Sta

tic a

nd D

ynam

ic M

odul

i – s

o eq

ual,

and

yet s

o di

ffere

nt

124

- Y

anhu

i Han

Num

eric

al M

odel

ing

of P

ore

Flu

id

Pre

ssur

e D

iffus

ion

Thr

ough

Hol

low

C

ylin

dric

al R

ock

Sam

ple

484

- T

rent

on T

. Cla

douh

osIm

prov

ing

geot

herm

al P

roje

ct

Eco

nom

ics

with

Mul

ti-zo

ne

Stim

ulat

ion:

Res

ults

from

the

New

berr

y V

olca

no E

GS

D

emon

stra

tion

144

- D

. Mar

cic

Inve

stig

atio

n, D

esig

n an

d C

onst

ruct

ion

in K

arst

5:00

-5:1

5pm

554

- M

.H.H

. Het

tem

aD

esig

n an

d In

terp

reta

tion

of

Labo

rato

ry E

xper

imen

ts to

det

erm

ine

Por

e V

olum

e C

ompr

essi

bilit

y of

S

ands

tone

559

- C

.L. P

etro

vitc

hLa

bora

tory

to F

ield

: Crit

ical

Sca

ling

of S

ingl

e F

ract

ures

507

- G

aute

Grin

dhau

gH

ard

Roc

k D

rillin

g pe

rfor

man

ce

impr

ovem

ent a

s re

sult

of s

yste

mat

ic

appr

oach

for

drill

bit

and

BH

A

sele

ctio

n

558

- J.

P. F

riedm

anD

esig

n an

d A

naly

sis

of M

ine

Adi

t-P

lugs

with

in a

Tai

lings

Sto

rage

Bas

in

5:15

-5:3

0pm

627

- C

.M.M

.S. L

ins

Oed

omet

er te

sts

for

eval

uatio

n of

k0

durin

g ch

emic

al d

isso

lutio

n

435

- A.M

. Raa

enA

not

e on

flui

d dr

iven

nat

ural

fr

actu

res

333

- A. R

iahi

Num

eric

al s

tudy

of t

he in

tera

ctio

n be

twee

n in

ject

ion

and

the

disc

rete

fr

actu

re n

etw

ork

in e

nhan

ced

geot

herm

al r

eser

voirs

389

- A. P

udew

ills

Sim

ulat

ion

of th

erm

o-m

echa

nica

l be

havi

our

of r

ock

salt

in th

e vi

cini

ty

of a

dis

posa

l drif

t and

the

inte

ract

ion

with

tech

nica

l bar

riers

5:30

-5:4

5pm

170

- X

. Ma

Fai

lure

cha

ract

eris

tics

of a

qua

rtz-

rich,

hig

h-po

rosi

ty s

ands

tone

su

bjec

ted

to tr

ue tr

iaxi

al te

stin

g

409

- L.

H. R

ibei

roA

Thr

ee-D

imen

sion

al C

ompo

sitio

nal

Mod

el fo

r H

ydra

ulic

Fra

ctur

ing

with

E

nerg

ized

Flu

ids

517

- Y. G

uglie

lmi

Rel

atio

nshi

ps b

etw

een

slow

slip

, se

ism

icity

and

flui

ds le

akag

e du

ring

a pr

essu

rized

faul

t zon

e ru

ptur

e in

si

tu e

xper

imen

t: Im

port

ance

for

rese

rvoi

r/ca

proc

k st

imul

atio

n

152

- S

.S. L

imC

ore

disk

ing

obse

rvat

ions

and

in-s

itu

stre

ss m

agni

tude

s

5:45

-6:0

0pm

205

- B

. Akb

ari

Effe

ct o

f Roc

k P

ore

Pre

ssur

e on

M

echa

nica

l Spe

cific

Ene

rgy

of R

ock

Cut

ting

Usi

ng S

ingl

e P

DC

Cut

ter

442

- R

. San

aee

Str

ess

effe

cts

on fl

ow p

artit

ioni

ng in

fr

actu

red

rese

rvoi

rs: e

quiv

alen

t po

rous

med

ia v

ersu

s po

ro-e

last

icity

co

uple

d m

odel

ing

386

- B

.M. S

vein

bjor

nsso

nD

rillin

g pe

rfor

man

ce a

nd p

rodu

ctiv

ity

of g

eoth

erm

al w

ells

- C

ase

hist

ory

from

Hen

gill

Geo

ther

mal

Are

a in

Ic

elan

d

288

- A. K

usak

aA

Stu

dy o

f the

Influ

ence

of T

unne

l S

hape

on

Roc

kbur

st P

rone

ness

U

sing

Num

eric

al M

odel

ing

Tues

day,

25

June

201

3


Sess

ion

33Se

ssio

n 34

Sess

ion

35Se

ssio

n 36

Met

ropo

litan

ISt

anfo

rdM

etro

polit

an II

Fran

cisc

an

Tim

eFr

actu

re M

echa

nics

II(p

p 16

8-17

0)Pr

oduc

tion

in W

eak

Roc

k,

Evap

orite

s an

d C

avin

g(p

p 17

0-17

3)

New

Dev

elop

men

ts in

C

ompu

tatio

nal R

ock

Mec

hani

cs(p

p 17

3-17

5)

Dam

s an

d Fo

unda

tions

(pp

176-

178)

8:00

-8:1

5am

199

- F. Z

hang

The

Influ

ence

of F

ract

ure

Net

wor

k C

onne

ctiv

ity o

n H

ydra

ulic

Fra

ctur

e E

ffect

iven

ess

and

Mic

rose

ism

icity

G

ener

atio

n

731

- K

halid

Zak

aG

eote

chni

cal P

it S

lope

Des

ign

for

Bre

wer

y C

reek

Pro

pert

y, Y

ukon

488

- B

. Dam

jana

cV

alid

atio

n of

Lat

tice

App

roac

h fo

r R

ock

Sta

bilit

y P

robl

ems

328

- K

. Han

naE

mer

genc

y S

inkh

ole

Miti

gatio

n an

d V

oid

Inve

stig

atio

n of

Aba

ndon

ed

Rai

lroad

Tun

nel a

long

U.S

. 24,

Te

nnes

see

Pas

s, C

olor

ado

- C

ase

Stu

dy

8:15

-8:3

0am

596

- F.

She

iban

iIm

pact

of F

ract

ure

Hei

ght o

n M

ixed

M

ode

Fra

ctur

e P

ropa

gatio

n: In

sigh

ts

from

3D

Dis

plac

emen

t Dis

cont

inui

ty

Mod

elin

g

207

- H

. Mal

eki

Sta

bilit

y A

naly

ses

of R

epla

cing

B

arrie

r P

illar

s B

etw

een

Sto

pes

with

B

ackf

ill in

Gils

onite

Min

es o

f Uta

h

476

- H

orac

io A

. Flo

rez

Oil

Res

ervo

ir's

Geo

met

ry

Rec

onst

ruct

ion

and

Mes

h G

ener

atio

n by

Usi

ng N

UR

BS

S

urfa

ces

497

- A.A

. Abu

El-E

laR

elia

bilit

y B

ased

Des

ign

of S

hallo

w

Fou

ndat

ions

on

Join

ted

Roc

k M

asse

s us

ing

RQ

D a

nd th

e U

niax

ial

Com

pres

sive

Str

engt

h of

Inta

ct R

ock

8:30

-8:4

5am

460

- V

.V. P

etun

inA

Fin

ite D

iffer

ence

App

roac

h To

M

odel

ing

Geo

mec

hani

cs In

H

ydra

ulic

Fra

ctur

ing

162

- L.

Ols

onT

he 2

-D a

nd 3

-D im

agin

g of

cor

e fo

r fr

actu

re m

appi

ng

224

- J.

H. H

azza

rdA

dvan

ces

in n

umer

ical

mod

elin

g of

m

icro

seis

mic

ity

613

- P.

Sch

lotfe

ldt

New

Par

k B

ridge

, Kic

king

Hor

se

Can

yon;

Pie

r 5

– A

Diff

icul

t F

ound

atio

n on

Roc

k

8:45

-9:0

0am

662

- S

.H. F

alla

hzad

ehE

xper

imen

tal I

nves

tigat

ion

of

Hyd

raul

ic F

ract

urin

g in

Ver

tical

and

H

oriz

onta

l Per

fora

ted

Bor

ehol

es

187

- S

.B. U

mar

Roc

k M

ass

Cha

ract

eriz

atio

n an

d C

once

ptua

l Mod

elin

g of

the

Prin

tzsk

öld

oreb

ody

of th

e M

alm

berg

et M

ine

572

- T.

Kat

saga

Con

tinuo

us M

onito

ring

of S

ynth

etic

S

eism

icity

: Slip

on

Join

ts

415

- Y

anan

Fan

Sus

cept

ibili

ty a

naly

sis

of e

arth

quak

e in

duce

d la

ndsl

ide-

dam

bas

ed o

n G

IS

9:00

-9:1

5am

513

- A.M

. Str

oisz

Fra

ctur

e in

itiat

ion

and

prop

agat

ion

in

rese

rvoi

r ro

cks

unde

r hi

gh in

ject

ion

pres

sure

487

- S

. Rog

ers

Vol

umet

ric F

ract

ure

Inte

nsity

M

easu

rem

ent f

or im

prov

ed r

ock

mas

s ch

arac

teris

atio

n an

d fr

agm

enta

tion

asse

ssm

ent i

n bl

ock

cavi

ng o

pera

tions

706

- N

. Bah

rani

A c

ompa

rison

bet

wee

n 2D

and

3D

bo

nded

-par

ticle

mod

els

for

rock

s

637

- S

.M. E

zzed

ine

Flo

w a

nd tr

ansp

ort o

f fin

es in

dam

s an

d em

bank

men

ts

9:15

-9:3

0am

203

- X

. Gar

cia

Rev

isiti

ng V

ertic

al H

ydra

ulic

Fra

ctur

e P

ropa

gatio

n T

hrou

gh L

ayer

ed

For

mat

ions

– A

Num

eric

al E

valu

atio

n

440

- M

. Mos

tofi

Dril

ling

Res

pons

e of

Impr

egna

ted

Dia

mon

d B

its: A

n E

xper

imen

tal

Inve

stig

atio

n

Wed

nesd

ay, 2

6 Ju

ne 2

013

weDneSDay teChniCal prOgram


Sess

ion

37Se

ssio

n 38

Sess

ion

39Se

ssio

n 40

Met

ropo

litan

ISt

anfo

rdM

etro

polit

an II

Fran

cisc

an

Tim

eR

eser

voir

Geo

mec

hani

cs II

(pp

178-

180)

Tunn

els

and

Cav

erns

II(p

p 18

1-18

3)H

igh

Perf

orm

ance

Com

putin

g:

The

Cha

lleng

e of

Har

ness

ing

HPC

fo

r Roc

k M

echa

nics

(pp

183-

186)

Frac

ture

Sta

tistic

s an

dR

ock

Mas

s M

easu

res

(pp

186-

188)

11:0

0-11

:15a

m

100

- C

. Chu

kwud

ozie

A N

ew M

odel

ing

App

roac

h to

Nat

ural

F

ract

urin

g P

roce

ss

374

- C

. Par

aske

vopo

ulou

A c

ompa

rison

of v

isou

s m

ater

ial

mod

el m

echa

nics

and

bou

ndar

y co

nditi

ons

584

- S

. Joh

nson

Mul

ti-sc

ale

frac

ture

cre

atio

n an

d ne

twor

k ge

nera

tion

durin

g hy

drau

lic

frac

turin

g

501

- C

.K. P

alle

ske

Impa

cts

of li

mite

d da

ta c

olle

ctio

n w

indo

ws

on a

ccur

ate

rock

mas

s si

mul

atio

n us

ing

disc

rete

frac

ture

ne

twor

ks

11:1

5-11

:30a

m

275

- D

.W. L

eeQ

uant

ifyin

g R

eser

voir

Com

pact

ion

in

an U

ncon

solid

ated

Plio

cene

R

eser

voir

Usi

ng T

ime-

Laps

e S

eism

ic, C

ontin

uous

Dow

nhol

e P

ress

ure

Mon

itorin

g, a

nd 3

D F

inite

412

- K

. Kam

emur

aE

ffect

iven

ess

of a

dvan

cing

ho

rizon

tal b

orin

g fo

r th

e tu

nnel

ing

in

the

com

plex

geo

logi

cal f

orm

atio

n

475

- H

orac

io A

. Flo

rez

A m

orta

r m

etho

d ba

sed

on N

UR

BS

fo

r cu

rved

3-D

inte

rfac

es

189

- M

ahdi

Zoo

raba

diS

emi-a

naly

tical

pro

cedu

re fo

r co

nsid

erin

g ro

ughn

ess

effe

ct o

n hy

drau

lic p

rope

rtie

s of

sta

ndar

d JR

C

prof

iles

11:3

0-11

:45a

m

740

- D

.A. T

horn

ton

Pre

dict

ive

Mod

elin

g of

the

Evo

lutio

n of

Fau

lt S

truc

ture

: 3-D

Mod

elin

g an

d C

oupl

ed G

eom

echa

nica

l/Flo

w

Sim

ulat

ion

148

- K

.K. P

anth

iP

re-in

ject

ion

vers

us p

ost-

inje

ctio

n gr

outin

g –

a re

view

of a

cas

e fr

om

the

Him

alay

a

703

- Z

. Lei

Blo

ck C

avin

g In

duce

d In

stab

ility

A

naly

sis

usin

g F

DE

M

381

- P.

M. C

epur

itis

Spa

tial M

odel

ing

of D

isco

ntin

uity

In

tens

ity –

Cha

lleng

es a

nd

Con

side

ratio

ns

11:4

5-12

:00p

m

536

- L.

Gra

nde

Geo

mec

hani

cal,

hydr

aulic

and

se

ism

ic p

rope

rtie

s of

unc

onso

lidat

ed

sedi

men

ts a

nd th

eir

appl

icat

ion

to

shal

low

res

ervo

irs

397

- J.

Oke

Mod

ifica

tion

of th

e S

uppo

rted

Lo

ngitu

dina

l Dis

plac

emen

t Pro

file

for

Tun

nel F

ace

Con

verg

ence

in W

eak

Roc

k

717

- A. V

erde

Effi

cien

t Sol

utio

n of

Lar

ge-S

cale

D

ispl

acem

ent D

isco

ntin

uity

P

robl

ems

usin

g th

e F

ast M

ultip

ole

Met

hod

465

- L.

R. R

icha

rds

Est

imat

ion

of H

oek-

Bro

wn

para

met

er

mi u

sing

Bra

zilia

n te

nsile

test

12:0

0-12

:15p

m

219

- K

. Fis

cher

Fie

ld-s

cale

geo

mec

hani

cal m

odel

ing

of a

n in

tens

ely

faul

ted

gas

rese

rvoi

r

532

- M

. Die

deric

hsU

ltra-

Long

Ter

m G

eom

echa

nics

D

esig

n F

or a

Dee

p G

eolo

gica

l R

epos

itory

in S

edim

enta

ry R

ock

226

- S

.R. S

obol

ikA

naly

zing

the

Effe

ct o

f Lar

ge

Pre

ssur

e C

hang

es o

n th

e O

pera

tiona

l Sta

bilit

y of

Lar

ge-

Dia

met

er C

aver

ns fo

r th

e S

trat

egic

P

etro

leum

Res

erve

322

- T.

Sire

nS

patia

l dis

trib

utio

n of

You

ng's

m

odul

us, P

oiss

on's

rat

io a

nd E

DZ

ar

ound

TB

M a

nd D

&B

tunn

els

in

hard

cry

stal

line

rock

12:1

5-12

:30p

m

461

- M

.A. G

alar

raga

Ana

lytic

al M

odel

of F

ault

Rea

ctiv

atio

n fo

r F

utur

e W

ater

In

ject

ion

in a

Dee

pwat

er T

urbi

dite

s O

il F

ield

, Offs

hore

Bra

zil

352

- P.

H.S

.W. K

ulat

ilake

Tun

nel s

tres

s an

alys

es in

3-D

usi

ng

equi

vale

nt c

ontin

uum

and

di

scon

tinuu

m p

roce

dure

s

363

- T.

Koy

ama

CF

D-D

EM

sim

ulat

ion

for

grou

t in

ject

ion

test

usi

ng p

aral

lel p

late

fr

actu

re

485

- M

.C. v

an d

er P

ouw

Kra

anT

he Im

port

ance

of S

peci

fyin

g R

ockm

ass

Fai

lure

Mec

hani

sms

in

Geo

tech

nica

l Bas

elin

e R

epor

ts

Wed

nesd

ay, 2

6 Ju

ne 2

013


Sess

ion

41Se

ssio

n 42

Sess

ion

43Se

ssio

n 44

Met

ropo

litan

ISt

anfo

rdM

etro

polit

an II

Fran

cisc

an

Tim

eU

ncon

vent

iona

ls II

(pp

189-

191)

Expe

rimen

tal R

ock

Mec

hani

cs II

I -

Nov

el R

ocks

and

Tes

ting

Met

hods

(pp

191-

193)

Unc

erta

inty

Qua

ntifi

catio

n an

d Pa

ram

eter

Est

imat

ion

in

Geo

mec

hani

cs (p

p 19

4-19

6)

Roc

k M

ass

Stre

ngth

and

D

efor

mab

ility

(pp

197-

199)

12:3

0-12

:45p

m

716

- D

. Elm

oA

n in

itial

ass

essm

ent o

f the

impa

ct

of v

aryi

ng p

erf c

lust

er d

esig

n on

hy

drau

lic fr

actu

re e

ffect

iven

ess

251

- A.I.

Orn

ésD

isco

ntin

uum

mod

ellin

g of

vug

gy

carb

onat

e sp

ecim

ens:

impa

ct o

f vu

gs o

n st

reng

th a

nd s

tiffn

ess

291

- T

hom

as W

ick

Par

amet

er E

stim

atio

n fo

r th

e C

oupl

ed B

iot-

Lam

é-N

avie

r P

robl

em

in S

ubsu

rfac

e M

odel

ing

175

- Y

un L

uS

tren

gth

of in

tact

roc

k co

ntai

ning

fla

ws

12:4

5-1:

00pm

173

- Ji

an H

uang

Sim

ulat

ing

geom

echa

nica

l evo

lutio

n of

frac

ture

d sh

ale

rese

rvoi

r us

ing

a po

ro-v

isco

elas

tic c

onst

itutiv

e m

odel

534

- A. B

auer

Impa

ct o

f aci

dizi

ng-in

duce

d w

orm

hole

s in

cha

lk o

n ro

ck s

tren

gth

459-

J. C

onno

r La

ngfo

rdE

valu

atin

g un

cert

aint

y in

inta

ct a

nd

rock

mas

s pa

ram

eter

s fo

r th

e pu

rpos

es o

f rel

iabi

lity

asse

ssm

ent

377

- J.

J. D

ayA

ccou

ntin

g fo

r ro

ckm

ass

stru

ctur

e in

un

derg

roun

d an

d op

en p

it m

ine

desi

gn

1:00

-1:1

5pm

604

- A.M

. How

sC

hara

cter

izat

ion

of a

niso

trop

ic

dyna

mic

mec

hani

cal r

ock

prop

ertie

s in

sha

le g

as p

lays

393

- L.

Zin

smei

ster

Mec

hani

cal e

volu

tion

of a

n al

tere

d lim

esto

ne u

sing

2D

and

3D

dig

ital

imag

e co

rrel

atio

n

462

- J.

Viv

asS

eepa

ge c

hara

cter

izat

ion

in h

igh

rock

slo

pes

usin

g re

mot

e se

nsin

g

561

- J.

R. N

opol

aV

isco

plas

tic b

ehav

ior

of fi

ne-g

rain

ed

geol

ogic

al u

nits

and

its

appl

icab

ility

to

com

pres

sed

gas

cave

rns

1:15

-1:3

0pm

626

- H

. Son

eA

naly

sis

of in

tra-

rese

rvoi

r st

ress

va

riatio

ns in

sha

le g

as r

eser

voirs

ba

sed

on th

e va

riatio

n of

vis

coel

astic

pr

oper

ties

701

- E

. E. K

nigh

tS

plit

Hop

kins

on P

ress

ure

Bar

E

xper

imen

t Sim

ulat

ion

usin

g M

UN

RO

U

550

- A. B

edi

A c

ompa

rison

of B

ayes

ian

tech

niqu

es a

nd n

on-p

roba

bilis

tic

mod

els

in r

ock

engi

neer

ing

desi

gn

601

- D

. Unt

ereg

ger

Dam

age

plas

ticity

mod

el fo

r ro

ck

mas

s

1:30

-1:4

5pm

349

- M

.B. G

eilik

man

Per

mea

bilit

y M

odel

of S

hale

Gas

R

ock

with

Var

iabl

e S

olid

Mas

s

186

- H

. Mas

oum

iA

mod

ified

failu

re c

riter

ion

with

sca

le

effe

ct p

aram

eter

590

- H

. Cru

z-Ji

men

ezB

ayes

ian

Ana

lysi

s of

Ear

thqu

ake

Sei

smol

ogy

Mod

els

Und

er

Unc

erta

inty

182

- P.

Lai

Vis

ual E

nhan

cem

ent o

f 3D

Imag

es

of R

ock

Fac

es fo

r R

ock

Mas

s C

hara

cter

izat

ion

1:45

-2:0

0pm

557

- R

.J. W

alte

rsM

icro

seis

mic

ity a

nd s

urfa

ce

defo

rmat

ion

of a

hea

vy o

il re

serv

oir

unde

rgoi

ng c

yclic

ste

am s

timul

atio

n

391

- Y. P

opov

Con

tinuo

us C

ore

The

rmal

Pro

pert

ies

Mea

sure

men

ts a

nd A

naly

sis

632

- S

.M. E

zzed

ine

Unc

erta

inty

qua

ntifi

catio

n of

TH

MC

pr

oces

ses

in a

stim

ulat

ed fr

actu

re

netw

ork

663

- H

.W. T

irune

hD

isco

ntin

uity

map

ping

usi

ng G

roun

d-B

ased

LiD

AR

: Cas

e st

udy

from

an

open

pit

min

e

Wed

nesd

ay, 2

6 Ju

ne 2

013


teChniCal tOurS

TECHNICAL TOUR 1

Santa Cruz geologySaturday, 22 June; 9:30 am - 6:30 pm$110.00 Lunch included(Limited to 25 persons)

view sandstone intrusions, paleostress indicators, hydrocarbon fronts, dike sill complexes, and carbonate cold seep structures, all along the beautiful santa cruz coastline . J . casey moore, research professor of earth and planetary sciences from the university of california, santa cruz, will lead the viewing of the outcrops .

TECHNICAL TOUR 2

San francisco Bay geologic engineering tour with richard goodmanSunday, 23 June; 8:00 am - 5:00 pm$90.00 Lunch included(Limited to 52 persons)

this technical tour will include selections from the following locations: rock stability problems from historic quarry cuts into telegraph hill; fort point and the golden gate bridge serpentinites; franciscan melange at cliff house and sutro baths; rock slope repair in chert and shale near twin peaks (optional stop at twin peaks if time and weather permit); coastal defenses at pacifica; the devil’s slide and decomposed granite and faulted coastal terraces of montara beach . richard goodman, professor emeritus, university california, berkeley, will lead the tour .

TECHNICAL TOUR 3

the geysers/napa valleyThursday, 27 June; 7:30 a.m. – 6:30 p.m.$140.00 Lunch and Wine Included(Limited to 25 persons)

this tour will feature special technical visit to the geysers, one of the largest geothermal power operations in the world and site of a recent enhanced geothermal demonstration project . the return trip to san francisco will include a stop at a napa winery, the rutherford hill Winery, for local wine tastings and guided tour of the winery property, which includes a walk through spectacular wine-aging caves and a special tasting in the cellar . russ ewy, research scientist at chevron energy technology company and a member of the arma board, and mark Walters, senior geologist with calpine (operator of the geysers), will lead the tour of the geysers .


SpeCial aCtivitieScalifornia dreaming: the very best field trips

SPECIAL ACTIVITY 1alcatraz: “the rock”Sunday, 23 June 2013; 11:30 am – 3:30 pm$69 per person (includes transportation between Westin and dock, ferry ticket, Alcatraz admission ticket, and self-guided cellblock audio tour.

on this tour, you will be “sentenced” to a “short term” on the notorious alcatraz island federal penitentiary . from the san francisco waterfront, you will take a short ferry ride across the chilly waters of the bay to “the rock .” here you will visit the cells once occupied by some of the nation’s most infamous criminals . on this austere wind and fog-ridden island, it is easy to see why few attempts were made to escape into the treacherous bay with its undertows and turbulent waters . an expertly created audio tour contains interviews with former prisoners and guards from “the rock,” providing fascinating insight into prison life in the middle of the san francisco bay . after your “release” from alcatraz, the motorcoach will be standing by to return to the Westin .

SPECIAL ACTIVITY 2lunch at m.y. ChinaMonday, 24 June 2013; Lunchtime$95 per person (includes multi-course, family style authentic Chinese lunch)

see, taste and discover authentic, modern day chinese cuisine in the heart of downtown san francisco on the fourth floor of the dynamic Westfield center . inspired by years of experience traveling through china, this newest star, in a city filled with stars, brings back the best ingredients, flavors and techniques . Watch the chefs in action as they prepare every dish in front of your eyes . see world champion noodle dancers pull giant balls of dough into thousands of thin noodles in minutes using only their bare hands . even the dim sum is delicately hand-folded . ancient chinese tradition is brought to life and interpreted in a thoroughly modern way at this treasure . as he has done for over 30 years, celebrity chef martin yan (over 3,500 culinary tv shows and 30 cookbooks) shares the best of what he loves from traveling, cooking, and eating in china through a unique, multi-sensory dining experience . chef yan aspires to excite american palates and ignite a passion for chinese culture and tradition, integrating elements from his extensive travels through china into his newest restaurant, m .y . china . your lunch at this fun and approachable restaurant becomes an interactive experience, through the engaging, charismatic qualities of the renowned, global icon chef and extraordinary cuisine .


SPECIAL ACTIVITY 3San francisco highlightsTuesday, 25 June 2013; 9:00 am – 1:00 pm$58 per person (includes transportation and tour guide)

the forty nine square miles of san francisco are a colorful tapestry of steep hills, picturesque houses, clanging cable cars, fishing boats, summer fog, chinese pagodas, cosmopolitan cafés and breathtaking views . five continents and three centuries blend together on forty-three hills, waiting to be discovered . on this tour, you will see some of the legendary landmarks of “everybody’s favorite city .”

SPECIAL ACTIVITY 4an evening at “Beach Blanket Babylon”Wednesday, 26 June 26, 2013$80 per person (includes transportation, balcony seats, 25 person limit)

on this evening, you will attend the internationally acclaimed phenomenon, “beach blanket babylon .” a modern version of the commedia dell’arte, "beach blanket babylon" has celebrated an unprecedented 35 years and over 11,000 performances on the san francisco stage . this ever changing show is the most visually exciting and entertaining live performance you may ever see . its outrageous sets, props and costumes have become as much a part of san francisco as the golden gate bridge . after the show, the coach will be standing by to return you to the hotel . or you may wish to linger in north beach for a late-night espresso, returning to the hotel later on your own .


aBStraCt taBle Of COntentSSESSIoN 1: experimental rock mechanics i - shale and mudrocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

SESSIoN 2: mine seismicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

SESSIoN 3: co2 sequestration and utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

SESSIoN 4: rock slopes i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

SESSIoN 5: reservoir geomechanics i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

SESSIoN 6: deep mine rock mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

SESSIoN 7: transport and coupled processes in fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

SESSIoN 8: rock slopes ii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

SESSIoN 9: Wellbore stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

SESSIoN 10: numerical modeling in coal mines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

SESSIoN 11: thermal, hydrological, mechanical, chemical and biological influences upon rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

SESSIoN 12: constitutive models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

posters - co2 sequestration and utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

posters - transport and coupled processes in fractures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

posters - thermal, hydrological, mechanical, chemical and biological influences upon rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

posters - experimental rock mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

posters - Wellbore stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

posters - pore pressure and stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

posters - reservoir geomechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

posters - rock slopes iii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

posters - in situ stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

posters - grouting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

posters - rock testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

SESSIoN 13: coupled process models i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

SESSIoN 14: geomechanical challenges associated with geothermal drilling, stimulation and production i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

SESSIoN 15: geologic repository issues for nuclear Waste disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

SESSIoN 16: laboratory-scale rock mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

SESSIoN 17: unconventionals i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

SESSIoN 18: ground control i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

SESSIoN 19: rock physics and geophysics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

SESSIoN 20: discrete geomechanics i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

SESSIoN 21: fracture mechanics i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

SESSIoN 22: ground control ii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

SESSIoN 23: rock heterogeneity and scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116


SESSIoN 24: discrete geomechanics ii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

SESSIoN 25: pore pressure and stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

SESSIoN 26: coal mine rock mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

SESSIoN 27: acoustic emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

SESSIoN 28: rock mass characterization and ground improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

posters - geomechanical challenges associated with geothermal drilling, stimulation and production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

posters - new developments in computational rock mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

posters - uncertainty Quantification and parameter estimation in geomechanics . . . . . . . . . . . . . . . . . 136

posters - rock physics and geophysics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

posters - rock heterogeneity and scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

posters - mining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

posters - coupled process models iii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

posters - fracture mechanics and modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

posters - unconventionals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

posters - constitutive models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

posters - rock mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

posters - tunnels/caverns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

posters - laboratory-scale rock mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

SESSIoN 29: experimental rock mechanics ii - sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

SESSIoN 30: coupled process models ii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

SESSIoN 31: geomechanical challenges associated with geothermal drilling, stimulation and production ii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

SESSIoN 32: tunnels and caverns i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

SESSIoN 33: fracture mechanics ii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

SESSIoN 34: production in Weak rock, evaporites and caving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

SESSIoN 35: new developments in computational rock mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

SESSIoN 36: dams and foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

SESSIoN 37: reservoir geomechanics ii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

SESSIoN 38: tunnels and caverns ii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

SESSIoN 39: high performance computing: the challenge of harnessing hpc for rock mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

SESSIoN 40: fracture statistics and rock mass measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

SESSIoN 41: unconventionals ii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

SESSIoN 42: experimental rock mechanics iii – novel rocks and testing methods . . . . . . . . . . . 191

SESSIoN 43: uncertainty Quantification and parameter estimation in geomechanics . . . . . . . . . . 194

SESSIoN 44: rock mass strength and deformability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

AUThoR INDEx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200


SeSSiOn 1: eXperimental rOCk meChaniCS i - Shale anD muDrOCkMonday, 24 June, 8:00 am – 9:30 amChairs: Antony Mossop, Haiying Huang

ARMA 13-317

experience Using a novel 45 Degree transducer to Develop a General Unconventional Shale Geomechanical ModelMunir Sharf-Aldin and Richard RosenMarathon Oil, Houston, Texas, United StatesSanthosh Narasimhan and Meghana PaiAngleMetaRock Laboratories, Inc., Houston, Texas, United States

solution to the anisotropic stress equation evolved from eaton [6] requires knowledge of horizontal and vertical elastic properties . its application to derive a general well log based acoustic model is facilitated using laboratory acoustic measurements at horizontal, vertical, and 45 degree orientation . however, obtaining 45 degree samples are very difficult due to the fragile nature of laminated, textured, and unconventional shales . instead of using such samples, an acoustic transducer has been developed to measure velocity at 45 degrees; thus only needing simpler to cut vertical and horizontal samples . for the unconventional shales considered, the resulting model is robust and appears to fit a wide range of well data from different formations, fields and basins .

ARMA 13-519

Strength anisotropy of Mancos ShaleFjær, E.SINTEF Petroleum Research, Trondheim, NorwayNorwegian University of Science and Technology, Trondheim, NorwayNes, o.-M.Det norske oljeselskap ASA, Trondheim, Norway

an extensive set of uniaxial and triaxial compression tests was performed on plugs of mancos shale with different orientation relative to the bedding plane to study the strength anisotropy . post failure inspection of the plugs show that the failure planes are to some extent affected by the orientation of the applied stress relative to the bedding planes, especially when the orientation of the bedding planes relative to the applied stress is more or less the same as the expected orientation of the failure planes as derived from the friction angle for shear failure . this indicates that the bedding planes may represent weak planes which tend to fail before intrinsic failure occurs, whenever the orientation of these planes is suitable . the simple “plane of weakness” model can be used to predict strength as function of orientation for such a rock . a comparison of this model to the experimental data shows that the model does pick up some essential features of the experimental observations, but also that the weak planes seem to have an impact on strength even outside the range of orientations where the model predicts such impact . an extension of this model, taking into account that the weakness of the bedding planes may be patchy so that shear sliding may occur prior to failure is found to give better match with data .


ARMA 13-332

Generating Mechanical Stratigraphy in layered Rock Masses Using numerical averaging of cohesive-frictional Strength DeDontney, N., Crawford, B. and Alramahi, B. ExxonMobil Upstream Research Company, Houston, TX, USA

a fundamental question in geomechanical modeling relates to the most accurate and efficient workflow for transforming observed complexity in the earth to a simplified numerical model, with minimal loss of information . this workflow, oftentimes referred to as “upscaling”, is a technique for converting a detailed geologic model to a coarser-grid simulation such that the development of stress and deformation in the two systems are comparable . standard logging tools provide estimates of petrophysical rock properties at a resolution of decimeters, and numerous predictive algorithms have been described that subsequently enable the generation of elastoplastic mechanical properties from such wireline-based petrophysical observations . however, these log-generated mechanical properties can be highly variable over the length scale of a single element in a geomechanical model . the log data must therefore be “upscaled” to mechanical units that are of a tractable size for numerical simulation, and the mechanical properties assigned to these units need to represent the bulk deformation behavior of the heterogeneous material contained within them . to address this question, we examine different techniques for numerically “averaging” observed heterogeneity into a representative value, while restricting ourselves to a “layer cake” geometry . We also identify important length scales in the problem that influence how deformation is distributed amongst, or localized within, mechanical units . using this insight we are able to develop methods to intelligently generate units of mechanical stratigraphy, dependent on the model application, that are based on a distribution of mechanical properties with depth . to help validate the numerical methods used to “average” mechanical properties into an upscaled value, we apply the technique to strength data generated from laboratory testing of layered composite samples . stress and plastic strain development in large-scale geomechanical models that have been mechanically upscaled are compared with equivalent models containing full geologic complexity, and show good agreement .

ARMA 13-419

Using asymmetric yield Surfaces to Model Material anisotropyAkl, S. A.Cairo University – Soil Mechanics and Foundation Research Laboratory, Cairo, EgyptLouis, L.Shell Exploration & Production Company – Projects and Technologies, Houston, Texas, USA

this paper examines the relationship between the anisotropy of granular materials on a microscopic level and its macroscopic mechanical behavior . triaxial lab experiments concluded that the transverse isotropic nature of earth materials leads to asymmetric yield surfaces or limiting curves in the stress space [1-3] . several constitutive models captured these observations by formulating yield surfaces in the shape of distorted ellipses or other similar shapes [4-7] . the anisotropy of granular material from the point of view of material science is the anisotropic alignment of particles [8] . although the anisotropic structure of granular material is the main reason of its asymmetric yield behavior, there is a gap between material science theories and constitutive models of soil plasticity [9] . oda [9] was the first to attempt a combination between the material science approach and the continuum mechanics approaches by using a direct measurement of fabric anisotropy to formulate yield surfaces . this approach provided an asymmetric yield surface similar to that of classical continuum mechanics approaches such as the mit-e3 model [6] . the paper compares both approaches and applies them to the resedimented boston blue clay (rbbc) consolidated up to 10 mpa


to act as an analog material with relatively well known mechanical behavior [10] . the paper used high-resolution x-ray texture goniometry (hrxtg) data from day-stirrat et al . [11] to measure the fabric anisotropy of rbbc . both approaches validated one another and proved that asymmetric yield surfaces are a suitable representation of fabric cross-anisotropy .

ARMA 13-651

laboratory and constitutive Modeling of colorado Shale at high pressure and temperatureMohamadi, M., Gong, x. and Wan, R. G.University of Calgary, Calgary, Alberta, Canada

the thermal extraction of heavy oil from deep oil-sand deposits in alberta, canada represents a challenging geomechanical problem which involves both the reservoir material and the overlying cap-rock . in order to ensure the integrity of the shale cap-rock, it is essential to have a comprehensive understanding of the thermo-hydro-mechanical behavior of the shale . the present study pertains to the triaxial testing of Westgate shale from the colorado group formation which is of marine origin extending over a large area of the Western canada sedimentary basin (Wcsb) . tests were performed at in-situ effective confining pressures and operative temperatures under triaxial compression (tc) and constant mean effective stress (cms) conditions . the lab experimental results were thereafter used to calibrate a constitutive model based on both elastic and failure properties of the tested material . the calibrated constitutive model will be eventually used in a coupled solid-fluid finite element analysis of a boundary value problem .

ARMA 13-338

brittle failure processes in Veined clay Rock with large Strength contrasts between Vein and MatrixAmann, F.Swiss Federal Institute of Technology, Engineering Geology, SwitzerlandKaiser, P.K.Center for Excellence in Mining Innovation, Sudbury, CanadaÜndül, Ö.Engineering Faculty, Geological Engineering Department, Istanbul, Turkey

a series of unconfined and confined compression tests with acoustic emission monitoring and high resolution strain measurements was used in combination with mineralogical and micro-structural analyses to investigate the failure behavior of veined rock with large strength contrast between vein and matrix . the rock type used for this study was a sulfate-rich clay rock from the gipskeuper formation in switzerland, which typically shows a heterogeneous rock fabric consisting of distinct, weak clayey layers (matrix) and stiff anhydrite veins . the study showed that at low deviatoric stress the failure behavior is dominated by the strength of the weak matrix where microcracks are initiated . micro-structural and mineralogical variations were identified as the primary cause of strength and stiffness variations in the weak matrix . upon compressive loading, these heterogeneities may cause stress or strain heterogeneities and, as a consequence, localized failure processes at different strain or stress levels . depending on the orientation, distribution and mass fraction of stiff veins, specimen failure requires high stresses or strains in order to link micro-fractured region either by interface cracks (cracks alongside the interface between matrix and vein) or by cracks which penetrate stiff veins .


SeSSiOn 2: mine SeiSmiCityMonday, 24 June, 8:00 am – 9:30 amChairs: Kim McCarter, Zara Hosseini

ARMA 13-281

expansion, performance, and improvement of the caladay Mines, Wallace, iDDehn, K. K. and Knoll, S.US Silver & Gold, Wallace, ID, USA

seismic activity at the coeur, galena and caladay mines has been ongoing since the late 1950’s . the galena mine has experienced a number of large and damaging events, with at least one major event occurring yearly . a seismic system has been operating at the galena mine for 47 years . as technology improved modern systems replaced older ones . the operation and realtime reporting from the seismic system is highly valued by operations . improved metal prices, increased production, and depletion of reserves have led to mining into new areas, extracting remnant pillars, and reopening of the neighboring coeur and caladay mines . the existing seismic system is being expanded to 84 channels to keep up with mining fronts and to provide improved sensitivity in seismically active work areas . there are a number of challenges in maintaining the system and providing reliable data . aging infrastructure is causing problems for accessing areas for maintenance . the extremely long distances between the sensors and seismic recorders are causing degradation of signals . new network communication is required to establish coverage to the coeur and caladay mines . this paper will address the challenges being encountered, the success of the existing system, and the new expansion .

ARMA 13-450

implementation of a Seismic System at niobec Mine Dorion, Jean-FrançoisNiobec inc., St-Honoré, Québec, Canada hosseini, Zara ESG Solutions, Kingston, Ontario, Canada

the niobec underground niobium mine is located twenty-five kilometres northwest of ville de saguenay (chicoutimi), within the limits of the municipality of saint-honoré, Québec . the mine is north america’s only source of pyrochlore, the primary niobium ore . all of niobec ore is extracted by bulk open stope mining with no fill . a mining throughput rate of 10mtpy is expected with the future block caving method . the life-span of the mine is estimated at about 40 years with the known mineral resource . some seismic events have occurred in the last number of years . most of these events occurred in pillars between open stopes or directly in open stopes . damage from these events has included small rock projections, raveling and fractures . as niobec has no seismic detection system in place, the epicenter location of each event has been difficult to determine . the design of a seismic system was undertaken in the summer of 2012 . niobec will be able to monitor seismic activity for the current open stope mining operator as well as for the future block caving method by strategically placing the equipment in existing openings above any planned undercuts for the progression of the caves .


ARMA 13-661

application of fault Stability analysis techniques for Design of Deep engineering projectsCarter, T.G.Golder Associates, Toronto, Ontario, CanadaValley, B.C.Swiss Federal Institute of Technology, Zurich, Switzerland

because of the potentially problematic conditions created to deep mining or civil projects by adverse fault slip behaviour, assessing what geological structures are under a critical stress state is becoming an increasingly important endeavour . this paper presents common structural geology techniques that are not widely known or regularly applied either for deep civil engineering design or for deep high stress mining, but which can have merit for risk minimization for excavation development . several techniques are explored and guidelines for using fault mapping data and applying stress inversion approaches are presented for advancing understanding of past and current stress state – both of which are key to establishing propensity for slip on geological structures .

ARMA 13-297

induced Seismic force Reduction Using air Deck blasting at Mae Moh Mine, thailandBoonnumma, A. and Leelasukseree, C.Mining Engineering Department, Chiang Mai University, Chiang Mai, Thailand

mae moh mine is one of the deepest open pit mines in southeast asia, currently 300 m below the ground surface . according to its master mine plan, the mine depth will be approximately 500 m by year 2028 . it is located in lampang, 650 km north of bangkok . recently, it produced approximately 15 million tons of lignite and over 90 million m3 of waste a year to serve ten lignite-fired power plants, with total capacity of 2,400 mW . the mine and power plants are operated by a prominent thai state enterprise, electricity generating authority of thailand (egat) . to remove such a huge amount of dense overburden and interburden claystone, drill and blasting techniques have been utilized . the overburden and interburden are fractured and loosen by blasting suitable for the production and also to reduce fuel consumption and wear rate of excavators as well . there is, however, a major unwanted consequence of the blasting technique which is induced seismic force . the induced seismic force would potentially cause environmental impacts . to increase safety of the working environment and contribute to the social responsibility, the mine has lately replaced the conventional blasting technique with air deck blasting . With less amount of explosive usage, the air deck blasting results in less ground vibration with satisfied mine production . the measured peak particle velocity, related to the induced seismic force and the ground vibration, was reduced by 32-69 % . surprisingly, the air deck length recommended at 20% of the explosive charge can reduce the induced seismic force while increasing fragmentation and higher productivity .

ARMA 13-331

an improved and optimized positioning Method of Microseismic Source in MiningQuanjie Zhu, Fuxing Jiang, Yingkui Wu, Yongming Yin and Couxian Shu School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing, China Zhengxing Yu China Academy of Safety Science and Technology, Beijing, China


hongyang JuBeijing Anke Technology Co.,Ltd, Beijing, China

automatically positioning a microseismic source and picking the first arrival are challenging and a focus in microseismic technology research . in order to reduce error caused by artificial picking arrival and speeds in different mediums, a new automatic-picking method is proposed in this paper to process microseismic data with matlab . there are four steps in the method: (1) de-noising and filtering microseismic signals using empirical mode decomposition (emd); (2) picking the first arrival using the traditional sta/lta method with an improvement in the self-adaptive time-window and self-judgement threshold value; (3) after finding the shortest first arrival, source positioning is evaluated with the “four-four” method; (4) after removing abnormal values from the sources positions using cluster analysis with specific dispersion threshold, optimized source positions are obtained by averaging . this method has been validated in the case study of a coal mine in china . compared to other methods, the microseismic sources using this method can be positioned much more efficiently with high precision .

SeSSiOn 3: CO2 SeQueStratiOn anD utilizatiOnMonday, 24 June, 8:00 am – 9:30 amChairs: Laura Chiaramonte, Jonny Rutqvist

ARMA 13-221

a bayesian approach to Mitigate parameter Uncertainty in carbon Dioxide Sequestration Models Sarkarfarshi, M. and Gracie, R. Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada

carbon dioxide capture and sequestration (ccs) is a promising technology to reduce greenhouse gas concentration in atmosphere . risks associated with a carbon dioxide sequestration project are being considered by scientists, politicians and public . high level of uncertainty in mathematical models representing the cs system and physical characterizations of the reservoir is a challenge in obtaining accurate and meaningful risk assessment . site monitoring, provides valuable information about the behavior of ccs systems . however, no strong research has been conducted to integrate the monitoring data and system models in order to reduce the uncertainty in model forecast and risk assessment . in this study, a novel and computationally efficient framework has been developed for reducing parameter uncertainty in ccs models using the feedbacks from monitoring data . the methodology is demonstrated on a hypothetical injection problem in nisku formation, located in alberta, canada . it is shown that parameter uncertainty is mitigated effectively using the proposed methodology . it is shown that model forecast according to calibrated parameters is significantly less uncertain compared to initial estimations, which can result in more confident and meaningful risk assessment and decision making .

ARMA 13-470

hydraulically induced Shear failure during co2 injection into Deep ocean SedimentsLevine, J.S.National Energy Technology Laboratory, Pittsburgh, PA, USAKelkar, S. and Stauffer, P.h.Los Alamos National Laboratory, Los Alamos, NM, USA


carbon dioxide injected into seafloor sediments beneath the 2 .7 km co2/water density inversion in the ocean has the long-term advantage of buoyancy-trapping without the need for an overlying impermeable caprock . however, low permeability deep ocean carbonates require shear failure or fracturing to achieve viable injection rates . cohesion, elastic moduli, and strength of the sediments as well as in situ stress increase with depth below the seafloor, thus stimulation is likely to propagate vertically up to the seafloor . We analyze the effect of hydraulically induced shear failure during co2 injection into deep ocean carbonate sediments using lanl’s finite element heat and mass transfer code (fehm) . fehm models multiphase co2/brine flow while solving for changes in the geomechanical stress state due to overpressure of injected co2 . We implement failure as an increase in permeability due to mohr-coulomb slip . We present initial results for shear failure due to co2 injection into an idealized 3-d domain . the results show shear-induced failure from the injector toward the seafloor ahead of injected co2, approaching the seafloor at 62ktco2 injected, while co2 first leaks from the seafloor back into the ocean at 350 ktco2 injected . to our knowledge, this is the first presentation of 3-d modeling of co2 injection leading to shear failure .

ARMA 13-446

Site-Specific Geomechanical Modeling for predicting Stress changes around Depleted Gas Reservoirs considered for co2 Storage in the netherlandsorlic, B.TNO, Earth, Environmental and Life Sciences, Utrecht, The Netherlands

geomechanical simulations were conducted on a number of site-specific numerical models of depleted gas fields considered for co2 storage in the netherlands . simulations were aimed at assessing the maximum areal extent of stress perturbation around depleted reservoirs at the end of depletion period . simulation results indicate that the extent of stress changes around depleted reservoirs is at least one order of magnitude smaller compared to the extent of stress changes associated with industrial-scale co2 storage in saline aquifers . in the case of small compartmentalized gas reservoirs, a few to ten kilometers long and a few kilometers wide, without aquifer support or without pressure drop in supporting aquifers, the maximum extent of stress changes is limited to a few kilometers . on the other hand, the extent of the area affected by pressure perturbations and, consequently, stress perturbations in the case of co2 storage in saline aquifers is commonly a few tens to hundreds of kilometers away from the injection zone . the magnitude and pattern of induced stress changes around depleted reservoirs depend on many factors including the structural setting, reservoir shape and the geomechanical rock properties of different lithostratigraphic units .

ARMA 13-577

probabilistic Risk assessment of Mechanical Deformation due to co2 injection in a compartmentalized Reservoir Chiaramonte, L., White, J.A. and hao, Y. Lawrence Livermore National Laboratory, Livermore, USA Ringrose, P. Statoil/NTNU, Trondheim, Norway

pressure build-up caused by large-scale co2 injection is one of the key concerns during a carbon sequestration project, for well-known reasons such as the risk to seal integrity, fault stability and induced microseismicity, among others . furthermore, pressure build-up is directly related with storage capacity . in this work we study the geomechanical response to the co2 injection in the tubåen fm at snøhvit . during the first stage of the project co2 was separated from the produced gas and stored underground in the tubåen fm . at approximately 2600 m depth . the tubåen fm . corresponds to a delta plain environment dominated by fluvial distributary channels and some marine-tidal influence . the area is extensively faulted, characterized by a dominant east-west-trending fault system, but with the presence of faults at high angles


to this trend, leading to complex fault interactions . injection into the tubåen formation was limited by reservoir heterogeneities and reservoir compartmentalization, leading to higher than expected pressure rise during operations . this lead to a well intervention operation designed to improve injectivity and a revised injection plan, with injection into a different unit . in the present work we perform a probabilistic assessment of the mechanical deformation caused by the co2 injection and the potential for fault leakage and contamination of the producing interval in the adjacent block . for the majority of the cases, in the range of the evaluated parameters, we found that the increase in pressure due to co2 injection does not pose risk for fault reactivation . however, observed variations in the orientation of the maximum horizontal stress have a high impact on the potential for reactivation of the studied faults .

ARMA 13-617

the influence of caprock initial Damage on its fracturing process during co2 injection into a brine aquiferPan, P.Z., Feng, x.T. and Yan, F.State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, ChinaRutqvist, J.Lawrence Berkeley National Laboratory, Berkeley, USA

a newly developed numerical system, i .e . tough-rdca, is used to study the caprock stability during the injection of co2 into a brine aquifer . We consider different geological layers and different initial damage (single fracture and multiple fractures) in caprocks . our analysis shows that fluid pressure evolution, co2 saturation, fracture opening, propagation and coalescence are strongly dependent on the initial damage and its propagation in caprocks . it is concluded that the initial damage in caprock is very harmful to its stability since the fluid driven by co2 injection will pump into the initial damage or fracture and the fracture tip will propagate due to the fluid pressure application on the fracture surface . as a result, the co2 has a risk to get into the upper rock mass and finally contaminate the groundwater resources .

ARMA 13-255

Geomechanical effects on co2 leakage through fault Zones during large-Scale Underground injectionRinaldi A.P., Rutqvist J., and Jeanne P.Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA, USACappa, F.Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA, USAGeoAzur, University of Nice Sophia-Antipolis, Côte d’Azur Observatory, Nice, France

the importance of geomechanics including the potential for reactivating faults associated with large-scale geologic carbon sequestration operations has recently become more widely recognized . however, not withstanding the potential for triggering notable (felt) seismic events, the potential for buoyancy-driven co2 to reach potable groundwater and the ground surface is more important from safety and storage-efficiency perspectives . in this context, this work extends previous studies on the geomechanical modeling of fault responses during underground carbon dioxide injection, focusing on short-term integrity of the sealing caprock, and hence of potential leakage of either brine or co2 to shallow groundwater aquifers during active injection . We account for a stress/strain-dependent permeability and study the leakage through a fault zone as its permeability changes during a reactivation, also causing seismicity . We analyze several scenarios related to the injected amount of co2 (and hence as a function of the overpressure) both involving minor and major faults, and analyze the profile risks of leakage for different stress/strainpermeability coupling functions . We conclude that whereas it is very difficult to predict how much fault permeability could change upon reactivation, this process can have a significant impact on the leakage rate .


SeSSiOn 4: rOCk SlOpeS iMonday, 24 June, 8:00 am – 9:30 amChairs: Mark Diederichs, Florian Amann

ARMA 13-164

Role of 3D topography in Rock fall trajectories and Model Sensitivity to input parametersMacciotta, R. and Martin, C.D.Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada

rock falls are frequent hazards for railroad corridors cutting through mountainous areas . mitigation of the associated risk depends on estimations of the rock fall spatial distribution, falling block velocity and height when reaching the track or railroad alignment . Where no rock fall event records exist, lack of data makes these estimations extremely uncertain . three dimensional modeling of rock fall trajectories can aid in reducing this uncertainty . however, there are issues related to the reliability of the estimated velocities, heights and event distribution based on models lacking proper calibration . this paper presents a study of the sensitivity to input parameters for a three dimensional, lumped mass, rock fall model along a section of railway through the canadian cordillera . it was found that the spatial distribution of rock fall trajectories is consistent with site records for ranges of the input variables commonly reported in the literature . estimated block heights and velocities showed greater variability . three dimensional analyses can aid in the evaluation of relative hazards along transportation routes, however estimates of falling block height and velocity for protection design requires further model calibration .

ARMA 13-195

a new failure Mode chart for toppling and Sliding with consideration of earthquake inertia forceYagoda – Biran, G. and hatzor, Y.h.Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Be’er-Sheva, Israel

the toppling vs . sliding failure mode chart for a slender block resting on an inclined place and subjected to gravitational loading with the analytical solutions for limiting equilibrium have been published long ago and are currently used routinely in rock slope stability investigations . the failure mode of a block on an incline is a function of three angles: the block angle δ, defining the geometry of the block, the slope inclination angle angle a, and the interface friction angle φ . We generalize here the mode chart to three dimensions . We present a new failure mode chart that incorporates a pseudo-static horizontal force F, simulating the seismic forces that act upon a block during an earthquake . in the new chart, the failure mode of a block is a function of three angles as well, with δ and φ remaining the same, but a new angle is introduced, ψ= a + β, with β being the angle between the resultant of blocks weight and W and F, and the vertical direction, and replaces a . We present 2d and 3d numerical simulations that confirm the analytical basis for the proposed stability and mode chart .


ARMA 13-744

DeM Modeling of Jointed Rock SlopesDonzé, F.V. and harthong, B.Université Joseph Fourier - Grenoble 1 / Grenoble INP / CNRS, Laboratoire 3S-R, Grenoble, France Scholtès, L. Université de Lorraine / ENSG / CNRS / CREGU, Laboratoire GeoRessources, Vandœuvre-lès-Nancy, France

an enhanced version of the discrete element method (dem) has been developed for the analysis of fractured rock masses . in addition to the discrete representation of the intact medium, structural defects can be explicitly taken into account in the modeling to represent pre-existing fractures or joints . besides its intrinsic capability to model fracture initiation and propagation starting from simple interaction laws, the model can simulate brittle behavior characterized by high values of ucs/ts ratio associated with non-linear failure envelopes, as observed for stiff rocks . in the present work, the method is used to study jointed rock slopes where instabilities involve coupled mechanisms related to both deformations along existing discontinuities and brittle fracture of intact rock . in case of complex fracture systems, it is possible to plug discrete fracture networks (dfn) into the model to characterize the mechanical behavior of fractured rock masses by controlling the size distribution of the fractures, their spatial correlation and their intensity .

ARMA 13-258

the application of Vector Sum Method on three-Dimensional Rock Slope Rock Slope Stability analysisMingwei Guo, Shuilin Wang, Conghua Yuan and xiurun GeState Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei, China

based on the vector sum method, a practical rock slope near the bridge is analyzed . different from traditional analysis methods, the vector sum method gives not only the safety factor but also the preferred sliding direction of sliding mass, which facilitates the supporting measures of the slope . moreover, this method is simple in calculating process, and has clear physical meaning . in order to rational assess the stability of rock slope, this proposed method and the finite element strength reduction technique are used in practical rock slope . besides the gravity load of the rock mass, the seismic load is taken into account, and the earthquake load is simply assumed to be a quasi-static load in this paper . the calculating results showed that the safety factor with the proposed method is in good agreement with that with the finite element strength reduction technique . according to the calculating results with both methods above, it can be rationally considered that the factor of safety for this rock slope is about 1 .60 under seismic load .

ARMA 13-314

the Mitchell creek landslide, bc, canada: investigation using Remote Sensing and numerical ModelingClayton, M.A.Simon Fraser University, Burnaby, B.C., Canada; BGC Engineering Inc., Vancouver, B.C., CanadaStead, D.Simon Fraser University, Burnaby, B.C., CanadaKinakin, D.BGC Engineering Inc., Vancouver, B.C., Canada


the mitchell creek landslide, a large rock slope instability, has been identified in the coast mountains of northwestern british columbia, canada during the course of mineral exploration in the area . the instability has been estimated to be 60 mm3 with an annual movement rate of approximately 0 .5 m . toppling and sliding mechanisms have been identified in the slope, and failure surface geometry suggests an active-passive wedge style landslide with a zone of intense rock damage developed in the mid-slope . geotechnical site investigations and remote sensing data have been used to characterize the landslide . geomechanical data and laboratory testing results are summarized . aerial photography dating from 1949 captures the development of visible slope deformation features . a three dimensional zone of failing rock has been delineated using borehole data and surface interpretation from surface mapping and photography . photogrammetry software has been used to create three-dimensional surfaces to track development of the instability . this geometry has been used in preliminary continuum modeling to evaluate the failure mechanisms controlling slope movement .

ARMA 13-378

the effects of earthquakes on Rock Slopes Aydan, Ö.Tokai University, Institute of Oceanic Research and Development, Shizuoka, Japan

many recent earthquakes caused many large scale rock slope failures, some of which are wrongly named as landslides . the scale and the impact of rock slope failures are very large and the form of failure differs depending upon the geological structures of slopes . first the author describes some model set-ups and experiments to investigate the effects of shaking or faulting due to earthquakes on rock slopes . then fundamental characteristics of the rock slope failures induced by the earthquakes are described and evaluated according to some empirical and theoretical models . furthermore, the observations for slope failures in relation to earthquake magnitude and epicenter distance were compared with several empirical relations available in literature . some of major rock slope failures induced by earthquakes are selected and the post-failure motions are simulated and compared with observations . in addition the effects of tsunamis on rock slopes are explained through the recent mega-earthquakes and are discussed .

SeSSiOn 5: reServOir geOmeChaniCS iMonday, 24 June, 11:00 am – 12:30 pmChairs: Gang Han, Yonggui Guo

ARMA 13-304

Sand production initiation criteria and their Validation Papamichos, E. Aristotle University of Thessaloniki, Greece and SINTEF Petroleum Research, Trondheim, Norway Furui, K. ConocoPhillips, Stavanger, Norway

the paper investigates the capability of a simplified mohr-coulomb (mc) analytical model to predict satisfactorily fully anisotropic loading experimental results on hole failure, as well as numerical predictions from several parametric analyses of field cases based on a 3d non-linear fem borehole and perforation failure analysis model (sand3d), which employs the critical plastic strain failure criterion coupled with a drucker-prager failure surface . the comparisons with the experimental data and the field simulations demonstrate that the mc model is insufficient for satisfactory predictions under anisotropic loadings . a drucker-prager type model is advanced and shows significantly improved analytical predictions under any


loading condition . two field case comparison examples show that the developed analytical sand production initiation model accounts for the effect of intermediate stress and gives good matches to the formation failure envelopes predicted by the numerical model .

ARMA 13-163

Development and calibrations of a coupled Reservoir Geomechanic Model for Valhall field Gang han, Ben Vaughn, Andrew Davids, and John Spokes Hess Corporation, Houston/Stavanger, USA/Norway Robert Newman and Jose AdachiSchlumberger, Bracknell/Houston, UK/USA

it is well known that the valhall field in the norwegian north sea has experienced significant seafloor subsidence due to compaction in the chalk reservoir . this paper documents the development of a new coupled reservoir geomechanical model to help understand the dynamic changes in the reservoir and the overburden, and to improve history-matching, reserve estimation, and production forecast . With 1 .3 million grid cells and 56 layers in the geomechanical model, different coupling schemes have been investigated and compared to recommend the most effective approach . the model is calibrated using multiple sources: seafloor subsidence from gps and bathymetry, reservoir compaction data from 4d seismic, pore pressure and stress measurement over time, individual well geomechanical models, history of bottom hole flowing pressure, and production of oil, water, and gas from wells and the field . While it confirms that the depletion has significantly reduced horizontal and vertical stresses in the reservoir and some of the overburden, local stress arching and increased horizontal stress anisotropy are observed as well . the majority of plastic deformation occurs in the reservoir, while fault reactivation is widespread in the overburden . compaction in the reservoir can lead to major reductions in vertical and horizontal permeability while localized injection may only recover a portion of the original permeability . history-matching therefore needs be performed in a manner consistent with the rock deformation in each reservoir layer, emphasizing the importance of integrating reservoir simulation with a geomechanical model for the valhall field .

ARMA 13-300

field Scale Geomechanical Modeling for prediction of fault Stability during Underground Gas Storage operations in a Depleted Gas field in the netherlandsorlic, B., Wassing, B.B.T. and Geel, C.R.TNO, Earth, Environmental and Life Sciences, Utrecht, The Netherlands

a geomechanical modeling study was conducted to investigate stability of major faults during past gas production and future underground gas storage operations in a depleted gas field in the netherlands . the field experienced induced seismicity during gas production, which was most likely caused by the reactivation of an internal central fault separating the two major reservoir blocks . a 3d field scale geomechanical finite element model of the gas field was developed with realistic representation of the structural geology and juxtaposition of various lithologies across the central fault . the model was calibrated to match the subsidence data and the approximate location of the critically stressed, reactivated part of the fault in agreement with the seismological localization of the hypocenters of the past major seismic events . the model predicted a maximum shear slip of up to 2 cm associated with gas production . additional, but a smaller, fault slip of up to 0 .5 cm could be expected during the subsequent phase of cushion gas injection . during annual cycles of gas injection and production, the central fault is not critically stressed and the predicted stress changes lie in the elastic region . although the fault slip is unlikely, continuous monitoring of induced seismicity is essential .


ARMA 13-427

Discrete element Modeling of fault Mechanics and permeability evolution for Gas production and Storage: effect of Shale content and Distribution Terheege, J.h. and hoedeman, G.C. TNO, Geological Survey of the Netherlands, Utrecht, The Netherlands

the presence of clay in fault zones has a dramatic effect on both fault mechanics and permeability . Quantification of this effect relies on small scale laboratory experiments or indirect observations from hydrocarbon fields, for which systematic variation of clay content, clay distribution, and deformation conditions can be problematic . two-dimensional discrete element models of fault zones were deformed in simple shear to assess the effect of shale on failure criteria and sealing capacity using a systematic series of model simulations . comparison between the evolution of shear stress and development of microcracks shows that changes in shear stress are correlated with alignment of microcracks, resulting in fractures with similar orientations as R- and Y-shears that can accommodate local deformation . both shale content and distribution have a marked effect on the failure criteria of all fault models, i .e . with increasing volumetric shale content cohesion decreases up to a factor ~20 and friction coefficients drops below ~0 .1 for some distributions . a tradeoff between permeability reduction due to the presence of low permeable clay and permeability increase due to local failure of fault rock determines the location of spill points and integrity of fault seals during gas storage

ARMA 13-282

Measuring the biot Stress coefficient and its implications on the effective Stress estimate Nermoen, A.1, Korsnes, R.2, Christensen, h.F.3, Trads, N.3, hiorth, A.1, 2 and Madland, M.V.2 1 International Research Institute of Stavanger (IRIS AS), Prof. Olav Hanssensvei 15, NO-4068 Stavanger, Norway 2 University of Stavanger, Petroleum Institute, 4036 Stavanger, Norway 3 GEO (former Danish Geotechnical Institute), Lyngby, Denmark

reservoir compaction is an effective mechanism for enhanced oil recovery (eor) and a threat to well bore stability and installations resting on the sea floor . it is of great importance to understand the underlying physical and chemical processes in compacting formations in order to precisely manage the reservoir development . it is a common procedure to reduce the set of state variables by introducing an equivalent effective stress variable calculated from the overburden weight and a fraction of the pore pressure . the fraction of the pore pressure is termed the biot effective stress coefficient . a precise determination of the effective stress is needed to predict compaction, since it is the effective stress that imparts deformation on the matrix . Within a reservoir, the overburden and pore pressure are measurable quantities, while the biot stress coefficient and therefore the exact value of the effective stress itself remain unknown without the use of tailored experimental techniques . here, we present the results from four independent testing methods for estimating the biot stress coefficient of high porosity chalk . We discuss the microscopic interpretation of the biot coefficient and show how the biot coefficient may be pore pressure sensitive . as such, the attempt to reduce the number of variables by introducing an equivalent effective stress state with the usage of a constant coefficient is potentially flawed for wider ranges of the pore pressure .


ARMA 13-355

a post-Depletion Subsidence Mechanism in the Southern coastal Zone of louisiana, USa Chang, Chandong Department of Geology, Chungnam National University, Daejeon, South Korea Mallman, E.P.* and Zoback, M.D. Department of Geophysics, Stanford University, Stanford, CA, USA *now at BP, Aberdeen, UK

extensive leveling surveys in the southern coast of louisiana indicate that active petroleum production and associated reservoir compaction are one of the major causes that brought about observed surface subsidence, which were locally more severe above depleted oil and gas fields . however, the rate of subsidence accelerated after reservoir depletion and production cessation . in order to explain the post-depletion acceleration of subsidence, we propose the compaction in reservoir-surrounding shale, which is driven by gradual drainage of pore fluid from the over- and underlying shales to reservoir sands . We use a one-dimensional semi-analytic compaction model, in which shale compaction is modeled using a superposition of poroelastic and viscoplastic rheology, employing the concept of the primary and the secondary consolidation of soil . the model results show that despite extremely low permeability, the total amount of shale compaction associated with a slow drainage of pore fluid can be comparable to the sand compaction within a decade, and that the resulting subsidence rate can accelerate even after depletion .

SeSSiOn 6: Deep mine rOCk meChaniCSMonday, 24 June, 11:00 am – 12:30 pmChairs: John Hanning, Hani Mitri

ARMA 13-406

a Study of the influence of fragmentation in ore-pass hang-Up phenomenaxuhai Tang, Adriana Paluszny, and Robert W. ZimmermanDepartment of Earth Science and Engineering, Imperial College, London, UK

fragmentation strongly influences the interlocking hang-up phenomena, a common occurrence in conjunction with cohesive arching around draw points in block caving systems . this work presents a brief numerical study of the influence of fragmentation on interlocking hang-up phenomena . fragment interaction and breakup are simulated numerically by combining the impulse-based energy tracking method (etm) and the finite element method (fem) in three dimensions . numerical tests with varying size of ore fragments are carried out . the breakage of rock fragments is modeled during the entire simulation and the influence of fragmentation is investigated in terms of productivity and the efficiency of draw point extraction . simulation results with fragmentation are compared to non-fragmentation numerical tests . it is observed that with fragmentation, 1 .93% and 2 .57% more volume of ore fragments are extracted before hang-up when the initial diameter of ore fragments is 5 .775 m and 7 .5 m, respectively .


ARMA 13-347

laboratory-Scale Strain and temperature Response of a Distributed optical fiber Sensor Madjdabadi, B. M. Civil Engineering Department, University of Waterloo, Waterloo, Ontario, Canada Benoît Valley Geological Institute, ETH Zürich, Switzerland Leah Siczkar Civil Engineering Department, University of Waterloo, Waterloo, Ontario, Canada Maurice B. Dusseault Earth and Environmental Sciences Department, University of Waterloo, Waterloo, Ontario, Canada Peter K. Kaiser CEMI, Sudbury, Ontario, Canada

distributed optical fiber sensors (dofss), used initially in structural health monitoring for high-rise buildings and bridges, are attracting attention in the field of underground structures, including mining . designed for long-term study of deformations, dofss are more efficient when installed away from excavation damaged zone (edZ) in a borehole filled with a grout mixture to measure elastic strain field responses to excavations . the dofs sensing cable, as a component of a complex compliance system, i .e . rockmass and grout, is being assessed through laboratory work . a test program is underway to observe dofs response to various perturbations including strain and joint displacement . initially, tests on unstrained sensors are performed in order to assess measurement repeatability and noise-to-signal ratio at both local and global scales . then, the various lengths of the cable, from 1 m down to 1 cm, will be stretched up to 0 .5% strain . in other tests, the same lengths of the cable will be exposed to shear displacement, such as might occur in the vicinity of a joint or fault that experiences shear . the results from these tests will answer uncertainties and questions regarding the scaling factor between straining sections over a full sampling window, i .e . spatial resolution, and a partial sampling window, i .e . validity of calibration factors provided by the supplier, and assessing effects of coating and plastic protective layers of the sensor . issues such as shear deformation responses of cable and bending direction of the cable are being evaluated . initial results on unstrained cable to assess measurement repeatability showed variability in length assessment between successive readings . this variability particularly impacts the data interpretation from the strain sensors since these sensors present locally large brillouin frequency gradients which results in locally large variability in differential readings . our detailed experimental results will be presented in the paper .

ARMA 13-217

Research on Deep ore-lode’s extension Direction based on Digital borehole imageChuanying Wang, Zengqiang han and Sheng hu State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, China hengyin Zhu and Bohua Wang No.313 Geological Party of Anhui Bureau of Geology and Mineral Exploration, Luan, Anhui, China

structure characteristics of rock and orebody in deep borehole are obtained by borehole camera technology . based on theory of metallogeny and geostatistics, distribution rules of different kinds of discontinuity are summarized and relevance analysis is carried out between discontinuities’ dominant orientation and lodes’ extension direction . comparative analysis is carried out between the result of lodes’ connectivity and the actual depth of orebody . the result indicates: (1) in the high-resolution digital borehole image, discontinuities’ orientation and other parameters of rock and orebody in deep borehole can be showed visually . (2) there are some differences between discontinuities’ dominant orientation of different statistical zone in the borehole: the distribution of discontinuities in the rock is discrete with no obvious regular


pattern, and the distribution of discontinuities in the orebody is more centralized with apparent dominant orientation . (3) there are more orebody in the boreholes whose orientations are forecasted by the data of Zk61 than in the boreholes whose orientation are not . forecast results are consistent with a higher degree of actual lodes distribution, suggesting method of analyzing lodes’ extension direction based on digital borehole camera technology is feasible .

ARMA 13-478

Quantifying the effects of adverse Geology on pillar Strength through numerical Modeling Preston, R.P. and Stead, D. Simon Fraser University, Burnaby, British Columbia, Canada McIntire, h. The Doe Run Company, Viburnum, Missouri, USA Roberts, D.P. Golder Associates Ltd., Burnaby, British Columbia, Canada

secondary pillar mining at the doe run series of underground lead mines near viburnum missouri often requires predictive modeling of pillar conditions to determine factors of safety . pillar strengths used in modeling are based on empirical case studies as well as confinement theory . in some cases, pillars are identified with adverse geological structures, which reduce their strength . such conditions can include highly persistent jointing, and bands of solution breccia or heavy mineralization . current practice for such structures involves reducing pillar strengths for modeling by 7 or 11 percent, at the discretion of the engineer . udec modeling with voronoi tessellation to simulate intact rock fractures was undertaken to examine the relationship between pillar height and strength reduction due to persistent jointing . the results of these numerical experiments are intended to provide guidelines for strength reductions in current pillar stability modeling . current modeling results suggest a linearly increasing strength reduction of up to 19% for pillars with w/h of 0 .67 and up to 67% for pillar with w/h of 0 .33 . modeled strengths were normalized to the compressive strength of the pillar host rock and compared to empirical strength curves with encouraging results .

SeSSiOn 7: tranSpOrt anD COupleD prOCeSSeS in fraCtureSMonday, 24 June, 11: 00 am – 12:30 pmChair: Russ Detwiler

ARMA 13-257

permeability Structure of a Strike-Slip fault Karasaki, K. Lawrence Berkeley National Laboratory, Berkeley, CA, USA onishi, C.T. US Geological Survey, Menlo Park, CA, USA Goto, J. Nuclear Waste Management Organization of Japan, Mita, Tokyo, Japan

a study was conducted on the Wildcat fault in berkeley, ca to develop a methodology for characterizing the hydrologic properties of a fault . the rocks are extensively sheared and fractured . the Wildcat, a strike-slip fault, appears to consist of multiple fault planes . that the exact location of the main fault is still at dispute


among participating researchers highlights the fact that it is very difficult to uniquely characterize such a complex fault zone . the hydrologic characteristics of the Wildcat fault zone suggest a dual nature—with high permeability along the direction of the fault zone and low permeability across it . data from pumping tests conducted in the high permeability zone along the fault plane exhibit 10:1 near-horizontal anisotropy . the main philosophy behind our overall approach to the hydrologic characterization of such a complex fractured system is to let the system take its own average by conducting large scale tests and conducting long term monitoring instead of collecting a multitude of data at small length and time scales, or at a discrete fracture scale and to “up-scale,” which is extremely tenuous at best .

ARMA 13-197

exploring alternative characterizations of fracture Stiffness and their Respective Scaling behaviors Morris, J.P. and Prioul, R. Schlumberger-Doll Research, One Hampshire St, Cambridge, MA, USA Jocker, J. Schlumberger, Parkstraat 83, The Hague, The Netherlands

it is common to quantify fracture mechanical properties by the specific stiffness, which depends upon both the host rock properties and the stress-dependent distribution of aperture within the fracture itself . for example, fractures exhibit increasing specific stiffness with increasing normal stress and narrow-aperture fractures are typically stiffer . furthermore, differences in the sample size or stress state of a measurement can complicate interpretation of specific stiffness . the “intrinsic stiffness” provides an alternative measure of fracture mechanical properties that removes the first order effects of size and stress-dependence . We demonstrate this concept with a numerical investigation into the scaling of fracture stiffness with the size of the fracture and the normal stress state to which the fracture is exposed . We find that while the specific stiffness exhibits high variability depending on size and stress state, the intrinsic stiffness is far less variable . this suggests that the intrinsic stiffness can provide a useful objective measure of the stiffness of fractures regardless of their size or normal stress states at which they are analyzed .

ARMA 13-433

Dispersive Waves propagating along a Surface fracture Abell, B. C. and Pyrak-Nolte, L. J. Purdue University, West Lafayette, IN, USA

significant work in the past few decades has led to a well-developed understanding of seismic wave propagation in fractured media . however, previous research has focused on fractures within rock as opposed to fractures at the surface of a rock . a theoretical and experimental study was performed to examine seismic wave propagation along a fracture at the surface, i .e ., along the intersection of two quarter-spaces . a theoretical model that couples two wedges, using displacement discontinuity boundary conditions, was developed that gives rise to a new guided waveform that is dispersive, depends on fracture specific stiffness at the intersection of a fracture with a free surface and exhibits velocities that range from the single wedge-mode velocity to the rayleigh wave velocity at a free surface . the existence and behavior of this new guided-mode was verified using a synthetic fracture created between two aluminum blocks . this new guided-mode enables characterization of fracture specific stiffness of fractures, joints and other discontinuities at the surface of an outcrop .


ARMA 13-445

Decoupling Reaction and Deformation in natural fractures with X-Ray Micro-tomography and particle image VelocimetryWalsh, S.D.C., Smith, M.M. and Carroll, S.A.Lawrence Livermore National Laboratory, Livermore, California, USA

this paper describes how particle image velocimetry (piv) techniques applied to x-ray computed tomography (xrct) data may be used to differentiate intensity changes due to chemical alteration from those of mechanical deformation . the xrct-piv method provides a non-invasive means of tracking solid deformation that is robust despite chemical alteration and noise . the results of the xrct-piv analysis can be used to map reacted regions back to the sample’s undeformed configuration and thereby obtain a more accurate identification of reacted regions . the approach is demonstrated on tomographic datasets from a core-flood experiment examining reactive transport of carbonated brine through a naturally fractured sample from the ohaaki geothermal field in new Zealand .

prepared by llnl under contract de-ac52-07na27344 .

ARMA 13-638

Micro-Scale Simulation of fracture alteration caused by coupled chemical and Mechanical processesAmeli, P., Detwiler, R. L. and Elkhoury J. E.Department of Civil and Environmental Engineering, University of California, Irvine, California, USAMorris, J. P.Lawrence Livermore National Laboratory, Livermore, CA, USANow at: Schlumberger-Doll Research, One Hampshire St, Cambridge, Massachusetts, USA

in this study we present a computational model that couples two previously developed codes to calculate the combined influence of mechanical deformation and chemical alteration of fractures subject to constant normal stress and reactive fluid . micro-scale roughness of the fracture surfaces is represented explicitly in the model and elastic deformation of the rough surfaces are calculated using a semi-analytical approach that ensures the surfaces remain in static equilibrium throughout the simulations . chemical alteration of the surfaces is modeled using a depth-averaged reactive transport model, which leads to alteration of the contacting fracture surfaces . the mechanical deformation and chemical alteration calculations are explicitly coupled, which is supported by the disparate timescales required for equilibration of stresses and reactive transport processes . results show that the transition from transport-limited conditions (low flow rates) to reaction-rate-limited conditions (high flow rates) causes a shift from monotonically increasing permeability to a more complicated process in which permeability initially increases and then decreases as contacting asperities begin to dissolve . these results are qualitatively consistent with a number of experimental observations reported in the literature and suggest the potential importance of the relative magnitude of mass transport and reaction kinetics on the evolution of fracture permeability in fractures .


ARMA 13-438

particle Swarms in Variable aperture fracturesBoomsma, E.B.Department of Physics, Purdue University, West Lafayette, IN, USAPyrak-Nolte, L.J.Department of Physics, Purdue University, West Lafayette, IN, USADepartment of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN, USASchool of Civil Engineering, Purdue University, West Lafayette, IN, USA

experiments were performed to determine the effect of a rough walled fracture on the evolution and maintenance of particle swarms, i .e . coherent collections of colloidal size particles . of particular interest is the response of a swarm to sudden changes in confinement and drag caused by variations in fracture aperture . two different rough fracture geometries were used and are compared to smooth-walled converging and diverging synthetic fractures . the variation in aperture along a swarm’s transport path exerted a strong influence swarm evolution and, in many cases, enhanced swarm stability and velocity . converging apertures tend to decelerate a swarm because of increasing confinement and drag from the fracture surfaces, while diverging apertures resulted in the acceleration of a swarm . as long as an unrestricted flow path exists, swarms will maintain their cohesion, even if a fracture contains obstacles to swarm flow (asperities) . however, if the aperture of the flow path is too small, swarms will bifurcate around an obstacle and produce smaller sub-swarms that will continue on separate paths .

SeSSiOn 8: rOCk SlOpeS iiMonday, 24 June, 11:00 am – 12:30 pmChairs: Herbert Einstein, John Kemeny

ARMA 13-428

challenges in Design and construction of Retaining Walls in complex Geologyhsi, J.P., hutton, L.D. and oo, N.T.SMEC Australia

the banora point upgrade project is a 2 .5km long six-lane divided freeway in northern new south Wales, australia . the main features of the project included two interchanges, a 300m long viaduct, a large cutting through sexton hill with an associated 100m wide land bridge and retaining walls reaching 490m in length and up to 22m high . the geology at sexton hill comprises a volcanic succession of variably weathered basalt flows and agglomerate deposits overlying mesozoic sedimentary rocks at a depth of approximately 48m beneath the crest of the hill . from design through to construction of the retaining walls, the variability of the ground conditions presented significant challenges to the designer and contractor, including: · presence of high strength corestones up to 2m in diameter within the basaltic residual soils of up to 6m thick; and · layers of extremely high strength basalt within the agglomerate of irregular weathering and alteration patterns above the sedimentary rocks at depth . two types of retaining system for the cut had been chosen . these included cantilever/anchored piled retaining wall and soil nail wall . With respect to the piled wall, the effectiveness of this system depends heavily on the piles and the ground anchors being able to socket into competent rock . due to the extremely complex and variable geology, the design had allowed some flexibility to accommodate uncertainties of the ground conditions . the design assumptions needed to be confirmed during construction . a rigorous site verification process was developed to monitor variations in ground conditions and to implement design and/or construction modifications, if required . specific construction equipment had to be used to overcome difficulties during the installation of piles and ground anchors, such


as percussion drills and cluster hammers . in-situ testing was undertaken to ensure the design capacities of the anchors and soil nails were achieved, and instrumentation and monitoring were implemented to confirm the performance of the retaining walls . this paper will present the site geology, the interpreted geotechnical model, the adopted retaining wall systems, the design methodology, the implemented instrumentation and the actual field performance .

ARMA 13-486

probabilistic-numerical Modeling of Stability of a Rock Slope in amasya-turkeyGheibie, S. and Duzgun, S.h.B.Mining Engineering Department, Middle East Technical University, Ankara, TurkeyAkgun, A.Geological Engineering Department, Karadeniz Technical University, Trabzon, Turkey

developments in computation facilities and increase in application of sophisticated mathematical methods in engineering problems have affected the methods of slope stability analysis . in recent years, the numerical modeling methods have extensively applied instead of limit equilibrium methods . also, the probabilistic methods are considered in rock slope designs to quantify the uncertainties involved in the slope stability problem . in this paper, a probabilistic-numerical approach is proposed, which is based on integration of three dimensional distinct element method (dem) and probabilistic approach for stability analysis of rock slopes . barton models were used to model the behavior of rock discontinuities and the shear strain was considered as failure indicator of discontinuities . the proposed methodology was applied to a rock slope in amasya, turkey . the effect of basic friction angle and cohesion of joints infilling material and its strength reduction due to weathering were included in the analysis . the shearing behavior of fourteen discontinuities and the failure probability of each block were investigated, by using reliability index (β) obtained for each discontinuity .

ARMA 13-585

Resin Grouted Rock anchors: case histories of failures and MitigationGates, W.C.B.Jacobs Associates, Seattle, Washington, USA

selection of the appropriate bonding agent for rock anchors is critical to the outcome of the job . the author has observed several projects where rock anchors have failed because the wrong bonding agent was used . examples include failures in vuggy weak limestone as well as very strong granitic rock . contractors tend to select resin grouted rock anchors (rgra) because they are faster, cleaner, and simpler to install, requiring less curing time, a shorter bond zone, one grout cycle, and are economical . the problem is that there are some major disadvantages with rgra . the resin bonding agent performs poorly in weak, broken and vuggy rock because the resin cartridges require a tight borehole to achieve proper mixing and bonding between the rock and the anchor and don’t account for extra voids in the rock around the anchor . loss of the resin into the voids creates gaps along the anchor and reduces the bond strength . as an alternative, cement grouted rock anchors (cgra) tend to be more reliable in weak, vuggy, porous rock . because of the inherent problems with rgra, the author recommends cgra because one can achieve a stronger bond in weak, fractured and vuggy rock or poorly drilled holes . the pumped grout tends to flow into the voids around the anchor and form a stronger more secure bond .


ARMA 13-588

application of a Quantitative approach for kinematic analysis of Rock Slope failures along cut Slopes in ohio Admassu, Y. Kent State University Ashtabula, Ashtabula, Ohio, USA Shakoor, A. Kent State University, Kent, Ohio, USA

stability of rock slopes primarily depends upon the orientation of discontinuities with respect to orientation of the slope face . the method of analyzing potential modes of rock slope failure, due to the presence of unfavorably oriented discontinuities, is known as kinematic analysis . stereonets are widely used to carry out kinematic analysis for rock slopes . the stereonet-based method provides qualitative solutions and is dependent on the presence of tight clusters of discontinuities for which representative orientation values can be assigned . in addition, the stereonet-based method does not easily handle the problem of variability in discontinuity data . in this study, a quantitative approach for kinematic analysis using the software, dipanalyst, is used and compared with the stereonet-based analysis for 12 cut slopes along highways in ohio . the quantitative approach calculates failure indices which are calculated as ratios of the number of discontinuities that cause plane failures or toppling failures, or the number of intersection lines that cause wedge failures, to the total number of discontinuities or intersection lines . the calculated failure indices are unaffected by the absence of tight clusters of discontinuity data or variability within a cluster set . discontinuity data from the 12 cut slopes in ohio were used to demonstrate the application of quantitative approach and compare the results with those by the stereonet-based analysis . the quantitative approach was able to identify slopes with a potential for failure that was not apparent from the stereonet-based analysis . sensitivity analysis was also performed with dipanalyst, showing that a slope angle of 500 will not result in failure index values of greater than 0 .1 .

ARMA 13-692

interpretation of pit Scale faults at an Unexposed bedrock Site Using exclusively borehole Data: a case Study at the ekati pigeon pit Site Keneti, S. A. R., Chaparro, C. and hunt, C. EBA, A Tetra Tech Company, Vancouver, British Columbia, Canada Wishart, J. BHP Billiton, Yellowknife, Northwest Territories, Canada

characterization of the major geological structures (intermediate and overall scale faults/shear zones) is a critical component for developing a model of structural domains for rock slope design in mines in structurally controlled environment . faults at the proposed ekati pigeon pit site can only be interpreted by drilling information, since there is no outcrop at and around the proposed pit site . in order to develop a 3d fault model, a technique was needed to determine where faults exist at the proposed pit area and how they connect between boreholes so that their persistence and orientation could be assessed . in this study, cumulative fracture frequency (cff) was plotted for the geotechnical drill holes to assist in potential fault identification . any substantial increase in the cumulative fracture frequency was considered as a potential major fault which later was cross-checked with core photos and the recorded description of infill materials . the identified faults then were used in gemcom gems™ to examine their possible connectivity and to construct a 3d fault model . based on the estimated length, thickness and orientation of the faults, a qualitative risk assessment was eventually conducted to evaluate the risk associated with each fault . it was perceived from the analysis that 6 faults out of 34 individual faults identified preliminarily from the cff analysis may present moderate to high risks for potential inter-ramp instability .


SeSSiOn 9: wellBOre StaBilityMonday, 24 June, 2:00 pm – 3:30 pmChairs: Nicholas Thompson, Ewerton Araujo

ARMA 13-234

Geomechanical Modeling of the Mad Dog Salt, Gulf of MexicoNikolinakou, M.A., Merrell, M.P., Luo, G., Flemings P. B., and hudec, M.R.Bureau of Economic Geology, The University of Texas at Austin, Texas, USA

our study shows that large salt bodies push laterally and elevate the horizontal stresses in front of salt and in minibasins . We built in abaQus 2-dimensional finite-element models of the mad dog field, deepwater northern gulf of mexico . We used wide-azimuth, prestack depthmigrated seismic data provided by bp & partners to realistically represent the salt geometry and bathymetry . We modeled the salt as viscoelastic and the sediments as elastic materials, and we calculated how the salt relaxation alters the stresses within the wall rocks . We show that shallow salt bodies with a large horizontal extent are characterized by an isostatic stress equal to the overburden value . consequently, the horizontal stress increases and the salt applies a thrust loading onto the sediments . in minibasins and along inclined salt faces, we predict high effective-stress ratios (values close to 1) . We further demonstrate that even in later stages of salt evacuation, presence of an interconnecting salt base is sufficient to maintain the salt stress equal to the overburden value and elevate the horizontal stresses within minibasins . our results compare well with lot and fit measurements from the mad dog field and illustrate that, contrary to traditional basin models, geomechanical analyses can explain horizontal stresses close to the overburden value .

ARMA 13-223

interface Modeling to predict Wellbore Damage for big hill Strategic petroleum ReservePark, B.Y.Sandia National Laboratories, Albuquerque, NM, USA

oil leaks were found in wellbores of caverns 105 and 109 at the big hill strategic petroleum reserve site . according to the field observations, two instances of casing damage occurred at the depth of the interface between the caprock and top of salt . this damage could be caused by interface movement induced by cavern volume closure due to salt creep . a three dimensional finite element model, which allows each cavern to be configured individually, was constructed to investigate shear and vertical displacements across each interface . the model contains interfaces between each lithology and a shear zone to examine the interface behavior in a realistic manner . this analysis results indicate that the casings of caverns 105 and 109 failed, respectively, from shear stress that exceeded shear strength due to the horizontal movement of the top of salt relative to the caprock, and tensile stress due to the downward movement of the top of salt from the caprock . the casings of caverns 101, 110, 111 and 114, located at the far ends of the field, are predicted to be failed by shear stress in the near future . the casings of inmost caverns 107 and 108 are predicted to be failed by tensile stress in the near future .


ARMA 13-132

case Studies on Wellbore Stability of tight Sand formation in West chinaxinpu ShenHalliburton, Houston, TX, USA

there are plenty of tight sand gas resources in west china . the depth of the target formation in this kind of resource is usually as deep as 6000 to 7000 m, and it is usually under salt . pore pressure prediction and wellbore stability analysis for a set of wells has been performed . the top-table method was used to derive the pore pressure of the target wells from relevant offset wells . results of the pore pressure prediction for the target well with input data from offset wells are shown in fig .1 in the middle track . because the stress pattern in this area is a reverse fault, the overburden gradient is taken as the fracture gradient . sfg calculated for two different offset wells are shown on the left and right tracks respectively . the values of sfg calculated at the original location of the offset well are visualized and compared with the value of sfg calculated using the top-table method at the target well . based on the resultant solution of sfg and fg calculated with top-table method from two different offset wells, the sfg and fg of the target well are determined and . this work presents two case studies of safe mud design in sub-salt tight sand gas formations . the results of the sfg and fg provide a best-practice and a useful reference for wellbore stability analyses in this region .

ARMA 13-346

borehole Shale Stability analysis to facilitate Successful Drilling of a horizontal Well in the north Sea Nes, o.-M. SINTEF Petroleum Research, Trondheim, Norway. Currently: Det norske oljeselskap ASA, Trondheim, Norway Brenna, A. Det norske oljeselskap ASA, Trondheim, Norway Gran, K. Det norske oljeselskap ASA, Oslo, Norway Saasen, A. Det norske oljeselskap ASA, Oslo, Norway; University of Stavanger, Stavanger, Norway

time dependent borehole stability problems may pose a significant challenge while drilling through shales, not only in the overburden, but also in interbedded shale stringers located within the reservoir zone . a north sea field case is presented where borehole instabilities in such an interbedded shale made it difficult to successfully reach the target when drilling the 8 .5” diameter horizontal section . prior to drilling the final well, a dedicated borehole stability analysis was therefore performed, accounting for time dependent borehole stability as function of type of drilling fluid in mechanically anisotropic shale . available log data and experience from previously drilled tracks were used as input to calibrate and verify the borehole stability model . thereafter, the stable drilling fluid density window for the planned, final well was predicted . this included the effect of variable effective drilling fluid density throughout the drilling and completion process, depending upon whether the drilling fluid was circulated or not . based on amongst others recommendations from this borehole stability analysis, the final well was successfully drilled and completed . this shows the potential benefit from properly accounting for rock mechanical effects while drilling in shales .


ARMA 13-490

Discrete element Modeling of transversely isotropic RockPark, B. and Min, K.-B.Department of Energy Systems Engineering, Seoul National University, Seoul, South Korea

discrete element model has been successfully applied in emulating the elastic modulus, poisson’s ratio and strength parameters of rock by controlling the micro parameters of dem . although the consideration of anisotropy is important in many rock mechanics applications, dem still remains as a tool for modeling an isotropic rock . in this study, dem modeling was performed in order to represent the transversely isotropic rock such as shale, gneiss and schist . the smooth joint model was employed to represent the weak planes in order to form the transversely isotropic rock . discrete element model was verified using the transformation of compliance tensor in transversely isotropic rock . verification with respect to the strength anisotropy also resulted in good agreement with analytical model . the strength and elastic modulus from dem model were compared with the laboratory experiments, resulting in good agreements . this model in anisotropic rock can pave the way for wide variety of engineering applications such as hydraulic fracturing for shale gas production and wellbore stability analysis .

ARMA 13-411

impact of Drilling Mechanics on the Geomechanical Model: an example from Gorgon Development Drilling campaign, offshore australia Avila, J.L. Chevron Australia Pty Ltd., Perth, Western Australia, Australia

chevron australia commenced gorgon project development drilling in 2011 in the offshore northwest shelf . challenges existed in both operating the gorgon field in the remote waters off Western australia, as well as building a geomechanical model to assist with wellbore stability estimates . the eight-well exploration and appraisal campaign occurred from 1981 to 1998 incorporating wells drilled with both water and synthetic-based mud . along with understanding the vintage and quality of logging while drilling (lWd) and wireline logs in varying hole conditions, a critical component of the geomechanical analysis was evaluating how hole conditions correlated to drilling mechanics . this was crucial to accurately estimate the stresses and rock properties in the field, so that overly high mud weights were not recommended for inclined wells, especially through the production zones . extensive washout zones occurred, even when using synthetic muds, initially suggesting that rocks were weak or under high stress . close examination of the drilling mechanics revealed zones of low rate of penetration (rop), increased weight on bit and torque, resulting in high vibration . review of lWd and drilling reports also showed correlations between caliper enlargement and circulating on-bottom zones . hence, failure to incorporate available drilling mechanics and history would have resulted in over-estimation of stresses and unnecessarily high mud weight recommendations .


SeSSiOn 10: numeriCal mODeling in COal mineSMonday, 24 June, 2:00 pm – 3:30 pmChairs: Essie Esterhuizen, Yi Lou

ARMA 13-143

Quantifying the benefit of cable bolts as Supplementary Support in coal Mines Using the Strength Reduction Method Murphy, M.M. and Esterhuizen, G.S. Office of Mine Safety and Health Research, National Institute for Occupational Safety and Health, Pittsburgh, PA, USA

the national institute for occupational safety and health has recently implemented the strength reduction method to evaluate coal mine entry stability in flac3d . the method can evaluate the performance of a support system and calculate a stability factor for the entry . for this paper, two studies were analyzed to quantify the impact that cable bolts have on the stability of the entry . the first study investigated the impact of replacing fully grouted bolts with cable bolts for a variety of mining conditions . the strength reduction method was useful for quantifying the additional stability provided by the cable bolts for the mining conditions evaluated . the results were validated with case histories from the analysis of roof bolt systems (arbs) database . the second study investigated the benefit of using an angled cable bolt with a steel strap . it was found that with a strap, the cable bolts are better utilized to provide stability . the study also found that the capacity of the cable bolt was not sufficient to provide adequate roof support when used with thicker roof straps . the strength reduction method was useful in quantifying the effectiveness of the cable bolts and determining the weakest link in the support system .

ARMA 13-479

inferring Mine floor properties from pillar Size and floor heave Tesarik, D.R., Whyatt, J.K. and Larson, M.K. Office of Mine Safety and Health Research, National Institute for Occupational Safety and Health, Spokane, WA, USA

consistency between actual in-mine and modeled ground response to mining is essential if a model is to be used as a mine design tool . a new procedure is presented in this paper that infers mohr-coulomb floor properties that will synchronize floor heave behavior between mine and model . the procedure works where the presence of floor heave depends on pillar size, as has been observed in a deep western u .s . longwall coal mine . in this case, floor heave was observed near pillars approximately 52 .4 m (172 ft) wide but was absent around pillars approximately 23 m (76 ft) wide, as the longwall passed . pillars were idealized in flac3d models as a single square column that includes the roof, pillar, and floor . coal in mine pillars was modeled as a hoek-brown material with parameters tuned to match one of bieniawski’s in situ compression tests, scaled to an unconfined compressive strength of 6 .2 mpa (900 psi) . models of various pillar shapes replicated bieniawski pillar strength equation estimates for pillar width-to-height ratios up to 8 . mohr-coulomb properties in the floor were then varied to define a boundary between heave and no-heave floor response to loading for each pillar size . the intersection of these solution sets served to bound mohr-coulomb properties for the mine floor . a representative set of properties within this region reduced capacity of the 52 .4-m (172-ft) wide pillar, which has a width-to-height ratio of 17, by 46% compared to a linear extrapolation of bieniawski’s equation . pillar capacities with inferred floor properties are easily fit to the holland-gaddy and maleki empirical equations . this procedure provides an alternative, and significantly different, extrapolation of coal pillar capacity that correctly models observed entry behavior, yet requires only careful observation to ascertain .


ARMA 13-201

numerical Modeling of the performance of active and passive bolts installed at an illinois basin coal Mine Ray, Anil K. and Gadde, Murali M. Peabody Energy, St. Louis, Missouri, USA Spearing, Anthony J.S. Southern Illinois University, Carbondale, Illinois, USA

numerical modeling based approaches have been used in past to understand the performance of different roof bolt systems under varying geo-mining conditions to be used as primary supports in underground coal mines . however, modeling exercises coupled with field instrumentation data are few and far between . considering the popularity and versatility of numerical modeling, an attempt is made in this paper to see if it is possible to explain the trends in bolt loads as observed by some in-situ studies . specifically, this paper describes the in-situ monitoring of roof bolt behavior at an illinois basin coal mine and then discusses the results from a numerical modeling exercise conducted to explain the observed bolt performance .

ARMA 13-174

Modeling Unstable failure of coal pillars in Underground Mining Using the Discrete element MethodKias, E.M.C. and ozbay, U.Colorado School of Mines, Golden, Colorado, USA

the failure mode of mine faces and pillars is affected by geometry and material properties of the surrounding rock . as mining progresses, the changing geometry affects the distribution of stresses and loading stiffness of the mine . this work builds on previous efforts in modeling underground excavations by investigating parameters that could be used to indicate instances of unstable pillar failure . a mechanically coupled discrete element model of coal is utilized to study the effect of geometry and loading system stiffness on pillar failure . first, the coupled model is verified in stable and unstable loading conditions using unconfined compressive strength tests with variable platen elastic modulus . unstable versus stable failure of the coal specimen is detected by comparing the stiffness of the loading system to the unloading stiffness of the coal during failure . a transition from stable to unstable failure occurs when the loading system stiffness is less than the post-peak stiffness of the coal . a resultant force based damping mechanism is used to maintain quasi-static conditions during the simulations . Work done by the damping mechanism is low for stable failures, but it increases in tests beyond the stable-unstable transition . this analysis is extended to a series of pillar tests with increasing width-to-height ratios . stiffness measurements show unstable and stable failures by assigning different loading system moduli . damping work is consistently higher during unstable pillar failure . comparing local damping work and bond failure reveals increased localization of failure during unstable failure .

ARMA 13-165

Distinct element analysis of Discontinuity Stable and Unstable Shear failureGu, R. and ozbay, U.Colorado School of Mines, Golden, Colorado, USA

existing geological discontinuities around underground mines, such as joints, faults and bedding planes, need to be considered in designing and managing mines to prevent potential wall failures . some of these discontinuities can be the sources for destructive rockburst events, which may be caused by unstable shear failures along large planar structures . this paper presents the results from a series of numerical modeling


studies of mining induced planar failures using the distinct element model udec . the objective is firstly to develop a methodology for modeling unstable shear failures on large discontinuities and secondly to further the understanding of the mechanisms involved during stable and unstable failures . the simulation results show that the models are able to capture elastic unloading process and reversal of shear sense during stable shear failures . the studies of shear displacements on discontinuities around advancing mining excavations indicate that both stable and unstable discontinuity shear failures may be triggered depending on the stress state affected on the discontinuity, strength and post- peak properties of the discontinuity, and the stiffness of the discontinuity wall rocks . the changes to the discontinuity loading stiffness caused by changing mining geometry appear to significantly affect the failure modes in terms of the failures being stable, semi-unstable and unstable . rapid increases in shear stress before failure initiations are also observed in the regions of unstable shear failures .

ARMA 13-198

estimation of parting Stability and Support Requirements during Depillaring in two contiguous coal Seams Raghwendra Singh, S. K. Singh, A. Kushwaha and A. Sinha Central Institute of Mining and Fuel Research, Dhanbad, Jharkhand, India

bord and pillar is the most common and traditional method of coal extraction in india . this method accounts for over 95% of coal production from underground mines . multiple seam coal production from in india, accounts for approximately 10% of the underground coal mines . in india, there are number of cases of parting failures in mines due to instability of the interburden between contiguous seam workings . the factors affecting parting stability in contiguous depillaring have been identified as horizontal to vertical in situ stress ratio, width of splits/slices, rock mass rating, compressive strength of parting, thickness of parting and relative position of the upper and lower production faces . series of FLAC models were run to cover all these variables to derive empirical equations for parting stability and support requirements in contiguous seams operations in indian coal fields . two case studies are used to validate the new empirical equations for parting stability and support requirements .

SeSSiOn 11: thermal, hyDrOlOgiCal, meChaniCal, ChemiCal anD BiOlOgiCal influenCeS upOn rOCkMonday, 24 June, 2:00 pm – 3:30 pmChairs: Mileva Radonjic, Jonny Rutqvist

ARMA 13-145

Modeling hydraulic and chemical processes in crushable Granular MaterialsBuscarnera, G.Northwestern University, Evanston, IL, USA

the paper presents a conceptual approach for capturing the interplay between multi-physical processes and the mechanism of particle breakage in granular geomaterials . the study addresses two specific processes in a separate fashion: (i) the interaction between granular solids and multiple pore fluids and (ii) the effect of mineral dissolution . in both cases, grain crushing is reproduced through the breakage mechanics theory . couplings between mechanical and non-mechanical phenomena are reproduced via particle scale modeling . the role of partially saturated conditions is captured through the capillary theory, while simplified


microscopic schemes are used to relate the evolution of the chemical state variables to changes in particle geometry . these consideration define scaling laws for each mechanism . the macroscopic implications of the two considered processes in terms of inelastic mechanical properties are finally derived through statistical homogenization . the analytical results disclose a relation between the hydro-chemical state variables and the yielding threshold under compressive stresses . at variance with prior formulations, such dependencies are obtained as emergent properties by advocating that the main contribution to the energy dissipation derives from the brittle breakage of the mineral compounds . these results stress the importance of identifying the microscopic physical processes that regulate inelastic deformation . for this reason, they can be a conceptual springboard for the development of micromechanically-based multi-physical models for granular media .

ARMA 13-218

formation Mechanisms of beachrocks in okinawa and ishikawa, Japan Danjo, T. and Kawasaki, S. Hokkaido University, Sapporo, Hokkaido, Japan hata, T. Toyama Prefectural University, Imizu, Toyama, Japan

beachrocks are coastal deposits cemented mainly by calcium carbonate cement; these deposits are found in the tidal zone of sandy beaches in tropical and subtropical regions . manmade beachrocks have the potential to inhibit coastal erosion; considering this important application, we performed field investigations and laboratory tests to understand the formation mechanisms of beachrocks in okinawa and ishikawa, Japan . We performed a needle penetration test, determined viable count, and conducted elemental and mineral analyses . our investigation of the formation mechanisms of the beachrocks showed that in okinawa, the evaporation of seawater and/or urease activity of the microorganisms might have resulted in the precipitation of high-mg calcite (hmc), leading to the formation of beachrocks . on the other hand, in ishikawa, beachrocks and sand were present near a spring . here, the ph value of the spring water was 4 .7, and the spring water has a higher concentration of al3+ . the mixing of spring water with seawater could have led to the precipitation of the cement containing al and si between sand particles, resulting in the formation of the beachrock . thus, we have interpreted the formation mechanisms of beachrocks .

ARMA 13-650

influence of infusion Rate and Magma Rheology on the Growth of lava DomesTaha husain and Derek ElsworthEnergy and Mineral Engineering, G3 Center and EMS Energy Institute, The Pennsylvania State University, University Park, PA, USABarry VoightGeosciences, G3 Center and EMS Energy, Institute, The Pennsylvania State University, University Park, PA, USAGlen Mattioli and Pamela JansmaDepartment of Earth and Environmental Sciences, University of Texas at Arlington, Arlington, TX, USA

lava domes are conical structures that grow from the interior by the infusion of viscous magma from a central volcanic conduit . their behavior is characterized by repeated cycles of growth punctuated by collapse as the structure becomes oversized for the strength of the composite magma that rheologically stiffens principally by off-gassing . high effusion rates result in frequent and energetic collapses, and low effusion rates result


in stable growth . We explore the different growth mechanics using a two dimensional particle dynamics model . the model computes the natural evolution of a deformable talus formed by rheological stiffening driven by degassing-induced crystallization of magma, which dominates solidification . the deformable talus is modeled as a frictional material, while the softer core is cohesion dominated . infusion rate and magma rheology together with crystallization temperature and volatile content govern the distribution of strength in the structure for the distribution of cohesive core and frictional talus . in this study the quality of the model is tested against existing experimental and observational models of lava dome growth . the dem model follows the natural development, collapse and rearrangement of the lava dome talus, which is infeasible using simple analytical models .

ARMA 13-253

impacts of cold co2 injection in Deep Saline aquifers on the Rock Mechanical integrityVilarrasa, V.Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA, USACarrera, J.GHS, Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Barcelona, SpainSilva, o.Department of Groundwater and Soils, Amphos21 Consulting S.L., Barcelona, Spainolivella, S.Dept Geotechnical Engineering and Geosciences (UPC-BarcelonaTech), Barcelona, Spain

injecting co2 into aquifers at depths greater than 800 m brings co2 to a supercritical state where its density is large enough to ensure an efficient use of pore space . however, co2 may not be in thermal equilibrium with the medium when it enters the reservoir because pressure and temperature injection conditions at the wellhead can be diverse and co2 will not equilibrate with the geothermal gradient if the flow rate is high . this is especially true when injecting liquid, i .e . cold, co2, which is highly advantageous from the point of view of demanded compression energy . in such case, thermal stress changes will be induced, which will affect rock stability . coupled thermo-hydro-mechanical simulations of co2 injection produce a region around the injection well in thermal equilibrium with the injected co2 . further away, co2 thermally equilibrates with the medium in an abrupt front . thermal contraction of the reservoir can lead to shear slip of pre-existing fractures, triggering microseismic events, for large temperature contrasts in stiff rocks, which could enhance injectivity . in contrast, the mechanical stability of the caprock is improved in stress regimes where the maximum principal stress is the vertical .

ARMA 13-621

thermal-hydraulic-Mechanical processes Modeling to evaluate Salt-based Repositories in the long-termBlanco Martín, L., Rutqvist J., Birkholzer J.T. and houseworth, J.E.Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA, USA

the coupled thermal-hydraulic-mechanical response of a hypothetical high-level nuclear waste repository in a saliniferous rock formation is explored in this study . although only short-term results are presented in this paper, the ultimate aim of the ongoing research is to evaluate the mechanical and hydraulic barrier integrity of the repository over the long-term . the design adopted involves metallic waste packages horizontally disposed in drifts subsequently backfilled with crushed salt . some of the thm interactions studied concern porosity and permeability changes within the backfill as consolidation occurs, and also permeability changes within the natural rock salt due to thermomechanically and hydraulically-induced damage processes . the simulations are conducted using an updated version of tough2-flac3d, developed at lawrence berkeley national laboratory . the mechanical behavior of the host rock is modeled


using the lux/Wolters constitutive model, developed at clausthal university of technology . Well-adapted relationships are used to couple non-isothermal multiphase flow and geomechanics . in order to ensure the grids consistency, the tough2 mesh is updated as large strains take place . the comparison between th and thm results shows the relevance of the latter to better simulate the long-term response of structures envisaged for nuclear waste disposal in saliniferous formations .

ARMA 13-241

effect of confining pressure on permeability during Deformation and failure of Several Rocks under compressionAlam A.K.M.B., Niioka M. and Fujii Y.Rock Mechanics Laboratory, Faculty of Engineering, Hokkaido University, Japan

triaxial test was carried out under confining pressure of 1-15 mpa at 22°c by using an ultra compact triaxial cell on shikotsu welded tuff, kimachi sandstone and inada granite . the permeability was measured by using constant flow or transient pulse method . in case of tuff with increasing stress, permeability decreased to residual strength state . in case of sandstone permeability began to decrease, reached minima before peak stress, began to increase again and reached almost stable value under residual strength state; the permeability from consolidation to residual strength state increased under 1 mpa, was almost the same values under 5-10 mpa with some exceptions, it decreased under 11-15 mpa . for granite, the permeability and stress relationship was the same as sandstone; the permeability ratio of consolidation to residual strength decreased with increasing confining pressure up to 9 mpa, afterward the permeability began to increase under 11-15 mpa . from the experimental results, sealability can be improved in edZ for all the rocks . for tuff improvement of sealability can also be expected in edZ; for sandstone it is achievable if enough support pressure is applied but for granite it cannot be expected .

SeSSiOn 12: COnStitutive mODelSMonday, 24 June, 2:00 pm – 3:30 pmChair: Mark Diederichs

ARMA 13-305

Modeling Stiffness anisotropy induced by crack opening in Rocks Subjected to thermal versus Mechanical Stress GradientsZhu, C., Arson, C., and xu, h.Geosystems group, School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA

a thermodynamic framework is proposed to model the coupled effects of mechanical and thermal stresses in rocks . the model is based on continuum damage mechanics with damage defined as the second-order crack density tensor . the free energy of damaged rock is expressed as a function of deformation, temperature, and damage . the damage criterion controls mode i crack propagation, captures temperature-induced decrease of rock toughness, and accounts for the increase of energy release rate necessary to propagate cracks in a damaged medium . two loading paths have been simulated: (1) increase of ambient temperature followed by a triaxial compression test, (2) triaxial compression test followed by a confined heating phase . results show that: (1) under anisotropic mechanical boundary conditions, heating produces damage, (2) higher temperature induces larger damage and deformation, (3) degradation of rock toughness due to an increase in


temperature affects the damage threshold . the proposed framework is expected to bring new insights in the design and reliability assessment of geotechnical reservoirs and repositories, such as nuclear waste disposals, geothermal systems, carbon dioxide sequestration systems, and high-pressure gas reservoirs .

ARMA 13-407

Queenston formation: tunnel back analysis and forward Shaft prediction Perras, M.A., Ghazvinian, E. and Diederichs, M.S. Queen’s University, Kingston, Ontario, Canada Lam, T.Nuclear Waste Management Organization, Toronto, Ontario, Canada

the niagara tunnel project (ntp) is a 10 .1km long water diversion tunnel in niagara falls, ontario, which was excavated by a 7 .2m radius tunnel boring machine . approximately half the tunnel length was excavated through the Queenston formation, which locally is a red shale to mudstone . a large notch formed, in the tunnel crown and invert, during excavation reaching 4m in height at the tunnel crown in areas . the failed zone was accurately modeled using the damage initiation and spalling limit approach utilizing the average laboratory testing results in the range of the tunnel depth, approximately 140m below ground surface . the stress ratios which correctly captured the observed notch were determined to be a ko=4 .0 and khh=1 .4 . using the same calibrated approach, average laboratory test results, a series of models were computed over the range of stress conditions for a shaft excavation in the Queenston formation at the proposed deep geological repository (dgr) for low and intermediate level nuclear Waste storage near kincardine, ontario . the maximum damage depth was determined to be 1 .9m deep, with an average of 1 .5m . important differences are discussed between the tunnel orientation for ntp (parallel to bedding) and the dgr shaft (perpendicular to bedding) . the models show that the observed normalized depth of failure at the ntp would over predict the depth of damage expected in the Queenston formation at the dgr .

ARMA 13-350

Development of an orthotropic constitutive Model for a Jointed Rock Mass Kulatilake, P.h.S.W. and Wu, Q. University of Arizona, Tucson, Arizona, USA

fracture data available for a limestone rock mass were used to build and validate a stochastic 3-d fracture network model . a procedure is proposed to investigate the size effect and the rev and equivalent continuum behaviors of fracture and mechanical properties in 3-d of the jointed rock mass having finite size fractures capturing the anisotropic effects arising from the fracture system . an rev size of about 25 m, which is about 8 times the mean fracture size of joint sets, was found to represent the mechanical properties of the rock mass . a number of relations are developed between the rock mass mechanical parameters and fracture tensor components in 3-d . based on the mechanical parameter values obtained in every 45 degree direction in 3-d, the principal values, principal directions and tensors are developed for rock mass mechanical parameters to represent the rev size properties . an incrementally linear elastic, orthotropic constitutive model is suggested to represent the equivalent continuum pre-failure mechanical behavior of the rock mass by incorporating the effect of fracture geometry by the fracture tensor components .


ARMA 13-524

non-Destructive testing of Rock Mass Deformation in Spent nuclear fuel Disposal Research facilitiesKantia, P.Geofcon, Rovaniemi, Finlandheikkinen, E.Pöyry Finland Oy, Vantaa, FinlandCosma, C. and Enescu, N.Vibrometric Canada Ltd, Toronto, Ontario, CanadaLehtimäki, T.SKB, Forsmark, SwedenKemppainen, K.Posiva Oy, Eurajoki, Finland

posiva in finland and skb in sweden are preparing for spent nuclear fuel disposal in crystalline bedrock . disposal relies on the geological kbs-3 multiple barrier concept . in this concept surrounding rock mass is considered as one barrier preventing radionuclide transportation to the biosphere . excavation of disposal tunnels will be conducted using a drill and blast (d&b) tunneling method . blasting and stress field redistribution unavoidably causes an excavation damaged zone (edZ) which needed to be investigated . this study concentrates on characterization methods revealing the properties and significance of the edZ . non-destructive testing (ndt) methods were advised to enhance coverage and efficiency of investigations . chosen study methods were seismic reflection and tomography, electrical resistivity tomography, ground penetrating radar investigations, borehole imaging, hydraulic measurements and laboratory analysis of rock samples . results obtained from different scales and the chosen methods were compared . analysis led to observation of discontinuous character and varying thickness of the edZ . research indicates a fairly thin, 5-30 cm thick edZ layer on rock surfaces . excavation and stress redistribution induced fractures might contribute to hydraulic flow close to the tunnel perimeter . locating and mapping of these potential hydraulic paths can be performed with high resolution geophysical ndt methods .

ARMA 13-394

theoretical and numerical Modeling of Rock hysteresis based on Sliding of Microcracks Morteza Nejati, Adriana Paluszny, and Robert W. Zimmerman Department of Earth Science and Engineering, Imperial College, London, UK

nonlinearity and hysteresis are two key features of elastic rock deformation . this behavior can be attributed to the presence of cracks and crack-like voids . the hysteretic behavior of rocks is related to the concept of unrecovered energy . two main processes lead to the existence of unrecovered energy in the sliding crack model: (i) the work of frictional forces and (ii) the strain energy trapped in the solid . in this paper, a theoretical and numerical analysis will be presented to extend the work of david et al . [1] to consider 3d penny-shaped cracks . a 3d finite element analysis is used to evaluate the sliding crack model numerically . in this approach, the penalty method is used to simulate the contact behavior of the crack faces . the stick-slip condition of the crack faces is simulated by employing the constitutive frictional law of amontons . the results show that no residual strain is developed in the body containing randomly oriented cracks if one assumes a uniform stress over all the crack cells . the energy loss is therefore equal to the work of frictional forces on the crack faces .


ARMA 13-348

towards a thermodynamic framework to Model particle crushing and SievingBakhtiary, E.Georgia Institute of Technology, Atlanta, Georgia, USAArson, C.Georgia Institute of Technology, Atlanta, Georgia, USA

crushing implies the division of particles into smaller parts, and may involve a change in shape . continuum-based models of crushing give an average representation of elastic weakening, often in the form of a visco-plastic deformation law . particulate mechanics and discrete element methods (dem) are better suited to capture the loss of compression and shear strength with particle crushing . in dem, a representative elementary volume typically contains several thousands of particles, which involves high computational costs . in all of these approaches, the assembly of grains is a closed thermodynamic system . elementary simulations of sequences alternating crushing and sieving are presented in this paper showing that the gsd obtained after each sequence is the same . however, the key point in the energy balance is the loss of mass induced by sieving, which requires additional modeling . the bases of thermodynamics of open systems subject to crushing are presented, within the framework of breakage mechanics . the proposed approach is expected to bring new insights to the modeling of friction sliding during faulting, ballast particle crushing and optimization of processes used in powder engineering . keywords: crushing, particulate mechanics, continuum mechanics, phenomenological modeling, pore size distribution, energy optimization, grain size distribution .

pOSter SeSSiOn: CO2 SeQueStratiOn anD utilizatiOnMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-246

Relation between fault Zone architecture, earthquake Magnitude and leakage associated with co2 injection in a Multilayered Sedimentary System Pierre Jeanne, Antonio Pio Rinaldi and Jonny Rutqvist Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA, USA Frédéric Cappa Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA,USA GeoAzur, University of Nice Sophia-Antipolis, Cote d’Azur Observatory, Nice, France Yves GuglielmiCEREGE, Aix-Marseille University, France

in this study, we have examined the influence of the fault zone characteristics on pressure diffusion and fault reactivation by co2 injection . especially, we studied the effect of lithological and rock physical properties on the fault zone response inside a multilayer sedimentary system . through numerical analysis, we compared four models where the complexity of the fault zone internal architecture is considered . results show how the presence of hydromechanical heterogeneity influences the pressure diffusion, as well as the effective normal and shear stress evolutions . the more complex the fault zone architecture is and the more heterogeneities that are present, the faster the pressurization within the damage zone occurs . but, these hydromechanical heterogeneities (i) strengthen the fault zone resulting in earthquake of smaller magnitude, and (ii) impede fluid migration along the fault . We also show that the effects of the hydromechanical heterogeneities within the reservoir are negligible relative to those between the caprock and the reservoir .


ARMA 13- 737

Development of Reconstituted indian coals to investigate coal Response to carbon Dioxide exposure Vishal, V. IITB Monash Research Academy, IIT Bombay, Powai, Mumbai, India Ranjith, P. G. Department of Civil Engineering, Monash University, Clayton, Australia Singh, T. N. Department of Earth Sciences, IIT Bombay, Powai, Mumbai, India

carbon capture and storage into deep geological reservoirs like coal seams has gathered worldwide attention . the potential of coal to adsorb co2 and preferentially release methane partly offsets the cost of capture, transport and storage of the greenhouse gases . for such projects, it is important to understand the influence of geomechanical properties of coal on cap rock integrity and long term safety . however, coal being highly heterogeneous from basin to basin, seam to seam, and those within the seam, it is difficult to determine the properties of the whole seam . this makes it difficult to characterize and understand the properties of coal for developing ideal models for optimization of sequestration process and generating useful correlations . therefore, in this study, bituminous coal samples from Jharia basin of gondwana supergroup, india were crushed into fine powders, milled, sieved and compacted to develop synthetic or reconstituted coal specimens . using a new loading framework, four samples were developed at the same time . each coal specimen was developed at a compaction pressure ranging from 11 mpa to 24 mpa . after developing these samples, they were tested for their geomechanical attributes . it was found that the mechanical of reconstituted coal like density and strength were quite homogenous as compared to the natural samples . increase in compaction load lead to formation of coal samples having higher strengths . this methodology was applied for the first time for indian coals and is expected to be very useful for further investigation on co2 response in coal to overcome the difficulty of the heterogeneity .

ARMA 13-739

in-Situ Stress constraints from borehole Data in the context of co2-Storage Site characterizationNatalia V. Zakharova and David S. GoldbergLamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USADaniel CollinsSandia Technologies, LLC, Houston, TX, USA

induced seismicity presents a significant risk for carbon sequestration in low-permeability fractured formations because even small-magnitude earthquakes and slip on pre-existing fractures threaten the integrity of the seal of co2 repositories . high-resolution wellbore images allow identification of both natural discontinuities and drilling-induced failures indicative of insitu stress orientation . combined with other geophysical logs, images allow for evaluation of geomechanical properties and facilitate modeling of effective stress perturbation due to co2 injection . in this study we review borehole techniques for stress analysis and discuss their application for a potential co2-storage site in the northern newark basin in the northeastern u .s . parts of the basin are located near the new york metropolitan area, therefore, assessing induced seismicity risk is critical for this site . preliminary analysis suggests reverse faulting/strike-slip stress regime but indicates that a more accurate estimate of the least horizontal stress is needed for evaluating the permissible range of injection pressure . potential risks and implications for carbon storage at this locality are discussed, followed by suggested future work .


ARMA 13-184

coupled Semi-analytical Solution for co2 injection-induced Surface Uplift and caprock Deflection Chao Li and Paul BaresSwiss Federal Institute of Technology, EPFL, Lausanne, Switzerland Lyesse Laloui Swiss Federal Institute of Technology, EPFL, Lausanne, Switzerland King Abdulaziz University, Jeddah, Saudi Arabia

this study focuses on a specific problem related to the surface uplift induced by the injection of co2 at depth . the adopted methodology includes the development of a mathematical model that incorporates the deformable behaviour of storage media and the flow of two immiscible fluids (co2 and water) within the aquifers while the surface rock or caprock layer is modelled as a thin plate . governing equations are solved for the axisymmetric flexural deflection due to a constant rate of injection of co2 . comparison of the results with the surface uplift measurements (in salah project), show good agreement . the results show that this semi-analytical solution is capable of capturing the pressure build-up during the very early stage of injection, resulting in a high rate of surface uplift . compared to a fem simulation, the calculation time required using the semi-analytical solution is very short; it can be employed as a preliminary design tool for risk assessment using parameters such as the injection rate, porosity, rock properties and geological structures . this semi-analytical solution provides a convenient way to estimate the influence of high injection rates of co2 on the surface uplift . the methodology in this development can easily incorporate other pressure distributions; thus advances in hydrology researches can also benefit this approach .

ARMA 13-592

experimental Study of Reactive flow in an eau claire fracture exposed to co2-Rich brine Deng, h., Fitts, J. P. and Peters, C.A. Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA Li, L. Department of Energy and Mineral Engineering, Pennsylvania State University, University Park, PA, USA Crandall, D. URS Corporation Morgantown, WV, USA National Energy Technology Laboratory, Morgantown, WV, USA Bromhal, G. National Energy Technology Laboratory, Morgantown, WV, USA

fractures in caprocks represent potential integrity breaches and this integrity may be altered over time if the permeability evolves substantially due to reaction with flowing fluids . this is especially relevant in the context of co2 geological storage in which acid-promoted reactions are possible, leading to physical changes of fracture permeability and therefore leakage potential . in this study, we report an experimental study of reactive flow in a core sample from the eau claire formation . the core had been collected to characterize the primary sealing unit for the futuregen 2 .0 project, which is injecting co2 into the underlying mt simon sandstone . synthetic brine was saturated with co2 at 11 .0 mpa and flowed through the fracture at a confining pressure of 12 .8 mpa for three weeks . computed tomographic (ct) images from x-ray scanning before and after the experiment showed a small decrease in average aperture . the effective hydraulic aperture calculated from flow and pressure measurements decreased from 6 μm to 4 μm, and is consistent with the ct analyses . composition maps of ca abundance based on x-ray fluorescence indicate dissolution of ca-bearing minerals close to the fracture surface . however, extensive mineralogical analyses from sem-bse, eds and xrd showed low potential of reactivity and


no evidence of any secondary precipitation . the decrease of the fracture permeability is consistent with pressure-enhanced dissolution of critical asperities, but the ct image resolution does not allow direct observation of this mechanism . this experimental study provides one piece of evidence supporting the suitability of the eau claire as a reliable caprock .

pOSter SeSSiOn: tranSpOrt anD COupleD prOCeSSeS in fraCtureSMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-634

numerical Simulation of Supercritical carbon Dioxide leakages in fractured porous Reservoir Ezzedine, S.M. CED/NSED, Lawrence Livermore National Laboratory, NSED, Livermore, CA, USA Ryerson, F.J. and McNab, W.W. AEED, Lawrence Livermore National Laboratory, AEED, Livermore, CA, USA Glascoe, L. G. CED, Lawrence Livermore National Laboratory, NSED, Livermore, CA, USA

We present a numerical model that simulates flow and transport of co2 into a multi-layered subsurface system . results show the impact of the injection and leakage rates on the time-evolution of the spread of the co2 plume, its interception of the fractured cap-rock and the risk associated with the contamination of the overlaying aquifer . spatial and temporal moments have been calculated for different, deterministic of stochastic, subsurface physical and chemical properties . spatial moments enable assessing the extent of the region of investigation under conditions of uncertainty . furthermore, several leakage scenarios show the intermittence behavior and development of the co2 plume in the subsurface .

ARMA 13-520

non-linear fluid flow through Rough-Walled fractures: the Role of Shear Displacement on the critical Reynolds number Javadi, M. and Sharifzadeh, M. Department of Mining & Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran

this paper experimentally examines the role of shear slip on the variation of critical reynolds number and non-linearity of fluid flow through rough-walled rock fractures . first, a criterion was developed by comprehensive using of forchheimer’s law to quantify the onset of non-linearity of fluid flow . hydromechanical laboratory experiments were performed on different initially closely mated rock fractures undergoing shear sliding to evaluate effects of mechanical displacements on non-linear flow . at each shear sliding step, several high-precision water flow tests with different hydraulic gradients were carried out and the critical reynolds number was determined based on the developed criterion . the results show that; (i) the quadratic polynomial regression in the form of the forchheimer’s law provides a good accuracy, (ii) during shear sliding, the coefficients of viscous and inertial pressure drop experiences about four and seven orders of magnitude reduction, respectively, and (iii) the critical reynolds number varies from 0 .001 to 25 and experiences about four orders of magnitude enlarging by increasing shear displacement from zero to 20 mm .


ARMA 13-392

Mesoscopic evaluation of non-linear fluid flow through Rough-walled fractures Using ‘t Model’Javadi, M. and Sharifzadeh, M. Department of Mining & Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran

the main subject of this paper is to examine the mesoscopic non-linear fluid flow through three-dimensional rough-walled fractures . computational domain of an artificial three-dimensional fracture was generated and both laminar and turbulent flow through the void specimen were simulated using finite volume method for a wide range of flow rates . geometrical domain of the fracture was discretized to 125 sub-fractures and calculated average pressure drop of sub-fractures from each flow rate of turbulent flow simulation were compared with those predicted by t model . the results show that: 1) by increasing reynolds number, the difference between laminar and turbulent flow simulations increases as the relative error increases from 3 .2% to 17 .3% for reynolds number of 4 .5 to 89 .5, respectively, 2) the effect of non-linear flow increases with reynolds number and the forchheimer law was fitted very well to both laminar and turbulent flow simulations, and t model predictions, 2) there is an appropriate correspondence between predicted sub-fracture’s pressure drops obtained by t model and turbulent flow simulation .

pOSter SeSSiOn: thermal, hyDrOlOgiCal, meChaniCal, ChemiCal anD BiOlOgiCal influenCeS upOn rOCkMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-266

experimental analysis of the Retention behavior of ShalesFerrari A.1, Favero V. 1 and Laloui L. 1, 2

1Laboratory for Soil Mechanics (LMS) ,Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland2King Abdulaziz University, Jeddah, Saudi Arabia

Water retention mechanism has a primary importance in either fluid trapping due to the capillary forces or in the resaturation of shale formations after desaturation . this paper illustrates the advances in the experimental analysis of the water retention behaviour of shales under non-isochoric conditions which have recently been achieved by the authors . the testing methodologies, which allow for the determination of the main drying and wetting paths, involve the direct control of the shale water content and the subsequent measurement of the total suction at equilibrium by a psychrometer . furthermore, the volume change response of the material upon total suction variations is investigated: a fluid displacement technique with a non-polar liquid is used in order to assess the volume changes of the shale samples and to compute the degree of saturation . selected results are presented for two mesozoic shales from the northern region of switzerland: the opalinus clay from mont terri and the so called “brown dogger” from the schlattingen site in the molasse basin .


ARMA 13-236

long-term observation of Rock permeability under high pressure and temperature conditions and its Microstructural interpretationYasuhara, h. and Kinoshita, N.Ehime University, Matsuyama, JapanTakahashi, M.Agency of Industrial Science and Technology, Tsukuba, JapanNakashima, S.Yamaguchi University, Ube, JapanKishida, K.Kyoto University, Kyoto, Japan

a series of long-term permeability experiments using berea sandstone and horonobe mudstone has been conducted so as to understand the evolution of rock permeability under stressed and temperature-elevated conditions . the well-controlled experiments are carried out at confining pressures of 3 .0 – 15 mpa and temperatures of 20 or 25 and 90°c . flow-through experiments are conducted regularly (i .e ., 5 or 10 day interval) to examine the evolution of rock permeability throughout the experiments – it should be noted that each experiment is kept always more than 500 days . effluent concentrations are also measured for the ten elements of si, al, k, fe, ca, na, mg, ti, s, and cl that are included mainly in the targeted rocks . rock samples were prepared for a sem-edx and/or a micro-focus x-ray ct to observe its microstructure . the sem-edx observation revealed that mineral dissolution dominates over mineral precipitation, and the micro-focus x-ray ct observation shows a slight increase in pore volume for the sandstone sample that has experienced long-term confining pressure and temperature .

ARMA 13-285

characterization of Shale Rocks under Dynamic Geochemical interaction with brine-co2 fluidolabode, A.o. and Radonjic, M. Louisiana State University, Baton Rouge, LA, USA

caprock integrity is critical in ensuring that geological sequestration of anthropogenic carbon dioxide (co2) meets engineering and carbon accounting goals . the interaction of shale caprock with brine enriched co2 under continuous contact conditions should be investigated in order to adequately characterize geological reservoirs for their ability to effectively sequester co2 in large quantity . simulation results reported in literature had predicted that influx-triggered mineral dissolution/precipitation reactions within typical shale caprocks can continuously reduce micro-fracture networks, while pressure and effective-stress evolution initially increase then gradually constrict them . this experimental work applied specific analytical techniques in investigating changes in surface/near-surface properties of crushed shale rocks after exposure (by flooding) to co2-brine . nano-scale measurement of changes in internal specific surface area, pore volume and linear/cumulative pore size distribution (using the bet technique) showed that changes in the shale caprock due to geochemical interaction with aqueous co2 can affect petrophysical properties . diffusive transport of co2 as well as carbon accounting could be significantly affected over the long term . the estimation of dimensionless quantities such as peclet (pe) and peclet-damkohler (peda) numbers that are associated with geochemical reactivity of rocks and acidic fluid transport through porous media revealed the impact of diffusion and reaction rate on shale caprock in co2 sequestration .


pOSter SeSSiOn: eXperimental rOCk meChaniCSMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-447

Review of dynamic fracture testing methods and fracture behaviour of rock materialsZhang, Q.B.École Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering, Laboratory of Rock Mechanics (LMR), Lausanne, Switzerland

the purpose of this review is to present the state-of-the-art in dynamic fracture testing methods and fracture behaviour of rock materials . the review begins by briefly introducing the history of rock dynamic fracture and explaining the significance of studying these issues . the split hopkinson pressure bar technique is widely used and the major development for rock materials is briefly summarized . an in-depth description and evaluation of various dynamic testing methods are presented in section 2 . in section 3, dynamic fracture behaviour of rock materials is reviewed and discussed in detail . dynamic fracture parameters are obtained by quantitative assessments of testing methods, and controlling factors and failure patterns are also discussed to validate these properties . fracture toughness and fracture behaviour change with loading rate, in particular, the responses distinguishably change after loading rate exceeds a critical value . dynamic testing methods should be carefully examined and satisfied the fundamental of theory, such as the distribution of dynamic stress, stress equilibrium and failure patterns .

ARMA 13-468

Saturation of porous Rock and Measurement of the b coefficientMakhnenko, R.Y. and Labuz, J.F.University of Minnesota, Minneapolis, MN, USA

laboratory testing of fluid-saturated rock is often needed to properly duplicate field conditions, where pores in rock are filled with a liquid . it is desirable that laboratory specimens be fully saturated, because it reduces the number of unknown parameters and allows calculation of some of the rock’s poroelastic moduli . however, full saturation is difficult to achieve in rock specimens because of the air bubbles trapped in pores . in order to dissolve air bubbles, back pressure can be applied to the specimens, decreasing the size of air bubbles and reducing the time needed to dissolve them in water . a process to saturate berea sandstone is presented . skempton’s b coefficient was measured at each increment of back pressure while keeping the effective mean stress approximately the same . a b-value that was constant and independent of the magnitude of the back pressure indicated full saturation . the maximum b achieved for the sandstone at 5 mpa effective mean stress was 0 .58 . this value was confirmed by calculation of skempton’s coefficient from other poroelastic parameters . moreover, full saturation was assured by the measurement of a constant p-wave velocity with increasing back pressure .

ARMA 13-546

petrophysical characterization of organic-Rich Shales: a new Standardized protocol Junhao Zhou, Chang Min Jung, Martin E. Chenevert and Mukul M. Sharma The University of Texas at Austin, Austin, Texas, USA


in this paper we present a standard protocol for measuring the petrophysical properties of hydrocarbon bearing shales . the importance of using preserved shale samples is clearly demonstrated . these techniques are adapted from methods we originally developed for non-hydrocarbon bearing shales over the past 25 years . results from a series of experiments that determine the following petrophysical properties of hydrocarbon bearing shales are presented: native shale water activity, permeability, swelling parallel and perpendicular to the bedding planes, brinell hardness, p-wave and s-wave velocities . changes in these properties such as brinell hardness and sonic velocities were measured before and after shale samples were brought into contact with water-based fluids . between these measurements, swelling tests were performed to examine the sensitivity of shale to different water-based fluids . our unique 2-d strain indicator enabled us to measure swelling in two directions simultaneously . young’s modulus and poisson’s ratio were calculated from p and s-wave velocity data . a pressure transient technique was employed to measure the permeability of water-based fluid passing through a shale sample and capillary entry pressure . the measurement techniques and procedures presented in this paper provide a standard measurement protocol for the petrophysical characterization

ARMA 13-641

fluid-Dependent Weakening of chalk - lubrication of inter-Granular contacts due to fluid compressibility hedegaard, K. University of Bergen, NorwayTechnical University of Denmark, Denmark

the strength of high porosity, low permeability, and weakly cemented chalk is highly dependent on the type of saturating fluid . this paper proposes that a key factor in the mechanism behind fluid-induced weakening of chalk is the compressibility of the fluid in the friction-dominated inter-granular contacts . the hypothesis is based on the assumption that the fully drained porous chalk has immobile surface-bound fluid . in the inter-granular contact, this immobile fluid will work as a compressible buffer preventing the normal force to press the grains together, resulting in lubrication of the inter-granular contacts and thus in reduction of the inter-granular friction making shearing easier . a compressibility ratio, r, is proposed as a measure of the lubrication efficiency of the immobile surface-bound fluid at the inter-granular contacts, with r≈1 being the transition point between poor and good lubricity . the hypothesis is based on experimental results of triaxial tests on outcrop chalk samples from sigerslev Quarry, stevns, denmark . the samples were pre-saturated with fluids of five different compressibilities, and then loaded through pore-collapse stress .

ARMA 13-432

the behavior of carthage Marble and terratek Sandstone during high pressure, high temperature compression testsZhang, P., Mishra, B. and heasley, K.A.National Energy Technology Laboratory-Regional University Alliance (NETL-RUA), West Virginia University, Morgantown, WV, USA

a suite of high pressure, high temperature (hpht) triaxial compression tests were performed on carthage marble and terratek sandstone in order to provide accurate input properties for numerical models in support of the extreme drilling laboratory (xdl) of doe-netl . both rock types were tested in a servo-controlled triaxial test frame at temperatures that ranged from 25° c (77° f) to 180° c (356° f) and at confining pressure that varied from 34 .5 mpa (5 ksi) to 200 mpa (29 ksi) . results from the tests showed that the strength of both rock types increased with increasing confining pressure; however, there was a reduction in the confining stress induced strength increase with increase in


temperature . further the failure behavior was seen to transition from brittle to ductile as the confining pressure increased from 103 mpa (15 ksi) to 200 mpa (29 ksi) . ultimately, a multi-variable linear regression analysis of the test data was used to develop empirical formulae which define the relationship between the rock properties (failure strength, elastic modulus, poisson’s ratio, friction angle, cohesion and dilation angle) and the confining pressure and temperature .

ARMA 13-429

the impact of Surface charge on capillary pressure and Mechanical behaviour of chalk R. Ahsan1, M. Megawati1, A. hiorth1,2 and M. V. Madland1

1University of Stavanger, Petroleum Institute, Stavanger, Norway 2International Research Institute of Stavanger (IRIS AS), Prof. Olav Hanssensvei, Stavanger, Norway

the objective of the study is to investigate how the presence of sulfate in pore water not only affects the mechanical behavior of chalk, but, also how it affects wettability change and the capillary pressure curve . We present the spontaneous imbibition capillary pressure curves determined by the porous plate technique, mechanical test results, adsorption studies, and resistivity measurements which altogether demonstrate that a negative surface charge, resulting from sulfate adsorption from the pore water, impacts the oil production as well as the rock mechanical behavior of high-porosity chalk . na2so4 brine imbibed and/or flooded into chalk cores at 130 °c not only contributes to a significant increase in oil production, but also causes a significant reduction in bulk modulus and yield point compared with that of nacl brine at the same conditions . chemical analyses of core effluent show that calcite dissolution is unlikely to account for the increased oil production and the mechanical behaviour .

pOSter SeSSiOn: wellBOre StaBilityMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-294

analysis of Wellbore instability caused by Weak bedding-plane Slippage for arbitrary-oriented boreholes: theory and case StudyMoinfar, A.The University of Texas at Austin, Austin, TX, USATajer, E.University of Southern California, Los Angeles, CA, USA

Wellbore stability analysis can save millions of dollars by reducing non-productive time associated with borehole failures during drilling . We have developed an integrated approach to evaluate wellbore stability along any arbitrary well trajectory in the presence of weak bedding planes . We present a case study from the monterey formation in california, wherein a weak layer overlays the target reservoir and the buildup-section of horizontal wells started in this weak layer . the developed approach is used to show that the weak layer slippage is the main cause of severe drilling problems encountered in the field . the predictions of our wellbore stability modeling are consistent with field observations that modest deviations from a vertical well in the weak layer can result in severe drilling instabilities and also, horizontal wells drilled to the south-West in the field are more prone to borehole instabilities than those drilled to the north-east . finally, we recommend well trajectories to mitigate borehole instabilities caused by the weak layer slippage .


ARMA 13-434

numerical 3D Stability analysis of Wells Drilled through Salt Zones orozco, S.o., Fontoura, S.A.B. and Inoue, N. ATHENA – Computational Geomechanics Group, GTEP – Group of Technology in Petroleum Engineering PUC-Rio – Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil

drilling through salt zones is an important current endeavor in many areas offshore of brazil . the conventional well design workflow does not recognize the complex nature of the stress field near these salt bodies . therefore, a reliable assessment of the in-situ stresses must be carried out considering a field (global) scale of the problem and the presence of major structures in the overburden . the proposed stability analysis is carried out in three stages . firstly, a global finite element analysis is employed to evaluate the in-situ stresses at a global scale considering the geometry of a salt body . secondly, the global scale in-situ stresses are introduced in a local model, that we call Substructure, by using two proposed stress transfer techniques . finally, optimal mud weights are calculated combining numerical stress results with analytical equations . these two stress transfer techniques are also proposed for transferring stresses to submodels inside a global model domain for wellbore stability purposes .

ARMA 13-652

a numerical analysis of Wellbores in Shale with Viscoplastic behavior heidari Moghadam, M. Department of Civil Engineering, The University of Texas at Austin, Austin, Texas, USA

inaccurate analysis of shale time-dependent response to well boring results in an elevated cost and time to save the wellbores . shale creep behavior is not eliminated by measures adopted to preclude pore pressure dissipation . to accurately characterize the contribution of shale creep in the stability of open-hole sections, an advanced viscoplastic model is used and numerically implemented in a finite element model . the accuracy of the model and its numerical implementation is qualitatively validated by comparing the results of the analysis of a vertical borehole with the relevant field observations . the model can predict the evolution with time of the orientation of the maximum borehole closure . the model can also characterize the shale softening behavior as the mechanism underlying localized bulging of the shale formation into the wellbore . for the wellbore studied in the paper, the size of the bulges, as incipient falling cutting blocks, is shown to determine the open hole stable time .

ARMA 13-495

Self-excited axial Vibrations of a Drilling assembly: Modeling and experimental investigationKovalyshen, Y.Drilling Mechanics Group, CSIRO Earth and Resource Engineering, Kensington, WA, Australia

this paper deals with self-excited axial vibrations of a drilling assembly . in particular, an analytical model of selfexited axial vibration that accounts for regenerative effect is presented . the paper also introduces a state-of-the-art laboratory drilling equipment dubbed aspen . the experimental observations are shown to be in good agreement with the predictions of the analytical model . the paper also provides some insight into possible strategies of vibration detection during field operations .


ARMA 13-316

Wellbore trajectory planning for complex Stress States himmelberg, N. and Eckert, A. Missouri University of Science and Technology, Rolla, Missouri, USA

conventional wellbore trajectory planning is commonly based on an andersonian state of stress [sos] . based on various failure criteria the optimum well azimuth and inclination for a specific depth can be determined using stereographic projections of the safe mud weight window . for more complex geologic scenarios where the vertical and horizontal stresses are not principal stresses conventional wellbore trajectory planning has limitations . for an arbitrary non-andersonian sos safe trajectory orientations calculated for only a few locations along a well path will not be sufficient when determining an optimal trajectory for the entire well . in this paper a new methodology using the full stress tensor is developed to determine optimal well trajectories for complex in-situ stress scenarios . this study uses a 3d finite element analysis to simulate the sos based on an integrated 3d mem . the model yields the complete stress tensor at every location for a planned future well path . using standard equations to determine the wellbore sos for inclined wellbores the safe operational pressure window can be determined . this procedure is applied to multiple well trajectories of varying combinations of azimuth and inclination targeting a specific reservoir section .

ARMA 13-103

an objective Method for Wellbore Stability analysis Bai, M. Halliburton, Houston, Texas, USA

this paper proposes a new method for determining the quality of wellbore stability through an objective consideration of the cumulative effects of wellbore failure . the method combines the weighted functions of hole enlargement from a caliper measurement and calculated shear failure . the method is called the Wellbore Quality index (WQi) . unlike other methods, WQi assesses wellbore stability without being constrained by the failure mechanism (cause), regardless of whether it is mechanical, hydraulic, chemical, or operational . this is because using the hole-enlargement measurement is non-discriminative . consequently, WQi is effective even when limited data is available (e .g ., only a routine one-arm caliper log is available and the hole-enlargement mechanism is unknown) . When high-quality data is available (e .g ., oriented caliper measurements, image logs, pore pressure and fracture gradient measurements, and rock core testing results), WQi becomes a valuable and objective calibration tool for assessing wellbore instability . it demonstrates a significant improvement over conventional mechanism-biased wellbore stability analysis methods used to match field observations . furthermore, when using dimensionless analysis with filtering, WQi can differentiate the effect of each failure mechanism and determine the underlying physics of the wellbore failure . this is because the scaling of the wellbore failure tends to be mechanism-dependent and the associated failure dimensions are often clustered in particular regions .


pOSter SeSSiOn: pOre preSSure anD StreSSMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-110

Scanning electron Microscopy (SeM) and profilometer Scanning Microscopy to estimate in Situ Stresses in a Dolomite core SpecimenMahbaz, S.B., Goddard, A. and Dusseault, M.B.University of Waterloo, Waterloo, Ontario, Canada

knowledge of the in situ stress state is an essential element of a geomechanics study . current methods of evaluating in situ stress are based on direct and indirect measurements on the centimeter to kilometer scale . a new core-based technique to estimate in situ stress magnitudes and orientations is tested in this study . the method is based on the nanometer to micrometer scale study of samples to identify nano-features and micro-features that have a direct or indirect relation to in situ stress magnitudes and orientations . a dense dolomite core was divided into three parts; each sample was loaded with a different uniaxial load ranging from 0-45mpa, and then scanning electron microscope (sem) images were taken and analyzed for sections from each of the samples . more specifically, microcracks and micro-laminations were detected, classified, and quantified at the nano- to microscale . lastly, the surface roughness of the sample sections was studied by taking advantage of profilometer scanning microscope images in relation to the applied stress load . this paper details the experimental procedures used and the results obtained to date .

ARMA 13-141

Minimum horizontal Stress profile from Rock Strength for Montney formation in north east british columbia canadaSong, L. and G. harelandUniversity of Calgary, Calgary, AB, Canada

this study utilized log data, drilling data and core reports to generate the formation rock strength which was then used to calculate sh for a montney well . three methods were used . the first method employed onyia’s equation which incorporates sonic velocity from log data to calculate the continuous rock strength value . the second method uses the andrews’ equation, which uses both sonic velocity and porosity data . the third method uses drilling, bit and lithology data to generate continuous rock strength with commercially available drilling simulation software . the minimum horizontal stress is calculated using the harikrishnan method which iterates minimum horizontal stress (sh) from angle of internal friction generated from the rock strength value . closure pressure from fall-off injection test is used as a calibration point to acquire the tectonic stress . sh calculated from onyia and andrews’ rock strength show very little signature . the sh calculated from the drilling software rock strength shows equivalent value with all other methods for montney formation . sh generated from rock strength has a proportional relation with the value of rock strength, the higher the rock strength, the higher the stress . comparisons are made between the sh profiles generated from the elastic moduli i .e . young’s modulus and poisson’s ratio and the sh profile generated from the rock strength value .


ARMA 13-125

effect of pore pressure changes on formation fracture pressure in non-hydrostatic Stress field Mojtaba P. Shahri, Stefan Z. Miska, Mengjiao Yu and Mehmet E. ozbayoglu The University of Tulsa Drilling Research Projects, Tulsa, OK, United States

there has been an increasing consciousness regarding to the stress changes associated with reservoir depletion as the industry moves toward more challenging jobs in deep-water or depleted reservoirs . these stress changes have a significant impact on the design of wells in these situations . therefore, accurate prediction of reservoir stress path, i .e ., change in horizontal stresses with pore pressure, is of vital importance .

in this paper, a new formulation of stress path is developed that enable us to predict the effect of pore pressure on both minimum and maximum horizontal stresses in the presence of non-hydrostatic stress field for future well design consideration . according to the results, change of minimum horizontal stress with pore pressure is always larger than the change of maximum horizontal stress . non-equal change of horizontal stresses increases the difference between them during production history . using the new formulation, we are able to find the effect of pore pressure on formation fracture pressure in deviated wells, as well . fracture initiation pressure change with pore pressure is larger parallel to the direction of maximum horizontal stress . thus, we would have less wellbore instability problems if we drill toward the minimum horizontal stress direction after depletion .

pOSter SeSSiOn: reServOir geOmeChaniCSMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-150

Stress analysis and Wellbore Stability in Unconventional Reservoirs Mehdi ostadhassan1, Steve Benson1, Siavash Zamiran2 and Bailey Bubach3

1Dept. of Petroleum Engineering, University of North Dakota, Grand Forks, ND, USA 2Dept. of Civil Engineering, Science and Research Branch, Islamic Azad University, Markazi, Iran3Dept. of Geology & Geological Engineering, University of North Dakota, Grand Forks, ND, USA

this study will provide insight to evaluate the potential risks involved with the alteration of in situ effective stresses around the borehole and the risks associated with the reservoir pressure decline . We studied how years of production and reservoir depletion may cause future major geological hazards in the area of study . Wellbore instability and stress distribution analysis around a vertical borehole is also carried out in the bakken formation including elastic anisotropy of the layer . We calculated the magnitude of maximum principal horizontal stress as a major input parameter through a new method . this study shows the importance of geomechanical modeling in the petroleum industry with the recent growth of drilling plans in unconventional reservoirs as a novel source of energy where many of them are fine layered, anisotropic and naturally fractured . for this study, dynamic elastic properties were collected through the bakken formation using advanced sonic logs . the interpretation of these data is significant in estimating the rock strength, pore pressure, and in situ stresses . the measured dynamic elastic moduli were converted to static ones and were used as input into poroelasticity equations to calculate the magnitude of the horizontal principal stresses . the direction of the maximum principal horizontal stress was determined to be n70e by analyzing fast shear azimuth (fsa) using major fractures which have caused more than 20% shear anisotropy . finally stress analysis and wellbore stability were performed and compared in the current state of the reservoir stress state and after 5 years of production . stress polygons are created in the reservoir (horizontal section of the well) to predict future natural hazards . the results confirm the possible occurrence of normal faulting in the region and existence of borehole breakouts after years of production .


ARMA 13-306

numerical Modeling of tensile thermal Stresses in Rock around a cased Well caused by injection of a cold fluidLavrov, A. and Cerasi, P.SINTEF Petroleum Research, Trondheim, Norway

drilling of high pressure/high temperature (hpht) wells and injection of liquefied (cold) co2 into underground formations produce thermal stresses in the surrounding rocks . the induced tensile stresses may exceed the tensile strength of the formation or other materials (casing, cement) . this may create tensile fractures affecting the well integrity . finite-element modeling of cooling-induced thermal stresses around a cased injection well was carried out . the formation was a sandstone-shalesandstone or shale-sandstone-shale sequence . the results demonstrated that tensile hoop stresses developed in the rock with relatively high thermal expansion coefficient (shale) upon cooling by 40-50°c . a contrast in the coefficient of thermal expansion between different strata played a key role in the development of tensile stresses . the contrast in the young’s modulus, on the other hand, had little effect . upon cooling by 80°c, the tensile hoop stress zone extended about 10 cm from the cement into the surrounding shale, and the stresses were sufficiently high to fracture the rock .

ARMA 13-611

Geological and Geomechanical characterization of in situ oil Sands caprock in the athabasca oil Sands area, alberta, canadahaug, K.M. and Mei, S.Energy Resources Conservation Board/Alberta Geological Survey, Edmonton, Alberta, CanadaGreene, P.Energy Resources Conservation Board, Calgary, Alberta, CanadaSchneider, C.L.University of Alberta, Edmonton, Alberta, Canada

although the majority of in situ oil sands schemes in alberta do not encounter significant reservoir containment problems, there have been documented occurrences of fluid releases because of compromised caprock seals . the energy resources conservation board recognized the need for a greater understanding of the caprock and a project to characterize the geological and geomechanical factors was initiated . the objective of this project is to characterize the units above and below bitumen zones to determine which geological factors may affect the quality of the caprock seal . mapping of the cretaceous strata focuses on the spatial extent and thickness of the lower clearwater shale unit overlying the mcmurray formation reservoir . mapping of the underlying devonian strata is targeted at better understanding the potential effects of salt dissolution and collapse of overlying strata on the integrity of the caprock seal . in addition, this project examined the stress regime above the in situ operations in the study area to evaluate the effects the operations would have on the stress regime quality of the caprock seal . initial numerical model results demonstrated that stress reduction above an in situ operation may lead to the creation of vertical fractures if the fracture gradient is exceeded .


ARMA 13-697

evaluation of numerical Simulation procedures for prediction of Solids production in oil producing Wells André Luís Müller Research Engineer, Tecgraf, Pontifical Catholic University, Rio de Janeiro, Brazil Eurípedes do Amaral Vargas Jr. Associate Professor, Dept. of Civil Engineering, Pontifical Catholic University, Rio de Janeiro, Brazil Clemente José Gonçalves Senior Engineer, Research Division (Cenpes), Petrobras, Rio de Janeiro, Brazil

solids/sand production is a serious problem faced by the petroleum industry during production stages . particles or groups of particles of formation rock are produced together with oil or gas being pumped which has highly damaging effects on pipes and valves . solids production can be caused by several factors including the stresses developed around the boreholes/perforations, the drawdown, mechanical and hydraulic properties of the formation rock and the type of containment measures adopted . numerical simulation of sand/solids production presents a considerable challenge as intricacies of failure processes must be correctly simulated in order to correctly predict rates of solids production . the present paper is a sequel to the paper presented in the 2011 arma symposium (muller et al [1]) . the 2011 paper presented the development of a finite element based program for simulating the process of solids production, considering fluid-mechanical coupling in standard and cosserat elasto-plastic continua in a hypothetical borehole . the present paper presents results from the simulation of two observed failure modes in laboratory experiments using the program developed in [1] . the analyzed modes are the slit type mode and the slip lines type mode . unlike the 2011 paper, the present paper focuses on hydrostatic states of stress only .

ARMA 13-535

temperature Dependence of Ultrasonic Velocities in ShalesBauer, A., holt, R.M., Bakk, A., Fjær, E. and Stenebråten, J.SINTEF Petroleum Research, Trondheim, Norway

acoustic velocities in shales show a relatively strong temperature dependence, which has to be accounted for in the interpretation of time-lapse seismic if temperature changes are anticipated in caprocks or intra-reservoir shales, e .g . in thermal enhanced oil recovery operations or subsurface co2 sequestration . as shown in the present study, the temperature dependence of ultrasonic velocities in shales can be described by the gassmann fluid-substitution model by assuming a linear temperature dependence of the rock matrix . the cause for this temperature dependence is not understood yet . sintef’s shale rock physics model predicts the right trend when assuming a temperature dependence of the bound-water stiffness similar to that of ice . it is also likely that the temperature dependence of velocities is frequency dependent and that temperature changes result in different velocity changes at seismic, sonic, and ultrasonic frequencies .


pOSter SeSSiOn: rOCk SlOpeS iiiMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-237

Mechanisms of falling Rock formation at Steep Slope due to temperature perturbationS.S.S.S.M. Keppetipolaa1, Yoshiaki Fujii1 and Nariaki Kodamab2

1Rock Mechanics Laboratory, Faculty of Engineering, Hokkaido University, Japan2Hakodate National College of Technology, Hakodate, Japan

to clarify the mechanisms of formation of falling rocks, a 2d finite element modeling was performed to numerically analyze natural stress development at a fracture tip for a rock mass (20 m x 20 m) with a rock beam of 3 .0 m thickness and 10 m long . the cyclic temperature variations between 10 to 40ºc (warm region) and -10 to 20ºc (cold region) were assumed . in the warm region, the fracture closure due to difference in thermal expansion in the rock beam was prohibited inducing a vertical bending tensile stress (σy) in summer while in winter, the fracture opened due to difference in thermal shrinkage in the rock beam inducing a horizontal tensile stress (σx) at the fracture tip . in the cold region σy was also observed in winter due to fracture closure by difference of freezing expansion in the rock beam was observed . the σx developed during both regions were large enough for the fracture propagation . the repeated occurrence of σy would result in breakage of the rock beam from its bottom by either subcritical or fatigue crack growth ensuing a rock fall at a steep rock slope .

ARMA 13-337

Study on Stability of Slope located at the Down-Road through calculated Wetness index of Valley terrainhonggyun Kim, ho-Bon Koo, Young-Suck oak and Sang-hee ShinKorea Institute of Construction Technology (KCIT), Goyang, Kyonggi-Do, Korea

the road in mountainous or riverside area often has the slope of down-road and up-road . the stability of down-road slope is dependent on intensity of valley water at upper area of the road and wetness index was estimated to represent the stability quantitatively . Wetness index of the valley at upper area of the road connected to the collapsed slope was 9-10 .5, indicating the higher value than surroundings which seemed to be attributable to higher intensity of water flow . the collapse of complex failure pattern occurred on investigated slope and as a result of stereographic projection analysis, the sign of plane, wedge and toppling failure was perceived . according to safety factor by limit equilibrium analysis, the safety factor of plane and wedge failure was less than reference value when applying 50% of groundwater level . Weakness or failure of down-road slope is affected by water flow intensity at upper area of the road and effective water flow control is a must for stability .

ARMA 13-356

Stability analysis through a Step-by-Step infiltration interpretation at Granitoid Soil Slope in koreaho-bon Koo, Seung-hyun Kim, Jong-hyun Lee and Jung-Yup LeeKorea Institute of Construction Technology, Goyang City, Gyounggi Province, South KoreaJong-oh KimMinistry of Land, Transport and Maritime Affairs, Government Complex Sejong, Sejong-City, South Korea

cut slopes are newly made during new road constructs or a prior road expands . however, if the excavations are in progress unlike the initial design, the collapse should be often occurred . granitoid rocks are generally


high-quality rock in the view of a geotechnical outlook, because they rarely contain systematic joints or fault zones . although the rock type at the sanhak site is granodiorite, a collapsed slope has a deep soil layer and shows no residual structures such as discontinuities or faults . xrd, granularity, and compaction test, quartz, plagiclase, k-feldspar and mica is detected by semi-quantitative analysis with xrd as well as illite, kaolinite, chlorite, vermiculite and smectite . infiltration interpretation using seep/W and slope/W is shown as progressing remedial method with scrutiny and stability analysis . during the rainy season, uncertainty is reduced with stability analysis combined with penetration interpretation . to study the step-by-step infiltration interpretation using seep/W and slope/W of the slope, variation in pore-water pressure, and the factor of safety considering three cases in rainy condition; current cross-section, initial planning cross-section, revised planning cross-section . the groundwater level is risen up to 20 m when the rainfall duration is long . in the initial plan, the safety factor for 2days is sufficient, but the safety factor for 4days is insufficient based on the rainfall duration . in the revised plan, however, the safety factor is secure for 4 days on rainfall duration . therefore, a slope degree as 1:1 .8 should be maintained for ensuring the permanent stability at the sanhak site .

ARMA 13-591

Discussion of Risk factors for triggering of Rockslide avalanche Dams in pakistan, afghanistan, and tajikistan and Mitigation Strategies J. David Rogers Missouri University of Science & Technology, Rolla, MO, USA M. Farooq Ahmed Missouri University of Science & Technology, Rolla, MO, USA On leave - University of Engineering and Technology Lahore, Pakistan

landslide dams have posed a significant, but infrequent threat to mankind because they usually occur in mountainous areas that are sparsely populated . in tectonically active areas like the hindu kush, pamir, and himalayan ranges of pakistan, afghanistan, and tajikistan, most landslide dams are triggered by earthquakes, although cumulative precipitation has also triggered deep-seated landslides . usoi dam (1911) in tajikistan is presently the highest landslide dam in the world, and is still filling more than 100 years after it formed . the historic lake shewa landslide dam in afghanistan poses a major threat to thousands of people living downstream . northern pakistan is also plagued by landslide dams because it is a region of high seismicity with severe seasonal precipitation cycles (monsoons) . the partial breaching of the seismically triggered hattian bala landslide dam (formed in 2005) and the attabad landslide dam (formed in 2010) signify the importance of developing viable mitigation techniques because the emergency spillway excavations may not be sufficient to protect the toes of these dams from erosion .

pOSter SeSSiOn: in Situ StreSSMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13- 323

the concept of entropy of information linked to the concept of Sensitivity numbers, for optimizing overcoring testsde Mello Franco, J.A. Rock Mechanics Engineering Consultant, Rio de Janeiro,RJ, Brazil


Luis Arnaldo Mejia Camones Pontifical Catholic University, Rio de Janeiro,RJ, Brazil Vargas Jr., Eurípides do Amaral Pontifical Catholic University, Rio de Janeiro,RJ, Brazil

this paper aims at showing the utilization of the concept of sensitivity numbers in order to optimize field tests so that the reliability of the results obtained is maximized . this will be done with the help of the entropy of information concept, as developed by [1], thoroughly reviewed and applied by de mello franco, [2] to a continuous homogeneous isotropic and linearly elastic medium . in de mello franco, [2] the concept of sensitivity numbers is adapted to overcoring problems and linked to the previous entropy of information concept . this paper presents this development in which these concepts are utilized for optimization of the distribution of rosettes, with a previously chosen layout, performed the overcoring tests in continuous rock mass . a synthetic case is modeled, sensitivity numbers are calculated, their entropy number is valuated and the best positions for the rosettes are consequently determined .

pOSter SeSSiOn: grOutingMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-156

Research on the Detection Method of bored pile bottom Sediment thickness han Zengqiang, Wang Chuanying, hu Sheng and hu Qian State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, China

based on theoretical analysis and experimental tests, a detection method of bored pile bottom sediment thickness was studied . further, a penetration test system applied to detect bored pile bottom sediment thickness was developed based on pile bottom sediment definition and its mechanical property . embedded arm computer was used to collect data in this system and system control software was developed by microsoft embedded visual c++ 4 .0 . by detecting interface between sediment and natural clay, pile bottom sediment thickness was measured . finally, this system’s precision and environmental requirement were analyzed by field test . the result showed that this method can complete accurate measurement of sediment thickness with only 0 .01~0 .09cm error and little effect on test environment .

ARMA 13-233

Development of Grouting Management Support System and its application to actual Dam GroutingShinji UtsukiHAZAMA Corporation, Tokyo, Japan Yoshitada MitoKyoto University, Kyoto, Japan

according to the technical guide for grouting method for dam construction in Japan modified in the year 2003, one of the key issues for grouting is quality assurance and effectiveness by minimizing the amount of injected grout . hence, the grouting management support system was newly developed by combining joint


density diagram and geostatistical simulations . in this system, the joint density diagram was used to determine most effective direction for the grout injection boreholes and the hydraulic conductivity fields before/after grout injection were estimated by geostatistical simulations . in this paper, the newly developed system was introduced and applied to the actual dam construction site .

pOSter SeSSiOn: rOCk teStingMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-120

parametric Study of Damage controlled test to predict brittle failure of RocksCheon, D.S., Park, E.S., Jung, Y.B. and Lee, T.J.Korea Institute of Geoscience & Mineral Resources, Daejeon, Korea

to predict the brittle failure experienced at the underground research laboratory (url) in canada, numerical simulations were carried out . however, none of the suggested modeling approaches predicted a failure zone that matched the shape of the v-shaped notch . in order to solve this problem, a new model, the cohesion weakening-friction strengthening (cWfs) model, was proposed . in applying this model, determining the cohesion and friction damage strain limits is crucial . these limits are obtained from a damage-controlled test . in practice, the limits determined from this test are identical . in theory, however, the friction damage strain limit is equal to or greater than the cohesion damage strain limit . moreover, at times the test cannot be successfully performed because of the brittle nature of the rocks . the purpose of this paper is to evaluate the proper limits for predicting brittle failure . the limits were experimentally determined for several rocks, and numerical simulations were carried out based on the obtained values . the experiments and simulations show that the adequate limits are 0 .1 - 0 .5 % for cohesion damage strains, the difference between the cohesion and friction damage strain limits are 0 - 0 .17 % .

SeSSiOn 13: COupleD prOCeSS mODelS iMonday, 24 June, 4:30 pm – 6:00 pmChairs: Ghazal Izadi, Derek Elsworth

ARMA 13-368

computational investigation of trends in initial Shut-in pressure during Multi-stage hydraulic Stimulation in the barnett ShaleMcClure, Mark W.University of Texas, Austin, TX, USAZoback, Mark D.Stanford University, Stanford, CA, USA

in field data from multiple stage hydraulic fracturing treatments of five horizontal wells in the barnett shale, the initial shut-in pressure (isip) tended to increase along the wellbore as the stimulation of each well progressed . the increasing trend was less prominent in wells where there was greater shut-in time between stages . We investigated these trends using (1) a hydraulic fracturing simulator that couples fluid flow and fracture deformation in discrete fracture network models and (2) a simple expression derived from


the scaling of induced stresses with distance . based on the scaling relationship, we found that if stress shadowing alone caused the increasing trend in isip, then isip should have approximately plateaued after a few stages . in contrast to this prediction, isip in three of the wells escalated across the entire lateral . We conclude that stress shadowing alone cannot account for these trends . in a simulation performed with the hydraulic fracturing model, stress shadow and bottom hole pressure dropped over time after shut-in despite the fact that fluid leakoff into the matrix was not included in the simulation . the weakening of stress shadow occurred because of time-dependent spreading of fluid into a larger number of more spatially dispersed, open fractures .

ARMA 13-556

creep behavior of coal and Shale Related to adsorption of Reservoir fluidshol, S. and Zoback, M.D.Stanford University, Department of Geophysics, Stanford, CA, USA

hydraulic fracturing operations in unconventional gas reservoirs generally achieve a fast, drastic increase of permeability and production rates . although modeling of the underlying short-term mechanical response of these reservoirs has proven successful via conventional geomechanical approaches, predicting long-term behavior is still challenging as coal and shale layers interact with reservoir fluids, and thereby deform in a time-dependent manner . this time-dependence, and hence the impact on long-term reservoir performance, are presently not understood . in this paper, we propose a theoretical/thermodynamic model that explains the observed compaction creep as a serial coupling between 1) stress-driven desorption of the fluid species, 2) diffusion of the desorbed species out of the solid, and 3) consequent shrinkage . comparing our model with observations made in the laboratory shows a qualitative agreement with mechanical data on co2-saturated coal and pure illite, which provides confidence in the approach chosen . the adsorption-diffusion mechanism described here may be important in solving problems encountered during hydraulic fracturing of (adsorbing) clay- and organic matter-rich horizons .

ARMA 13-404

incorporating the electrokinetic effects into the poroelastic Wellbore and cylinder problem for applications in Shale Drilling and characterization Tran, M.h. and Abousleiman, Y.N. The Integrated PoroMechanics Institute, University of Oklahoma, Norman, OK, USA

in this work, the anisotropic porochemoelectroelastic theory is presented and applied to derive the solutions for an inclined wellbore drilled in transversely isotropic shale formation . the solutions for some common laboratory testing conditions such as the triaxial test, Ko test, etc . are also given . the analyses show that the pore pressure diffusion is affected not only by the hydraulic permeability, solute diffusion coefficient, and the membrane efficiency, but also by the electrokinetic contribution from the presence of shale negative fixed charges that manifest itself as an osmotic pressure at the mud-shale interface due to the donnan equilibrium condition . the donnan pore pressure couples with the load-generated and the activity-generated pore pressure can complicate the evolution of pore pressure, and effective stress distributions in the shale . since wellbore stability and laboratory analyses are often performed based on effective stresses, ignoring the porochemoelectroelastic behavior of shale will mislead the predictions and assessment of potential problems in field operations and lab interpretations .


ARMA 13-575

a 3-Dimensional fracture propagation Model for long-term Water injection hwang, J. and Sharma, M.M. The University of Texas at Austin, Austin, Texas, USA

a new water injection well model with fully 3-dimensional fracture propagation is proposed . the model uses an improved leak-off calculation based on the particle filtration model as the conventional fluid leak-off models do not work well . the extent of fracture growth and the relevant water injectivity were predicted precisely by combining these improvements with a model for the capture of the suspended particles on the fracture face, the in-situ stress changes induced by poro- and thermo-elastic effects, and the analytical fluid flow model in the reservoir . the simulation model is now capable of predicting the fracture propagation into the bounding layers . the fluid leak-off rate at a specific injection time and location is controlled by the degree of formation damage on the fracture face caused by particles .

ARMA 13-436

the influence of thermal- hydraulic- Mechanical- and chemical effects on the evolution of permeability, Seismicity and heat production in Geothermal Reservoirs Ghazal Izadi1, 2 and Derek Elsworth1 1Baker Hughes Inc. 2Department of Energy and Mineral Engineering, EMS Energy Institute and G3 Center, Pennsylvania State University, University Park, Pennsylvania, USA

We utilize a numerical model to examine thermal-hydrologic-mechanical-chemical processes leading to the evolution of induced seismicity in naturally fractured dual-porosity media . We use a continuum model to examine the thermo-hydro-mechanical behaviors due to variation in fluid pressure and thermal stress on different fracture networks within a prototypical enhanced geothermal system (egs) . discrete penny-shaped fractures are seeded within the reservoir volume with random orientations and a gaussian distribution of lengths . failure is calculated from coulomb strengths . energy release magnitude is utilized to obtain the magnitude-moment relation for induced seismicity by location and with time . this model is applied to the potential newberry egs field (usa) by assuming fracture sizes of 10 to 1200 m . models are classified by their conceptualization of the fractured reservoir geometry as both networks of discrete fractures and with equivalent fractured media as fill-in . this model is applied to a doublet injector-producer to explore the spatial and temporal triggering of seismicity for varied fracture network geometries at shallow (2000m) and deep (2750) depths . first we consider the identical network of large fractures (300 m fracture spacing) in both shallow and deep zones and infilled with smaller (10-200m) more closely spaced fractures with densities of 0 .5 m-1 in the shallow zone (b) and of 0 .9 m-1 in the deeper zone d . then we apply a different network where the spacing of the large fractures are halved (~150m) in both zones but with the small closely spaced fractures retained with densities of 0 .5m-1 in the shallow zone (b) and 0 .9m-1 in the deeper zone (d) . We evaluate the magnitude of seismic events that vary from -2 to +1 .9 with the largest event size (~1 .9) corresponding to the largest fracture size (~1200m) within the reservoir . We illustrate that the model with the higher fracture density generates both the most and the largest seismic events (ms =1 .9), thus the evolution of seismicity is quickest and migration of seismic events is fastest with radius from the injector compared with the case for more widely-spaced fractures . rate of hydraulic and thermal transport has a considerable influence on the amount, location and time of failure and ultimately event rate . thus the event rate is higher when the fracture network has the larger density (0 .9m-1) with closely-spaced fractures (150m) and is located at depth where the initial stresses are highest (zone d) . finally, we evaluate the thermal energy recovered during the production and the results show that the highest thermal energy is recovered from the deeper zone (d) with the more closely-spaced fractures (150m) .


ARMA 13-466

applications of partial fluid-Mechanical coupling in the Reservoir Geomechanics Scope Fontoura, S.A.B., Inoue, N., Lautenschläger, C. E. R. and Righetto, G. L. ATHENA – Computational Geomechanics Group, GTEP – Group of Technology in Petroleum Engineering PUC-Rio – Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil

this work presents some applications of partial fluid-mechanical coupling methodology developed by the computational geomechanics group athena/gtep – puc-rio . the methodology consists in an interrelation between commercial simulators of flow and stress, based on the consistent inclusion of new terms in flow equation to approximate fully coupled results . the developed scheme was compared with the results of software available in the oil industry and of fully coupled analysis, showing the methodology ruggedness . models were built with a fault zone considering partially coupled fluid-mechanical simulations, assigning the mohr-coulomb yielding criterion to the fault zone . the plasticity model showed consistent results with the process of reactivation . in the scope of hydrocarbon recovery, the methodology proved to be capable of simulating coupled process in a blackoil reservoir, indicating that the gas generation is affected by the geomechanical effect . the use of one-way partial coupling scheme, widely employed in the oil industry, showed results quite different when compared with the two-way partial coupling scheme, which was developed in a more rigorous way . the rigorous and reasoned choice of exchange parameters between flow and stress simulators is crucial in obtaining reliable results .

SeSSiOn 14: geOmeChaniCal ChallengeS aSSOCiateD with geOthermal Drilling, StimulatiOn anD prODuCtiOn iMonday, 24 June, 4:30 pm – 6:00 pmChairs: Stephen Bauer, Greg Stillman

ARMA 13-533

coulomb Stress change During and after tensile fracture opening in a Geothermal Reservoir Urpi, L., Blöcher, G. and Zimmermann, G. GFZ German Research Centre For Geosciences, Potsdam, Germany van Wees, J.-D. and Fokker, P. Netherlands Institute of Applied Geosciences TNO, Utrecht, The Netherlands

stress shadowing and the ratio of shear to normal stress in the rock surrounding a newly created tensile fracture are investigated . shearing on plane of weakness near the stimulated volume can be inhibited or promoted by change in poro- and thermo-elastic stress, while pore pressure increase tends to promote failure, via reduction of effective stress, when acting on a failure plane . a numerical model has been used to calculate the coupled poro-elastic response and it has been verified against analytical solution available in literature . the triggering of seismicity, by pore pressure change and stress changes, can be delayed by stress shadowing with respect to the expected occurrence triggered by pore pressure diffusion only . different shut-in schedule may be employed to mitigate unwanted seismicity response to stimulation treatment, according to our result an important role can be played by proppants in keeping the fracture open and therefore keeping the stress shadow in place while the overpressure diffuses .


ARMA 13-166

experimentation with hydraulic impulse Stimulation in a Scaled enhanced Geothermal Systems ReservoirFrash, L.P., Gutierrez, M.S. and hampton, J.C.Colorado School of Mines, Golden, CO, USA

an effective new hydraulic stimulation technique has been successfully tested on a recent laboratory simulated enhanced geothermal systems (egs) reservoir . the simulated reservoir consisted of a large 300x300x300 mm3 granite specimen subjected to an elevated boundary temperature of 50 ºc and true-triaxial confinement stresses of 12 .5, 8 .3, and 4 .1 mpa for the vertical, maximum horizontal, and minimum horizontal stress directions respectively . a scale injection borehole, traditional hydraulic fracture stimulation treatment, and production borehole were implemented while reservoir conditions were maintained throughout . the initial reservoir was found to give sub-optimal production rates but the execution of a new low-volume overcritical pressure pulse (lvop) stimulation treatment resulted in significant production rate improvement and an associated two-order magnitude improvement in effective permeability . details on the new method as well as supporting pressure, flow, strain, and acoustic emission data are provided . the results from an extensive series of injection-production tests are also presented in support .

ARMA 13-222

Seismic and aseismic Motions Generated by large Scale fluid injections in a Deep Granite MassifCornet, F.h.Institut de physique du Globe-Strasbourg, France

large scale hydraulic stimulations have been conducted at various depths on the geothermal site of soultz-sousforêts, in eastern france . in all cases these stimulations have generated microseismic activity which has been monitored with both a surface and a downhole network . this monitoring has shown that depending upon the relative magnitude of the pore pressure with respect to the local minimum principal stress magnitude, four different mechanisms control flow of water in such granite masses: diffusion through a poro-elastic rock mass or diffusion in preferential directions controlled either by slip on preexisting fractures, or by the development of fresh fracture zones, or by hydraulic fracturing . more importantly, this diffusion process induces large scale non seismic motions that, in turn, influence the seismic activity, in particular when injection stops .

ARMA 13-249

Development of a neutron Diffraction-based Strain Measurement capability for triaxial loading conditions Polsky, Y., Dessieux, L., An, K., Anovitz, L., Bingham, P. and Carmichael, J. Oak Ridge National Laboratory, Oak Ridge, TN, USA

understanding incipient failure conditions associated with the hydraulically- induced fracture of rock is critical to the realization of enhanced geothermal systems . the knowledge of critical stresses in particular defines the basis for rock failure and fracture initiation in all models of fracture propagation . the complex composition of rock requires extensive sample testing to produce a large number of stress states in order to comprehensively define the rock failure envelope . the typical tests performed do not directly measure stresses or strains within the materials and generally measure either bulk deformations or deformations of exposed surfaces . this paper describes the development of a neutron-diffraction based strain measurement technique that will permit the mapping of the lattice strains and macroscopic stresses within a geological material in a triaxial stress condition . it is believed that this capability will provide a powerful tool that


facilitates the investigation of a number of rock mechanics topics including the development of improved rock failure theories, the study of unusual rock deformation modes and the primary application interest of the authors, improved rock hydraulic fracture models .

ARMA 13-608

Modeling Shear Stimulation of the Desert peak eGS Well 27-15 Using a coupled thermal-hydrological-Mechanical Simulator Dempsey, D., Kelkar, S. and Lewis, K. Los Alamos National Laboratory, Los Alamos, NM, USA hickman, S. USGS, Menlo Park, CA, USA Davatzes, N. Temple University, Philadelphia, PA, USA Moos, D. Baker Hughes Inc., Palo Alto, CA, USA Zemach, E. Ormat Technologies Inc., Reno, NV, USA

a numerical model has been developed to describe injectivity improvements at well 27-15 in the desert peak geothermal field, nevada, under shear stimulation conditions . a mohr-coulomb failure criterion, coupled with an empirical fracture permeability law based on laboratory experiments, describes permeability evolution of a fractured rock volume under applied pore pressure and stresses, including thermal contributions . the model includes synthetic fracture populations acted on by an ambient stress field based on well-bore image logging and in situ stress measurements from well 27-15 . the permeability model is implemented in the software code fehm (finite element heat and mass transfer) and applied to the problem of injection at well 27-15 for four pressure steps less than the least principal stress . the calibrated model matches measured injection rates at all four stimulation pressures (1 .5, 2 .2, 3 .1 and 3 .7 mpa), capturing the timing and magnitude of injectivity increases observed during the 3 .1 mpa step . for the observed extensional stress state and under intermediate injection pressures, the model initially favors greatest permeability enhancement parallel to the maximum horizontal principal stress, a moderate vertical enhancement, and a smaller gain parallel to the minimum horizontal principal stress .

ARMA 13-279

a flow Model of the Deep Geothermal Reservoir of Soultz-Sous-forêts (france) Gentier, S., Rachez, x., Peter - Borie, M. and Loubaud, M. BRGM, Orléans, France

a dfn model (discrete fracture network) built on the basis of fracture data and integrating the regional structural knowledge, allows the reproduction of results of a tracer test performed during a hydraulic circulation test between three boreholes at a depth of 5000 m at the soultz-sous-forêts site . this model highlights the role of the various fracture sets in the understanding of the flow between the deep boreholes and the importance to build a discrete fractures model on the basis of probabilistic analysis of the fracturing data obtained from the well imageries . on the basis of this model, which is compatible with the results of the tracer tests which have been performed since 2005, a global model of the site of soultz-sous-forêts can now be envisaged .


SeSSiOn 15: geOlOgiC repOSitOry iSSueS fOr nuClear waSte DiSpOSalMonday, 24 June, 4:30 pm – 6:00 pmChairs: Frank Hansen, Jose Arguello

ARMA 13-456

benchmark calculations of the thermo-Mechanical behavior of Rock Salt– Results from a US-German Joint projecthampel, A.Scientific Consultant, Mainz, GermanyArgüello, J.G. and hansen, F.D.Sandia National Laboratories, Albuquerque, New Mexico, USAGünther, R.M., Salzer, K. and Minkley, W.Institut für Gebirgsmechanik GmbH (IfG), Leipzig, GermanyLux, K.-h., herchen, K. and Düsterloh, U.Technische Universität Clausthal (TUC), Clausthal-Zellerfeld, GermanyPudewills, A.Karlsruher Institut für Technologie (KIT), Karlsruhe, GermanyYildirim, S., Staudtmeister, K., Rokahr, R. and Zapf, D.Leibniz Universität Hannover (LUH), Hannover, GermanyGährken, A., Missal, C. and Stahlmann, J.Technische Universität Braunschweig (TUBS), Braunschweig, Germany

since 2004, three Joint projects on the comparison of constitutive models for the thermo-mechanical behavior of rock salt have been performed . the general objectives are to document, check, and compare the advanced models and modeling procedures, to validate their suitability for numerical simulations and reliability, to increase confidence in the results, and to enhance the acceptance of conclusions . this contribution focuses on the us-german collaboration in the third project phase since october 2010 with a check and comparison of the modeling of the temperature influence on the deformation behavior of rock salt . this is of particular importance for the design, operation, and evaluation of the long-term safety of underground repositories for the disposal of high-level radioactive waste in rock salt . examples of results from specifically performed laboratory tests, from recalculations of the tests, and from benchmark calculations of a heated borehole in the asse ii salt mine in germany are introduced . results from the borehole calculations with the considered models are compared with each other and with in-situ measurements . they demonstrate that the models are appropriate for modeling the thermo-mechanical deformation behavior of rock salt .

ARMA 13-370

Revisiting the 1980’s Wipp Room D and b in-Situ experiments: performing thermo-Mechanical Simulations of Rock Salt Using a State-of-the-art code Suite Argüello, J. Guadalupe and Rath, Jonathan S. Sandia National Laboratories, Albuquerque, NM, USA

several “thermal/structural interactions” full-scale in-situ experiments were fielded at the Waste isolation pilot plant in the mid 1980’s . data from two of these experiments, the mining development test (room d) and the overtest for simulated defense high-level Waste (room b), have been used previously to help


validate the legacy constitutive models and computer codes used to assess the performance of the disposal facility prior to its licensing and operation . since then, approximately 30 years of software and hardware advances have yielded efficient software frameworks and enabling tools/infrastructure to produce a new generation of high-fidelity simulation tools . one such current state-of-the-art modeling capability is the computer code suite, sierra mechanics . the capability to model waste repositories is a relatively recent addition to sierra mechanics . consequently, data from the same two Wipp rooms d & b are used in an effort, described herein, aimed at validating the code suite to this class of problems . Wipp rooms d & b are also being proposed for an international benchmarking exercise between us and german researchers . a review of the salient features for these two rooms that need to be captured in such an exercise will also be described and elaborated .

ARMA 13-303

high-temperature characterization of bedded permian SaltMellegard, K.D. and Callahan, G.D.RESPEC, Rapid City, South Dakota, USAhansen, F.D.Sandia National Laboratories, Albuquerque, New Mexico, USA

generic salt research and development sponsored by the department of energy includes uniaxial testing of bedded salt to 300°c . a suite of such testing was put forward as one of the prerequisite efforts for advancing the studies of heatgenerating waste in salt . precise loading was applied while each specimen was very accurately heated inside an environmental chamber . these reconnaissance tests extend the considerable database available for permian-bedded salt . most of these tests were developed during site characterization for the Waste isolation pilot plant . these laboratory studies examine temperature effects on elastic properties, time-dependent creep behavior, and ultimate strength in an unconfined condition . posttest microstructural observations allow assessment of deformational processes . fluid inclusions create vast differences in behavior between bedded and domal salt at high temperatures including a propensity for bedded salt to violently decrepitate at temperatures near 280°c while domal salt remains stable to 300°c . the test data developed for this paper provide an initial evaluation of how well the existing constitutive model extrapolates to temperatures outside of the substantial database at much lower temperatures and provides an indication of the model validity in the high temperature regimes .

ARMA 13-327

Underground infrastructure Rooms in Squeezing Rock – Geotechnical conditions in the konrad Mine during the conversion to a Repository for Radioactive Waste Missal, C. and Stahlmann, J. TU Braunschweig, Braunschweig, Germany Roehnert, M. DBE, Peine, Germany hahn, P. BfS, Salzgitter, Germany

the konrad mine is a former iron ore mine near salzgitter in lower saxony, germany . the mine will be modified to a repository for low and intermediate level radioactive waste in the next few years . the bedrock is characterized by complex geology . in particular, the “fladentonsteinserie” (a specific type of mudstone) shows squeezing behavior . since the necessary geomechanical parameters cannot be determined completely and reliably, the observation method should be applied for the proof of stability and usability . the


underground support system consists of a slotted lining with sliding anchors in the areas where squeezing rock is present . this allows converging of the bedrock . during the convergence period a bearing ring is formed within the rock mass . afterwards the final lining is created in reinforced shotcrete . dimensioning of the liner is made possible only by using this concept of construction .

ARMA 13-483

coupled thM analysis of a nuclear Waste Repository in crystalline Rock Sánchez, M. and Dontha, L.Texas A& M University, College Station, Texas, USAGens, A. Universitat Politècnica de Catalunya , Barcelona, Spain Guimarães, L. Federal University of Pernambuco, Recife, Brazil

this paper presents the thermo-hydro-mechanical (thm) analysis of an isolation system for high level nuclear waste . a geological disposal facility of such type encompasses both: natural (host rock) and engineered barriers (generally clay based) . the study deals on an ongoing large scale heating test at full scale that is being carried at the grimsel test site under actual conditions . the experiment reproduces the conditions of a hlW repository, at full scale under actual conditions . key thermo-hydro-mechanical (thm) variables such as temperature, relative humidity, stresses and fluid pressures were measured in the clay barrier and surrounding rock . the test is intensely instrumented and has provided the opportunity to study in detail the evolution of the main thm variables over a long period of time . a comprehensive laboratory investigation was carried out in the context of the febex and nf-pro european projects has allowed the identification of the model parameters to describe the thm behavior of the compacted clay and the sub-rounding rock . this paper focuses mainly on the numerical analysis of the main thm variables in the granite adjacent to the repository . overall, the comparisons between model predictions and observations are quite satisfactory .

ARMA 13-280

Significance of Rock thM parameters in Geological nuclear Waste Storage SimulationDupray, Fabrice1, Li, Chao1 and Laloui, Lyesse2

1École Polytechnique Fédérale De Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory for Soil Mechanics (LMS), Lausanne, Switzerland2King Abdulaziz University, Jeddah, Saudi Arabia

a deep geological repository involving a multi-barrier system constitutes one of the most promising options to isolate high-level radioactive waste from the human environment . in order to certify the efficiency of waste isolation, it is essential to understand the behavior of the confining geomaterials under a variety of environmental conditions . the efficiency of an engineered barrier system (ebs) is largely based on a combination of bentonite and host rock characteristics . to contribute to a better understanding of the processes involved in the ebs, a case study for sensitivity analysis has been defined and is studied using a thermo-hydro-mechanical (thm) finite element approach including a consistent thermo-plastic constitutive model for unsaturated soils . the model also features a coupled thm approach of the water retention curve for bentonite, using the acmegts constitutive model . regarding rock parameters, intrinsic permeability and relative permeability effects are evaluated . two regimes are found regarding the importance of the estimation of rock permeability: in the first one, precise assessment is unnecessary due to water inflow control by bentonite, while in the second one, a precise assessment is necessary to correctly estimate resaturation time . this study highlights the effects that need to be taken into consideration for a correct assessment of ebs behavior, from bentonite characteristics to the correct quantification of the thermo-hydro-mechanical couplings in host rock .


SeSSiOn 16: laBOratOry-SCale rOCk meChaniCSMonday, 24 June, 4:30 pm – 6:00 pmChair: Marte Gutierez

ARMA 13-240

the effect of Joint frequency on a Discontinuous Rock Mass under experimental compressive Strength testing conditions Sherpa, M.D., hagan, P.C. and Masoumi, h. School of Mining Engineering, The University of New South Wales (UNSW), Sydney, Australia

the dominating parameters of a discontinuous rock mass are joint orientation, joint frequency and joint strength . under experimental testing conditions, these parameters can individually influence rock mass strength, elastic properties and the mode of failure . this study aimed to assess the effects of joint frequency on rock mass properties, particularly in a confined stress state, as a review of the literature identified a lack of experimental information on the topic . a total of 24 uniaxial and 87 triaxial compressive strength tests were undertaken using intact and discontinuous, jointed sandstone core specimens, the latter having saw-cut joints orientated across the longitudinal axis of the core . based on the results, several conclusions have been made concerning the anisotropic effect factor, the Joint factor method and the mode of rock failure . first, the anisotropic effect factor can be adjusted for joint frequency . second, the joint strength parameter of the Joint factor method can also be modified and finally, a single shear failure plane was observed as the dominant mode of failure for both intact and jointed rock specimens under confinement . these conclusions provided and insight into the effects of joint frequency in a discontinuous rock mass .

ARMA 13-265

Volumetric behavior and consolidation of Shales at high confining StressesFerrari, A.1, Favero, V.1, Manca, D.1 and Laloui, L.1, 2

1Laboratory for Soil Mechanics (LMS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland2King Abdulaziz University, Jeddah, Saudi Arabia

the analysis of the volumetric behavior and the consolidation of shales require the involved materials to be tested under high confining stresses . the paper presents the apparatuses and the techniques that have been developed recently for testing shales under high-stress conditions . an advanced oedometric cell is introduced to analyse the transition from the over- to the normally consolidated state of shales; the apparatus allows investigating the volume change behavior of shales at high vertical stress (up to 100 mpa) in controlled suction and temperature conditions . the procedure for specimen preparation is also discussed . selected test results are presented for two shales from the northern region of switzerland .


ARMA 13-296

evolution of en-echelon flaws to a Shear Rupture in Moulded Gypsum under Uniaxial compression Yi Cheng, Louis Ngai Yuen Wong, Chunjiang ZouSchool of Civil and Environmental Engineering, Nanyang Technological University, Singapore

cracking processes in rock specimens containing one, two or multiple artificial flaws under compression have been studied systematically and extensively in the laboratory for the past decades . to enhance our understanding of the role of en-echelon cracks in the formation of a shear rupture, specimens containing artificial en-echelon flaws are studied in this paper . roack like material hydrocal-b11 gypsum is used to mould block specimens, which contain en-echelon flaws cut by the waterjet . the fracturing processes of the specimens under uniaxial loading are observed and recorded by a camcorder and high speed video system . for the studied en-echelon flaws arrangement, three stages of fracture development are observed . the results show that tensile wing cracks (tWcs) are involved in coalescing the pre-existing flaws and fragmenting the bridge zones . the tWc development is strongly influenced by the stress field around adjacent flaw tips as indicated by the curvature of their crack paths . the development of a shear rupture across the entire specimen is attributed to the development of two short clear cracks emanating from the two outer flaw tops, which coalesce with two previously initiated steeply inclined tensile cracks .

ARMA 13-503

the effect of anisotropy on crack Damage thresholds in brittle Rocks Ghazvinian, E., Perras, M. and Diederichs, M. GeoEngineering Centre, Queen’s University, Kingston, ON, Canada Labrie, D. CanmetMINING, Natural Resources Canada, Ottawa, ON, Canada

fabric-guided micro-fracturing phenomenon in brittle rock and its effect on crack damage thresholds remains a subject that challenges researchers . anisotropy of brittle rocks in terms of crack initiation (ci) and crack propagation (cd) thresholds plays a significant role on the extension and density of micro-fracturing in different directions in the walls of underground openings . to better understand the fabric-guided micro-fracturing phenomenon and also to study the effect of type of fabric in layered brittle rocks on their anisotropic behaviour, three types of brittle rock are investigated in terms of crack damage anisotropy in this paper . the rocks that are chosen for this study are limestone from the cobourg formation, Queenston shale and olkiluoto mica gneiss . for each rock type ci and cd thresholds are identified from the unconfined compressive strength (ucs) test data, performed on specimens with different layering orientation in respect to the loading axis . the anisotropic behaviour of the three rock types are investigated at different stress levels and the contributing factors to this behaviour are discussed .


ARMA 13-580

Stress induced electric field measurements of different rock lithology using the electric potential Sensor Aydin, A. University of Sussex, Brighton, Sussex, UK Dobbs, M.R., Reeves, h.J., Kirkham, M.P. and Graham, C.C. British Geological Survey, Keyworth, Nottinghamshire, UK

the work presented in this paper is of experiments to investigate the measurement of stress induced changes in the electric potential field of rock using the electric potential sensor, a technology invented at the university of sussex . isrm-type standard uniaxial compressive stress-to-failure tests were undertaken on a selection of igneous, metamorphic and sedimentary rock . during loading, changes in the electric field, strain and acoustic emissions were recorded . the results demonstrate the presence of stress-induced electric field signals, which increase in amplitude and frequency simultaneously (to 60 khz), up to the point of failure . this is true for all lithologies tested, except schist and gabbro . these latter two lithologies exhibit multiple high frequency transients of electric field during the course of loading and some d .c . level electric field variation features . the results are significant in determining which lithologies this activity may be amenable to and the characteristics the electric field profile takes as failure approaches, especially regarding precursory information . further work is needed in analysis and comparison with acoustic emission data . the association with the stress-state exhibited by the electric field may also have the potential to be applied to rock at larger scales .

ARMA 13-336

analysis of physical and Mechanical properties of impure Salt RockWei Liu, Yinping Li, Chunhe Yang, Shuai heng and Bingwu Wang State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei, China

to reveal the physical and mechanical characteristics of impure salt rock, especially the mechanism of splitting fracture under high confining pressure, the test-matrix consisting of chemical components analysis, sem (scanning electron microscope), uniaxial and conventional tri-axial compression tests has been carried out . the experimental results and theoretical analysis revealed that: the main components of impurities in salt rock, which distribute with dotted pattern inner big grains or with agglomerate and banded patterns among grains, are glauberite and anhydrite and some argillaceous minerals . on micro-size, the impurities mainly distribute among salt grain boundaries or act as the cement matrix of salt grains . the presence of impurities will, in turn, a certain extent increase the strength and reduce the flexibility of the salt rock, for which the meso-mechanism can be explained as impurities have modified the mechanical properties of the boundaries among adjoined halite grains so that the self-heal ability will be of some reduction . compared to the pure salt rock, impurities can cause more unrecoverable damage to accumulate under tri-axial compression tests . different with the main distributed impurities, uneven distributed impurities tend to cause uncoordinated deformation and local fracture . moreover, in the final phase of strain-hardening under high confining pressure tests, the uneven distributed impurities may even cause the membrane’s damage in local fracture regions and then induce the sample’s splitting fracture and “stress-drop” phenomenon . the “stress-drop” can be simply explained by criterion of mohr-coulomb . the research above has indicated some influence of impurities on salt rock and also made some references for the further study of impure salt rock and reasonable stability investigations of the storage caverns in salt rock formation .


SeSSiOn 17: unCOnventiOnalS iTuesday, 25 June, 8:00 am – 9:30 amChairs: Tom Bratton, Amie Hows

ARMA 13-666

Geomechanics considerations for hydraulic fracture productivitySuarez-Rivera, R., Burghardt, J., Edelman, E. and Stanchits, S. Schlumberger Innovation Center, Salt Lake City, Utah, USASurdi, A.TerraTek, a Schlumberger company, Salt Lake City, Utah, USA

Well productivity in unconventional reservoirs depends on contacting good reservoir quality rock with sufficient surface area, via hydraulic fracturing, and more importantly on preserving surface area and fracture conductivity over long-term production . thus, understanding the created fracture system is fundamental for understanding well production . in this paper we present fracture propagation experiments on texturally complex, organic-rich, tight shale outcrop blocks of the niobrara formation . after hydraulically fracturing the block we conducted unpropped fracture conductivity measurements under changing closure stress . subsequently we re-fractured the block with proppant laden slick water . When the desired amount of sand was transported and just before screening out, we stopped proppant injection and conducted fracture conductivity measurements on the propped fracture . these measurements of propped and unpropped fracture conductivity were compared to corresponding measurements on small samples . results show that the larger fractures, whether propped or unpropped, retain higher fracture conductivity with increasing stress . We also observe substantial fracture complexity associated with the textural complexity in the rock . as a result there is substantial variability in the concentration and distribution of the proppant in the fracture . post-test analysis allowed us to describe the fractured system as consisting of four easily identifiable regions: the wellbore, the connection between the wellbore and the fracture system, the near-wellbore fracture, and the far-wellbore fracture network . understanding the role of each of these regions to hydrocarbon production helps identifying the often competing causes of production decline over time . results show that the requirements for optimizing hydrocarbon flow in these four regions are different, but reasonable compromises can be made to sustain production from the overall fracture system .

ARMA 13-200

Stress Shadow evaluations for chicontepec – evaluating new completion options Rios, A.M. and Gutiérrez, G. PEMEX, Poza Rica, Mexico Nagel, N.B., Zhang, F., Sanchez-Nagel, M.A. and Lee, B. Itasca Houston, Inc., Houston, Texas, USA

many unconventional plays exhibit low matrix permeability, which means accessing or generating surface area during hydraulic fracture stimulations is critical to the economic success of the wells . as a result, it is common to see 10s of frac stages per well (as many as 60 or more) and specific efforts to stimulate the natural fractures (to increase ‘complexity’) . changes in stage spacing or well configuration (such as simul-fracs or zipper-fracs) have been tried in order to alter either or both the stress field and the pore pressure field to enhance the shearing of natural fractures . in this paper, we present the results of several numerical studies to quantitatively evaluate the effects of both regular and irregular stage spacing and several different well configurations/completion techniques at chicontepec in mexico . building upon the original theoretical work of sneddon and others, multi-stage, single-well and multi-well completions were simulated in order to quantify the changes in the principal stresses and shear stresses causes by multiple, propped hydraulic fractures .


ARMA 13-289

controls of anisotropic in-situ Stress and permeability in optimization of Wells and hydraulic fractures for Unconventional Reservoirs: examples from the Western canada Sedimentary basin Cui, A., Brezovski, R. and Glover, K. Trican Geological Solutions Ltd, Calgary, AB, Canada

exploitation of unconventional hydrocarbon resources relies heavily on drilling horizontal wells and pumping multi-stage hydraulic fractures, which is capital intensive and requires optimal well and fracture placements for economic success . the optimization process is a challenging task because it requires a wide spectrum of data on reservoir and mechanic properties . this study investigates the controlling effects of anisotropic in-situ stress and permeability on optimizing well and hydraulic fracture placements based on laboratory stress-dependent permeability measurements and field production data of several unconventional formations (montney, nordegg, cardium, and bakken) in the Western canada sedimentary basin (Wcsb) . in-situ horizontal stresses in Wcsb are highly anisotropic with the maximum horizontal stress (shmax) approximately in ne direction . the strong stress anisotropy and pre-existing major ne-striking natural fractures likely result in strong anisotropy of horizontal permeability with the maximum permeability in ne direction . optimization on horizontal well placements and fracturing treatments should be conducted with transformed coordinate based on the permeability anisotropy . se or nW horizontal wellbores drilled in the direction of the minimum horizontal stress (shmin) are likely stimulated with transverse fractures as commonly expected, but high fracture tortuosity near-wellbore may occur due to the nearly 90° turning as fractures propagate away from wellbore . for ns or eW wells deviating from shmin, fractures oblique to wellbore are likely initiated and propagate away from wellbore without turning, and thus high fracture conductivity near wellbore are expected with lower fracture initiation pressures . consequently, better production can be expected for the ns or eW horizontal wells . this may explain partly that se montney wells at the studied location have much lower cumulative hydrocarbon productions than the ns or eW wells . however, the oblique fractures of ns or eW wells cover less reservoir area and smaller well spacing is required to cover the same reservoir area as for se wells .

ARMA 13-140

Understanding Shale failure from laboratory analysis to field operations Matzar, L.A. and Gamwell, C.G. Halliburton, Houston, Texas, USA

the mohr-coulomb failure envelope calculated from various testing typically defines an envelope consistent with shear failure of a material subjected to normal compressive stress . in a laboratory environment, shale samples with laminated structures tested under low or no confining stress can exhibit a unique failure mechanism different from the shear failure mechanism . rather than failure in shear, shale tends to split vertically along the laminar structure . this specific failure mechanism is experimentally compared with the shear failure mechanism . three sets of samples were tested under uniaxial and triaxial conditions (3 .45, 6 .90, and 13 .80 mpa) . samples were cored and tested both parallel and perpendicular to the bedding plane of the shale used in this study . ultimately, it was discovered that splitting failure has a noticeable effect on the overall results of testing . additionally, samples cored perpendicular to the bedding plane exhibited significant differences in collected and calculated data .


ARMA 13-312

failure behavior of anisotropic Shales Mehdi Mokhtari, Adel A. Alqahtani and Azra N. Tutuncu Colorado School of Mines, Golden, Colorado, USA

improving the recovery of hydrocarbon from shale reservoirs requires incorporation of formation anisotropy into drilling, completion, and hydraulic fracturing operations . in this study, we conducted simultaneous measurements of triaxial deformation and ultrasonic tests on a series of mancos shale samples collected at various angles to the bedding . the mechanical and acoustic characteristics of the core samples before and after the failure have been studied . the minimum formation strength was obtained for the sample with 60o from the bedding plane . the post-failure radial deformation data as well as the inspection of the failed samples indicate that sliding on the bedding plane has occurred on the core sample with 60o bedding angle . on the other hand, the vertical and horizontal core samples exhibited stepwise failure noticeable on the radial deformation data with steps corresponding to multiple fractures on the recovered cores . the compressional wave velocities have indicated a logarithmic dependence on the axial stress applied . the compressional velocity for the horizontal sample was 30% higher than the velocity for the vertical sample . finally, the effect of post-failure fracture, confining pressure and residual strength on compressional and shear velocities are discussed .

ARMA 13-578

nanoindentation Studies on Shales Priyavrat Shukla, Vikas Kumar, Mark Curtis, Carl h. Sondergeld and Chandra S. Rai University of Oklahoma, Norman, Oklahoma, USA

thousands of shale wells are being drilled and fracked each year . these extremely tight formations are impossible to produce without fracking, which in turn requires knowledge of mechanical properties of shale . the chemical and mechanical instability of shales limits the recovery of full length cores and plugs necessary for conventional mechanical testing . recovering cores is expensive . nanoindentation provides a means to obtain young’s modulus and hardness of rocks from drill cuttings, fragments and sidewall cores which are millimeters in size . the measurements obtained are reliable and agree well with other standard measurements . additionally, measurement over the whole pay zone through drill cuttings can help in improving hydraulic fracturing design . this paper will focus on the applicability of nanoindentation to shales . it will also present a correlation to estimate rock mechanical properties based on the measurements of principal rock components affecting mechanical behavior: mineralogy, porosity and organic content . the precise measurement capability of the nanoindenter also enables the study of rock frame and organic content separately . nanoindentation measurement provides a measure of anisotropy when bedding directions are known .

SeSSiOn 18: grOunD COntrOl iTuesday, 25 June, 8:00 am – 9:30 amChairs: Doug Tesarik, Langsten Radford

ARMA 13-477

identifying Root causes for Subsidence over abandoned coal Mine – a case StudyLuo, Y. and Qiu, B.West Virginia University, Morgantown, WV, USA

correctly identifying root cause for subsidence events in areas over abandoned coal mines is often a difficult task . it is important to collect available data about the reported subsidence event including historical


events, observed and measured ground and structural deformations, geological and mining conditions, etc . comprehensive analysis of the collected information should be performed to characterize the reported event . a detailed comparison between the identified characteristics and those of mine subsidence events often could lead to delineation whether the event is caused by abandoned mine . for the events possibly not caused by mining, identifying the root cause could be even more difficult . this paper presents the investigation of a complicated subsidence case over an abandoned coal mine . the collected data, analysis and findings are detailed . the root cause other than the abandoned mine has been identified .

ARMA 13-448

Stability evaluation of Stopes and pillars at MaX Mine and Development of a Surpac-flac3D Model building techniqueSchmid, C.J., Newcomen, h.W., and Buchanan, M.BGC Engineering Inc., Kamloops, BC, CanadaCorkum, A.G.BGC Engineering Inc., Halifax, NS, Canada

ground fall events and the subsequent complete failure of a sill pillar at the max molybdenum mine near trout lake, b .c . initiated a geotechnical review of the excavations and proposed extraction sequence . this included a review of the mine’s excavation stability history, expansion of the mine’s geotechnical instrumentation program, and stability analyses using empirical and numerical methods . to expedite the numerical modeling component of the stability analyses, an attribution methodology was developed by bgc engineering inc . (bgc) . this methodology was used to attribute a flac3dtm model with3d as-built models from surpactm, resulting in increased accuracy of the model geometry and a suitably refined high quality mesh . this results in efficient and accurate modeling and significant time savings during flac3d model generation . the flac3dnmodel was calibrated from back-analysis of mine performance using instrumentation data and observations from ground fall events . recommendations for sill pillar and stope dimensions for future mine developments were developed, and were used to successfully

ARMA 13-134

Qa/Qc and Use for cemented Rock fill at the turquoise Ridge Joint Venture, nevada Rai, A.R. and Sandbak, L.A. Barrick Gold, TRJV Mine, Golconda, NV, USA Kallu, R. University of Nevada, Reno, NV, USA

high strength cemented rock fill (crf) is necessary for adequate mine design using the underhand cut and fill method . Quality assurance/ quality control programs insure adequate strengths for design purposes and safety . optimization is dependent on: 1) the type of aggregate material: crf strengths have increased 20-30% with the switch from basalt to the limestone aggregate . 2) cement and cement to flyash ratios: the average crf strengths have increased over time, even as we have decreased cement by supplementing it with fly ash . the original formula recipes had cement: flyash ratio of 75:25, which has been reduced to a 60:40, and then to a 50:50 mix of cement and flyash . 3) sieve sizes: an in-house sieve analysis lab program which includes analysis of clays and atterberg limits gives us the ability to set optimum sieve size distributions as the aggregate size decreases to less than the optimum 3” minus sizes . 4) Water content; Water is the only variable that is allowed to be adjusted for consistency for jamming in the headings . the addition of plasticizer helps keep water content low, retain mix consistency, which results in lower strength variability . 5) standard operating procedures: training on adequate sample preparation and


testing to insure repetition, standardization, and number of samples needed to insure we meet our design criteria . it is imperative to detect crf strengths changes early enough to adjust or change our recipes to match our design requirements, and maximize safety for undergrounds miners working under crf .

ARMA 13-138

cemented paste backfill at Stillwater Minehughes, P.B. and Pakalnis, R.University of British Columbia, Vancouver, British Columbia, CanadaDeen, J. and Ferster, M.Stillwater Mining Company, Nye, Montana, USA

stillwater mine has successfully utilized underhand cut and fill mining with cemented paste backfill (cpb) in extracting ore from a narrow vein deposit; this mining method has been applied since 2001 . a testing of the unconfined compressive strength of all cemented paste backfill pours has been established as part of a Qa/Qc program . the database of the testing has the results of 17,212 ucs samples . this paper discusses the application of cpb within the mine plan at stillwater with focus on the lesson learned with respect to ground control, mine production, and backfill production and delivery . further a statistical analysis is carried out to determine relationships from the database . the following relationships are investigated: strength vs . cement content, age vs . strength, moisture content vs . strength, underground vs . surface strength of backfill . in addition, the results of a novel in-situ testing method for cpb are presented .

ARMA 13-118

Slope Monitoring of large Scale experiment of Undercut Slope at Mae Moh Mine, thailandMavong, N. and Thepjun, A.Geotechnical Engineering Department, Mae Moh Mine, Electricity Generating Authority of Thailand, Lampang, ThailandLeelasukseree, C.Mining Engineering Department, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand

electricity generation authority of thailand (egat)’s mae moh mine is one of the largest surface mines in southeast asia . its annual production is approximately 15 million tons of lignite and 90 million m3 of waste . the complexity of geological structures causes a number of geotechnical difficulties . typically, lignite exploitation makes the weak green clay seam, g1 seam, daylighted along the footwall, and possibly causes a massive failure of underburden claystone . the cut and fill mining technique has been initiated as a large scale field experiment at the mae moh mine’s northeast footwall slope, which is estimated to be a 3 million m3 of potential sliding block . With this technique, the g1 interface will be partially daylighted . therefore, arch formation is formed in the sliding block and could perform as a temporary support at a certain undercut span width . this was studied using 3dec, a 3d numerical analysis code . to date, this mining area is under construction and a monitoring program has been installed with an automatic deformation monitoring system, inclinometers, and piezometers . the purposes of the monitoring program were not only for collecting the behavior of displacement and water pressure in the partially undercut slope, but also to perform as a criterion for failure warning system during mining operation . the monitoring data obviously shows that the displacement of the undercut slope related to the undercut operation and the precipitation amount . this field monitoring data is useful to make a better understanding of the undercut slope behavior at mae moh mine . moreover, it can be used for improving the 3d numerical analyses more accurately by calibrating the key mechanical properties of the rockmass at mae moh mine .


ARMA 13-130

application of close Range photogrammetry to Monitor Displacements in open pit Mines Saeedeh Rezaei Mine Engineer, Freeport-McMoRan Copper and Gold Inc., Tyrone, NM, USAMehrdad Razavi Associate Professor of Mining Engineering, Department of Mineral Engineering, New Mexico Institute of Mining and Technology, Socorro, NM, USAAli Rahnama Geomechanical Mining Engineer, Freeport-McMoRan Copper and Gold Inc., Oro Valley, AZ, USA

in this study, close range photogrammetry has been evaluated to monitor displacements in open pit mines . a proper displacement monitoring program can provide useful information that can be used in design as well as the ability to predict a failure . many displacement monitoring techniques are available, however not all are reliable, accurate, and cost effective . close range photogrammetry (crp) is a monitoring method with high accuracy, reliability, and cost effectiveness, and ability for measuring places that are inaccessible . in crp, multiple series of photographs are taken from different positions with different angles at different time intervals . these photos are processed using crp code and 3d models are constructed . furthermore, a point cloud with precise coordinates of each point can be obtained . by comparing 3d models, movements of each specific point can be measured . this method has been demonstrated at one of the properties of the freeport-mcmoran company . in this project, movement rates are determined by comparing different 3d models . these results are then compared to results of other monitoring methods to validate the crp displacement method . results evaluate crp as a reliable method to monitor displacements in open pit mines .

SeSSiOn 19: rOCk phySiCS anD geOphySiCSTuesday, 25 June, 8:00 am – 9:30 amChairs: Dave Dewhurst, Nicolas Guy

ARMA 13-151

Mechanics, physics, chemistry and Shale Rock propertiesDewhurst, D.N., Bunger, A., Josh, M., Sarout, J., Delle Piane, C., Esteban, L. and Clennell, M.B.Shale Research Centre, CSIRO Earth Science and Resource Engineering, Perth, Western Australia

the fundamental mechanics, physics and chemistry of shale behaviour remain poorly understood, partly due to neglect and partly due to poor experimental practice . this paper will review the role of water content, water saturation and cation exchange capacity (cec) on shale mechanical and petrophysical properties . decreasing water content increases shale strength and static young’s modulus under both fully and partially saturated conditions . partial saturation increases s-wave velocity but decreases p-wave velocity, so the dynamic stiffness response depends on the particular modulus in question – shear and young’s increase while bulk decreases . cec correlates well with rock strength (cohesion, friction) and is also strongly correlated to parameters such as the reflection coefficient (membrane efficiency) and the osmotic chemomechanical coupling coefficient . cec is also directly related to dielectric dispersion and holds the tantalising possibility of estimating shale strength from dielectric logs although more work is required across the different scales of investigation . finally, the dielectric response of shales seems to correlate very well with p-wave velocity at certain frequencies . hence, the mechanical, physical and chemical properties of shales are all intimately interlinked, requiring multi-disciplinary approaches to unravel the fundamentals behind the processes occurring in these rocks .


ARMA 13-343

low-frequency (<100 hz) Dynamic fracture compliance Measurement in the laboratoryNakagawa, S.E.O. Lawrence Berkeley National Laboratory, Berkeley, CA, USA

although the mechanical compliance of fractures can have a large impact on estimation of oil and gas reservoir stress state and fluid contents, only a limited number of fracture compliance measurements are available, particularly in the subkilohertz frequency range relevant to the field seismic measurements . also, most laboratory measurements are for the normal fracture compliance, and measurements for the shear fracture compliance are rather rare . for this reason, a laboratory device was developed which allows us to measure both normal and shear specific compliances of an interface (fracture) simultaneously, in the frequency range of ~1 hz–100 hz . using this device, dynamic fracture compliances of a sheared, water-saturated and drained fracture were measured, under small fracture-normal stress . for the saturated fracture, the normal fracture compliance was clearly frequency dependent, with the relaxation frequency at 10~20 hz . this result, however, did not agree well with an analytical model which predicted much larger compliance changes and a higher relaxation frequency than the experiment . observed normal to shear fracture stiffness ratio ranged from 1 .8–2 .8 for the saturated fracture and 1 .7–1 .9 for the drained fracture, both decreasing with increasing normal stress on the fracture . interestingly, for a fracture containing a thin rubber membrane, the normal-to-shear compliance ratio increased with the stress, apparently exhibiting the opposite behavior .

ARMA 13-405

Relationship between Shear and normal Stiffness for a fracture Subjected to Mixed-Mode loading Choi, MK. and Bobet, A. School of Civil Engineering, Purdue University, West Lafayette, IN, USA Pyrak-Nolte, L. J. Department of Physics, Purdue University, West Lafayette, IN, USA School of Civil Engineering, Purdue University, West Lafayette, IN, USA Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN, USA

a series of laboratory experiments were performed on synthetic fractures in gypsum and lucite to study the ratio of shear to normal fracture specific stiffness of a single fracture subjected to normal and shear stress . the specimens were made by placing two blocks in contact to form a fracture . the fracture surface was manufactured such that it was either well-mated or non-mated . for well-mated fracture surfaces, asperities were created by casting gypsum against sandpaper . after the first block hardened, the second block was cast against the rough surface of the first block . non-mated fracture surfaces were fabricated with two lucite blocks that were polished (lucite pl) or sand-blasted (lucite sb) along the contact surface . in the experiments, each specimen was subjected to normal and shear loading while the fracture was probed with transmitted compressional and shear waves . shear and normal fracture stiffnesses were calculated using the displacement discontinuity theory . the stiffness ratio determined from the experiments was compared to a theoretical ratio that was determined assuming that the transmission of compressional and shear waves was equal . the experimental results show that the fracture roughness of the non-mated fractures affects the stiffness ratio and that the shear fracture specific stiffness for well-mated fractures is sensitive to the applied shear stress .


ARMA 13-541

the anisotropy of Ultrasonic Waves Velocity and attenuation of Migmatite Samples under Uniaxial loadingPetružálek, M., Lokajíček, T. and Svitek, T.Institute of Geology AS CR, v. v. i., Prague, Czech Republic

a method of velocity anisotropy analysis based on conventional ultrasonic transmission technique is presented . multiple transducers were used to ultrasonic sounding and monitoring of acoustic emission . a sparse network of transducers located on the rock core surface allows approximation of elastic waves velocity distribution as an ellipsoidal surface . the shape and orientation of velocity ellipsoid is a measure of velocity anisotropy . a study of changes in velocity anisotropy and attenuation was performed on uniaxially loaded migmatite samples with distinct foliation . the cylindrical migmatite samples had a horizontal foliation and one of them had a pre-existed crack . the ultrasonic measurement was carried out during applying a uniaxial constant strain-rate loading . orientation of the velocity ellipsoid corresponded to the anisotropy of rock structure up to activation of a failure plane . prior to brittle failure, the axis of minimum velocity rotated from its initial direction normal to the foliation to a direction normal to the failure plane, which was determined from location of ae events . the changes in attenuation, induced by uniaxial loading, corresponded to the velocity changes and shown higher sensitivity to the actual stress-strain state of rock samples .

ARMA 13-614

elastodynamic Simulation of tunnel Detection experiments in heterogeneous Geological MediaSherman, C.S., Rector, J. and Glaser, S.D.University of California Berkeley, Berkeley, California, USA

the detection of unknown tunnels and underground voids, such as old mine workings or solution cavities in karst terrain, is a challenging problem and an important concern for geomechanical design, public safety, and domestic security . over the years many near-surface seismic methods have been developed and used to find such openings, but with oftentimes poor results . the most promising of these techniques include surface wave backscattering, surface wave transmission, and body wave diffraction imaging . one confounding element is accounting for the natural heterogeneity of the subsurface velocity model . in our proposed method, we simultaneously solve the problems of wave propagation around a void and through a heterogeneous embedding medium . We generate a range of three-dimensional, synthetic, heterogeneous velocity models using fractal statistics, embed them with fluid-filled tunnels, and then simulate commonly used void detection experiments using the elastodynamic wave propagation code e3d . our results show that, even for small levels of heterogeneity, the primary scattered wavefield and undesirable resonant coupling between the void and heterogeneities may obscure the useful signal . in addition, our results show that as the magnitude of heterogeneity in the velocity model increases and the fractal dimension increases, the confidence level in geophysical anomalies decreases and the void detection threshold size increases due to scattering and reflections in the medium .

ARMA 13-676

influence of SaGD process on Seismic Velocities Guy, N., Nauroy, J.-F. and Baroni, A. IFP Energies nouvelles, Rueil-Malmaison, France

thermal enhanced oil recovery (eor) processes such as steam assisted gravity drainage (sagd) are commonly used in heavy oil production . these recovery processes commonly lead to significant changes in situ conditions and modify saturation, pore pressure and temperature, in situ stress and rock behaviour . the


work presented herein aims at evaluating and modelling the effect of sagd process on heavy oil sands seismic velocities . in this paper, numerical simulations describing a sagd based heavy oil recovery that have been performed considering a synthetic case and involving geomechanical coupling to taking into account the effect of rock dilatancy on thermal reservoir flow are used to provide an estimation of the evolution of pressure, temperature, saturation, stress and strain . furthermore, a model describing the seismic velocities of canadian oil sand mass under different conditions of temperature and stress [1] is considered . this model is based on the approach of ciz and shapiro [2] and has been used to evaluate the change of seismic velocities of the heavy oil sands reservoir during a sagd based heavy oil recovery considering the results provided by the numerical simulations . results appear to be useful for 4d seismic data interpretation and to locate the steam chamber .

SeSSiOn 20: DiSCrete geOmeChaniCS iTuesday, 25 June, 8:00 am – 9:30 amChairs: Nick Sitar, Mary McLaughlin

ARMA 13-320

Response Spectra of Slender columns as obtained with 2D-DDa and Geophysical Site Response testsYagoda-Biran, G. and hatzor Y.h.Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Be’er-Sheva, Israel

the capability of the numerical dda method to perform site response analysis is tested . We compare the resonance frequency obtained for a multi-drum column when modeling it with dda and testing it in the field . When the numerical control parameters are properly selected we obtain a good agreement between dda and the geophysical site response survey in the field . We find that the choice of the contact spring stiffness, or the numerical penalty, is directly related to the obtained resonance frequency mode in dda . the best agreement with the physical test is obtained with a relatively soft contact spring stiffness of k = (1/20) eo*lo, where eo is the young’s modulus of the blocks and lo is the average block diameter . this optimal k value falls within the range of acceptable k values obtained in preliminary calibration tests performed independently of the field data . We find that the obtained resonance frequency is independent of the time step interval selected . furthermore, dda returns only a single resonance mode whereas the geophysical test results indicate two modes . this discrepancy is explained by the fixed base used in the dda model which inhibits soil structure interactions .

ARMA 13-362

Stability analysis of Masonry Structures in angkor thom, cambodia Using elasto-plastic nMM-DDa with Subloading cam-clay Model hashimoto, R., Koyama, T. and ohnishi, Y. Kyoto University, Kyoto, Japan Kikumoto, M. Yokohama National University, Kanagawa, Japan Yamada, S. and Araya, M. Waseda University, Tokyo, Japan Iwasaki, Y. Geo-Research Institute, Osaka, Japan


there are many historic remains in the world and among them many masonry structures are in danger of collapse . to select suitable methods for restoration and preservation, it is important to evaluate the stability of masonry structures considering the interaction between foundation ground and masonry building, and accurate calculation of stress distribution inside the masonry structure is required . in the previous works, nmm-dda (coupled numerical manifold method and discontinuous deformation analysis), one of the discontinuum based numerical methods was developed to satisfy these requirements . however, the nmm-dda code treats only elastic and/or elasto-perfectly plastic materials (for both dda blocks and nmm elements) and cannot treat different deformation/failure processes of soils with different ocr (over consolidated ratio) density, void ratio . . hence, in this study, subloading cam-clay model was newly introduced to the nmm-dda code and applied to the stability analysis of prasat suor prat n1 tower in the angkor monuments, cambodia .

ARMA 13-416

explicit three Dimensional Discontinuous Deformation analysis for blocky SystemRoozbeh Geraili MikolaJacobs Associates and Dept. of Civil and Environmental Engineering, UC Berkeley, San Francisco, CA, USANicholas SitarEdward G. Cahill and John R. Cahill Professor, Dept. of Civil and Environmental Engineering, UC Berkeley, Berkeley, CA, USA

We present a 3d-dda formulation that uses an explicit time integration procedure and an efficient contact detection algorithm optimized to minimize the computational effort . the advantages of the explicit formulation are that the global stiffness matrix does not need to be assembled and the linear equations do not need to be solved by matrix inversion . consequently, the computational effort and memory requirement can be reduced considerably, which is important for efficient solution of large 3d problems . in addition, the computational efficiency is increased by eliminating unnecessary contact computations using a grid based nearest neighbor search . the grid divides space into a number of cells of equal size and each object is then associated with the cells it overlaps . as only objects overlapping a common cell can possibly be in contact, in-depth tests are only performed on objects found sharing cells with the block tested for collision . the contacts between the blocks are detected by using fast common- plane (fcp) approach . the halfedge (he) data structure approach is used to handle the navigation into the topological information associated with polyherdral objects (vertices, edges, faces) . the halfedge data structure allows for quick traversal between faces, edges, and vertices due to the explicitly linked structure of the network . examples are provided which demonstrate the capabilities of new algorithm and the size of problem that can be analyzed .

ARMA 13-489

numerical Stability on Rock fall problems by 3-D DDaSasaki, T. and hagiwara, ISuncoh Consultants Co. Ltd., Tokyo, Japanohnishi, Y. and Koyama, T.Department of Urban Management, Kyoto University, Kyoto, JapanMiki, S.KisoJiban Consultants Co. Ltd., Tokyo, Japan

the authors analyse rock fall problems using three dimensional discontinuous deformation analysis (3d-dda) developed by shi (2001) . the shapes of the mountains or valleys are very complex and require much computation time for integrations; up to 80 to 90 per cent of the total calculation time in the three dimensional analyses . the ratios between the base blocks of the modelled mountain and the rock fall blocks


are extremely large and cause numerical instability in the linear algebraic equations losing effective digits in the space domain . the authors have improved the fixed block option for rock fall problems based on three-dimensional dda . the fixed block option assumes a rigid body for a block and we calculate the rock fall models using the fixed block option for the base blocks of the modelled mountain and assume an elastic body for the falling blocks . since, introducing these assumptions, the integration of the complex shapes of the base blocks of the mountain can be avoided for each time step . hence, the calculation time is ten times faster than when using the original algorithm and realizes good numerical stability .

ARMA 13-492

application of nMM-DDa to earthquake induced Slope failure and landslideMiki, S.Kiso-Jiban Consultants Co. Ltd., Tokyo, JapanSasaki, T.Suncoh Consultants Co. Ltd., Tokyo, Japanohnishi, Y., Nishiyama S. and Koyama, TDepartment of Urban Management, Kyoto University, Kyoto, Japan

discontinuous deformation analysis (dda) and numerical manifold method (nmm) have been used for the analyses of discontinuous rock masses . for the dynamic response analysis of rock slopes, it is necessary to consider the local variation of seismic forces, especially when the slope size is large and/or the slope geometry becomes complicated . in dda, there is difficulty to consider the local displacements and stress condition in a block . on the other hand, nmm can simulate both continuous and discontinuous deformation of the block systems . however, the rigid body rotation of blocks cannot be treated properly because nmm does not deal with the rigid body rotation in explicit form . according to the above-mentioned reasons, it is reasonable to combine dda and nmm from practical point of view . in this paper, the formulation of the coupled nmm and dda (nmm-dda) was presented . since the processes to establish the equilibrium equations (minimizing potential energy) and kinematics of block system are same between dda and nmm, these two can be combined easily by choosing displacements of the dda blocks and nmm cover nodes as unknowns . some applications of the nmm-dda to earthquake response analysis of the rock slope were presented .

ARMA 13-498

energy-Work-based confined-Unconfined Seepage Modeling Using numerical Manifold Method Wang, Yuan College of Civil and Transportation Engineering, Hohai University, Nanjing, China Earth Science Division, Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA, USA hu, Mengsu College of Civil and Transportation Engineering, Hohai University, Nanjing, China Earth Science Division, Lawrence Berkeley National Laboratory (LBNL), Berkeley, USA Rutqvist, Jonny Earth Science Division, Lawrence Berkeley National Laboratory (LBNL), Berkeley, USA

in this paper we present developments and applications of a new code for confined-unconfined seepage analysis based on the numerical manifold method (nmm) . We approach the problem using an energy-work-based seepage model which provides a clear definition and physical meaning of the seepage energy terms when assembling the governing equations . a unique feature of our approach is that it enables the application of the nmm to non-homogenous seepage analysis, based on our pipe model analogous to the


penalty spring commonly applied in mechanical analysis . We verified the proposed model and the nmm code by comparison of our simulation results to analytical solutions for confined seepage and to available numerical models for a number of unconfined fluid flow examples, including a case with non-homogeneous material domain . We show that nmm, based on a two-cover-mesh system, can in the case of unconfined seepage achieve high accuracy and convergence speed with rather coarse meshes and without the need for remeshing as the phreatic surface changes .

SeSSiOn 21: fraCture meChaniCS iTuesday, 25 June, 11:00 am – 12:30 pmChairs: John Dudley, Mikhail Geilikman

ARMA 13-252

injection-Sensitive Mechanics of hydraulic fracture interaction with Discontinuities Chuprakov, D., Melchaeva o. and Prioul R. Schlumberger-Doll Research, Cambridge, MA, USA

We develop a new analytical model, called opent, that solves the elasticity problem of a hydraulic fracture (hf) contact with a pre-existing discontinuity (nf) and the condition for hf re-initiation at the nf . the model also accounts for fluid penetration into the permeable nfs . for any angle of fracture intersection, the elastic problem of a blunted dislocation discontinuity is solved for the opening and sliding generated at the discontinuity . the sites and orientations of a new tensile crack nucleation are determined based on a mixed stress- and energy-criterion . in the case of tilted fracture intersection, the finite offset of the new crack initiation point along the discontinuity is computed . We show that aside from known controlling parameters such stress contrast, cohesional properties of the nfs and angle of intersection, the fluid injection parameters such as the injection rate and the fluid viscosity are of first-order in the crossing behavior . the model is validated with three independent laboratory experiments, analytical criteria of blanton, extended criterion of renshaw-pollard, as well as fully-coupled numerical simulations . the relative computational efficiency of opent model (compared to the numerical models) makes the model attractive for implementation in modern engineering tools simulating hydraulic fracture propagation in naturally fractured environments .

ARMA 13-700

breakdown pressures Due to infiltration and exclusion in finite length boreholesGan Q. and Elsworth, D.Energy and Mineral Engineering, G3 center and EMS Energy Institute, The Pennsylvania State University, University Park, PA, USAAlpern, J.S. and Marone, C.Geosciences, G3 center and EMS Energy, Institute, The Pennsylvania State University, University Park, PA, USAConnolly, P.Chevron Energy Technology Company, Houston, TX, USA

the theory of effective stress suggests that the breakdown pressure of a borehole should be a function of ambient stress and strength of the rock, alone . however, our experiments on finite boreholes indicate that the breakdown pressure is a strong function of fracturing fluid type/state as well . We explain reasons for this behavior including the roles of different fluid types and state in controlling the breakdown process . We propose


that the fluid interfacial tension controls whether fluid invades pore space at the borehole wall and this in turn changes the local stress regime hence breakdown pressure . interfacial tension is modulated by fluid state, as sub- or supercritical, and thus gas type and state influence the breakdown pressure . We develop expressions for the breakdown pressure in circular section boreholes of both infinite and finite length to validate our hypothesis . importantly, the analysis accommodates the influence of fluid infiltration or exclusion into the borehole wall . for the development of a radial hydraulic fracture (longitudinal failure) the solutions are those of Detournay and Cheng (1992) and show a higher breakdown pressure for impermeable (Hubbert and Willis, 1957) relative to permeable (Haimson and Fairhurst, 1967) . a similar difference in breakdown pressure exists for failure on a transverse fracture that is perpendicular to the borehole axis, in this case modulated by a parameter , where is poisson ratio and the biot coefficient . a numerical solution is obtained for this finite length borehole to define tensile stresses at the borehole wall due to a decomposed loading from an external confining stress and interior pressurization . numerical results agree with the breakdown pressure records recovered for experiments for pressurization by co2 and argon:

ARMA 13-153

Understanding Geochemical interaction of proppant-formation for improved conductivity of hydraulic fractures Raysoni, N. Halliburton, Pune, India Weaver, J. Halliburton, Duncan, Oklahoma, USA

this paper presents proppant-pack-permeability and proppant crush-strength data collected from a selection of hydrothermal tests performed in sealed test cells packed with a specific ceramic alumnia proppant and formation material with no flow and no mechanical closure stress . proppant performance was determined by evaluating the proppant after a set number of days of hydrothermal exposure at 300 and 450°f . these tests were performed both with and without formation material present to demonstrate the impact of reservoir/proppant compatibility . scanning electron microscope (sem) and energy-dispersive x-ray spectroscopy (edx) analyses verified that dynamic molecular rearrangement occurs even at 300°f, but at an accelerated rate when the temperature was higher . extensive efforts to quantify both the accuracy and repeatability of testing procedures used in this study were made and are presented . Zeolites were identified as responsible for much of the fines material created during the testing cycle, which indicates that zeolite formation is also dependent on the chemistry of the proppant . similar results have been reported for tests conducted under dynamic flow conditions . this paper presents data that illustrates the importance of compatibility when selecting the best proppant for long-term fracture conductivity; and it suggests that methods in addition to api crush and conductivity procedures need to be developed and implemented to properly rank proppant performance .

ARMA 13-403

comparison of brittleness indices in organic-rich Shale formations Yang, Yi and Zoback, M.D. Stanford University, Stanford, California, USA Sone, hirokiGFZ German Research Centre For Geosciences, Potsdam, Germany hows, AmieShell International Exploration and Production, Houston, Texas, USA


brittleness is now widely used as a key parameter to evaluate the potential effectiveness of hydraulic fracture initiation and propagation in low permeability shale formations . various types of brittleness indices have been proposed from laboratory and well log data . however, there is no consensus definition of brittleness, resulting in brittleness being characterized in different ways . in this study, we calculated four brittleness indices based on triaxial test data on shale plugs from four reservoirs . measured elastic properties such as young’s modulus and poisson’s ratio are also utilized . our results show that brittleness described by different brittleness indices can vary considerably, even when the same mechanical test data are used, and the different indices do not correlate well with rock strength or elastic properties . We propose that the tendency for hydraulic fracture initiation and propagation cannot be simply described by any single brittleness index . rather, hydraulic fracturing is controlled by combined factors including in situ stress, mineralogical composition (especially clay content), elastic moduli, the presence of pre-existing fractures, the manner of well completion .

ARMA 13-659

Distinct element analysis for hydraulic fracturing in Shale -effect of brittleness on the fracture propagation- Michiharu hiyama, hiroyuki Shimizu and Takatoshi Ito Institute of Fluid Science, Tohoku Univ., Sendai Japan Tetsuya Tamagawa and Kazuhiko Tezuka Technical Division Research Center, Japan Petroleum Exploration Co. Ltd, Chiba, Japan

hydraulic fracturing is one of the most important techniques for development of shale oil and gas resources . brittleness index is considered to be an important factor for hydraulic fracturing . the effect of brittleness index on the fracture propagation was investigated by original flow-coupled dem code . as the simulation results, followings were found . When rock models with small young’s modulus are used, average aperture of all microcracks is larger than those with large young’s modulus because it can deform easily . therefore fracturing fluid infiltrates into the fracture tip immediately, and fluid pressure in fracture tip rises . as a result, stress intensity factor at fracture tip increases with the fracture length, and fracture propagates rapidly to one side of borehole . on the other hand, when rock models with large young’s modulus are used, only a small amount of fracturing fluid can infiltrate into the fracture tip due to small aperture of a fracture . thus fluid pressure at fracture tip cannot increase easily, and the increments of stress intensity factor are lower at fracture tip . thus, fracture propagates slowly to both side of borehole . young’s modulus that is a parameter of brittleness index significantly influences on the hydraulic fracturing propagation .

ARMA 13-254

comparisons of plane propagation from Dilating casing and conventional perforations when Stimulating the Milk River formation hocking, G. GeoSierra, Atlanta, Georgia, USA Cavender, T.W., hunter, T. and Li, G. Halliburton, Houston, Texas, USA

the milk river formation, a tight-gas reservoir, is a weak mudstone within a shallow, low-energy lake environment, with thin sand lenses of upward coarsely grading sequences . stimulation of wells in the milk river formation are compared for a) conventional perforations in a cased hole and b) expanded dilating casings in nearby offset wells . all wells were stimulated with an energized fracturing fluid carrying 20/40-mesh sand proppant and completed at seven depth horizons . Wellhead treatment pressures for the conventionally perforated stimulations are 20 mpa at depth, rising to 27 .5 mpa at the shallowest horizon .


surface tiltmeter data show fracture planes are vertical at depth and horizontal at shallower depths, with an apparent stress crossover at ~400 m depth . Wellhead treatment pressures for the split dilating casing are constant at 17 .5 mpa for all depths, with all fractures vertical and no stress crossover observed . therefore, the stress crossover is attributed as an artifact of stimulating through perforations and is not formation stress related . it is concluded that, within formations acting in the non-brittle regime, the well stimulation procedure dictates the outcome . stimulations through perforations do not excite the least energy dissipating mechanism in non-brittle weak formations .

SeSSiOn 22: grOunD COntrOl iiTuesday, 25 June, 11:00 am – 12:30 pmChairs: Doug Tesarik, Michael Murphy

ARMA 13-642

case Studies of Rock Reinforcement components and Systems testingThompson, A.G. and Villaescusa, E.CRCMining/Western Australian School of Mines-Curtin University, Kalgoorlie, WA, Australia

rock reinforcement is widely used in tunnels and surface and underground mines . a large number of proprietary products are available in various configurations of components . While the mechanical properties of the primary element are available from product brochures, the associated component properties may vary widely and adversely influence the overall performance of the system . field pull out tests are most commonly used to measure the system response in the toe anchor region . however, the response of the collar region is less commonly considered but maybe more important . several case studies are described in which various components and systems of rock bolts and cable bolts have been subjected to static loading in the laboratory and in the field . the results generally demonstrate the importance of considering the properties of all the components and not simply those of the primary element . in some cases, the internal fixtures have strengths much less than the elements . often it has also been found that the fixture at the collar has significantly less strength than the element and this will result in complete loss of function in restraining surface support hardware such as plates, mesh and reinforced shotcrete .

ARMA 13-689

Developments in empirical approaches to Mining in frozen Rock Mass Ballantyne, S.1, Roworth, M.2, Pakalnis, R.1, Caceres, C.3 and Mawson, S.4 1University of British Columbia, Vancouver, Canada 2Golder Associates, Toronto, Ontario, Canada 3Independent consultant, Vancouver, British Columbia, Canada 4Cameco Corporation, Cigar Lake Mine

artificial ground freezing continues to prove as an effective approach to successful underground excavations in weak rock mass conditions . numerous mining and civil projects use artificial freezing worldwide; however uncertainties remain with respect to understanding and predicting behavior of frozen rock mass . it is well established that frozen rock has increased strengths relative to unfrozen states . empirical data from recent case studies also shows that rock mass ratings of weak rock are increased by up to 38% . this paper discusses ongoing frozen rock testing at the university of british columbia and development of empirical approaches to ground control in frozen ground . emphasis is on observed increases in rock mass ratings . challenges in representative numerical models are discussed, including heterogeneous material properties, distinct deformation rates, and varying temperature effects .


ARMA 13-135

Shotcrete Strength testing at the turquoise Ridge Joint Venture, nevada Sandbak, L.A. and Rai, A. R. Barrick Gold, TRJV Mine, Golconda, NV, USA

due to the highly fractured nature of the rock, shotcrete at trJv is not considered ground support by itself . shotcrete is applied to all primary and long term development headings, and may be applied in other headings where needed to supplement the primary bolt and wire mesh support . .early strength shotcrete (1-5 hours) tests are based on niosh portable shotcrete testing equipment . the testing using compressive break tests are done in accordance with astm c116-90 . this is to be correlated with a separate method of early strength shotecrete using pull tests on anchor nails . shotecrete 3-day, 7 day, and 28-day compressive tests are performed on 10 cm x 20 cm (4 x8 inch) cylinders . long term 28-day test samples are based on astm c39 for compressive tests . the 28-day long range strength of sprayed shotcrete of low slump shotcrete average approximately 20 .7 mpa (3000 psi), but reductions in water content have decreased the slump and increased the 28-day strength to over 34 .5mpa (5000 psi) compressive strength . the current slump goal is to keep the slump to a low 4-6 inches . the average strengths have exceeded 27 .6 mpa to 34 .5 mpa (4000-5000 psi) goal, and can be attributed to slump testing, shotcrete plant automation, and shotcrete nozzle man training .

ARMA 13-563

Developing an approach for Reliability analysis of bench face angle Design in open pits with Structurally controlled Sliding failure Keneti, S. A. R., Chaparro, C. and hunt, C. EBA, A Tetra Tech Company, Vancouver, British Columbia, Canada

a step by step “repeatable” procedure of the reliability-based methodology for bench face angle (bfa) design, which does not use in-house software, is presented in this paper . the published references on reliability bfa design use non-commercially available software as the basis for the reliability approach . in this study, a technique was developed for probabilistic reliability design which does use commercially available software to assess bench scale instabilities . back break analysis using cumulative frequency analysis and stochastic simulations of discontinuities properties such as orientation and dips were conducted to analyze the likelihood for plane shear and wedge type failures to occur for given bench face configurations and orientations . for this purpose, monte-carlo generated joints analyses using rocscience sWedge computer program was conducted along with stereographic analysis using rocscience dips computer program to calculate the probability of failure and the related back break length at bench scale . reliability plots for bfa were generated using a spread sheet (in microsoft excel) developed specifically for this study .


SeSSiOn 23: rOCk heterOgeneity anD SCalingTuesday, 25 June, 11:00 am – 12:30 pmChairs: Roberto Suarez-Rivera, Alexander Chudnovsky

ARMA 13-678

field-Scale Geomechanical characterization of the haynesville Shale Rodriguez-herrera, A.E., Suarez-Rivera, R. and handwerger, D. Schlumberger herring, S. and Stevens, K. Encana, Dallas, Texas, USA Marino, S., Paddock, D., Sonneland, L. and haege, M. Schlumberger

in this paper we describe the use of a heterogeneous earth model (hem) for field scale geomechanical modeling of a large region with seismic, well-log, and core data in the haynesville shale . results are used to ascertain the distribution of completion quality across the play by means of geomechanical modeling based on core-measured properties propagated to the seismic-scale . the development of the hem is a topic of another paper, also submitted to this conference . in that, we explain with sufficient detail, the integration of core, log and seismic data and the comprehensive laboratory characterization that is necessary for populating the geomechanical model . in this paper, we start by uploading the hem geometry model and the distribution of material properties, to a large scale finite element model (fem) . We impose boundary conditions to realistically represent the overburden and lateral stresses . multiple measurements of the minimum horizontal stress (from mini-frac measurements) are used to constrain the boundary conditions and to ascertain a good match between the stresses resulting from the imposed boundary conditions, and the measured values . the finite element model helps us evaluating the distribution of stress magnitudes and orientations resulting from the realistic geologic and tectonic setting as well as the overburden loading . results allow us to address the importance of understanding the vertical and lateral variability in properties and the corresponding variability of stress (magnitude and direction) . results have strong implications on well placement for hydraulic fracturing and wellbore stability applications .

ARMA 13-261

on the limitations of effective Medium approaches for estimating fracture Width in anisotropic RocksChertov, M.Schlumberger

it is always tempting to be able to replace a complex problem requiring characterization of multiple input parameters with a simplified one that requires reduced number of inputs and takes less effort and time to develop and then apply the solution procedures to obtain an approximate solution reasonably close to the true one . during the modeling of heterogeneous geologic rock masses, in which the main variability is typically realized as horizontal lamination at different scales, this approach is often implemented as homogenization or upscaling of multiple adjacent layers into fewer and thicker layers with equivalent parameters or responses . even with the most powerful computational resources, numerical simulations of rocks require that real variability of rock properties be smoothed to the level that can be reproduced on the numerical mesh with the highest refinement . this work quantifies how large the worst-case scenario errors can be when the homogenization approach is applied to a particular problem of estimating the width of a fracture in a layered formation in cases of both isotropic and anisotropic elastic layers .


ARMA 13-366

textural and compositional heterogeneity of tight Shales at the Micro-Scale Schieber, J. and Mastalerz, M. Indiana University, Bloomington, Indiana, USA Green, S. and Suarez-Rivera, R. Schlumberger Innovation Center, Salt Lake City, Utah, USA

how a mud becomes rock and what controls its physical properties is encoded in the fine scale microscopic details of its constituents . these details are analyzed via high resolution sem imaging over multiple length scales of shale components (fecal pellets, silt streaks, etc .) and fine-scale stratification (sub-mm to mm scale) . shale cores are further characterized through continuous measurement of physical properties at mm resolution (quantitative geologic analysis), to acquire a data volume sensitive to changes in texture and composition . the process permits differentiation of core intervals with unique characteristics, designated as shale microfacies, and sampled, at the microfacies level, for high resolution imaging and analysis . examination of argon ion milled areas of approximately 5 mm by 5 mm size allows us to overcome the contextual limitations of traditional sem study of shales, where typical observation footprints range from of 50 to 100 μm in size . the combination of quantitative geologic analysis, measurement driven identification of shale microfacies, and multi-millimeter size sem imaging represents a quantitative approach to the intrinsic variability of tight shales . the method is applicable independent of the core section available, and lets us carry forward high resolution property associations to other locations of a core where the same microfacies exist .

ARMA 13-656

Reduction of Macroscale calibration experiments through constraints on anisotropic elastic StiffnessesColovos, J.W. and Brannon, R.B.University of Utah, Salt Lake City, Utah, USAPinsky, P.M.Stanford University, Stanford, California, USA

geomaterials that are assumed to have symmetry about a single preferred direction have five independent transversely isotropic elastic constants . these elastic constants can be determined from data obtained through a series of macroscale calibration experiments, but only a subset of these five constants can be found directly from axial and lateral stressstrain measurements on a single cylindrical sample of material . substructural axisymmetric inhomogeneities present in the material and decoupling methods used in modeling can imply constraints on transversely isotropic elastic constants, potentially reducing the number of macroscale experiments needed to characterize a geomaterial model . morphology of substructural heterogeneities, such as distributions of microscale inclusions, cracks, pores and fibers, lead to homogenization or distribution parameters that affect the fourth-order elastic stiffness of the material . constitutive models that decouple the elastic stiffness often neglect interaction components, which impose constraints on the transversely isotropic elastic constants . We consider the mathematically motivated decoupling of tensorially linear and non-linear functions of a structural or fabric tensor . neglecting the non-linear components, as often done for rock models, imposes a constraint that the lateral shear modulus depends on the remaining elastic constants . We also consider the mathematically motivated decoupling of purely-volumetric and purely-deviatoric components, often used in the field of biomechanics . When the mixed volumetric-deviatoric components are neglected, the axial and lateral poisson’s ratios are constrained to become dependent on the two tensile moduli and a new independent bulk modulus type parameter . the described constraints reduce the number of independent elastic constants from five to four . in biomechanics, the accuracy of the approximation from the constraints can be verified through knowledge that the substructural source of anisotropy is


fibers embedded in a mostly incompressible water matrix . the potential for using similar techniques to investigate approximations that use constraints on elastic constants is discussed for geomaterials, specifically non-interacting cracked solids, with the goal of reducing the number of macroscale experiments needed to characterize a geomaterial model .

ARMA 13-653

Microfracturing of coal Related to adsorption-induced Swelling and Matrix-Scale heterogeneityhol, S.Utrecht University, HPT laboratory, Utrecht, The Netherlandsnow at: Stanford University, Department of Geophysics, Stanford, CA, USASpiers, C.J.Utrecht University, HPT laboratory, Utrecht, The Netherlands

We report dilatometry experiments conducted on unconfined mm-scale coal samples . the samples were exposed to co2 at pressures up to 100 mpa, at a temperature of 40 °c . cycling the co2 pressure between 0 and 100 mpa resulted in reversible and irreversible strains . substantial hysteresis was observed in strain versus pressure response in the first and second pressurization cycles . only after two or three cycles, the measured strain response became fully reversible, and equilibration was four times faster compared to the first cycle . sem imaging showed that microfractures had formed in our samples during the tests . We infer that these were caused by heterogeneous swelling of the coal macerals, and were responsible for the strain hysteresis and fast co2 penetration into the samples under the experimental conditions used here . under in situ effective stresses, microfractures are unlikely to form or open . We argue that, therefore, enhanced coalbed methane (ecbm) production can be achieved only by active reservoir stimulation .

ARMA 13-630

enhancing heat extraction and Minimizing Water losses by Deploying Silica Gel in enhanced Geothermal Systems Ezzedine, S. M. CED, Lawrence Livermore National Laboratory, NSED, Livermore, CA, USABourcier, W., hunt, J. and Roberts, S. AEED, Lawrence Livermore National Laboratory, AEED, Livermore, CA, USA

We carried out modeling studies to demonstrate how the silica agent can be used and show how we anticipate the silica blocking and diverting agent will perform on a simple thermal test within a single fracture . the modeling code enables us to calculate the drawdown and flow rates for desired scenarios for comparison to those without the silica blocking agent . We illustrate gel deployment in a single fracture for enhancing heat extraction and minimizing water uses . We have begun simulating silica gel in a three dimensional fracture network . logistics for a parametric study for optimal use of silica gel are discussed . We conclude by a short discussion on gel deployment under conditions of uncertainty in the egs subsurface characterization .


SeSSiOn 24: DiSCrete geOmeChaniCS iiTuesday, 25 June, 11:00 am – 12:30 pmChairs: Nick Sitar, Mary McLaughlin

ARMA 13-269

basic equations of two Dimensional and three Dimensional contactsGen-hua ShiDDA Company, Belmont, California, USA

contacts between two general 2d or 3d blocks can be complex . there are different contact points in different block positions . there may also have more than one contact point pairs in the same block position . this paper describes general equations of entrance for contacts between two general 2d or 3d blocks . the boundary of entrance block is entrance surface . giving a reference point, the concept of entrance surface simplifies the contact computation in following ways . case 1 is first entrance . if the reference point is outside the entrance block and moves on the entrance surface, contact takes place . the reference point on the entrance surface defines the contact planes . case 2 is shortest exit . if the reference point moves already inside the entrance block, a nearest point on entrance surface can be computed and the contact planes can be found .

ARMA 13-168

Relationship between Grain Size and fracture properties of Rock Tarokh, A. Department of Civil Engineering, University of Minnesota, Minneapolis, MN, USA Fakhimi, A. Department of Mineral Engineering, New Mexico Institute of Mining and Technology, Socorro, NM, USASchool of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran

development of an inelastic zone ahead of a crack tip known as process zone is a common phenomenon observed in many quasi-brittle materials . some experimental and numerical efforts have been conducted to scrutinize the parameters affecting the size of process zone . this study investigates the role of grain size on the process zone and size effect parameters by conducting a discrete element simulation of rock fracture . a softening contact bond model is used to study the development of the process zone around a notch tip in three-point bending tests . the numerical simulation is utilized to obtain nominal tensile strength, apparent fracture toughness and width of process zone . bazant’s size effect law parameters were obtained using the change in nominal tensile strength with specimen size and it was found that by increasing the grain size, brittleness of the material decreases . it is also shown that apparent fracture toughness is in general a function of specimen and grain size and it increases with the increase in grain size .the change in process zone width with specimen size is investigated too . it is illustrated that for a less brittle material, the impact of grain size on the width of process zone is greater . based on dimensional analysis, for sufficiently large specimens, a linear relationship between width of process zone and grain size is suggested .


ARMA 13-388

Discontinuum-Mechanical behaviour of Salt Rocks and the practical Relevance for the integrity of Salinar barriers Minkley, W., Knauth, M. and Brückner, D. IfG, Institute for Geomechanics, Leipzig, Germany

up to now salt rocks have been predominantly regarded as a continuum and the mechanical effect of the present discontinuities have been neglected to a great extent . however, for a complete understanding of geomechanical phenomena this approach proves to be insufficient . discontinuum-mechanical aspects are of importance for the integrity of salinar barriers, not only in the macro-, but also in the micro-scale . in the grain scale, polycristalline salt represents a discontinuum constituted of intergrown crystal grains . grain boundaries are micro-mechanical weakness planes that preferably fail under loading . for the mechanical description we therefore employ an elasto-visco-plastic model for the salt crystals as well as an adhesive frictional model for the grain boundaries . the discontinuum-mechanical approach has been deduced from experimental investigations in the laboratory and in situ . based on this discontinuum-mechanical approach, hydro-mechanical coupling like the pressure-driven percolation of fluids, intergranular microcracking and hydraulic fracturing can be analyzed . the results demonstrate how the integrity of salinar barriers depends on hydro-mechanical processes on the grain-scale . the discontinuum-mechanical micro-structure of salt rocks characterizes essential properties and is the key to the physical understanding of pressure-driven percolation of fluids by the creation of connectivity within the salt rocks as soon as the fluid pressure overcomes the normal stress on the grain boundaries . practical applications are the investigation of the integrity of salinar barriers in potash and salt mining, the proof of the relevancy of hydro-thermo-mechanical loading in connection with the final disposal of heat-generation radioactive waste and the usage of fluid-filled caverns for waste disposal as well as cavern abandonment .

ARMA 13-583

numerical simulation of damage during laboratory testing on rock using a 3D-feM/DeM approachhamdi, P. and Stead, D.Resource Geotechnics Research Group, Simon Fraser University, Burnaby, British Columbia, CanadaElmo, D.Institute of Mining Engineering, University of British Columbia, Vancouver, British Columbia, Canada

the suitability of hybrid 2d-fem/dem methods for simulating brittle failure laboratory testing has been described by numerous researchers emphasizing their ability to illustrate clearly the transition from an intact rock continuum to a discontinuum fractured state . however, there remains a need to further characterize brittle failure under varying 3d stress paths . this work presents for the first time a wide range of simulated 3d-fem/dem stress conditions encountered in conventional laboratory testing . the scope of this study is to simulate the brazilian and unconfined compressive strength (ucs) tests in 3d using the hybrid fem/dem code elfen . the fracture pattern and mechanical response of 3d models are investigated and the results then compared with the equivalent 2d models . as a part of an ongoing research at simon fraser university, a damage intesity parameter (d21) is introduced and preliminary application in quantifying damage during laboratory testing discussed .


ARMA 13- 673

numerical investigation of crack propagation and failure Mechanism of layered Rocks Liu, W.C. and Tien, Y.M. Department of Civil Engineering, National Central University, Jhongli City, Taoyuan County, Taiwan Juang, C.h. Department of Civil Engineering, Clemson University, Clemson SC, USA Lin, J.S. Department of Civil Engineering, University of Pittsburgh, Pittsburgh, PA, USA

this paper presents the numerical investigation results of failure process, failure modes and strength anisotropy of layered rock under a series of uniaxial compression and brazilian tests . this paper employs 2-d particle flow code (pfc2d) to simulate layered rock models for different inclination angles(θ) that varies from 0° (the layer is perpendicular to the loading direction) to 90°(the layer is parallel to the loading direction) . based on the numerical simulation results, the uniaxial compressive strength decreases with the increase of the inclination angle at 0°≦θ≦60° then the uniaxial compressive strength slightly increases at 60°≦θ≦90° . three kinds of failure modes under uniaxial compression test could be observed: (a) sliding failure across layers mode, (b) sliding failure along layer mode, and (c) tensile split along layer mode . the inclination angle has a more significant effect on the tensile behavior of layered rock under brazilian test . the tensile strength of layered rock decreases with the increase of the inclination angle . through the numerical investigation of failure process during brazilian test, the micro-cracks roughly initiate at 50% of ultimate stress near the contact boundary then propagate slowly until the peak is reached . after the ultimate stress is reached, the mico-cracks start to form macro-cracks and the failure of layered rock under brazilian test can classified into four modes: (a) split across layer mode: the cracks propagate across layers at 0°≦θ≦30°, (b) sliding along layer mode: the cracks slide along the layer at 45°≦θ≦60°, (c) mixed mode: both split across layer and sliding along layer mode could be observed at θ=75°, and (d) split along layer mode: the cracks propagate along layers at θ=90° . furthermore, the numerical simulation results compare with the experimental data from cho et al . (2012) . although the failure modes under brazilian test at 45°≦θ≦75° are a little difference, the uniaxial compressive strength, failure modes under uniaxial compression test, and tensile strength agree well with the experimental data from cho et al . (2012) .

ARMA 13-600

block theory application to Unlined Rock Spillway erodibility assessment George, M.F. and Sitar, N. University of California, Berkeley, CA, USA

scour of rock is a complex process and can be very problematic for dams when excessive scour threatens dam stability . removal of individual rock blocks is one of the principal mechanisms by which scour can occur, particularly in unlined spillways and on dam abutments/foundations . to alleviate some of the complexity, commonly used methods for scour prediction tend to simplify the rock mass using rectangular block geometries or incorporate empirical relationships for the rock mass and do not actually model the physical scour process . such simplifications can be problematic, particularly for block analysis, where the 3d orientation of discontinuities within the rock mass largely influence block removability . to better represent the 3d structure of the rock mass, block theory is used to evaluate stability of removable rock blocks subject to hydraulic forces . block theory provides a rigorous methodology to identify removable blocks, determine potential failure modes, and assess block stability . an actively eroding unlined spillway at a dam site in northern california is used to demonstrate the use of this approach for the evaluation of the scour potential at the site .


SeSSiOn 25: pOre preSSure anD StreSSTuesday, 25 June, 2:00 pm – 3:30 pmChairs: Maria Nikolinakou, Sherif Akl

ARMA 13-527

iterative 3D Geomechanical Modeling to Determine Distribution and impact of Stresses in Deepwater Gulf of Mexico Subsalt and near-Salt environmentsNagy, Z.R., Lee, D.W. and Sayers, C.M.Schlumberger, Houston, Texas, USAZapata, T.R. and Silvestro, J.L.YPF Services USA Corp., The Woodlands, Texas, USA

a 3d finite-element model (fem), covering an area of 300 km2 in the deepwater gulf of mexico, was used to determine the stress distribution around salt structures, and to study the impact on well design decisions . a 3d model was necessary to accurately determine the full stress tensor (i .e ., changes of stress magnitude and orientation around the salt body) . an iterative workflow to fine-tune properties and stresses has been developed to validate wellbore failure and to explain drilling events . the 3d fem was built using a geological model, high-quality seismic velocity data, and results from 1d mechanical earth models . the model indicates that the stress magnitude and orientation are modified by salt morphology . in particular, locations at the salt/sediment interface, this phenomenon resulted in significant stress rotation and high von mises stress . in these circumstances, the safe drilling mud weight window can quickly disappear, forcing the operator to manage both wellbore instability and mud loss, and with no choice but to sidetrack or select a new well location . the described case study illustrates the application of the 3d fem, which was able to explain drilling events (including an abandoned wellbore), provide input for calculating the mud weight window (range between shear failure and minimum stress), and guide well design . the significance of this study is that, as more well trajectories are drilled in these complex environments, robust, predictive 3d fems will be necessary to assess potential risk prior to drilling and to improve well planning .

ARMA 13-729

predicting the paleo evolution of overpressured Geological Structures Rance, J.M. and Profit, M.L. Rockfield Software Limited, Swansea, Wales, UK Dee, S.J. BP, Sunbury, England, UK Roberts, D.T. Cardiff University, Cardiff, Wales, UK

forward modeling the formation of geological structures can provide additional insight into their evolution . the ability of these models to replicate the evolution without the requirement for seeding means that important information relating to the material state and development of, or absence, of overpressures can be extracted . case studies are presented relating to forward modeling the evolution of the acg anticline using the finite/discrete element software package elfen . 2d sections are modeled with the software under a variety of conditions . modeled pore pressure distribution with depth is compared to a reference with favorable results . final geometries interpreted from seismic data also match model predictions .


ARMA 13-302

an alternative interpretation of leakoff and lost circulation pressure MeasurementsChan, A.W.Shell Exploration & Production Co, New Orleans, LA, USAhauser, M., Couzens-Schultz, B.A. and Gray, G.Shell Exploration & Production Co, Houston, TX, USA

leak-off pressure and lost circulation data are generally thought to be reflective of minimum stress . We propose that in the analysis of these data for stress and fracture gradient information, an alternative interpretation be considered where the data may reflect a shear failure along zones of pre-existing weakness rather than opening of tensile fractures against the minimum stress . this mechanism has been discussed in a small number of borehole stability and hydrofracture papers, but has not been widely applied to leak-off test or lost circulation interpretation . in this paper, we will revisit and expand the concept introduced recently by couzens-schultz and chan (2010) based on abnormally low leak-off tests in an active thrust belt to the analysis of lost circulation observations in modern day deltaic environments . three potential failure mechanisms have been identified for characterizing leakoff tests: (1) tensile opening of a pre-existing fracture, (2) creation of a new tensile fracture in an intact homogeneous formation, and, (3) injection-induced shear dilation/reactivation along pre-existing planes of weakness . in the gulf of mexico, leak-off test interpretation has historically focused on mechanisms (1) and (2) which appear to explain the majority of test results . similarly, lost circulation interpretation historically focuses on mechanisms (1) and (2) and is thought to directly reflect the minimum horizontal stress . however, shear dilation/fault reactivation can also occur in the normal-stress environment . this mechanism requires some pre-existing planes of weakness such as faults or fracture networks . if such zones are present, failure can occur at pressures well below the minimum far-field stress that is typically considered a safe upper bound for mud pressure . We illustrate an integrated approach to consider all three failure mechanisms, using a well-calibrated stress model to constrain the principal stresses and the stress polygon in order to graphically illustrate the range of in situ stresses which would explain leak-off test and lost circulation results . a mud loss event is shown to be inconsistent with the tensile modes in a normal stress environment, but in good agreement with expectations for shear failure along pre-existing faults . our proposed interpretation has been the subject of some controversy; however, we believe that it can easily explain otherwise anomalous data that are: (1) either thrown out because they do not fit established trends or expectations, or (2) used to significantly alter the subsurface stress model in a way that is inconsistent with other stress-related information . our examples should illustrate that the shear dilation/reactivation mechanism is viable for both leak-off pressure and lost circulation data and it can be used in both active tectonic settings as well as passive margin settings where we more typically explore .

ARMA 13-545

Wireline Stress testing in Reservoir Sands Some Geomechanical considerations and a case from the norwegian continental Shelf Bautmans, P., helstrup, o.A. and Constable, K.C. Statoil ASA, Norway Pfeiffer, T. Schlumberger, Bergen, Norway

recently developed wireline formation tester technology, namely a high rate pump module and improved packer elements, has allowed microfracturing data to be acquired in high permeability, high leak-off environments . this paper examines some of the major influencing factors on the microfrac pressure data and consequently the derived closure pressures, to help understand how representative a stress derived from a small scale measurement might


compare to the far field stress . data from a case study from the norwegian continental shelf is presented, the detailed analysis of which has improved the understanding of the technique and acquired data . this has allowed some existing interpretation techniques to be extended and operational best practices to be developed .

ARMA 13-308

Revisiting Well Design and formation pressure prediction: case Study from Gulf of Mexico Mannon, T.P. University of Louisiana at Lafayette, Lafayette, LA, USA Stone Energy, Lafayette, LA, USA Salehi, S. University of Louisiana at Lafayette, Lafayette, LA, USA

improving well design has and always will be the primary goal in drilling operations in the oil and gas industry . to address this issue, an analysis of wellbore stability and well design improvement has been conducted . this study will show a systematic approach to well design by focusing on best practices for mudweight window projection for a field in mississippi canyon, gulf of mexico . the field includes depleted reservoirs and is in close proximity of salt intrusions . analysis of offset wells has been conducted in the interest of developing an accurate picture of the subsurface environment by making connections between depth, non-productive time (npt) events, and mudweights used . commonly practiced petrophysical methods of pore pressure, fracture pressure, and shear failure gradient prediction have been applied to key offset wells in order to enhance the well design for a proposed well . for the first time in the literature, the accuracy of the commonly accepted, seismic interval velocity based and the relatively new, seismic frequency based methodologies for pore pressure prediction are compared . each of these methods is compared to the petrophysically derived mudweight windows for the key offset wells and the proposed well in this field, showing higher reliability in the frequency based approach . additionally, the interval velocity method yielded erroneous results in a fast-rock-velocity channel zone and the near salt proximity environments, whereas the frequency based method appeared unaffected by either of these factors .

ARMA 13-121

the effect of bedding plane orientation on pore pressure in Shale formations: laboratory testing and Mathematical ModelingDokhani, V., Yu, M. and Miska, S.Z.The University of Tulsa, Tulsa, Oklahoma, USA

in this study, shale-fluid interaction is investigated through experimental approach under simulated in situ conditions to determine the effect of bedding plane orientation on fluid flow through shale . current wellbore stability models are developed based on isotropic conditions, where fluid transport coefficients are assumed to be constant in all flow directions . this paper also presents a novel mathematical method, which takes into account two-dimensional coupled flow of water and solutes due to hydraulic and chemical potential imposed by drilling fluid and / or shale formation . the model allows the user to study the role of fluid communication between matrix and fracture within the shale formation . the coupled equations are solved numerically using the finite difference method to evaluate pore pressure and solute concentration distributions in the vicinity of the borehole . using obtained transport coefficients from the experimental data, sensitivity analysis is performed to provide insights into the effect of fracture spacing and bedding plane orientation on pore pressure distribution around the wellbore . numerical results indicate that the presence of fissures and fractures changes the pore pressure distribution significantly around the wellbore and directly affect shale mechanical strength . this work can be used to enhance the wellbore stability analysis in fractured shale formations .


SeSSiOn 26: COal mine rOCk meChaniCSTuesday, 25 June, 2:00 pm – 3:30 pmChairs: Erik Westman, Greg Husenfus

ARMA 13-183

Geotechnical-Geophysical Void Mapping and foamed-Sand backfilling of the Rapson coal Mine, colorado Springs, colorado – case Studyhanna, K., Pfeiffer, J. and hodges, S.Zapata Incorporated, Golden, CO, USAAmundson, A.L.Colorado Division of Reclamation, Mining and Safety, Denver, CO, USAPalladino, R.Cellular Concrete Solutions, Golden, CO, USASzynakiewicz, T.Hayward Baker Incorporated, Broomfield, CO, USA

the presence of mined-out areas of voids underlying residential areas represents a significant risk to public safety and infrastructure . the country club circle (ccc) colorado springs neighborhood is underlain by the abandoned rapson coal mine, which was worked from 1900 to 1915 prior to residential development . through the years, numerous subsidence-sinkhole events have repeatedly occurred, causing serious safety hazards and damaging structures, streets, and utilities . the colorado division of reclamation, mining and safety (cdrms) developed a comprehensive abandoned mine subsidence risk assessment and reclamation program through a proactive method for delineating and mapping mines that exist beneath the residential area . in order to develop proactive solutions to minimize risk where mine workings are present, Zapata incorporated (Zapata) implemented a multi-phase subsurface geotechnical exploration plan that included a variety of high-resolution geophysical technologies, focused exploratory boring, and imaging of existing mine workings . based on the results of the geotechnicalgeophysical studies, cdrms initiated the mine reclamation plan to stabilize the remaining voids and caved areas beneath the neighborhood using foamed-sand slurry and low-mobility grouting . this paper describes the collaboration between drms, Zapata, cellular concrete solutions (ccs), and hayward baker inc . (hbi) to facilitate completion of the geophysical investigation and subsidence mitigation work .

ARMA 13-154

practical estimation of Rock properties for Modeling bedded coal Mine Strata Using the coal Mine Roof Rating Esterhuizen, G.S., Bajpayee, T.S., Ellenberger, J.L. and Murphy, M.M.National Institute for Occupational Safety and Health, Pittsburgh, Pennsylvania, USA

numerical models are increasingly used as tools to design support for coal mine entries . a critical part of the design process is to obtain rock strength parameters that are representative of the large-scale rock mass surrounding the excavations . the coal mine roof rating (cmrr) is a rock classification system that was developed to characterize the bedded strata found in coal mines . procedures were developed to estimate rock strength properties suitable for numerical modeling based on the cmrr outputs . the rock matrix and bedding strength are quantified separately for the different rock units . the rock units are modeled using the ubiquitous joint approach, accounting for laboratory- to field-scale strength reduction . contacts between units are modeled as explicit interfaces . procedures for estimating the bedding cohesion, tensile strength and friction angle from cmrr data are presented . the strength estimation and modeling procedures are calibrated against several field monitoring sites to ensure that realistic results are obtained . two cases are presented to demonstrate the approach and the match with field monitoring results .


ARMA 13-443

applications of Subsurface Subsidence theories to Ground control in coal Mines Qiu, B. and Luo, Y. West Virginia University, Morgantown, WV, USA

the overburden strata movements, from the immediate roof up to the ground surface, caused by underground longwall mining subsidence, are essential for analyzing related ground control problems and improving mine planning and developments . a good subsurface subsidence prediction model has the capability to connect the surface subsidence with the seam level strata movements, and to predict the movements and deformations for the strata between them accurately . this paper will apply the subsidence theory in solving two important ground control problems in coal mines: support system design for pre-driven longwall recovery room, and pillar stability assessment in multi-seam mining operations . for the support system design of the pre-driven recovery room, dynamic subsidence prediction theory is used to estimate the roof deflection and deformation with the varying support capacities as the longwall face approaches the recovery room . in assessing stability of mine pillars in multi-seam mining situation, mathematical models have been developed to use the total strain or void intensity in expansion zone from the subsurface subsidence prediction model in estimating the pillar load and strength . the mathematical models for these two applications are presented in this paper . the models are validated with field data .

ARMA 13-734

extraction Design for Multiple Seams highwall Mining in india – a case example Porathur, J.L. Central Institute of Mining and Fuel Research, Regional Center, MECL Complex, Seminary Hills, Nagpur, IndiaKarekal, S.Centre for Earth Science and Resource Engineering, CSIRO, Brisbane, Australia Roy, P.P. Central Institute of Mining and Fuel Research, Dhanbad, Jharkhand, IndiaVerma, C.P.Central Institute of Mining and Fuel Research, Regional Center, Nagpur, India

highwall mining is a mechanized and productive method compared to conventional underground mining methods . it leads to added recovery of coal which is otherwise lost in the pit below the highwall . the major challenge envisaged is however the designing of web pillars in complex indian geomining conditions, invariably comprising of multiple seams, some in close proximity, and multiple-pass extractions in thick seams . the method has been recently introduced in india in december 2010 with the operation of addcar continuous highwall mining machine at ramagundem opencast project-ii (ocp-ii) of singareni collieries company ltd . (sccl) . after successful extraction of two seams at ocp-ii, the machine is now extracting at neighbouring medapalli opencast project (mocp) of sccl . in this paper, hybrid empirical and numerical techniques employed to design web pillars in multiple seam scenario of mocp mine is discussed in detail . the paper explains the procedure adopted to design web pillars for the two blocks demarcated in mocp considering maximum coal recovery and long-term stability . the paper also reviews the general prospects of highwall mining in india taking cues from the mocp mine .


ARMA 13-105

Geotechnical Study of coal Rib failure at ananta coal Mine, orissa, indiadr . v . k . singh Central Institute of Mining and Fuel Research Dhanbad, Jharkhand, India

the paper deals with the geotechnical studies carried out to understand the possible reasons of 30m high coal rib failure and the adjoining dump failure . the slope design was also done to excavate the blocked coal in rib . the 30m high coal rib was under cut at its toe level due to fire . the unsupported bottom most toe portion of the standing 30m high coal rib was under the maximum stress but the overhanging coal rib slope, detached from its toe due to fire, was having least strength due to long time exposure and fire . the triggered failure caused horizontal shifting of coal rib up to the overhanging/ undercut burnt coal level along the bedding plane of the coal seam which was dipping towards the pit . the adjoining ob dump subsided behind the coal rib with formation of numerous cracks on the surface . the failed slope was designed to mine out the blocked coal in the rib . the remaining dump slope should be reformed with bench height and width of 5m and 6m respectively and 45° bench angle . the ultimate slope of southern coal rib should be mined with a maximum bench height of 10m and minimum bench width of 8m .

ARMA 13-605

application of artificial neural networks for predicting the height of Destressed Zone above the Mined panel in longwall coal MiningMajdi, A. and Rezaei, M.School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran

due to extraction of coal seam, in longwall coal mining, the immediate roof strata of mined panel are disturbed and sag downwards . then, the resulting movement of the roof strata extends upwards and will cause the disturbed roof strata be fractured . subsequently, the roof pressures will be redistributed and transferred to the neighboring solid sections where the face abutment, adjacent access tunnels and the barrier pillars are located . hence, an accurate determination of the height of this fracture zone which is called the height of destressed zone (hdZ) is essential to maintain the desired mine extraction efficiency and to generate a safe mine working environment . the paper describes two predictive models based on artificial neural network (ann) and statistical analysis for predicting the height of destressed zone . a suitable dataset including the panel and the roof strata geometrical characteristics along with their mechanical properties were collected from literatures which have been divided into two groups, that is, training and testing datasets . to evaluate the performance of the employed models, the coefficient of determination (r2), variance account for (vaf), mean absolute error (ea) and mean relative error (er) indices were calculated based on the testing data . comparison of the above mentioned results showed that the performance of ann model is superior to the statistical model . finally, the results are compared with the existing methods and the in-situ measurements . the comparative results confirm a reasonable agreement that exists among the methods as well as with the in-situ measurements .


SeSSiOn 27: aCOuStiC emiSSiOnSTuesday, 25 June, 2:00 pm – 3:30 pmChairs: Sergey Stanchits, Steve Glaser

ARMA 13-295

Ultrasonic transmission and acoustic emission Monitoring of injection-induced fracture processes in Rock Samples Masuda, K. and Satoh, T. Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan Nishizawa, o. Research Institute of Innovative Technology for the Earth, Kyoto, Japan

injection-induced fracture processes in rock samples are monitored by using ultrasonic transmission and acoustic emission (ae) techniques . We injected water into dry, cylindrically shaped granite samples under constant differential stress and confining pressure . during water migration, we measured p- and s-wave velocities . We also monitored ae and measured the strains of the sample surface . We estimated two crack characteristics, namely, the crack shape and degree of water saturation, and their changes during water migration . We developed a procedure for estimating the crack status inside a rock sample based on a cracked solid model using measured p- and s-wave velocities and porosity . We found that during injection of water to induce failure of a stressed rock sample, the aspect ratio of cracks increased from 1/400 to about 1/220 and the degree of water saturation increased . We used analyses of pulse widths of p waves of ae to investigate source durations of rupture processes for injection-induced and stress-induced microseismicity . after elimination of the effects of the event size and the hypocentral distance from the observed pulse widths, we detected changes in source durations for stress-induced and injection-induced microseismicity .

ARMA 13-400

analysis of continuous acoustic emission Waveform Records from Rock fracturing experimentsGoodfellow, S.D., Nasseri, M.h.B. and Young, R.P. Department of Civil Engineering, University of Toronto, Toronto, Ontario, CanadaFlynn, J.W. and Reyes-Montes, J.M.Applied Seismology Consultants, Shrewsbury, United Kingdom

an analysis of continuous acoustic emission waveforms from a triaxial rock fracture experiment is presented in this paper . a cylindrical sample of Westerly granite was heated to a temperature of 850oc before being triaxially deformed in a geophysical imaging cell . the sample was loaded hydrostatically to 25 mpa and then differentially until failure at a strain rate of 1 .6e-6 s-1 . acoustic emissions were acquired continuously at a sample rate of 10 mhz on 18 channels for the duration of the experiment . 14 channels were amplified at 40 db and the rest at 6 db . amplification was turned down on four channels to record unclipped waveforms during failure . approximately 20,000 events were harvested from the continuous waveforms . a time varying velocity model was used to source locate 4,357 ae events . continuous ae waveforms from the 40 db and 6 db channels were analyzed during the first and final stress drops . by superimposing a 40 db waveform on a 6 db waveforms from two neighboring sensors, we were able to see the loss of amplitude information just prior to and during the first stress drop . the use of broad-band ae transducers allowed us to investigated changes in waveform frequency content throughout the experiment using both discrete and continuous waveform data . changes in power percentages within different frequency bands, were shown to follow changes in event magnitudes and in the angle between the source receiver raypath and the loading axis .


ARMA 13-664

Monitoring the early onset of hydraulic fracture initiation by acoustic emission and Volumetric Deformation Measurements Stanchits, S., Edelman, E. and Suarez-Rivera, R. Schlumberger Innovation Center, Salt Lake City, UT, USA Surdi, A. and Gathogo, P. TerraTek, A Schlumberger Company, Salt Lake City, UT, USA

in this paper, the results of laboratory studies of fracture initiation, early propagation and breakdown are reported . three experiments were conducted on a low permeability sandstone block, loaded in a poly-axial test frame, to representative effective in-situ stress conditions . the blocks were instrumented with acoustic emission (ae) and volumetric deformation sensors . in two experiments fluids of different viscosity were injected into the wellbore, fluid injection was interrupted soon after the breakdown pressure had been reached . this allowed us to investigate hydraulic fracture initiation . in the third test fracture initiation criteria were applied to stop hydraulic fracture propagation significantly earlier, prior to breakdown, and as it propagated a short distance from the wellbore . analysis of ae results shows an increase in ae activity and a change in the ae spatial correlation, during the fracture initiation . this early stage of fracturing correlates strongly with the onset of rock volumetric deformation, and is confirmed by the analysis of ultrasonic transmission monitoring . the rock micro-structure, after the test, was investigated by analysis of sem images . these indicated the development of leak-off zone near the wellbore and a dry hydraulic fracture at the farther distance from the wellbore .

ARMA 13-586

acoustic Mapping and Microscopic analysis of laboratory induced hydraulic fractures under triaxial Stress conditions Damani, A., Rai, C.S., Sharma, A. and Sondergeld, C.h. University of Oklahoma, Norman, Oklahoma, USA

While hydraulic fracturing is well understood at a macro-scale, the physics behind the micro-scale phenomena is still not well understood . laboratory ( acoustic emission and ae monitoring ) studies and the scanning electron microscopic (sem) analysis of the induced hydraulic fracture morphology provide critical insight into the complex failure process occurring at a micro-scale . We report the results of controlled laboratory triaxial hydraulic fracturing and acoustic monitoring experiments . We performed tests on four inch diameter lyons sandstone samples subjected to a triaxial stress state . triaxial conditions replicate in situ reservoir conditions . the effects of stresses, fluid saturation and injection fluid viscosity on the ae response and the fracture morphology have been investigated . the episodic nature of rock failure is recorded from the real time acoustic response . double couple focal mechanisms indicative of shear failure dominate the recorded ae events . tensional and compressional sources are also recorded but are far outnumbered by the shear events . the saturation state and injection fluid viscosity are observed to affect the induced fracture complexity significantly . sem observations of the fracture morphology confirm the complexity observed in the ae response .


ARMA 13-298

Multi-Modal Monitoring of Slip along frictional Discontinuitieshedayat, A. and Bobet, A.School of Civil Engineering, Purdue University, West Lafayette, IN, USAPyrak-Nolte, L. J.Department of Physics, Department of Earth and Atmospheric Sciences, and the School of Civil Engineering, Purdue University, West Lafayette, IN, USA

seismic wave transmission and digital image correlation (dic) are employed to study slip processes along frictional discontinuities . a series of biaxial compression experiments are performed on gypsum specimens with non-homogeneous contact surfaces . the specimens are composed of two blocks with perfectly mated contact surfaces with a smooth surface with low frictional strength on the upper half and a rough surface with high frictional strength on the lower half . compressional, p, and shear, s, wave pulses were transmitted through the discontinuity and digital images of the specimen surface were acquired during the test . a distinct peak in the amplitude of transmitted wave occurs prior to the peak shear strength and is considered a “precursor” to the failure . precursors indicate that slip initiates from the smooth surface and extends to the rough surface as the shear load is increased . from the dic data, slip is identified as a jump in the displacement field across the discontinuity that initiates from the smooth surface and propagates to the rough surface . precursors are associated with an increase of the rate of relative displacement across the discontinuity and are a measure of a reduction of the fracture’s shear stiffness .

ARMA 13- 639

experimental evidence of Micromechanical processes that control localization of Shear Rupture nucleationSelvadurai, P.A. and Glaser, S.D.Civil and Environmental Engineering, University of California, Berkeley, CA, USA

developing a mechanistic understanding of the nucleation of fault rupture would help explain many behaviors of rock masses, from earthquake mechanics to response of dam foundations subjected to subsurface fluid injection . this paper presents a contact model to quantify the localized stress conditions required for a sliding block to transition from a quasistatic/stable phase to a dynamic high-speed/unstable phase . based on our experimentally developed contact model, we propose that the initiation of sliding takes place at the displacement incongruity where the compliant aseismic portion of the fault merges into the stiff, “locked” portions controlled by stress interactions along the preexisting fault defined by the regions of actual contact . a fault is experimentally modeled by a 400 mm x 80 mm x 10 mm pmma slider sheared across a large pmma base sample . a pressure-sensitive film was employed to localize, size, and measure normal stress on contact junctions of the interface . the film allowed for the development of an experimentally derived friction model which implicitly incorporates two measures of contact information: i) the heterogeneity of the normal stress field occurring across asperities and ii) the distribution of asperity sizes in localized portions of the fault . using multiple non-contact inductive displacement sensors, we identified, via velocity measurements, regions where the slip transitions from the quasi-static to a dynamic phase . these nucleation zones draw a parallel to regions on a fault between compliant and stiff zones as defined by the contact model .


SeSSiOn 28: rOCk maSS CharaCterizatiOn anD grOunD imprOvementTuesday, 25 June, 2:00 pm – 3:30 pmChairs: Trevor Carter and Derek Martin

ARMA 13-284

theoretical approaches in Grouting fractures of the Rock Mass: theories and applicationsYaghoobi Rafi, Jalaleddin, Tsuji, Masakuni and Stille, håkanRoyal Institute of Technology, Stockholm, Sweden

currently there is a great deal of specific attention on improving the grouting methods since optimizing the grouting process will have significant impact on performance and economy of projects as well as safeguarding the purity of nature . the main problem with existing grouting method is lack of knowledge about the spread of grout, i .e . there is no clue if the grout has been penetrated enough or if it has been over spread . also the state of fractures during grouting is unknown . in the last decade, theoretical approach has been developed which enables estimation of the grout spread in real time . furthermore, by replacing the estimated penetration length with injected volume, dilation of the rock fractures is monitored in real time . in this paper, this analytical solution has been examined and competency of its application has been discussed . implementing this theory with data from city line project confirms the usage of high applied pressure in this project which will lead to shortening of the grouting time .

ARMA 13-449

in-line Ultrasound based Rheology - a new tool for the Measurement of flow and Rheological properties of cement based Grout Mashuqur RahmanKTH-Royal Institute of Technology, Stockholm, Sweden Ulf håkansson KTH-Royal Institute of Technology, Stockholm, Sweden and Skanska AB, Solna, Sweden

measuring the rheological properties of cement based grouts and observing the change of the properties with time directly in-line are highly required, however, still unavailable during the grouting operation . the ‘ultrasound velocity profiling’ combined with ‘pressure difference’ (uvp+pd) method is a promising novel method for determining the rheological properties, e .g . viscosity and yield stress of used grout directly in-line, in real time and in a flowing condition . followed by a pre-study, a laboratory based set-up consisting a progressive cavity type of pump and a flow loop were used for the experiments . in addition, a data recording system (logac) was used as a reference . a widely used grouting cement, micro fine injektering 30 (ic30) of water to cement ratio 0 .6, and 0 .7 were used in this study . after performing a series of successful feasibility tests, it was found possible to determine the rheological properties of cement based grouts directly in-line and the change of the properties of cement grout with time was observed . the ‘uvp+pd’ method was also found an effective tool for the flow visualization, flow measurement and grout pump characterization . the future work of this project will focus on implementing this ultrasound based methodology in the grouting rigs for field applications .


ARMA 13-514

hydraulic characterization and Grouting of twin parallel tunnels at Äspö hard Rock laboratory, Sweden olofsson, I. Swedish Nuclear Fuel and Waste Management Company, Stockholm, Sweden holmberg, M. Tunnel Engineering, Nyköping, Sweden Ittner, h. and Christiansson, R. Swedish Nuclear Fuel and Waste Management Company, Stockholm, Sweden

about 300 m of tunnels have been constructed in 2012 at ca 400 m depth to expand skb’s hard rock underground laboratory . the main design constraints for the project were: (1) the hydraulic head above the tunnel must be maintained to at least 350 m at the end of construction, and (2) as little grouting as possible should be used in order to deliver undisturbed conditions for some experiments that will take place in some of the excavated tunnels . the most practical means to meet the first constraint was to plan for tunnel pre-grouting as part of the excavation cycle . to meet the second constraint the spread of the grout must be controlled by optimizing the grouting strategy . this paper describes how the project met these constraints by: characterizing the fracture flow system prior to start of excavation work, establishing correlations between predicted hydraulic aperture and grout takes; and conducting the design and execution of the grouting methodology using the observational method .

ARMA 13-672

Quantification of the Geological Strength index charthoek, E.Vancouver, British Columbia, CanadaCarter, T.G.Golder Associates, Toronto, Ontario, CanadaDiederichs, M.S.Queens University, Kingston, Ontario, Canada

the original geological strength index chart was developed on the assumption that observations of the rock mass would be made by qualified and experienced geologists or engineering geologists . With the ever increasing use of the gsi chart as the basis for the selection of input parameters for numerical analysis, often by individuals without the strong geologic understanding of rock mass variability necessary to interpret the graphical gsi chart properly, some uniformity and quantification of the chart seems necessary . this paper presents a proposed quantification of the gsi chart on the basis of two well-established parameters - Joint condition and rQd . recommendations for future development of more robust scales are presented .

ARMA 13-597

Some interesting abandoned Mine Stabilization projects in australiaDavid L KnottAssociate Geotechnical Engineer, Coffey Geotechnics Pty Ltd, Warabrook, NSW, Australia

three examples of australian practice dealing with development over abandoned coal mines are presented . coal mining started in newcastle, north of sydney in about 1800 using convict miners . in portions of new south Wales, approval for development over mined areas is regulated by the mine subsidence board (msb), a government agency that is responsible for repairing structures damaged


by subsidence . the msb is funded by a levy on coal and it regulates investigation and development standards to limit its exposure to claims, a process that provides uniform guidelines for development . sites above abandoned mine workings were able to be developed by stabilizing the underlying workings by injecting a flowable cement fly ash grout through grout holes drilled from the surface and / or over-excavation . shafts must also be mitigated .

pOSter SeSSiOn: geOmeChaniCal ChallengeS aSSOCiateD with geOthermal Drilling, StimulatiOn anD prODuCtiOnTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-315

investigation of laboratory hydraulic fracture Source Mechanisms Using acoustic emission hampton, J., Frash, L. and Gutierrez, M. Colorado School of Mines, Golden, Colorado, USA

multiple laboratory scale hydraulic fracture stimulation treatments were performed on colorado rose red granite and medium strength concrete grout . the samples were approximately 30x30x30 cm3 and boundary conditions consisted of a single unconfined test and a true-triaxially confined and heated test in order to simulate enhanced geothermal systems (egs) reservoir conditions . high viscosity valvoline® durablend® sae 80W90 oil and low viscosity brine solution were used as fracturing fluid with granite and analog rock, respectively . hydraulic fractures were obtained utilizing open hole fracturing intervals . acoustic emissions (ae) were monitored throughout testing from six observation points, using wideband piezoelectric transducers manufactured by physical acoustics corporation (pac), in order to characterize the stimulated reservoir and perform simplified moment tensor analysis to obtain source mechanisms . the simplified moment tensor analysis only utilizes first arrival characteristics to determine crack type classifications from a unified decomposition of eigenvalues . the ae event source mechanism locations were plotted in order to determine if spatial relationships existed . tensile, shear and mixed mode fractures were observed throughout testing . differing factors were investigated as potential causes of the tensile and shear distribution including viscosity of fracturing fluid, brittleness of source material, homogeneity of source material, presence of natural fractures and stress conditions .

ARMA 13-278

Role of the 3D network of faults on the Response to hydraulic Stimulation of Deep Geothermal Wells Gentier, S., Rachez, x., Blaisonneau, A. and Guillon, T. BRGM, Orléans, France

the results of the stimulations of the deep wells at soultz-sous-forêt show that the well presenting the best initial injectivity is not necessarily the most efficient after stimulation . the combination of shearing triggering mechanisms related to the relative orientation of faults with respect to stresses, with the “structural patterns” of the different wells related to geological hazard can largely explain the different responses to hydraulic stimulation from a well to another . the “structural pattern” includes, in this study, not only directional characteristics but different characteristics of the elements constituting the network of faults (aperture, roughness, mechanical properties) . the models presented in the paper show the possibility of an “indirect stimulation” of some faults a priori less favorably oriented from the direct stimulation of faults


more favorably oriented . to go further in the exploitation of the models, the link of the hydro-mechanical behavior of the fault network with the triggering of major microseismic events is initiated and highlights the need to introduce a more sophisticated fault behavior law such as continuously yielding Joint model .

ARMA 13-325

influence of high temperature on the Mechanical behaviour of australian Strathbogie Granites with Different Grain SizesShao, S.S. Department of Civil Engineering, Monash University, Melbourne, Victoria, Australia Ranjith, P.G.Deep Earth Energy Lab, Monash University, Melbourne, Victoria, Australia Chen, B.K.Department of Mechanical & Aerospace Engineering, Monash University, Melbourne, Victoria, Australia

mechanical properties of strathbogie granites were studied through compressive testing . this study focuses on the influence of temperature on peak strength, elastic modulus and total stain development . rock samples include medium and coarse grained granites . rock specimens were heated to various temperatures (from room temperature to 800 °c) . it was observed the compressive strength of both medium and coarse granites increased as the temperature was increased up to 200 °c, but decreased sharply above this temperature . stress-strain curves at 800 °c showed plasticity behaviour in which brittle-plastic transition was observed . the results indicated that the fracture initiation stress was more sensitive to the influence of grain size due to the length of initial cracks, and was inversely related to both porosity and mean grain size . stress-strain data were incorporated into a finite element (fe) model (abaQus 6 .7 .1), so that both elastic and plastic behaviour could be predicted over a wide range of temperatures .

ARMA 13-342

numerical Study of horizontal proppant flow and transport in a narrow hydraulic fracture Tomac, I. and Gutierrez, M. Colorado School of Mines, Golden, Colorado, USA

this study focuses on micro-mechanical understanding of horizontal proppant flow and transport in a narrow hydraulic fracture . this research is motivated by problems encountered in practice related to proppant placement problems, such as proppant pack formation in shear fractures, and clogging and bridging . for this study a numerical discrete element method coupled with continuum fluid dynamics and new user-defined contact model are used . particles contact model accounts for lubrication of a thin fluid layer between two approaching particles and dissipate their kinetic energy . consequently, particles that are driven towards each other by the shear flow stay nearby each other and form clusters . higher particle concentration and interaction with walls in narrow fracture enhances proppant agglomeration . as a result, stable and unstable packs significantly decrease an overall efficiency of proppant placement, causing abruption of fluid flow and proppant transport . the results of the study give a new understanding of pressure, fluid viscosity, proppant concentration and size, and fracture width on the difference between horizontal proppant and fluid velocities in the fracture and clogging of narrow channels with proppant .


ARMA 13-471

optimizing Drilling parameters: a preliminary attempt--Drilling crab orchard SandstoneZhang, Wu, Ayers, William J. and Brown, L. JamieNational Energy Technology Laboratory, U.S. Department of Energy, Morgantown, West Virginia, USA

one of national energy technology laboratory (netl)’s primary research goals for the extreme drilling laboratory is to optimize drilling methods and technologies that reduce the risk and cost of deep drilling . this can be achieved by minimizing the energy levels necessary to attain an optimum rate of penetration (rop) given a specific set of downhole parameters . this report discusses the relationship among mechanical specific energy (MSE), rate of penetration (ROP), weight on bit (WOB), rotation speed of bit per minute (RPM), torque, rock type, and down-hole conditions as used to derive mechanics specific energy (MSE) as a function of WOB and RPM . this derived energy level is expected to provide a method to ascertain the lowest possible energy level required to achieve a targeted ROP . With limitations on available test data, the proof and approach used for this research is a first approximation of the validity of the method . more representative data is required to optimize the proposed drilling operational parameters . the results of this research could be applicable to conventional or hpht drilling in the pursuit of cost and energy efficient drilling operations .

pOSter SeSSiOn: new DevelOpmentS in COmputatiOnal rOCk meChaniCSTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-454

Modeling fracture of Quasibrittle Materials: a comparative Study Yaneng Zhou and Jeen-Shang LinDepartment of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, USA

for many rock mechanics applications involving fractures, continuum damage mechanics based models are attractive alternatives to the conventional fracture mechanics approach . the damage mechanics based modeling together with an erosion scheme can capture the fracture and fragmentation process . but how credible is the damage mechanics based model? this study addresses this question through a comparative study . the cohesive crack model has been established as a well suited tool to study fractures in quasibrittle materials if the crack growth path is known . We set up a plane stress problem in which a plate underwent mode i fracture due to tension . the problem had no initial crack but the crack initiation location and crack growth path, when stressed, were known . albeit the limited scope, the study demonstrated that damage mechanics based model gave compatible results with those from the cohesive crack model if model parameters were properly calibrated .

ARMA 13-515

loading conditions in the brazilian test Simulation by DeMNakashima, S., Taguchi, K., Moritoshi, A. and Shimizu, N.Yamaguchi University, Ube, Yamaguchi, JapanFunatsu, T.Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan

the particle flow code (pfc), a simulation code based on the distinct element method (dem), is an effective numerical tool for simulating the failure process of hard rock . by introducing contact- and parallel-


bond and clump logic, the code has become better able to express the ratio of uniaxial compressive strength to tensile strength of hard rock . on the other hand, a problem has arisen, namely, that pfc simulations with the clumped particle model cannot reproduce rapid strain-softening behavior in brazilian tensile tests . in addition, cracks propagate too widely in the specimens; this differs from the experimental facts . attributing the above problems to the loading configuration, some two-dimensional pfc simulations of brazilian tests were conducted in this study under several loading conditions . strip loading (line loading in two dimensions) and line loading (point loading in two dimensions) were taken into consideration . from the simulation results, point loading was found to be effective for expressing rapid strain-softening behavior and crack propagation in brazilian tensile tests .

pOSter SeSSiOn: unCertainty QuantifiCatiOn anD parameter eStimatiOn in geOmeChaniCSTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-171

insights into the Relationship between Single Grain and api/iSo crush Strength when applied to proppants with or Without Diagenesis Raysoni, N., Pinto, M. and Kothamasu, R. Halliburton Technology Centre, Pune, India

laboratory studies indicate that proppants are susceptible to proppant diagenesis, which can result in decreased proppant strength, fines generation, and, consequently, reduced fracture conductivity . in the laboratory, proppant diagenesis is studied by subjecting a mixture of ceramic bauxitic proppant, formation, and fluid to temperature and stress for a significant duration of time and then observing the effect of these parameters on proppant strength and conductivity . the api/iso crush test is cumbersome when adopted to characterize proppant strength post-diagenesis because it requires separation of proppant from the tested proppant-formation mixture . an alternative statistical method is to conduct single grain crush tests pre- and post-diagenesis for a set of proppants and perform Weibull analysis on the test results . advantages of this method include simplicity and ease of use, small sample quantity requirement, and applicability to all proppant types (including flowback proppant samples) . in the present work, single grain and api/iso crush tests were performed on two conditions for the proppants—virgin proppants and those that have undergone some degree of diagenesis . the correlation between the results obtained from the two test procedures was investigated . this investigation provides insights into the suitability of the single grain crush test as a method for characterizing the strength of proppants before and after having undergone diagenesis .

ARMA 13-202

a log-Derived Database for Geomechanical properties of Geological formations in alberta, canada Soltanzadeh, h. Alberta Innovates – Technology Futures, Edmonton, Alberta, Canada

during the past decades, the alberta basin has been the locus of conventional and unconventional petroleum production and surface and underground mining and it is expected to be subject of new underground operations such as co2 storage, possible storage of compressed air, and geothermal energy production in near future . most of these subsurface activities are influenced or constrained by the geomechanical


behaviour of the host rock and its mechanical properties . therefore, databases containing geomechanical properties of geological formations are extremely valuable for performing geomechanical studies for these activities . this paper introduces a database of rock properties developed based on the existing wireline logs in more than 2200 wells in alberta . the developed database includes geometric and geographic information for these wells and their intersecting formations, in addition to rock properties such as shear and compressional wave velocities, dynamic poisson’s ratios, and dynamic young’s moduli . it also includes statistical analyses of the log data to help the user to assess the reliability of the measurements . empirical relations may also be employed to estimate strength properties of rocks based on the log data collected in this database . the developed database is a rich source of geomechanical data and may be utilized for geomechanical characterization of geological formations in the alberta basin and possibly elsewhere, as illustrated using the two case studies presented in this paper .

pOSter SeSSiOn: rOCk phySiCS anD geOphySiCSTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-493

Geophysical logging of DUSel core and Geotechnical applications Roggenthen, W. M. and Koch, C. D. Dept. of Geology and Geological Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA

a well-documented coring program was conducted as part of the geotechnical characterization for preparation of the preliminary design for the deep underground science and engineering (dusel) project . a total of 1645 m of holes were drilled and cored with more than 90% recovery of the hQ core in most of the coring runs . the lithologies sampled by the cores included amphibolites, rhyolites, and phyllites . approximately 60% of the recovered core were measured for acoustic velocities (vp, vs) and magnetic susceptibilities . the amphibolites had the highest acoustic velocities followed by the phyllites and rhyolites . magnetic susceptibilities of the rhyolites were very low, and the amphibolite and phyllites values were variable . the variability may be due to fracturing and subsequent filling of the fractures by pyrrhotite . calculated values of poisson’s ratio and young’s modulus from the acoustic measurements are comparable to those derived from geomechanical testing . the acoustic measurements did not have a good correlation with the geotechnical logging performed on the cores, probably because the acoustic measurements were performed on intact samples whereas geotechnical logging is more sensitive to locating discontinuities .

ARMA 13-311

prediction of Reservoir Water Saturation using Support Vector Regression in an iranian carbonate Reservoir Mollajan, A. and Memarian, h. University of Tehran, Tehran, Iran Jalali, M.R. University of Waterloo, Ontario, Canada

determination of water saturation is one of the most important items in reservoir characterization and calculation of hydrocarbon volume in place . the most common approach in estimation of water saturation is based on petrophysical models . the existing models have many operational restrictions which may lead


to error in estimation of water saturation . the current paper is made an attempt to develop the support vector machine (svm) method for estimating reservoir water saturation (sw) from petrophysical logs (pls) related to four wells of an iranian carbonate reservoir . in order to show the superiority of the proposed method, sw was predicted by a back-propagation artificial neural network (bp-ann) model as well as three conventional equations (i .e . archie, hossin and dual-water) . the results were compared based on determination coefficient (r2), root mean square error (rmse), and mean absolut error (mae) indexes . the measured r2 of predicted sw in the test data, using svm was 0 .88, whereas it was 0 .81 by both ann model and dual-water equation as best fitted model . the rmse and mae were 0 .02 and 0 .82 by svm, whereas they were 0 .12 and 1 .04 by ann and 0 .04 and 0 .96 by dual-water .

pOSter SeSSiOn: rOCk heterOgeneity anD SCalingTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-194

a 3D grain based model for characterizing the geometric heterogeneity of brittle rock.Lan, hengxingDepartment of Civil & Environmental Engineering, University of Alberta, Edmonton, CanadaState Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, ChinaMartin, C.D.Department of Civil & Environmental Engineering, University of Alberta, Edmonton, CanadaQi, ShengwenKey Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, ChinaLi, TianbinSKLGP, Chengdu University of Technology, Chengdu, China

in analyzing intact rock strength, an important factor is heterogeneity . at the grain-scale, intact crystalline rock consists of a variety of mineral grains of different sizes and shapes . these features give rise to the micro-scale heterogeneity . a three dimensional grain based universal distinct element model (3d-gbm) was developed to generate a deformable polyhedral grain-like structure to simulate the microstructure of brittle intact rock . the geometric heterogeneity is introduced into 3d-gbm by capturing the mineral grain size distribution . a geometric sorting coefficient is used to account for the degree of geometric heterogeneity . a number of rock-like samples are generated using a 3d-gbm realization methodology with different sorting coefficients . the effect of micro-scale geometric heterogeneity on the rock strength is explored by investigating the relationship between micro-scale behaviors and macro-scale responses . the observed characteristics of stress distribution and cracking behaviors are discussed .


pOSter SeSSiOn: miningTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-126

the effect of Slope curvature in Rock Mass Shear Strength Derivations for Stability Modeling of foliated Rock MassesNarendranathan, S. and Thomas, R.D.h.Coffey Mining Pty Ltd., West Perth, Western Australia, Australia

in open pits the instability mechanisms are multifaceted involving, shearing along or over the asperities of the defect surface and or block rotation at very low normal stresses and shearing along or through asperities and block rotation including rock mass failure due to intact rock breakage at somewhat higher degrees of confinement . in an open pit environment it is common to have pit designs with varying profiles . this difference in wall geometry would result in varying magnitudes of effective shear strength being mobilised . the contribution of the lateral confinement to the degree of shear strength mobilised is often overlooked in these strength models . in this paper a case study will be presented, which compares the different slope performance outcomes within similar geotechnical conditions with, the only variant being the slope geometry and the influence of lateral confinement . an algorithm will be developed, based on observations from this site case study, linking the concavity of a slope face to the degree of (extra) shear strength mobilised . it is the authors intent that this algorithm can be used in a similar manner to which highway engineers use ’curve-speed models’ to determine safe approach speeds for corners given a particular road curvature, (in our case pit slope concavity) and approach speed (rock mass characteristics) . this relationship has been successfully implemented for forward analyses at the mine in question, and has lead to the successful optimisation of slope geometry .

ARMA 13-736

influence of bio-Stabilisation on Dump Slopes – a Discrete element Modeling approachPradhan, S.P., Vishal, V., Singh, N. and Singh, T.N. Department of Earth Sciences, Indian Institute of Technology Bombay, Mumbai

biological stabilisation of dump slope is one of the widely used techniques for controlling erosion and stabilisation of dump slope . vegetation physically and mechanically reinforces the dump material, resists erosion and reduces pore water pressure . it also provides some information about the slope movement . dump materials are heterogeneous, anisotropic and behave neither like soil nor like rock . the modeling of such materials is difficult and continuum material models and continuum boundary conditions do not provide appropriate and accurate results . the present paper evaluates the effect of vegetation on dump slope stability for a given dump geometry through discrete element modeling approach . the dump slope angle and height was kept constant at 37° and 60m respectively, and its stability is analyzed with and without vegetation cover . it is found that vegetation increases the stability of the slope by reducing the maximum displacement approximately 85 .5% . hence, the bioremedial measures are more effective than the physical measures to protect against erosion and contamination without deteriorating the surrounding ecological balance .


ARMA 13-682

numerical Simulation of top-coal caving in Steeply Dipping and thick coal Seam MiningF. Cui, x.P. Lai and J.T. CaoXi’an University of Science and Technology, Xi’an, Shan Xi, ChinaKey Laboratory of Western Mines and hazard Prevention, Xi’an, Shan Xi, China

most of the coal seams in the urumqi coal field, xinjiang province, china, dip at angle 45 degrees or more and are classified as steeply dipping coal seams . the multiple coal seams can be combined for mining with a maximum width of about 50 m, and the minimum width is only 20 m . the total thickness of coal seams is 170 m, and the vertical height is more than 400 m . the condition makes it impossible for the coal company to achieve high production and efficiency using the traditional slicing mining method . at present, the only method used for these seams is the horizontal section top-coal caving mining . however, the hard coal (f=2) in section with large height (above 20 m) is difficult to cave for extracting . some special measures must be taken to facilitate the top-coal caving . in this paper, the caving effect in steeply dipping and thick coal seams with weakening measures at different angles is studied by numerical simulation . the migration path and the falling quantity of discrete coal particles are analyzed, and the distribution characteristics of hinged force between flowing blocks are intuitively presented . the load changes of supports in the process of top-coal caving are monitored in real time . the equations for approximating the caving zone in the flow model are established . the mining practice shows that, the coal mass can effectively fragment the coal mass with the pre-blasting method for the improvement of top-coal recovery .

ARMA 13-220

analysis of Surrounding Rock Macro Stress arch-Shell of longwall face in Steeply Dipping Seam Miningh.W. Wang, Y.P. Wu and P.S. xieXi’an University of Science and Technology, Xi’an, Shaanxi, China

a steeply dipping seam is one with its dip angle in the range of 35°~55° . mining of such coal seams is recognized to be difficult in the mining industry . based on the results of physical simulation experiments and numerical simulation of steeply dipping seam mining, the mechanics characteristic of surrounding rock macro stress arch-shell (msas) is analyzed . according to the analysis, the msas is a high stress form which bears the main load and is formed under the action of rock self-organization after stress distribution . it is a spatial distribution form of intensity envelope curve under a strength criterion and has geometry shape asymmetry and stress distribution heterogeneity . the analyzing model and coordinate system of msas is established, then configuration equation is derived and stability criterion is given . there are three failure forms of the key parts of instability: tensile instability in shell roof, compress-shear instability in shell shoulder and composite instability in shell base . according to the instability process of key parts of the msas, instability mode of the msas can be divided into shell base-roof (shoulder) instability mode and shell roof (shoulder)-base instability mode . the results enrich the mining theory of complex coal seams and provide a theoretical basis for safe and efficient mining in steeply dipping seam .

ARMA 13-136

controlling Drift profile in Mining Small top cut panels – turquoise Ridge case Study Rai, A.R. and Westhoff, D. Barrick Gold, TRJV Mine, Golconda, NV, USA

turquoise ridge Joint venture (trJv) mine contains highly fractured rock; it becomes critical to control the various factors influencing the drift profile . the ground support by itself is a great challenge at trJv


in small top cut 3m x 3m (10ft x 10ft) drifts and fill panels due to the limited space similar to narrow vein mining . the case will discuss application of improved technology applications and results correlated with a current mining method and will address the poor quality rock masses encountered at turquoise ridge . an important design criterion for delivering a clean heading profile and significant factors like a) accuracy of drilling pattern and b) controlled blasting and c) mechanization are discussed .

pOSter SeSSiOn: COupleD prOCeSS mODelS iiiTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-686

a numerical investigation of fracture pattern and fracture aperture Development in Multi-layered Rock using a combined finite-Discrete element MethodGuo, L., Latham, J.-P., xiang, J. and Lei, Q.Department of Earth Science and Engineering, Imperial College London, London, UK

naturally fractured reservoirs are an important source of hydrocarbons . fracture patterns characterising such reservoirs can be generated stochastically, but these have limited ability to capture realistic cross-cutting, branching and truncation relations . computational models capable of generating fracture geometries according to geomechanical principles offer a means to create a numerical representation of a more realistic rock mass structure . in this work, the fractures initiate and propagate discretely using the combined finite-discrete element method . the fracturing behaviour is modelled by a combined single and smeared crack model . a seven-layer limestone model is simulated under various loading conditions, including direction tension parallel to the layering with different vertical pressures, and bending with clamped and supported boundaries . the aim is to illustrate fracture pattern and fracture aperture development in stratified systems . the results show higher vertical pressures enabled fractures to propagate across layer interfaces to form through-going fractures . delamination at layer interfaces occurred after fracture initiation had taken place on each side of the interface .

ARMA 13-504

analysis of effect factor in Shale Wellbore Stability Qian Wang, Zhaowei Chen, Pengpeng Ma and Yingjian JiangDrilling Technology Research Department, CNPC Drilling Research Institute, Beijing, China

a fluid-solid-chemistry coupling model is built considering fluid flow and ion transmission induced by shale-drilling fluid system electrochemical potential osmosis, nonlinearity of flow and solute diffusion in shale-drilling fluid system, and solid deformation resulted by fluid flow and ion transmission . pore pressure and stress field around the wellbore wall was computed by finite element method, and the effect of shale and drilling fluid parameters on collapse index and caving pressure was analyzed . the research results demonstrate that large shale permeability, large solute diffusion coefficient were favor of shale stability . drilling fluid with high concentration and reflection coefficient was beneficial for shale stability . high mud weight can sometimes result instability for shale formation . While the swelling coefficient of shale-drilling fluid system decreases, the shale hydration can be alleviated . especially for the case that the drilling fluid concentration was larger than the shale pore fluid, the chemical reverse osmosis may cause shale dehydration . the collapse index of small shale wellbore altered with time was more obvious than large wellbore .


ARMA 13-500

predicting productivity of hydraulic fracturing with pre-pad acidPingli Liu, Fei Liu, Liqiang Zhao, Zhifeng Luo and Nianyin LiState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, ChinaMa xuLow Permeability Oil Fields National Engineering Laboratory, Technology Research Institute, PetroChina Changqing Oilfield Company, PetroChina, Xi’an, China

laboratory tests and field pilot applications have shown that hydraulic fracturing with pre-pad acid can effectively mitigate or even eliminate the damages to matrix permeability and fracture conductivity due to fracturing fluid invasion, gel filter cake on fracture face and gel residue inside fracture, and eventually improve stimulation effect . therefore, accurate and quantitative prediction of post-frac productivity of wells simulated by hydraulic fracturing with pre-pad acid is key for designing and optimizing such fracturing treatments . based on the principle of hydroelectricity similarity between the post-frac fluid flow in a reservoir around wellbore and the current in an electrical circuit, this paper took into consideration the stimulation mechanisms of both pre-pad acid and hydraulic fracturing, and developed an effective and accurate impedance model to predict post-frac productivity . the studies using this model in this paper show that the damages by the major factors, fracturing fluid invasion into matrix, gel filter cake on fracture face and gel residue inside the fracture may reduce well productivity by 6~10%, 7~10% and 5~7%, respectively . moreover, this model predicts that pre-pad acid hydraulic fracturing can enhance post-frac productivity by 10~23% compared to a conventional hydraulic fracturing treatment . therefore, the studies and the model in this paper can provide theoretical and practical guidance to optimize stimulation plan of pre-pad acid hydraulic fracturing treatments .

ARMA 13-382

3D numerical Reconstruction of poorly connected porous Sandstones Jiangtao Zheng 1, Yang Ju2, 3, Jinbo Wang1, 4, Yongming Yang1, xi Zhao1 and Feng Gao3 1School of Mechanics and Civil Engineering, China University of Mining & Technology, Beijing, China 2State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & Technology, Beijing, China 3State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining Technology, Xuzhou, China 4Hydrogeology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, MS, USA

the poorly connected porous sandstones are the mainly concerned materials in a variety of engineering practices which naturally involves a large number of discontinuous and geometry- irregular micro-pores . these pores significantly affect the physical and mechanical properties of the rock . a reliable numerical reconstruction porous rock model provides an effective and economic way for the research of the influences of the micro-pores to the rock macro-properties . in this paper, we present a novel numerical method to reconstruct poorly connected porous sandstone . a fractal descriptor is employed to characterize the complex morphology of pore structures . additionally, a modified simulated annealing algorithm was developed to accelerate the 3d reconstruction process . besides, the finite element models are established based on the real rock ct configuration and the reconstructed configuration . based on them, the mechanical properties of the sandstone can be analyzed . the analysis indicates that the 3d reconstruction model has better pore-geometry similarity with real rock model, higher reconstruction efficiency, and more accurate predictions of mechanical properties of the poorly connected porous sandstone .


ARMA 13-383

evolution of coal permeability under Unconstrained Swelling: contribution of Matrix-fracture interactionZhongwei ChenSchool of Mechanical and Mining Engineering, The University of Queensland, QLD, AustraliaJishan LiuSchool of Mechanical Engineering, The University of Western Australia, WA, AustraliaDerek Elsworth and Shugang WangDepartment of Energy and Geo-Environmental Engineering, Penn State University, USAYu WuState Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Xuzhou, Jiangsu, China

coal permeability model is needed to define the transient characteristics of coal permeability evolution due to adsorbing gas injection . a broad variety of models have evolved to represent the effects of sorption, swelling/shrinkage and effective stresses on the evolution of permeability . this work evaluated the performance of these models against analytical solutions for both unconstrained swelling and constrained swelling conditions . constrained model predictions are apparently consistent with typical laboratory measurements . nevertheless, this consistency is due to the mismatch between model boundary condition (constrained) and experiment boundary condition (unconstrained), demonstrating that current permeability models can hardly explain net reductions in coal permeability where swelling is unconstrained . to explore the possible reason, a full coupling approach was applied to explicitly model the interactions of coal matrix-fracture and translate these interactions into the permeability change . in this approach, the important non-linear responses of coal matrix to the effective stress are quantified through the incorporation of heterogeneous distributions of coal properties into complex mechanical coupling with gas transport . When swelling coefficient and modulus vary spatially relative to the fracture void, a net reduction in coal permeability is achieved from the initial no-swelling state to the final equilibrium state . these modeling results are consistent with the observed responses under the unconstrained swelling conditions, which demonstrates the contribution of this work .

ARMA 13-351

near-field and far-field thermo-Mechanical Modelling of conceptual Deep Geological Repositories for Used nuclear fuel in crystalline Rock Carvalho, J.L. and Steed, C.M. Golder Associates Ltd., Mississauga, Ontario, Canada Birch, K. and Russell, S. Nuclear Waste Management Organization, Toronto, Ontario, Canada

the nuclear Waste management organization (nWmo) is implementing adaptive phased management for the long-term management of canada’s used nuclear fuel . flac3d, a three-dimensional finite difference code, was used to carry out coupled thermo-mechanical analyses to assess the spacing of used fuel containers in the placement rooms and the spacing between the rooms for an in-floor borehole placement method for a hypothetical repository in crystalline rock . the thermo-mechanical modelling was performed to determine the container spacing within a room and the placement room spacing in a single-level repository at 500 m depth and a multi-level repository with levels at 400 m and 800 m depth, while meeting preliminary design requirements for temperature, mechanical stability and minimum excavation damage . modelling results show that two thermal peaks may occur – one in early time and another at large time . the second peak is strongly controlled by the room spacing and, in the multi-level case, by the level spacing . results also show that thermal stresses increase the calculated excavation damage around the in-floor boreholes as well as the floor of the placement rooms from that caused by the original excavation . this damage represents a conservative scenario in which the buffer material around the containers and the backfill material (bentonite) are assumed to remain unsaturated throughout the modelled time period .


pOSter SeSSiOn: fraCture meChaniCS anD mODelingTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-660

experimental Study of hydraulic fracturing in Unconsolidated Sands Using X-ray ct Methodomori, Y., Jin, S. and Ito, T.Institute of Fluid Science, Tohoku University, JapanNagano, Y. and Sekine, K.Technology and Research Center, Japan Oil, Gas and Metals National Corporation, Japan

hydraulic fracturing is applied for oil and gas production enhancement not only to hard rocks but also to soft rocks such as unconsolidated sands . in the latter case, fracturing behavior is not suitably represented by existing models for brittle, linear-elastic rocks . thus we developed an apparatus for carrying out hydraulic fracturing experiment in a cylindrical specimen under triaxial compression and tried to observe the dynamic behavior of hydraulically-induced fracture in unconsolidated sands by using a x-ray ct scanner . in those ct images, we could detect clearly how the fracture propagated and then the fracturing fluid infiltrated around the fracture . as a result, we found that the shapes of the infiltrated regions changed obviously for two cases when the fracture was and was not induced, while there was a small difference in the peak pressure of fracturing fluid . those phenomena indicate that permeability of the specimen play an important role rather than fluid pressure on fracture formation .

ARMA 13-210

Geomechanical controls on productivity of low-permeability Shallow Reservoirs of the Milk River formationNadeem, M.NGPR, Medicine Hat, AB, CanadaCurrently with EnCana Corporation, Calgary, AB, CanadaDusseault, M.B.University of Waterloo, Waterloo, ON, Canada

this study focuses on productivity of low-permeability shallow biogenic gas reservoirs of the upper cretaceous milk river formation . this formation is one of the major producing intervals of biogenic gas in southeastern alberta and southwestern saskatchewan, canada . We show in situ stress measurements for shallow depths in this region that indicate a cross-over between the vertical stress and minimum horizontal stress at about 370 m depth; shallower than 370 m, the vertical stress is the minimum principal stress . In situ stresses have a profound effect on the orientation of induced hydraulic fractures and stress information can be used to predict whether induced hydraulic fractures are vertical or horizontal . this information is helpful in designing an optimum completion strategy for multi-layered compartmentalized shallow reservoirs and on choosing the best assets to develop . a vertical in situ stress map is constructed for the top of the milk river formation to examine possible relationships between the overburden stress and the productivity of the milk river formation reservoirs . We demonstrate that a strong relationship exists between the in situ stress and productivity: better well performance is observed in the regions where the vertical stress is lowest . hence, vertical in situ stress mapping is helpful to delineate areas of best productivity “sweet spots” .


ARMA 13-526

correlation between Microseismicity and Geomechanics factors affecting the hydraulic fracturing performance in Unconventional Reservoirs – a field case in neuquén, argentinaosorio, J.G. and Muzzio, M.E.Pluspetrol S.A., Buenos Aires, Argentina

this paper investigates the qualitative correlation between microseismicity and the geomechanics attributes affecting the hydraulic fracturing performance in vaca muerta formation - lJe and pso blocks – in neuquén, argentina . the paper includes typical results from 1d geomechanics models in the area, a short description of the microseismic setup, and qualitative correlation between microseismic occurrence and some geomechanics attributes such as stresses, brittleness, rock strength and elastic properties . results show that: fracture growing follows complex and asymmetric patterns; the highpressure/ high-stress behavior in the lower part of vaca muerta, where toc is at maximum, causes stress anisotropy and impacts formation brittleness unfavorably; low pore pressure and stresses and high stress anisotropy favor fracture complexity; low values of cohesion, tensile strength and poisson s ratio and high values of young s modulus correlate with microseismic occurrence .

ARMA 13-543

the influence of injection Rate on hydraulic fracturing of tri-axially Deformed Westerly GraniteGoodfellow, S. D., Nasseri, M. h. B. and Young, R. P. Department of Civil Engineering, University of Toronto, Toronto, Ontario, Canada

the results from two laboratory hydraulic fracture experiments are presented in this paper . experiments were conducted in a tri-axial geophysical imaging cell equipped with 18 broadband acoustic emission transducers . samples were loaded to a differential stress of 115 mpa and then distilled water (1 cp) was injected at a constant flow rate through a central cased borehole until failure . two flow rates, 0 . 2 ml/min and 0 .5 ml/min were investigated and their failure sequences were analyzed in detail . a flow rate of 0 .2 ml/min caused gradual failure with ae source locations aligning on two conjugate planes and ae activity lasting for ~120 ms . using an injection rate of 0 .5 ml/min initiated a two stage fracture process . ae hypocenters initially located around the borehole and then rapidly moved to the edge of the sample along a vertically oriented plane . the final burst of ae activity resembled a tremor-like-signal and lasted for approximately 22 ms . frequency analysis of continuous acoustic emission waveforms show that the maximum energy is initially held at high frequency and gradually shift to lower frequencies as the fracturing nears completion . x-ray computed tomography scans revealed complex fracture geometry .

ARMA 13-177

hydraulic fracturing Design optimization - bakken case Studyhadi Jabbari and Steven A. Benson Petroleum Engineering Department, University of North Dakota, Grand Forks, ND, USA

low permeability shale formations, such as the bakken, require a large fracture network to enhance well productivity . in this research, through a comprehensive fracture-simulation/reservoir-performance study, we evaluated the main parameters controlling the fracture stimulation in horizontal wells . the main goal was to investigate opportunities to optimize hydraulic fracturing and production of horizontal Williston basin bakken formation wells . the project area used in the investigation was located in Williams county, north


dakota . to design a successful hydraulic fracture treatment, three tasks were conducted: first, a reservoir simulation to evaluate the response of the reservoir to fracture stimulation and to calibrate the reservoir model was performed using two steps involving: a) sensitivity analysis (sa) to determine the significant well/reservoir properties and parameters and b) history matching (hm) simulation results to the production data from the stimulated horizontal well in the study area . second, the amount of fracturing materials was estimated and preliminary pump schedules were developed based on selected design parameters that include: half-length, pump rate, and maximum proppant concentration . design parameters screening was conducted using 2d fracture geometry solutions for fracture treatment parameters . an optimization task was performed to identify optimal stimulation treatment(s) that together with optimal operating conditions would return a maximum value for the objective function (e .g . net present value) . finally, fully-3d hydraulic fracture modeling was utilized to perform implicit, coupled, finite difference/finite element solutions to basic conservation equations . the pump schedule — obtained from the scoping design— was changed in terms of the pad volume and proppant schedule for treatment optimization . the overall goal of such a schedule refinement was to place the right amount of proppant in the right place along the fracture .

pOSter SeSSiOn: unCOnventiOnalSTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-341

biot tensor approach for improved lifecycle Well integrityBinh, Bui and Azra, N. TutuncuPetroleum Engineering Department, Colorado School of Mines

biot’s coefficient, a parameter connecting the effect of pore pressure on the effective stress in porous media, has been widely used to obtain the effective stress in isotropic formations . for anisotropic formations, recent experimental data and modeling results indicate that there is a difference between the horizontal and vertical biot’s coefficients . therefore, biot coefficient is not only stress dependent, but also shows direction dependence . hence, the complex stress and direction dependence imply that biot’s coefficient must be described in a tensor form . the tensor representation of biot’s coefficient helps to solve many mathematical difficulties and controversies surrounding the effective stress concept that is essential for realistic geomechanics measurements and modeling . moreover, it provides a more precise and flexible tool in modeling the effect of pore fluids on the effective stress . We conducted a theoretical study to verify the tensor form of the biot’s coefficient . data from published research has been analyzed to validate the model . the application of biot’s tensor has been analyzed to overcome mathematical difficulties . a new numerical model was developed using the biot’s tensor concept to calculate the effective stresses in different directions and the mud weight window obtained using this new approach was compared with the mud weight window obtained from conventional concepts . our computational results indicate a significant difference between two predicted mud weight windows, particularly for horizontal wells in anisotropic formations such as shale reservoirs and other unconventional resources . the model reduces to the simple better known form of the biot’s tensor when the formation is isotropic implying that the biot’s coefficients in all directions are the same . in other words, the 1-d form of the biot’s tensor is currently used for measurements and modeling in the petroleum industry . the biot’s tensor concept opens up a new modeling approach for geomechanical modeling and its coupling with reservoir fluid flow simulations . it is particularly important in calculating effective stress for anisotropic formations that are often encountered in unconventional reservoirs . therefore, this study presents a very important mathematical tool for coupled reservoir geomechanics modeling effort that utilizes a more realistic stress implication capturing typical scenarios experienced in unconventional reservoir formations .


ARMA 13-555

numerical evaluation of the impact of Geomechanics on Well performance in Shale Gas Reservoirs Yu, W. and Sepehrnoori, K.The University of Texas at Austin, Austin, TX, USA

this paper employs numerical reservoir simulation techniques, validated by field production data from barnett shale, to model hydraulic fractures and natural fractures in combination with the effects of gas desorption and geomechanics . based on published laboratory data of stress-dependent propped fracture conductivity due to proppant embedding in various shale samples, we mainly divide shale formation into three scenarios: stiff, medium and soft . the effects of these different scenarios of stress-dependent propped fracture conductivity on ultimate gas recovery are investigated . also, sensitivity studies are performed on the following factors to understand critical parameters that control this process: permeability, initial fracture conductivity, and bottom hole pressure . this work enables operators to develop an early understanding of the effect of geomechanics on shale gas wells performance .

ARMA 13-395

effects of Depletion/injection induced Stress changes on natural fracture Reactivation M. Reza Safari, Trevor oar, Queena Chou, hamed Chok, Neil Blair and Mutlu UnoWeatherford Chris D. hawkesUniversity of Saskatchewan

one of the key geomechanical parameters utilized to unlock fractured reservoirs is the reactivation potential of existing natural fractures . reservoir depletion and/or injection can significantly perturb the initial stress state, which may then lead to reactivation of existing fractures . the reactivation phenomenon could have a significant impact on the stimulated rock volume (srv) by creating additional flow paths, which within the reservoir might be desirable . in particular, if known a priori, reactivation potential could be utilized to optimize fracturing operations in unconventional reservoirs (i .e ., optimum well placement and timing) or aid with the design/assessment of caprock integrity . a variety of geomechanical models can be used to assess the reactivation potential of natural fractures . the models can include analytical, semi-analytical or numerical techniques . in this paper, a systematic review of multiple techniques to assess reactivation potential of fractures is first provided . the focus is then shifted towards an analytical/poro-thermo elastic workflow to quantify this potential while taking into account statistical distributions of fracture orientations and mechanical properties . the potential of reactivation within the injection/production zone(s) are then evaluated . the results are compared for different reservoir geometries and geologically plausible scenarios . a case study, with the purpose of defining critically stressed fracture trends and favorable conditions for stimulation is also investigated .


ARMA 13-667

Development of a heterogeneous earth Model in Unconventional Reservoirs, for early assessment of Reservoir potential R. Suarez-Rivera, D. handwerger and A. Rodriguez herreraSchlumberger S. herring and K. Stevens Encana Oil and Gas Geir Vaaland, D., Borgos, h., Marino, S. and Paddock, D. Schlumberger

in this paper, we describe a large effort to develop an integrated heterogeneous earth model for a large region of the haynesville play . the work includes a comprehensive geologic and petrologic study, based on the evaluation of multiple cores, analysis of a large number of well logs in the region and integration with seismic data . the work also includes extensive characterization of mechanical, geochemical and reservoir properties via laboratory testing . the result is a model that scales seismic data with log data, and with core data, based on fundamental measurements that respond to changes in texture and composition at these various scales . results provide the volumetric distribution of rock classes or regions with similar and dissimilar texture and composition . this classification defines the geometric heterogeneity of the system . results also provide rock physics models for propagating measured properties on core samples to measured log data and seismic data . thus continuous distributions of all core measured properties are possible at the log scale and also at the seismic scale . the advantage of integration with measured properties on core is that we can populate the model with necessary complex properties not otherwise independently obtainable from seismic data alone . for example, anisotropic elastic properties, anisotropic strength, creep, organic content, hydrocarbon filled porosity, rock fluid sensitivity, and others . the distribution of this array of relevant properties to each rock class, allows us to evaluate the real distribution of reservoir quality and completion quality in the region, and assess the variability in reservoir potential . this information is fundamental for early exploration and for the effective planning of field development .

ARMA 13-644

on the linear elastic fracture Mechanics application in barnett Shale hydraulic fracturingS. Mehran hosseiniThe University of Texas at Austin, Austin, TX, USA

linear elastic fracture mechanics (lefm) is used extensively in hydraulic fracturing design and evaluation . several studies on nonlinear and plastic effects in hydraulic fracturing treatments are done, where the treatment results are not consistent with lefm based models . most of the studies on application of lefm in rock and quasi-brittle material such as concrete are limited to lefm use in laboratory experiments to measure fracture toughness . these studies find lefm an inappropriate tool to describe fracture behavior in quasi-brittle material . in this paper we focus on lefm applicability to hydraulic fracturing problems using in-situ stress state and barnett shale mechanical properties published in the literature . lefm is successfully used for metallic material and the limitations on applicability of it has been studied and the results are reflected in the astm standards . in this paper we use the same method to study the applicability of lefm in hydraulic fracturing treatments of barnett shale . first, in order to have a general study, different faulting regimes are studied to find the bounding stresses in the case of hydrostatic pore pressure and overpressured reservoirs . second, the process zone and singularity-dominated zones are defined and characterized using the near crack tip and full stress distribution solutions . then, shear and tensile process zone based on full stress field solutions are calculated and compared to the size of the singularity-dominated zone . finally, based on the relative size of the singularity-dominated zone and process zone, it is concluded that lefm can not accurately describe hydraulic fracturing behavior in barnett shale .


pOSter SeSSiOn: COnStitutive mODelSMonday, 24 June, 3:30 pm – 4:30 pm

ARMA 13-375

Modeling the anisotropic Damaged Zone around hydraulic fractures: thermodynamic framework and Simulation of Mechanical testsxu, h. and Arson, C.School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USADamage Poro-Mechanics Lab, Georgia Institute of Technology, Atlanta, Georgia, USACenter for Tectonophysics, Texas A&M University, College Station, Texas, USABusetti, S.ConocoPhillips, Houston, Texas, USA

We model crack propagation and damage induced by deviatoric stress around the crack tip . a new damage model is proposed to describe the damaged zone near fractures, in order to predict the mesoscale geomechanical behavior of rock during hydraulic fracturing . the process of new damage development follows a thermodynamic framework . an associated flow rule is utilized for irreversible strain rate while a non-associated flow rule is applied for damage evolution . uniaxial tension and triaxial compression tests are simulated at the gauss point of one element in matlab with the new damage model . the results illustrate the influence of anisotropic damage on stiffness degradation and residual strain development . the implementation of this new damage model in the commercial fem software abaQus is undergoing . a preliminary brazilian tension test is computed for the elastic domain using abaQus’ umat subroutine . the result agrees well with the analytic solution . the new damage model for rock matches the theoretical expectations, and shows that the proposed model can predict anisotropic damage .

pOSter SeSSiOn: rOCk maSSTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-544

Modifications of the erodibility index Method for the evaluation of the Soft bedrock erosion huang, M.W., Liao, J.J. and Pan, Y.W. National Chiao Tung University, Hsinchu, Taiwan Cheng, M.h. Water Resources Planning Institute, Water Resources Agency, Ministry of Economic Affairs, Taichung, Taiwan

the erodibility index method proposed by annandale was a semi-empirical methodology to measure the resistance of rock under a range of hydraulic conditions . two modifications for determining the erodibility index were made to improve the evaluation of bedrock erosion based on the comparison of the calculated results and the field evidences . first, the block size number was modified for the estimation of rQd . second, the original empirical function of the critical stream power estimated in terms of the erodibility index may overestimate the actual critical stream power in open channel flow . a new relationship between the critical stream power and the erodibility index was obtained through the regression of the measured erosion data . then, the usage of the original relative ground structure number on the rate of knickpoint retreat does not justify the trend of measured rates of knickpoint retreat . the disagreement might be explained by the difference in the controlled erosion processes .


ARMA 13-715

Simulating brittle failure of Rocks by a new Strain-Softening ModelPeng, J., Rong, G. and Zhou, C.B.State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, ChinaRong, G.Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USACai, M.Bharti School of Engineering, Laurentian University, Sudbury, Ontario, CanadaDu, W.Changjiang Project Supervision & Consultant Company, Ltd. (Hubei), Wuhan, China

mohr-coulomb and hoek-brown failure criteria are the two most widely used failure criteria in rock engineering . to simulate brittle failure of rocks in deep tunnel, models based on these two failure criteria have been proposed, including the cohesion Weakening and friction strengthening (cWfs) model, the damage initiation and spalling limit (disl) model and the brittle-ductile-plastic (bdp) model . however, because of the issues of strain hardening under high confinement and large ambiguity in model parameter determination, these models face limitations in practical engineering application . based on progressive failure of rocks, we found that cracks propagate under compression and as a result the geological strength index (gsi) decreases with the increase of plastic strain . by defining the gsi value as a function of plastic strain, a strain-dependent gsisoftening model based on the hoek-brown failure criterion is proposed . this model is then implemented in FLAC3D to simulate the triaxial compression test of t2b marble in Jinping-ii hydropower station . it is found that this model is able to simulate the mechanical behavior of the brittle-ductile transition observed in the triaxial compression test of the Jinping marble .

pOSter SeSSiOn: tunnelS/CavernSTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-169

thermal Stratification in Rock caverns with Different aspect Ratios During the Standby Mode of operationPark, D., Ryu, D.W., Choi, B.h. and han, K.C.Korea Institute of Geoscience and Mineral Resources, Daejeon, South Korea

in the present study, using a computational fluid dynamics code, we numerically investigated the effect of the aspect ratio of rock caverns for underground thermal energy storage (utes) on thermal stratification during the standby mode of operation without energy flows due to charging and discharging processes . the numerical investigation was based on the lyckebo storage cavern in sweden . this cavern has a unique toroidal shape and is the first large-scale rock cavern for utes . heat transfer simulations were carried out for different aspect ratios ranging from 1 .0 to 4 .0, and the heating of the surrounding rock due to longterm tes was taken into account . in these simulations, the variation of the thermal stratification with respect to time was quantitatively examined based on indices for the degree of thermal stratification . the results of the numerical simulations showed that the thermal stratification in rock caverns varied depending on the aspect ratio and the duration of the standby mode . it was also demonstrated that better thermal stratification can be obtained by increasing the aspect ratio, the effect of which was significant when this ratio was below 3 .5 .


ARMA-13-268

Dynamic characteristics Research on anchor tunnel Surrounding Rock Gancheng xu, houyu Wang and Chengxue Li School of Civil Engineering, Beijing Jiaotong University, Beijing, China,

based on the theory of similarity, model tests about the dynamic characteristics of homogeneous, layered and massive surrounding rock with and without cross anchor cable show that the type of (homogeneous ,layered and massive)surrounding rock has limited influence on dynamic characteristics . this article analyses the fundamental reasons why there is little difference between the dynamic characteristics of reinforced and unreinforced model rock and points out increase of compression capability of model rock is the primary condition for improvement of dynamic characteristics of model rock . When reinforcement ratio of cable in model rock is relatively low, cable can improve the tensile strength of simulation materials, but has little effect on dynamic characteristics of model rock mass . simulated by ls-dyna, the results of the model tests show that angle and distance of anchor cable has limited influence on the dynamic characteristics of reinforced rock . however, cross anchor cable can increase tensile strength and shearing ability for material of rock mass, and therefore reduce the deformation of the tunnel structure significantly, which is conducive to the stability of the tunnel structure .

ARMA 13-137

fiber Reinforced concrete performance parameters using aStM-c-1550 and en-14488-5 for Rock Support in tunnels, MexicoGarduno Gallo, Amanda and Padilla Mejía, CarlosComision Federal de Electricidad, Mexico City, Mexico

for a long time, hydropower underground structures, such as tunnels and power house caverns, have been designed in mexico by comision federal de electricidad . this study is particularized to the hydroproject las cruces located in the state of nayarit, mexico . it considers a 183 m height roller compacted concrete (rcc) dam, two diversion tunnels of approximately 0 .7 km length, and a power house of 70 x 25 x 30 m . the rock class could be considered from very poor to good (according to barton s Q-system) . shotcrete and bolting will be required for temporal tunnels lining . this paper gives information about the first laboratory study held in mexico to establish relationships between performance parameters (energy absorption) derived using round panels (astm-c-1550) and square ones (en-14488-5) . it includes also the beam test (astm-c-1609) . the laboratory mixtures included site aggregates, steel and macro-synthetic fibers, on three dosages for each . the concrete matrix was the same, silicafume and a superplasticizer admixture were used . results establish performance of concrete reinforced with commercially available fibers in mexico . the information helps to optimize fiber content, choosing an adequate dosage in accordance to the energy absorption requirements for the diversion tunnels in the project .

ARMA 13-238

the influence of fault thickness on tunnel StabilityZhang, Z.Q. and Li, N.Institution of Geotechnical Eng., Xi’an University of Tech., Xi’an, P.R. ChinaChen, F.F.Xi’an University of Tech. and Science, Xi’an, P.R. ChinaSwoboda, G.University of Innsbruck, Innsbruck, Austria

faults distributed in surrounding rock mass always play a decisive role for the stability of the tunnel surrounding rock mass . in this paper, a series of numerical experiments is carried out to investigate the fault influence with different thickness on stability of surrounding rock mass and sprayed concrete lining at the


construction phase . to simulate these different thicknesses faults without remeshing, a practical method based on the equivalent theory on deformation and strength is established . this method is composed of two parts . the first one is the constraint joint element (coJo element), which is an element used to simulate the fault discontinuity behaviors; the second part is an affecting zone to simulate the fault deformation characteristics, which is a mesh zone with a constant width . the discrepancy on the deformation, stress and plastic region in surrounding rock mass is pointed out via analyzing these results under the researching cases with different fault thickness, as well as the inner force of spayed concrete lining . some disciplinary and quantificational regularity about the influence of different thickness faults are summarized . this regularity can perform as guidance to the site selection and layout, the design of the supporting system and the construction of underground openings encounter the weak fault .

ARMA 13-380

numerical Study on nature frequency identification of tunnel lining based on Microtremor Method Gao, Y., Jiang, Y. and Li, B. Graduate School of Engineering, Nagasaki University, Nagasaki, Japan Yang, L. Graduate School of Science and Technology, Nagasaki University, Nagasaki, Japan

many tunnels all over the world have been in service for several decades, which require effective inspection methods to assess their health conditions . microtremor, as a type of ambient vibration originating from natural or artificial oscillations without specific sources, has attracted more and more attentions in the recent studies on the microtremor dynamic properties of concrete structures . in this study, the microtremors of a tunnel lining were simulated numerically by using distinct element method (dem) . the power spectra density (psd) of signals obtained from numerical simulations was calculated and the nature frequencies were identified using the peak-picking method . the influences of rock-concrete interface, rock type and concrete type on their nature frequencies were also evaluated . the results of the numerical analysis show that the nature frequencies of tunnel lining change proportionally with the bonding condition (e .g . normal stiffness) of rock-concrete interface . as the concrete grade decreases, the third mode of frequency also decreases gradually while the variation of the first two modes of frequencies vanishes . additionally, the field microtremor measurements of tunnel lining were also carried out to verify the numerical results .

ARMA 13-441

assessment of the Stress path and Stress conditions around a borehole: implications for in Situ Stress estimation Using borehole breakouts Gaines, S. and Diederichs, M.S.Dept. of Geological Sciences and Geological Engineering, Queen’s University, Kingston, ON, Canada

despite its importance in engineering design, there remains significant uncertainty in determining in situ stress conditions, especially with respect to estimating stress magnitude . this is particularly true in deep borehole investigations, where borehole imaging techniques and the analysis of borehole breakouts, are commonly used to estimate the in situ stress conditions . significant research has focused on the stress path and damage around tunnels in order to predict damage and spalling behaviour, but little has been done to model the stress path around a borehole for the purpose of determining the impact on in situ stress estimation . in this paper, a three-dimensional numerical model has been created to analyze the stress path at the face of an advancing borehole under various stress conditions . the model provides an assessment of the deviatoric stresses around a borehole in order to estimate the extent and location of potentially overstressed zones that may contribute to damage in the rockmass . this research shows that, under certain conditions, the stress in the axial direction can contribute to damage around a borehole, which has significant implications with respect to back analyzing the far field stress conditions .


ARMA 13-413

Upheaval of Rock Mass during tunnel constructionSingh Rajbal Central Soil and Materials Research Station, New Delhi, India

this paper deals with measurement of upheaval in rock mass and remedial measures to tackle this problem . the tunnel was excavated using dress (drainage, reinforcement, excavation and support system) methodology in extremely poor strata in 298m reach of the 23 km long head race tunnel . instrumentation and quality control measures were implemented in tackling the adverse geological conditions . the rock mass in this reach was completely pulverised bands of quartzite, amphibolite and quartz biotite schist inter mingled with clayey mass and drippings/water seepages which resulted in unstable crown and face, large over breaks and flowing rock mass conditions . the upheaval was noticed during muck removal for tunnel lining . the bottom struts were damaged due to upheaval and were replaced by new one before the final lining of tunnel . the upheaval of rock mass has been discussed in details along with remedial measures and excavation methodology .

ARMA 13-452

analytical evaluation of Reinforcement effect of pcM Shotcrete Method Using fRp Grid for tunnel Maintenance Yukihiro higashi, Yujing Jiang and Bo Li Graduate School of Engineering, Nagasaki University, Nagasaki, Japan

degradation of lining concrete happens naturally in the tunnels that have been commissioned for several decades, which require proper maintenance to ensure their safety and effective functions . the pcm shotcrete method by means of frp grid, with the characters of high strength, low weight, high workability, strong resistance to corrosion, and little influence on the existing structures, has been used in tunnel maintenance to repair the damaged lining of some aged tunnels . up to now, the construction cases are still few, and the design routine of this method based on quantitative evaluation on the reinforcement effect has not been established . in this study, the shear bond strength and the shear stiffness of typical frp grids are estimated by conducting direct shear test . those parameters were input into a numerical model of tunnel to quantitatively estimate the displacement control effect of the frp-pcm method . the experiment and numerical simulation results show that the frp-pcm method has good reinforcement effect on tunnel lining .

ARMA 13-482

laboratory tests on total load-bearing capacity of tunnel’s Damaged permanent lining Reinforced with additional liningKusaka, A.Public Works Research Institute, Tsukuba, Ibaraki, JapanColorado School of Mines, Golden, Colorado, USAIsago, N. and Mashimo, h.Public Works Research Institute, Tsukuba, Ibaraki, Japan

tunnels that have suffered severe damage from earthquakes, ground swelling or ground squeezing can be repaired by installing an additional concrete lining according to the degree of their damage . however, the design of the additional lining is based on an empirical approach that does not consider the remaining strength of the original permanent lining . to solve the problem, two series of laboratory loading tests were performed . the first series consisted of continuous loading on both the damaged permanent lining and a new additional


concrete lining to simulate the swelling or squeezing of the ground . the second series entailed loading and unloading of the permanent lining, installing the additional lining after that, and then re-loading both linings to simulate earthquake conditions . the results indicated that the damaged permanent lining had a remaining strength that was effective in load-bearing capacity in combination with the additional lining, depending on the degree of the damage of the permanent lining . also, the total load-bearing capacity of the two linings was greater than that of each independent concrete lining, even in the case when the permanent lining was significantly damaged . these results aid in the rational design of an additional lining by considering the remaining load-bearing capacity of the already-damaged permanent lining .

ARMA 13-551

load-bearing behaviour of Sealed caverns in Rock Salt used for Disposal of hazardous WasteWolters, R., Lux, K.-h., Düsterloh, U. and Rutenberg, M.Clausthal University of Technology, Clausthal-Zellerfeld, Germany

numerical simulations of the long-term load-bearing behaviour of abandoned sealed caverns in rock salt are very complex, especially if the cavities are back-filled with hazardous waste, and this waste has been preconditioned to a slurry suitable for wet-in-wet emplacement technology . With respect to safety analysis, it is necessary to have adequate approaches for physically modelling the mechanical processes occurring in the surrounding salt rock mass, as well as for physically modelling the mechanical- hydraulic coupled processes occurring within the sealed cavern, as well as in the surrounding salt rock mass due to the nonexcludable infiltration of pore fluids from the waste . the Lux/Wolters constitutive model was developed not only specially for this question, but also for other purposes at chair in Waste disposal and geomechanics of clausthal university of technology . this model is based on intensive laboratory investigations and can be used for modelling the creep behaviour of salt induced by deviatoric stresses, and the thermomechanically induced damage and damage reduction processes possibly occurring in a rock salt mass, as well as for modelling changes in permeability resulting from thermomechanically or hydraulically induced damage or damage reduction processes . this paper presents the Lux/Wolters constitutive model and analyses the long-term load-bearing behaviour of abandoned waste-filled caverns after sealing, especially with respect to demonstrating the long-term safety of this kind of repository .

ARMA 13-571

Rock engineering challenges for extending the forsmark SfR, SwedenChristiansson, Rolf and Linde, BjörnSKB, Stockholm, SwedenCarlsson, AndersCarlsson GeoEngineering AB, Ludvika, SwedenMartin, C. DerekUniversity of Alberta, Edmonton, Alberta, Canada

the existing sfr facility located approximately 200 km north of stockholm has been in operation since 1988 . the skb facility for the storage of low and intermediate level nuclear waste consists of 4 caverns approximately 160 m long and one 30 m diameter silo 69 m high constructed in a fractured crystalline rock mass, typical of the scandinavian shield . a unique aspect of the facility is its shallow, 60 m, depth below the baltic ocean . the original facility was constructed with a minimal amount of grouting, and yet despite the fractured nature of the rock mass and the proximity of the ocean, remained relatively dry . current plans call for the design and construction of a new facility adjacent to the existing sfr that will more than double its waste handling capacity . the sfr extension will consist of 6 caverns approximately 275 m long that will range in cross-sectional area from 180 m2 to 320 m2 . in addition to the challenges of constructing the facility the design must also meet the requirements for long-term safety for both the existing and planned facility .


ARMA 13-157

Discussions on the longitudinal Displacement profile of tunnels in Strain-Softening RockmassWang, S. L., Guo, M.W., Zheng, h., Liu, Q.S. and Ge x.R.State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, P.R. China

the longitudinal displacement profile (ldp) of tunnels is employed to relate tunnel wall deformations to the physical location along the tunnel axis and to estimate the appropriate installation distance (from the face) for tunnel support systems . it is one of the three main components for convergence-confinement analysis in tunneling . over a long time, linear elastic model, elasto-perfectly plastic model and empirical method are used to predict ldp in convergence-confinement method . With the consideration that many types of geo-materials exhibit strain-softening behavior in practical engineering, strain-softening constitutive model is employed to obtain ldp curves . 3-dimensional analysis of a circular tunnel excavated in the rock-mass which is subject to the uniform far-field stress is performed by finite element method (fem) . numerical results are presented and they are compared with those obtained by the empirical ‘best fit’ to actual measured data . for the same elasto-plastic parameters used in the numerical examples, analysis of ldp curves indicates that the elasto-perfectly plastic model overestimates the radial displacements . Whereas the radial displacements predicted by strain-softening model are in good agreement with the empirical curve .

ARMA 13-379

an experimental Study on the Supporting effect of back-filling on abandoned Room and pillar Mines, Quarries and karstic caves, and its in-Situ Verification Aydan, Ö. Tokai University, Institute of Oceanic Research and Development, Shizuoka, Japan Tokashiki, N. Ryukyu University, Department of Civil Engineering, Nishihara, Okinawa, Japan Tano, h. Nihon University, Department of Civil Engineering, Koriyama, Japan

in this study, the outcomes of an experimental program on the supporting effect of backfilling on the response and stability of abandoned mines, quarries and karstic caves and its verification in actual backfilling applications are presented . the backfilling materials were granular and cohesive, and rock samples were lignite, mudstone, and sandstone of mitake, nagakute lignite, oya tuff and ryukyu limestone . during experiments, electrical resistivity, acoustic emission responses in addition to conventional load and displacement responses were measured . an acrylic cell with an internal diameter of 100 mm was prepared to provide lateral confinement for back-filled samples and its lateral confinement pressure was monitored in relation to the overall mechanical response during the pre and post-failure of pillars . several examples of applications for the verification of the backfilling effect are described and the implications in actual practices are discussed .


pOSter SeSSiOn: laBOratOry-SCale rOCk meChaniCSTuesday, 25 June, 3:30 pm – 4:30 pm

ARMA 13-680

the tangent Modulus in Rock under Uniaxial compression test hsieh, A. and Dyskin, A.V. School of Civil and Resource Engineering, the University of Western Australia, Crawley, WA, Australia Dight, P. The Australian Centre for Geomechanics, The University of Western Australia, Crawley, WA, Australia

the sources of nonlinear deformation in hard rock under short term uniaxial compression can be attributed to crack closure, sliding, compaction and crack generation . the common approach to finding the modulus of a “hard rock” is to determine the linear part of stress-strain curve . however, it is usually a difficult task, although several methods of resolving it have been proposed in the past . We believe that in some rock types there is no linear part as such and provide evidence to support the fact that nonlinear deformation contributed by crack closure, sliding and compaction in different degrees could co-exist within the same stress range . We demonstrate that the change in tangent modulus under different stress levels is attributable to the combination of crack closure, sliding and dilatancy . the difference in tangent modulus under different stress levels could reach more than 20gpa in some rocks . We have also found that the residual strain is relevant to the increase in the rock stiffness under repeated load . this relationship seems to be similar among different rock types .

ARMA 13-718

progress in interactions among Underground Research laboratories Wang, J.S.Y. Lawrence Berkeley National Laboratory, Berkeley, California, USA Guglielmi, Y. Aix-Marseille University, Marseille, France hudson, J.A. Imperial College, London, UKFeng, x.-T. Institute of Rock and Soil Mechanics, Wuhan, China

an isrm commission on underground research laboratory (url) networking was formed in 2011 for better exchanges of information among different societies, academia, laboratories, and industry on underground studies . the commissioners have interests in radioactive waste assessments, energy and environment evaluations, and physics rare event detections . Workshops, professional society meetings, and literature surveys are currently means for the commission to address its scope . there are urls established along roadway tunnels, dedicated facilities excavated, and borehole complexes drilled/tested for energy and environmental assessments . thus networking will allow defining the most complementary experiments to isolate the high diversity of effects in heterogeneous medium of interests to the rock mechanics community . in this article, we report some preliminary findings from our recent efforts since 2011 . for example, the american geophysical union 2012 annual meetings have sessions organized on energy and resource recovery, underground studies, and natural hazard related interactions . some discussions of interactions among geophysics, rock mechanics, petroleum geomechanics, and mining engineering were initiated . We discuss specifically how lsbb and potential other urls provide testing platforms for the observation of


faulting in weak and tight materials . a suggested testing method has been proposed for a pulsed and stepped test sequence to be applied in the field, with the method using the high pulse poroelasticity protocole - an injection and measuring device for hydromechanical testing in packed borehole intervals at depths . such approach could allow the in situ studies of static to dynamic frictional behaviors of large scale heterogeneities that are poorly described in conventional laboratories .

ARMA 13-742

error analysis of Sampling Spacing on Roughness of Rock Joint based on three Dimensional laser Scanning testingYunfeng GeChina University of Geosciences, Wuhan, Hubei, ChinaUniversity of Arizona, Tucson, Arizona, USAhuiming Tang, Liangqing Wang and Chengren xiongChina University of Geosciences, Wuhan, Hubei, China

the influence of different sampling spacing was investigated by applying the estimation of Joint roughness coefficient (Jrc) and profile mean angle (θp) values based on the rock joint surface three dimension model . laser scanner was employed to gather the original data of joint surface with sampling spacing of 0 .001m . then, according to the aforementioned data, the spline interpolation was introduced to generate all required data with whole range of sampling spacing from 0 .00001m to 0 .01m with an increment of 0 .00001m . both the Jrc and θp values were calculated to estimate the roughness of samples . the results show that the Jrc and θp values have a similar trend and increase with the decreasing of sampling spacing and reach an asymptotic value . error of estimation of roughness was arisen from the sampling spacing variation, and the accuracy of estimation cannot always be improved by decreasing of sampling spacing . When the sampling spacing was reduced at around 0 .00067m, there will be a slightly change on the Jrc and θp values in term of shale rock joint samples collected from Jiwei mountain landslide area .

ARMA 13-211

effect of l/D ratio on dynamic response of aluminum 7076 and the natural Motoqua Quartzite Sandstone in Saint George, Ut using Split hopkinson pressure bar (Shpb) hossein Changani, Aaron Young and Eunhye KimMining Engineering Department, University of Utah, Salt Lake City, Utah, USA

hopkinson introduced the split-hopkinson pressure bar (shpb) test in 1964 for testing the performance of dynamic projectile deformation . this testing apparatus has evolved and was introduced to the rock mechanics community less than a few decades ago . many researchers have different views on what is the proper length to diameter (l/d) ratio of the rock sample for a standard testing method . in this paper, we investigate different l/d ratios of 1 .24 inch diameter motoqua Quartzite sandstone samples . first of all, we will validate our shpb setting using aluminum 7075-t6 samples . this aluminum sample’s mechanical properties are well known and show consistent response under quasi-static and dynamic tests . this paper not only tested the sensitivity of the aluminum sample under different pressures, but also tested its behavior on different l/d ratios and showed the preliminary results of these tests . different l/d rock sample results will be shown in this paper .


SeSSiOn 29: eXperimental rOCk meChaniCS ii – SanDTuesday, 25 June, 4:30 pm – 6:00 pmChairs: Brian Crawford, Paul Hagin

ARMA 13-473

effect of initial Grain Size and packing on the evolution of elastic properties of poorly lithified SandstonesTorabi, A.Uni CIPR, Uni Research, Bergen, NorwaySkurtveit, E.Uni CIPR, Uni Research and Earth Science Department, University of Bergen, Norway and Norwegian Geotechnical Institute, Oslo, Norway

in order to understand the effect of initial grain size and packing (porosity) on the deformation behavior of porous sandstone, we have conducted two series of triaxial experiments including hydrostatic and axisymmetric tests . We study the evolutionary pattern of elastic properties of our material . We investigate elastic moduli such as static bulk and shear moduli as well as dynamic and static m-moduli for the samples under compaction and shear . our results show that initial packing (porosity) seems to be a more important factor than the initial grain size influencing the behavior of material under compaction . higher confining pressure in the axisymmetric experiments impacts the onset of shear-enhanced compaction . our investigation shows that static elastic moduli such as bulk and shear moduli and m-modulus vanish in the shear phase of the axisymmetric experiments indicating the effect of large strain and grain crushing in the samples . Whereas, the dynamic m-modulus increases along with compaction within the sample and is not sensitive to grain crushing observed in our final samples .

ARMA 13-521

Static and Dynamic Moduli – So equal, and yet So Different holt, R.M. NTNU and SINTEF Petroleum Research, Trondheim, Norway Fjær, E. and Bauer, A. SINTEF Petroleum Research and NTNU, Trondheim, Norway

engineering applications often require static mechanical properties as input, while available data only can be extracted from dynamic (seismic / sonic) measurements . dynamic moduli are often found to be larger than their static counterparts, and we demonstrate that this is the case by showing experimental results on unconsolidated and cemented sands plus on a gas shale analogue . the data demonstrate that static and dynamic bulk modulus is equal in a sample of perfectly smooth and spherical particles (glass beads) loaded in hydrostatic conditions . also, for well cemented sandstone in undamaged conditions do we find a match between the two kinds of measurements . however, in most cases, in particular when stresses are not hydrostatic, a discrepancy is observed . this discrepancy depends on stress and on stress path (e .g . loading vs . unloading) . non-elastic contribution to static deformation appears to be the main source of the difference between static and dynamic moduli, while in the shale sample; frequency dependent wave velocities make a significant contribution .


ARMA 13-554

Design and interpretation of laboratory experiments to Determine the pore Volume compressibility of Sandstone hettema, M.h.h. Statoil, Stavanger, Norway Raaen, A.M. and Naumann, M. Statoil, Trondheim/Bergen, Norway

the objective of this study is to outline the best possible way to determine the pore-volume compressibility as input to reservoir engineering simulations . the best manner to determine the pore volume compressibility from core measurements is to apply the conditions as they are in-situ in the reservoir: total stresses, stress changes and pore pressure changes over time, reservoir temperature, reservoir fluids and direct measurement of pore volume changes . in the article we discuss the possibilities and consequences of the mitigation of these requirements . one obvious mitigation is the application of effective stresses and loading under constant pore pressure . two clear advantages are that the total stresses become much lower and that the pore volume changes can be measured more accurately under constant pore pressure . the drawback of the method is that the interpretation of these test results requires knowledge of biot’s effective stress coefficient, which can be stress-dependent . We derive expressions for the equivalent reservoir pressure, a concept allowing for interpretation of non-linear pore volume compressibility data . finally we present and interpret laboratory data to demonstrate the power of the concept .

ARMA 13-627

oedometer tests for evaluation of K0 during chemical DissolutionLins, C.M.M.S., Lima, A. and Guimarães, L.J.N.Department of Civil Engineering, Federal University of Pernambuco, Recife, Brazil

injection and extraction of fluids may result in minerals dissolution . this chemical effect affects the initial state of stress and induces deformations in the reservoir rock caused by changes in the porosity and permeability . the purpose of this study is to investigate the time evolution of stress ratio (k0) during the dissolution process in order to analyze chemical and mechanical effects . to this aim, oedometer tests were carried out on synthetic samples (mixture of glass beads and nacl) using a modified oedometer cell with horizontal stress measure in order to simulate the chemical effects on rock reservoirs . the two grains are mixed under a salt-saturated brine and placed into the cell . in addition, different nacl concentrations (6, 12 and 20% of total mass) were tested to verify the k0 evolution . oedometer results show volumetric strain decreasing to 4, 8 and 17% for nacl concentrations of 6, 12 and 20%, respectively . during the nacl dissolution, the k0 decreases and a pronounced horizontal stress drop was observed for all nacl concentrations . then, the k0 increases due to the dilatancy phenomenon caused by the rearrangement of the internal granular structure, by consequence degradation of the material occurs given the shear strength decrease .

ARMA 13-170

failure characteristics of a Quartz-Rich, high-porosity Sandstone Subjected to true triaxial testing Ma, x. and haimson, B. Geological Engineering Program, University of Wisconsin, Madison, WI, USA

a series of true triaxial tests has been carried out on the quartz-rich, high-porosity bentheim sandstone (n = 24%) using a novel loading path that maintains constant the deviatoric stress state parameter (N) . We applied six different N ’s, spanning from axisymmetric compression (σ2 = σ3) to axisymmetric extension


(σ2 = σ1) . tests reveal the effect of mean stress (σoct) and deviatoric stress state parameter (N) on failure and failure-plane angle . regardless of N selected, the octahedral shear stress τoct at failure rises with increasing σoct, reaches a ‘cap’, and then drops for larger σoct . a single shear band, or fault, having an angle of about 80º is characteristic at the lowest σoct used (~20 mpa) . as σoct is increased, failure-plane angle decreases monotonically to about 50º when σoct reaches ~150 mpa . Within this range of σoct, rock deforms dilatantly . at higher σoct compactive features start developing . in the range of σoct = 150 - 200 mpa, multiple, conjugate shear-enhanced compaction bands develop at failure (angle below 45º) . at σoct ≥ 200 mpa, pure compaction bands with nearly 0º angle are formed . the tests also demonstrate the effect of the deviatoric stress state parameter N on failure and failure-plane angle . as N varies from +1 (axisymmetric compression, σ2 = σ3) to - 1 (axisymmetric extension, σ2 = σ1), σoct required for failure increases monotonically, demonstrating the strengthening effect of deviatoric stress state .

ARMA 13-205

effect of Rock pore pressure on Mechanical Specific energy of Rock cutting Using Single pDc cutterAkbari, B., Miska, S., Mengjiao, Y. and ozbayoglu, E.The University of Tulsa, Tulsa, Oklahoma, USA

this work is a continuation of a series of experimental investigations on the effect of various parameters on the response of the single pdc cutter . two sets of tests on torrey buff rock core samples were conducted using a high pressure single pdc cutter testing facility . the first set of tests were conducted by keeping the pore pressure at 410 psi and varying the confining pressure from 200 psi to 520 psi and; thereby, simulating a wide range of underbalanced to overbalanced drilling conditions . the second set was conducted by setting the pore pressure and confining pressure equal; i .e . the balanced pressure conditions with the pressures ranging from atmospheric pressure to 450 psi . the results of the first set of tests show that at 210 psi underbalance, the mechanical specific energy (mse) is 58% of the mse at the balanced conditions; while, extrapolating the trend the mse at 210 psi overbalance is 117% of mse at balanced pressure conditions . the second series shows an initial sharp increase of mse as the pressure increases up to about 200 psi where is a maximum in mse and then the values of mse start to slowly decline as the pressure further increases .

SeSSiOn 30: COupleD prOCeSS mODelS iiTuesday, 25 June, 4:30 pm – 6:00 pmChairs: Dan Moos, Dale Walters

ARMA 13- 631

inclusion of Geomechanics in Streamline Simulation for hydromechanical Modeling of Underground co2 Storage Koohmareh hosseini, B. and Chalaturnyk, R.J.University of Alberta, Department of Civil & Environmental Engineering, Edmonton, Alberta, CanadaDarcis, M.University of Stuttgart-Department of Hydromechanics and Hydrosystem Modeling, Stuttgart, BW, Germany

realistic hydromechanical simulation of carbon dioxide storage into deep saline aquifers is computationally intensive and thereby time consuming . large field heterogeneous models of stress-sensitive reservoirs with complex flow and geomechanical behavior are sometimes required to be modeled, which is very demanding . therefore, most recent studies on simulation of co2 sequestration in saline aquifers have been focused either on short-term migration or near field processes or large scale models with highly idealized geometries . this


paper presents a coupled geomechanics-streamline simulation technique for rapid hydromechanical simulation of large heterogeneous reservoirs with elastic geomechanical constitutive relations . streamline trajectories represent a three-dimensional velocity field during injection of co2 in porous medium, and therefore are helpful for model order reduction and inclusion of geomechanics in sub domains where streamlines density is relatively high . to assess the robustness and speed of the technique, a large reservoir-cap rock system with large number of grid-blocks was made . accuracy and speed of streamline-based method were compared to finite volume based flow geomechanical simulations for the same model with the same geometry . porosity and its relationship to absolute permeability were the primary geomechanically influenced variables studied in the simulations . the effective stress principle was applied to characterize the stress state and governing geomechanical differential equations were implemented based on mass and momentum conservation laws on a c++ platform with the box method (subdomain collocation method) as the discretization technique . the streamline tool used was 3dsl which is developed on a fortran platform . simulation results showed that streamlines can be helpful for fluid flow simulation or hydromechanical coupling particularly during the injection process when the fluid flow mechanism is advection-dominated . the method is demonstrated to increase model efficiency and reduce computational cost, particularly for heterogeneous reservoirs . the inclusion of geomechanics in streamline simulation thus represents a key step in the direction of quantifying uncertainty in co2 storage process for large scale, heterogeneous systems .

ARMA 13-124

numerical Modeling of pore fluid pressure Diffusion through hollow cylindrical Rock Sample Yanhui han and Gang Li Halliburton, Houston, Texas, USA

a hollow cylinder subjected to axial loading and inner and/or external fluid pressure provides an important vehicle for studying various phenomenon of rock behavior associated with field applications (e .g ., sand production in well completion and production [water, oil/gas, etc .]) . the poroelastic solutions for the hollow cylinder subjected to a stroke control mode and a non-hydrostatic lateral state of stress were derived in a previous work . the theoretical solutions are clean, precise, and efficient but constrained by the derivation assumptions (e .g ., in the authors’ derivation work, the geo-materials are assumed to be homogeneous and isotropic and behave linearly and elastically under various idealized loading modes) . to accurately capture the porous effects as well as the nonlinear behaviors of anisotropic, inhomogeneous hollow cylindrical samples subjected to arbitrary loading conditions, numerical solutions must be used; theoretical solutions can serve as touchstones to test the validity and accuracy of their numerical counterparts . in this paper, the linear poroelasticity theory is briefly reviewed and applied to derive the poroelastic solutions for pore fluid pressure diffusion through a hollow cylinder sitting in a hydrostatic stress field . a numerical model was set up in the fast lagrangian analysis of continua (flac) software to simulate the same problem . the numerical results are analyzed and compared with the derived analytical solutions . this work attempts to validate the capability of the flac simulator for modeling poroelastic processes, thus strengthening the foundation of its applications for exploring more complicated problems in which the derivation of the closed-form solutions become difficult (or impossible) because of the involvement of anisotropy, heterogeneity, plasticity, discontinuity, and other challenging issues .

ARMA 13-559

laboratory to field: critical Scaling of Single fracturesPetrovitch, C.L., Pyrak-Nolte, L.J. and Nolte, D.D.Purdue University, West Lafayette, IN, USA

experimental work suggests that the flow-stiffness relationship in single fractures relies on the geometry of the fracture, i .e . the size and spatial distributions of the void and contact areas . it is useful to understand the scaling of these distributions in relation to the hydromechanical properties of fractures to enable the extrapolation of


understanding from studies conducted on small laboratory samples to behavior on the field scale . in this study, we uncover the difficulties associated with interpreting measurements taken in the laboratory and show that the scaling is in fact fundamentally different than that of the field . finite-size scaling methods were used to extract critical thresholds for uncorrelated fractures under load and flow exponents were extracted .

ARMA 13-435

a note on fluid Driven natural fracturesRaaen, A. M.Statoil, Trondheim, Norway

lacazette and engelder (1992) argued that natural hydraulic fractures are driven by gas rather than water . the compressibility argument, which was the main basis of their reasoning, is shown to be flawed . based on basic and well-known fracture theory it is shown that the main contribution to the system compliance is the fracture itself rather than the fluid inside it . hence, the compressibility argument of lacazette and engelder can not distinguish the fracture fluid .

ARMA 13-409

a three-Dimensional compositional Model for hydraulic fracturing with energized fluids Ribeiro, L.h. and Sharma, M.M. The University of Texas at Austin, Austin, TX, USA

While several three-dimensional (3-d) fracturing models exist for incompressible water-based fluids, none are able to capture the thermal and compositional effects that are important when using energized fluids such as co2, n2, lpg, and foams . this paper introduces a new 3-d, compositional, non-isothermal, fracturing model designed for compressible fracturing fluids . the model predicts changes in fluid temperature, density, and composition . the model is capable of handling any multi-component mixture of fluids and chemicals . the simulator is validated for traditional fluid formulations against known analytical solutions, and against a well-established commercial fracturing simulator . results from the new simulator are then presented for energized fluids such as co2 and lpg . the simulator constitutes a new tool to quantify the potential benefits introduced by energizing the fracturing fluid, which is critical when selecting fracturing fluid candidates .

ARMA 13-442

Stress effects on flow partitioning in fractured Reservoirs: equivalent porous Media Versus poro-elasticity coupled Modeling Sanaee, R., oluyemi, G.F., hossain, M. and oyeneyin, M.B. Robert Gordon University, Aberdeen, United Kingdom

in this paper the effects of overburden stress on fracture-matrix flow partitioning were numerically analyzed using two different numerical approaches; the analysis was validated using a fractured clashach core flood laboratory experimental data . in the first numerical approach, the fracture aperture variation under different overburden stresses, measured using a back calculation method based on the treatment of the fracture as an equivalent porous medium, was adopted in a coupled darcy law, brinkman flow and navier-stokes fluid flow formulation . in the second numerical approach, poro-elasticity was applied in order to accurately account for fracture aperture change under overburden stress loading . the resulting displacements were coupled to the same fluid flow equations used in the first approach through a moving mesh technique . this was further coupled with stress dependent permeability within the matrix . flow partitioning from the two numerical approaches were compared to the experimental data . this comparison highlighted


the inefficiency of treating fractures as equivalent porous medium . moreover the cross-flow between the fracture and the matrix was monitored in both modeling approaches and a critical stress beyond which the matrix can no longer feed the fracture was identified . this critical stress can be very important in designing production scenarios for highly-stressed fractured reservoirs .

SeSSiOn 31: geOmeChaniCal ChallengeS aSSOCiateD with geOthermal Drilling, StimulatiOn anD prODuCtiOn iiTuesday, 25 June, 4:30 pm – 6:00 pmChairs: Doug Blankenship, Dan King

ARMA 13-307

Modeling and Monitoring of Deep injection at the northwest Geysers eGS Demonstration, california Rutqvist, J., Dobson, P.F., Jeanne, P., oldenburg, C.M. and Vasco, D.W. Lawrence Berkeley National Laboratory, Berkeley, California, USA Garcia, J., hartline, C. and Walters, M. Calpine Corporation, Middletown, California, USA

the northwest geyser egs demonstration project aims at creating an enhanced geothermal system (egs) by directly and systematically injecting cool water at relatively low pressure into a known high temperature (400°c) Zone (htZ) located under the conventional (240°c) steam reservoir . in this paper we present the results of coupled thermal, hydraulic, and mechanical (thm) modeling conducted to investigate injection strategies and effects of cold water injection upon the egs system, in particular to predict the extent of the stimulation zone for a given injection schedule . We present a comparison of model predictions with micro-earthquake (meQ ) monitoring data, as well as comparison with reservoir pressure and ground surface deformation data over the first several months of injection . using a simplified model in terms of geology and geometry, we were able to make a reasonable prediction of the extent of the stimulation zone and with reasonable parameter adjustments we could reproduce the observed evolution of reservoir pressure and surface deformations . however, we also found that the detailed evolution of reservoir pressure, meQ and ground-surface movements display prominent effects of more complex geology, including minor faults and fractures that provide preferential flow paths or are hydraulically bounding .

ARMA 13-484

improving Geothermal project economics with Multi-Zone Stimulation: Results from the newberry Volcano eGS DemonstrationTrenton T. Cladouhos, Susan Petty, Yini Nordin, Michael Moore, Kyla Grasso, Matt Uddenberg and Michael W. SwyerAltaRock Energy, Inc. Seattle, WA, USA

the newberry volcano egs demonstration in central oregon, a 3 year project begun in 2010, was designed to test recent technological advances designed to reduce the cost of power generated by egs in a hot, dry well (nWg 55-29) drilled in 2008 . first, the stimulation pumps used were designed to run for weeks and deliver large volumes of water at relatively low wellhead pressure . second, to stimulate multiple zones, altarock developed thermo-degradable zonal isolation materials (tZims) to temporarily seal off


fractures in a geothermal well to stimulate secondary fracture zones, and optimize the injection/production profile of the entire well . third, the project followed a project-specific induced seismicity mitigation plan (ismp) to evaluate, monitor for, and mitigate felt induced seismicity . stimulation started october 17, 2012 and continued for 7 weeks, with over 41,000 m3 of water injected . two tZim treatments successfully shifted the depth of stimulation . injectivity, dts, and seismic analysis indicate that fracture permeability in well nWg 55-29 was enhanced by two orders of magnitude .

ARMA 13-507

hard Rock Drilling performance improvement as Result of Systematic approach for Drill bit and bha SelectionGrindhaug, Gaute and Selnes, Knut SigveStatoil, Stavanger,Norway

using a systematic approach for selection of drill bits, including testing on basalt rock samples and up front use in test wells, leads to significant improvement of performance . additional focus on modeling and planning of bhas (bottom hole assemblies) improve stability and enhance drill bit performance by improving drilling conditions . the combination of well stabilized drilling assemblies and vibration mitigating tools in the bha lead to more stable drilling conditions and efficient use of energy to provide improved progress rates . additionally, mitigation of high vibration levels reduces the risk of bit damage and downhole tool failures, thus resulting in longer runs between trips . during drilling of the well, comprehensive use of vibration measurement tools in the bha supported continuous enhancement and provide learning’s for subsequent wells .

ARMA 13-333

numerical Study of the interaction between injection and the Discrete fracture network in enhanced Geothermal ReservoirsRiahi, A.Itasca Consulting Group, Inc., Toronto, Ontario, CanadaDamjanac, B.Itasca Consulting Group, Inc., Minneapolis, Minnesota, USA

this paper is focused on evaluating the potential of shear stimulation in enhancing productivity of low-permeability rocks using a computational modeling approach . in the adopted approach, fully coupled hydro-mechanical response of reservoirs with pre-existing fracture networks is simulated in a two-dimensional framework . a series of sensitivity studies have been performed in an initial attempt towards understanding how reservoir response to fluid injection is affected by some of the dfn characteristics and operational parameters such as injection rate .

ARMA 13-517

Relationships between Slow Slip, Seismicity and fluids leakage During a pressurized fault Zone Rupture in Situ experiment: importance for Reservoir/caprock Stimulation Monitoring and efficiency assessmentGuglielmi, Y. and henry, P.Aix-Marseille Université, CNRS, IRD, CEREGE, Aix en Provence, France


Cappa, F. and Derode, B.University of Nice Sophia-Antipolis, Côte d’Azur Observatory, Geoazur, Sophia-Antipolis, France

We present a field experiment where we nucleated slow slip at 0 .28 km depth through the artificial pressurization of a normal fault while continuously monitoring strain, seismicity and pore pressures . the episodicity of fault slip is related to dilatancy-strengthening revealed by transient pore-pressure drops that correspond to both permeability and porosity increase of the fault zone . We calculate that the slip is initiated by the fault material frictional weakening, the pore pressure increase just being the trigger . then, there is a competition between high pressure fluid diffusion in the fault zone and multiple slow ruptures that generate 80% of the seismic energy released by tremor-like seismic events . We show that the permeability/porosity increase progressively become the predominant control on slip of larger fault segments . We conclude that variations in the pressure transients and tremors are good indicators of the fluids migration and damaging effects in the fault zone . some of these events may be considered as precursors to the fault slip activation and some attributes of the signals could be inverted to estimate fault zones stability evolution . such results are of interest for seismologists and reservoir engineers in natural and induced earthquakes and fault leakage prediction and risk assessment .

ARMA 13-386

Drilling performance and productivity of Geothermal Wells - case history from hengill Geothermal area in iceland Sveinbjornsson, B.M. and Thorhallsson, S. Iceland GeoSurvey, Reykjavik, Iceland

drilling performance of 77 production and reinjection wells in the hengill geothermal area in iceland is analyzed . the study compares workdays, and time spent on seven different drilling activities, in drilling holes with two casing diameter pro-grams, both vertical and directional . the monte carlo method was applied to obtain a statistical estimate of the number of work-days and the cost of a 2235 m deep directional reference hole . on average this hole needed 45 workdays with a standard deviation of 7 .2 days . the cost was inferred from time and usage data as the actual costs were not available for the study . the average cost for a large diameter reference well is 4 .3 million usd or about 2000 usd/m . drilling problems due to loss of circulation or coll-apsing geological formations led to higher drilling costs for 24 wells but the majority of holes were drilled according to the origin-al schedule . the risk of drilling such holes in terms of cost and output is not as high as often alledged . to predict steam mass flow on the basis of the injectivity index, determined at the end of drilling, one must consider reservoir conditions and enthalpy of the expected inflow into wells . about 80% of the drilled wells are productive . the average generating capacity is ~5 .9 mWe per drill-ed well . injection of waste water from the power plant resulted in thousands of earthquakes, of magnitude up to ml 4 .

SeSSiOn 32: tunnelS anD CavernS iTuesday, 25 June, 4:30 pm – 6:00 pmChair: Fulvio Tonon

ARMA 13-732

oscillating Disc cutting technique for hard Rock excavationKarekal, S. CSIRO Earth Science and Resources Engineering, Brisbane, Queensland, Australia

the technology for the mechanical excavation of low to medium strength rock has been substantially well developed, and therefore it has been used in most cases as an alternative technology to drill and blast


excavation (gertsch, 1994) . however, in the case of hard rock excavation, especially for mining excavations, such advancement in the development of an efficient and effective cutting system has not yet been achieved . this is partly because of inadequate understanding of the basic mechanism of rock cutting and partly because of a lack of understanding in the fundamental processes involved in the rock cutting machines . this paper describes one of the advanced cutting technologies called the oscillating disc cutting for hard rock cutting and its advantages over other cutting systems are highlighted by comparing the results with that of conventional disc cutting technique employed in most tunnel-boring machines . the parameters such as oscillating frequency and the rock brittleness on the mean cutting forces are examined and their results are discussed . the experimental results clearly indicated the advantages of the cutting technology in the construction of a lightweight flexible machine for hard rock excavation .

ARMA 13-144

investigation, Design and construction in karst Marcic, D. and Kovacevic, M.S. University of Zagreb, Faculty of Civil Engineering, Zagreb, Croatia

during the last 20 years in the republic of croatia, a large number of engineering projects have been undertaken in karst, allowing engineers to acquire experience in the behaviour of karst as a material in which structures are built . the paper presents the results of engineering geological research of the physical and mechanical properties of karst . the contribution provided by geotechnical measurements and numerical back analysis in developing theoretical knowledge on karst behaviour is pointed out . using the example of three various construction pits, an interactive approach to design is presented which includes altering the design solution based on experience acquired during construction works . the paper presents experience gained in remedying a two-lane tunnel that had collapsed during construction works, the construction of a three-lane tunnel with very little overburden under residential buildings and the construction of a four-lane tunnel which leads to a six-lane width via a two-tunnel connection . also pointed out is that future research into karst should be directed towards separating the influence of karstification of carbonate rock from the influence of construction works on the strength and stiffness of karst, and a more reliable estimate of long-term deformation of geotechnical structures carried out in karst .

ARMA 13-558

Design and analysis of Mine adit-plugs within a tailings Storage basin Friedman, J.P. and Mohanty, S. Agapito Associates, Inc., Golden, Colorado, USA Rahe, J.h. Rahe Engineering, Inc., Golden, Colorado, USA

this paper discusses the development of an adit-plug system for sealing historical mine adits located within the tailings storage facility basin at the el boleo project in santa rosalía, mexico . the historical workings could possibly intersect proposed new mine workings that may allow future tailings to migrate from the tsf into the new mine workings, and eventually to areas outside the tsf creating potential instability and safety concerns . in order to seal the historical workings within the tsf limits, a plug system was designed to incorporate multiple barriers to minimize tailings migration and water inflow into the adits . the plug system includes a structural reinforced concrete plug, shotcrete liners around the plug, and a compacted, structural-fill buttress placed above and in front of the plug . analytical methods, including an empirical summation-of-forces approach and three-dimensional numerical modeling, have been used to evaluate the global stability of the adit-plug system . results of the analyses are presented .


ARMA 13-389

Simulation of thermo-Mechanical behavior of Rock Salt in the Vicinity of a Disposal Drift and the interaction with technical barriersPudewills, A.Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, Eggenstein-Leopoldshafen, Germany

the paper presents the current state of knowledge concerning the numerical simulation of the thermo-mechanical phenomena in the near field of a conceptual repository for disposal of heat-generating waste in deep rock-salt formations . special attention has been given to the consolidation behavior of backfill material due to its relevance as an engineering barrier in the underground disposal . to perform this task, finite element codes containing a set of time- and temperature-dependent constitutive models have been improved . the results of the numerical simulation show that under expected repository conditions the volume closure and the compaction of the backfill are mainly influenced by the temperature increase and the pre-excavation lithostatic stress at the waste emplacement level .

ARMA 13-152

core Disking observations and in-Situ Stress MagnitudesLim, S.S. and Martin, C.D.Dept. of Civil and Environmental Engineering, University of Alberta, Edmonton, CanadaChristiansson, R.SKB, Stockholm, Sweden

tensile stress plays a critical role in core disking . three dimensional numerical analyses were carried out to determine the distribution of theses tensile stresses in the vicinity of the advancing drill bit . a methodology was developed to examine the spatial distribution of the maximum, minimum, and average, maximum tensile stress . a criterion based on the averaged maximum tensile stress (amts) was found to give good agreement with the thickness of core disks measured on core from 75-mm-diameter boreholes . this approach was then used to establish a general core disking nomogram using site-specific geometry, the brazilian tensile strength, and the amts . the approach was applied to aecl’s underground research laboratory and found to be in agreement with field observations . it is also found that a large diameter hole with a rounded shape bit can significantly reduce the potential for core disking in and around core stub .

ARMA 13-288

a Study of the influence of tunnel Shape on Rockburst proneness Using numerical ModelingKusaka, A.Public Works Research Institute, Tsukuba, Ibaraki, JapanColorado School of Mines, Golden, Colorado, USAGarvey, R. and ozbay, U.Colorado School of Mines, Golden, Colorado, USA

the influence of tunnel shape on rockburst manifestation is analyzed in flac3d using several indicators including velocity and acceleration within the finite difference method . the tunnel is constructed in a rockmass defined by a mohr-coulomb strain-hardening/-softening constitutive law to approximate rockburst-prone brittle rock . three cross-sectional tunnel shapes are employed: circular, horse-shoe, and rectangular . the analysis is performed as a two-dimensional problem with an applied plane strain condition and a stress boundary used to simulate earth pressure . no supports are installed in the analysis for simplicity since the rockmass failure mode is the focus of this study . the influence of tunnel shape on rockburst


manifestation is analyzed using several indicators of unstable failure . the results indicated that the circular tunnel geometry is more stable than the other tunnel shapes against the occurrence of rockburst . the rectangular tunnel produced the highest magnitudes of the rockburst indicators and proved to be the most unstable of the three geometries which were tested .

SeSSiOn 33: fraCture meChaniCS iiWednesday, 26 June, 8:00 am – 9:30 amChairs: Neal Nagel, Fengshou Zhang

ARMA 13-199

the influence of fracture network connectivity on hydraulic fracture effectiveness and Microseismicity Generation Zhang, F., Nagel, N., Lee, B. and Sanchez-Nagel, M. Itasca Houston, Inc.

in this work, the effect of fracture network connectivity on hydraulic fracturing effectiveness was investigated using a discrete element numerical model . the simulation results show that natural fracture density can significantly affect hydraulic fracturing effectiveness, which was characterized by the ratio of the stimulated natural fracture area to the hydraulic fracture area, the leakoff ratio, and the synthetic microseismic events . the simulations with a ‘sparse’ dfn showed a flat microseismic distribution zone with few events, while the simulations with a ‘dense’ dfn showed a complex microseismic map indicating an intensive interaction between the created hydraulic fracture and the natural fractures . parametric studies on the effects of fluid viscosity, flow rate, dfn dilation angle and rock toughness were carried out, which also showed that dfn connectivity should be considered an important parameter in completion design and stimulation optimization . overall, this work illustrates that fracture network connectivity plays a critical role in hydraulic fracturing effectiveness, which, in-turn, affects treating pressures, the created microseismicity and corresponding stimulated volume, and, ultimately, well production .

ARMA 13-596

impact of fracture height on Mixed Mode fracture propagation: insights from 3D Displacement Discontinuity ModelingSheibani, F. and olson, J. E.The University of Texas at Austin, Austin, Texas, USA

natural or hydraulic fracture attributes such as planarity, path and connectivity affect fluid transport in reservoirs . although many fracture models are based on two-dimensional approximations, accurately predicting fracture propagation geometry requires accounting for the three-dimensional aspects of fractures . We focus on the effects of fracture height on lateral propagation of vertical fractures using a 3-d displacement discontinuity model to investigate the curving path and the angle of intersection for overlapping fractures, and the evolution of stress intensity factor and energy release rate during propagation around the fracture periphery . results show the curving path is strongly influenced by the spacing to height ratio of the overlapping fractures as well as the differential stress magnitude . in addition, the angle of intersection between two non-coincident but parallel en echelon fractures is shown to depend strongly on fracture height to length ratio, with intersection angles being asymptotic for “tall” fractures (large height to spacing ratios) and nearly orthogonal for “short” fractures . fracture height to spacing ratio also affects mode iii deformation and twist hackle generation . the degree of mixed mode i-iii loading caused by non-planar parent crack propagation is highlighted in addition to the more conventional of spatial or temporal remote stress orientation changes .


ARMA 13-460

a finite Difference approach to Modeling Geomechanics in hydraulic fracturing Petunin, V.V. Nitec LLC, Denver, CO, USA

the ability to both model the growth of a fracture system from a hydraulic fracture treatment and its closure over time due to pressure depletion is critical to understand and improve hydraulic fracture methodology . if the stimulated rock volume (srv) is pre-determined by the engineer and flowback water is discounted during history matching using a conventional reservoir simulator, the actual hydraulic fracturing treatment has no impact on the model . a holistic approach that incorporates the entire life of the well is key to history matching hydraulically fractured wells . the new reservoir simulation technology presented here contains novel features that allow for such a complete match of hydraulically fractured wells . field reported fracture fluid volumes are injected at the measured rates, stage by stage, in order to generate the srv . if the hydraulic fracture design is changed it will change the generated srv . this technique has been applied to wells in the Wolfcamp, three forks, and bakken shale oil fields . the quality of the history match has been higher than what was possible using pre-existing technology .

ARMA 13-662

experimental investigation of hydraulic fracturing in Vertical and horizontal perforated boreholes Fallahzadeh, S.h., Rasouli, V., Sarmadivaleh, M. Curtin University, Perth, WA, Australia

in this study, scaled hydraulic fracturing tests are conducted on 10 and 15 cm cubical mortar samples . the importance of scaled fracturing tests should be highlighted as the results of non-field-like fracturing tests cannot be compared with or used for actual fracturing operation . three independent principal stresses were applied to the samples using a true tri-axial stress cell (ttsc) . the hole and perforations were made into the sample after casting and curing were completed . various scenarios of vertical and horizontal wells and in-situ stress regimes were modeled . these two factors play a significant role in fracture initiation and near wellbore propagation parameters; however they are not independent from each other and should be analyzed simultaneously . the results showed that when the least stress component is perpendicular to the axis of the perforations, less fracturing pressures would be required . it is also shown that, even when the cement sheath is failed, the orientation of the perforations affects the fracturing process noticeably . furthermore, it was found that stress anisotropy influences the fracturing mechanism in a perforated borehole, and affects the geometry of the fracture close to the wellbore .

ARMA 13-513

fracture initiation and propagation in Reservoir Rocks under high injection pressureStroisz, A.M., Pradhan, S., Stenebråten, J., Lund, h.K. and Sønstebø, E.F.SINTEF Petroleum Research, Trondheim, NorwayFjær, E.NTNU and SINTEF Petroleum Research, Trondheim, Norway

fracturing is a common practice in the petroleum industry . its main application is to enhance productivity by increasing the permeability of the reservoir rocks . a new fracture surface helps co2 absorption during co2 storage . also for geothermal installation and gas production, which requires drilling through hard and hot porous rock, fractures play a major role . during fluid injection in such scenarios cracks open up and


existing fractures grow in porous reservoirs due to fluid pressure and stress imbalance and sometimes growth of fractures results in leakage or well-collapse, which are major safety issues . therefore, fracturing should be done in a controlled manner to avoid fracture propagation/fault activation that can trigger borehole failure or leakage (co2 storage) . in this study, rock fracturing is investigated through laboratory test with acoustic emission (ae) monitoring system . experiments have been performed on nine hollow cylinder cores of four rock types: castlegate sandstone, berea sandstone, red Wildmoor sandstone, and mons chalk . samples have been subjected to 5 mpa confining pressure and the borehole pressure was gradually increased to generate the fractures . our results show that the acoustic events – both number and amplitude of ae hits - clearly indicate initiation and further propagation of fracture . localization of the acoustic events, along a clear line, is in accordance to the position of two symmetric fractures seen on the core and confirmed by the micro-ct images .

ARMA 13-203

Revisiting Vertical hydraulic fracture propagation through layered formations – a numerical evaluation x. Garcia, N. Nagel, F. Zhang, M. Sanchez-Nagel and B. Lee Itasca Houston Inc., Houston, Texas, USA

in the oil and gas industry, vertical growth/containment of fractures during hydraulic fracturing is of pivotal importance to the success of well stimulations . experimental work have improved our understanding of the topic, but it is sometimes difficult to explore, in isolation, some of the multiple parameters involved in the problem . analytical models cannot account for the whole complexity of the problem, and although numerical models are an alternative, they also come with their own benefits and drawbacks . oversimplification, limitations on the size of the treatable systems, and erroneous/doubtful assumptions are sometimes drawbacks of numerical approaches . in this work, an effort is made to overcome some of these issues and present a numerical model which incorporates the physics of fracture growth and does not rely on prescribed constitute laws or continuum equations . the approach is based on the discrete element method (dem) and accounts for the physics of fracture growth from basic principles . the model has the benefit of being a hybrid model that includes the fine-details of tip mechanics plus the large-scale effects of an arbitrarily large surrounding medium . this approach was used to study, in isolation, the influence of toughness contrast on the propagation mode of a fracture through an interface separating two formations . the model captured the local scale effects of the interaction of the tip of a vertical fracture approaching a horizontal fracture while still being computationally efficient . the results obtained indicate that when varying the single parameter of toughness contrast, four main propagation modes were observed for mode i fractures: straight crossing across the interface between layers, arrest at the interface, propagation across the interface but with a t-shaped fracture, and reinitiation of the fracture with an offset (jog) .

SeSSiOn 34: prODuCtiOn in weak rOCk, evapOriteS anD CavingWednesday, 26 June, 8:00 am – 9:30 amChairs: Hamid Maleki, Leslie Gertscb

ARMA 13-731

Geotechnical pit Slope Design for brewery creek property, yukonKhalid Zaka and Carlos ChaparroEBA a Tetra Tech Company, Vancouver, BC, Canada

due to the nature of the rock mass strength the stability assessments for the design of the West big rock pit walls at pre-feasibility level considered both the rock fabric and the rock mass strength . kinematic analyses


(based on stereographic projections) were conducted to search for potential failures at bench scale, where the rock mass rating was found to be higher than 35-40 . stability analysis using limit equilibrium methods (based on rock mass strength) conducted to search for potential failures at overall pit slope scale . the analyses were based on geotechnical properties and data collected during the subsurface geotechnical programs . site investigation and preliminary geotechnical design details that incorporate site specific conditions for the proposed West big rock pit at brewery creek, are discussed in this paper .

ARMA 13-207

Stability analyses of Replacing barrier pillars between Stopes with backfill in Gilsonite Mines of UtahMaleki, h. Maleki Technologies, Inc., Spokane, WA, USAPerkes, S.Bureau of Land Management, Salt Lake City, Utah, USAheath, R.Bureau of Land Management, Vernal, Utah, USA

on federal land, gilsonite is presently being extracted by two major mining companies using simple, non-mechanized but practical mining methods . typically the 1-6-ft ( .3-2-m) wide vertical veins are extracted leaving a 35-ft (110-m) thick rich layer near the surface (crown pillar) and other barrier pillars 10-30-ft (3-10-m) thick between 100-ft (30-m) tall stopes . mining has historically been conducted in a descending order using a 10-ft (3-m) drift and slopes while systematically supporting the stope walls with timber . because of the superior grade of the crown pillar, there have been efforts to extract it locally by bridging the vein using concrete slabs . the extraction of barrier pillars placed between the stopes is a challenging problem that may be practical with significant improvements in mine economics and resource recovery and thus is the subject of these investigations . the blm is responsible for ultimate maximum recovery (umr, 43 cfr 3590 .0-5 (h) which states “that all portions of a leased federal mineral deposit shall be mined based on standard industry operating practices . to achieve umr as well as to maintain long-term stability, the authors have been working with gilsonite mines staff to find solutions for safe extraction of the sill pillars, barrier pillars, etc . this paper describes limited field data collection and numerical modeling conducted for evaluating feasibility of extracting barrier pillars and replacing them with cemented backfill . challenging engineering design problems pertaining to this study were (1) inadequate base geotechnical data (2) lack of empirical pillar designs for depositional environment of gilsonite veins and (3) limiting mining experience at depths exceeding 500-ft (150-m) .

ARMA 13-162

the 2-D and 3-D imaging of core for fracture Mappingolson, L. and Samson, C.Department of Earth Sciences, Carleton University, Ottawa, Ontario, CanadaMcKinnon, S.D.Department of Mining, Queen’s University, Kingston, Ontario, Canada

in this paper we present 2-d and 3-d image-based methods to detect fractures in drill core . With the first approach, fractures are detected from a profile along the central axis of a core sample . fracture detection strategies include taking the difference between the core profile and a model of unbroken core, identifying changes in slope with the first derivative and using the mean as a threshold . using the mean as a threshold is the simplest and most reliable fracture detector of the three profile methods . the second approach is to convert 3-d point cloud data to a 2-d image, with each pixel representing a distance measurement . these distance-based images do not show rock texture, thus established edge and object detection tools are better able to highlight fractures . once the fractures are identified, the length of each intact core section is measured . from these measurements the rock Quality designation (rQd) is calculated .


ARMA 13-187

Rock Mass characterization and conceptual Modeling of the printzsköld orebody of the Malmberget MineUmar, S.B. and Nordlund, E.Luleå University of Technology, Luleå, Norrbotten, SwedenSjöberg, J.Itasca Consultants AB, Luleå, Norrbotten, Sweden

the lkab malmberget mine is mined using sublevel caving . this mining method is cost-effective but results in successive caving of the host rock and mining-induced ground deformations . consequently, re-locations of residential areas have been in progress in malmberget ever since iron ore extraction on industrial scale commenced about a century ago . this study seeks to increase the understanding of the intrinsic characteristics of the rock mass governing deformation and caving activities . rock mass characterizations were done in two selected orebodies — printzsköld and fabian . two drill holes were drilled in each orebody from the surface . geotechnical core logging was performed using the rmr system . Weakness zones were categorized to determine what role they played in the caving process . point load testing was conducted for a sampling interval of about 5 m and selected uniaxial compressive strength tests were conducted to calibrate the point load index . tunnel mapping was conducted in the hangingwall of the printzsköld orebody . the finite element modeling code phase2 was used for a sensitivity analysis of rock strength parameters and to study factors that may influence initiation of caving of the hangingwall .

ARMA 13-487

Volumetric fracture intensity Measurement for improved Rock Mass characterisation and fragmentation assessment in block caving operations S. Rogers Golder Associates Ltd, Burnaby, BC, Canada D. Elmo Golder Associates Ltd, Burnaby, BC, Canada University of British Columbia, Vancouver, BC, Canada G. Webb Golder Associates Pty, Brisbane, Qlds, Australia A. Catalan Newcrest Mining Ltd, Orange, NSW, Australia Now Minera Esperanza, Grupo Antofagasta Minerals

recent discrete fracture network (dfn) related analysis of a number of block caving projects has demonstrated the role that the 3d volumetric fracture intensity measure (p32) plays on controlling a number of rock mass properties critical to caving operations . p32 represents the fracture area per unit volume and as such represents a non-directional intrinsic measure of the degree of rock mass fracturing, incorporating both a frequency measure and a fracture size component . analysis has shown that the p32 intensity of a dfn model strongly controls the overall fragmentation of the rock mass and so by taking the overall distribution of p32, the in situ fragmentation of a large rock mass volume can be easily determined in a computationally efficient way . With p32 also being shown to be one of the dominant controls on dfn derived directional stiffness measures, increasingly these dfn related work flows are being shown to be central to an improved rock mass characterisation process and ultimately the more accurate capturing of the caving process .


ARMA 13-440

Drilling Response of impregnated Diamond bits: an experimental investigationMostofi, M.Deep Exploration of Technology Cooperative Research Centre, Curtin University, AustraliaFranca, L.F.P. and Richard, T.CSIRO, Deep Exploration of Technology Cooperative Research Centre, Australia

the use of impregnated diamond (id) bits has dramatically increased in hard and abrasive drilling environments over the last few decades . although frequently used, the drilling performance of id bit is still quite volatile and inconsistent . the dissipation of energy at the bit/rock interface is postulated as a combination of two independent processes: pure cutting or fragmentation and friction across wear surfaces . in order to better understand the mechanisms governing the bit/rock interaction, it is necessary to isolate the processes mobilised across the interface . this paper deals with the steady-state drilling response of id bits, also called “stationary” response, in other words, the relationship between forces acting on the bit and depth of cut under conditions of constant wear state . a series of tests is performed with crowns/segments and bits on four different granites and one sedimentary limestone, using two kinematic controlled drilling rigs . the results have shown that the cutting response varies through three linear regimes that are characterised by different dominant mechanisms acting at the interface . the results also indicate how the micro-properties of the rock such as mineralogy and the segment properties (matrix hardness, wear status, concentration and diamond size) affect the response .

SeSSiOn 35: new DevelOpmentS in COmputatiOnal rOCk meChaniCSWednesday, 26 June, 8:00 am – 9:30 amChairs: John Harrison, Azadeh Riahi

ARMA 13-488

Validation of lattice approach for Rock Stability problems Damjanac, B., Cundall, P.A. and Varun Itasca Consulting Group, Inc., Minneapolis, Minnesota, USA

conventional design methods for rock slopes involve the use of continuum strength criteria for rock mass, such as hoek-brown . alternatively, a numerical approach has been developed based on the distinct element method . rather than using finite-sized particles, a greater efficiency can be realized with a lattice of point masses connected by springs . this model allows fracture by the breakage of springs and joint slip by using a smooth representation of joint segments . the methodology of a new 3d lattice program, Slope Model, is described in this paper . Slope Model allows a general geometry of a rock slope to be simulated . the rock mass contains joint segments derived from a user-specified discrete fracture network (dfn) . the code and the lattice approach are verified and validated for rock mass stability analysis by comparing the model predictions with analytical solutions and experimental data . the results of the validation of the lattice approach by comparison with solution and test data for bending of a beam, propagation of a wing crack, shearing of a rock bridge and flexural toppling are presented in this paper .


ARMA 13-476

oil Reservoir’s Geometry Reconstruction and Mesh Generation by Using nURbS SurfacesFlorez, horacio A. and Florez-Guzman, JorgeConocoPhillips, Houston, Texas, USAManzanilla-Morillo, RaulUniversidad Simon Bolivar, Caracas, Venezuela

in this paper the geometry of oil reservoirs is reconstructed by using nurbs surfaces . the technique exploits the reservoir’s static model simplicity to build a robust piecewise continuous geometrical representation by means of bézier bicubic patches . interpolation surfaces can manage the reservoir’s topology while translational surfaces allow extrapolating it towards its sideburdens . after that, transfinite interpolation (tfi) can be applied to generate decent hexahedral meshes . in order to test the procedure several open-to-the-public oil reservoir datasets are reconstructed and hexahedral meshes around them are generated . this reconstruction workflow also allows having different meshes for flow and mechanics by computing a projection operator in order to map pressures from the original flow mesh to the generated reference mechanics mesh . as an update respect to a previous version of this research, we already incorporate blending functions to the tfi procedure in order to attract the mesh towards the reservoir, which allows grading the hexahedral meshes in the appropriate manner . finally, field scale reservoir compaction and subsidence computations are carried out by using continuous galerkin fem for mechanics coupled with a compositional reservoir simulator in order to demonstrate the applicability of the proposed algorithm .

ARMA 13-224

advances in numerical Modeling of Microseismicityhazzard, J.h. and Pettitt, W.S.Itasca Consulting Group, Minneapolis, MN, USA

a simple technique is presented for extracting seismic information from slip on faults in distinct element models . it is shown that a simple static-dynamic friction law is sufficient to induce instability, and therefore produce seismic events . With this approach, all slips are seismic since the drop in frictional resistance is always faster than the drop in loading . in reality, not all events are seismic and the condition for instability depends on the system stiffness, fault roughness and normal stress . to simplify the problem, it is proposed that a user-defined minimum normal stress is required in the models for slips to be considered seismic . the method is shown to produce realistic behavior when simulating a laboratory experiment of slip on a single fault . a field-scale model with multiple intersecting faults is also presented . seismicity is recorded and magnitudes are realistic, but more investigation is required before this method can be used in realistic field-scale modeling .

ARMA 13-572

continuous Monitoring of Synthetic Seismicity: Slip on JointsKatsaga, T. and Pierce, M.E.Itasca Consulting Group, Inc., Minneapolis, USA

microseismicity often provides the most valuable information about in-situ rock mass behavior in terms of damage and associated mechanisms when subject to changes in the stress field . numerical investigation of simulated synthetic microseismicity along with experimental observations and field data can provide valuable insight into the details of damage initiation, development and discontinuity


interaction . a goal of this work is to develop a numerical slip-monitoring tool to extract synthetic seismicity from bonded-particle models, including synthetic rock mass (srm) models that involve explicit modeling of discontinuities . a slip-monitoring package was designed to continuously track and record slip events along with corresponding seismic information such as relative shear displacement accumulated during a slip, normal displacement, the magnitude of the shear force, slip rate and seismic moment . the developed slip-monitoring package includes various tools for clustering, filtering and plotting slip events and clusters, as well as extracting related synthetic seismicity information .

ARMA 13-706

a comparison between 2D and 3D bonded-particle Models for Rocks Bahrani, N. Geomechanics Research Centre, MIRARCO, Sudbury, ON, Canada Purvance, M. Itasca Consulting Group, Minneapolis, MN, USA Emam, S. Itasca Consultants S.A.S., Ecully, France

different strategies for modeling intact or jointed hard, brittle rock using the bonded-particle model (bpm) are reviewed . the analyses are done in two- and three-dimensions using the particle flow code (pfc; version 5 .0) . the purpose of this study is to compare the results of 2d and 3d bpms and investigate the applicability of 2d models for simulating the 3d nature of laboratory tests . for this purpose, direct tension and uniaxial compressive strength tests are simulated . the 2d bpm is first calibrated to the strength and deformability properties of a typical hard, brittle rock (i .e ., lac du bonnet granite) . the micro-properties of the calibrated 2d bpms are used as inputs for the 3d bpms and the results, including strength and modulus, are compared . sensitivity analyses in both 2d and 3d are carried out to investigate the influence of particle shape, bond strength ratio, particle friction coefficient, and bond stiffness ratio on the direct tensile to compressive strength ratio of the specimen . it is found that the 2d and 3d bpms comprised of spherical particles provide similar results . this is not the case for complex particle shapes (e .g ., bpm with particles comprised of two equal radius, rigidly attached spheres) . this is interpreted to arise from different interlocking levels between the complex shaped particles, introducing geometric non-linearity . it was found that the results of 2d and 3d bpms with spherical particles and inclined fractures are comparable in terms of strength and failure modes only when a rectangular through-going fracture is used .


SeSSiOn 36: DamS anD fOunDatiOnSWednesday, 26 June, 8:00 am – 9:30 amChairs: Hong Yang, David Scarpato

ARMA 13-328

emergency Sinkhole Mitigation and Void investigation of abandoned Railroad tunnel along U.S. 24, tennessee pass, colorado – case Studyhanna, K., hodges, S. and Nolte, J.Zapata Incorporated, Golden, CO, USAElsen, J., Goodrich, R., Figgs, M. and Thomas, D.Colorado Department of Transportation, Glenwood Springs, CO, USASzynakiewicz, T.Hayward Baker Incorporated, Broomfield, CO, USAVessley, M.Shannon and Wilson, Denver, CO, USA

in July 2012, a large sinkhole appeared on the north shoulder of u .s . 24 leading to the closure of the highway north of leadville . the sinkhole was a result of the partial collapse of an old denver & rio grande railroad tunnel that was excavated in the 1880’s and was used until the 1940’s . the tunnel is approximately 27 .4 m (90 ft) below the highway at this location and constructed through glacial soils . the sinkhole measured 10 .7 m (35 ft) in diameter and extended into the original tunnel . the colorado department of transportation wanted a repair that could safely reopen the roadway as quickly as possible due to the tourist and recreational importance of the highway . hayward baker inc . (hbi) performed the mitigation involving the placement of both high mobility and low mobility grout to stabilize the collapse feature . shannon and Wilson was the consulting engineering firm for cdot . Zapata incorporated (Zapata) performed subsurface video imagery and laser mapping of the remaining uncollapsed tunnel sections . the results obtained from the imagery and the 3d laser mapping will aid cdot engineers and geologists in planning future mitigation efforts on the remaining portions of open tunnel along u .s . 24 .

ARMA 13-497

Reliability based Design of Shallow foundations on Jointed Rock Masses using RQD and the Uniaxial compressive Strength of intact RockAbu El-Ela, A.A., Bowders, J.J. and Loehr, J.E.Civil and Environmental Engineering Dept., University of Missouri-Columbia, USA

in many cases, uniaxial compressive strength (ucs) for intact rock and rock quality designation (rQd) are the only information available for describing rock strength and discontinuities respectively; consequently, the design bearing capacity of jointed rock masses becomes a challenging task accompanied with undefined uncertainty . in this article, existing empirical relations developed for estimating rock mass strength based on rQd are reviewed and evaluated . other methods based on rock mass classification are also reviewed . the published data regarding rock mass strength have been statistically analyzed and the empirical model suggested by Zhang [1] for the strength of jointed rock mass was selected . probabilistic analyses were performed to make the selected model appropriate for the load resistance factor approach . monte carlo simulation (mcs) which is aashto’s preferred calibration tool has been used to numerically estimate the resistance factors corresponding to acceptable levels of risk . inputs for the probabilistic analyses included: frequency distributions for rQd, a range of dead-to-live load ratios sustained by shallow foundations, the


variability of the proposed model and coefficient of variations, c .o .v, of ucs . one million mcs trials were used to ensure the accuracy of the resistance factors . design charts for the resistance factors used in the design of shallow foundations on jointed rocks are presented .

ARMA 13-613

new park bridge, kicking horse canyon; pier 5 – a Difficult foundation on Rock Schlotfeldt, P., Panton, B. and humphries, R.Golder Associates Ltd., Vancouver, British Columbia, Canada Elmo, D. NBK Institute of Mining, University of British Columbia, Vancouver, Canada

highway 1 – the trans-canada highway – which is vital to the transportation system of canada - runs through the very rugged kicking horse canyon on the eastern edge of british columbia . the kicking horse canyon section of the highway has undergone several phases of upgrades in order to reduce bottlenecks, avalanches, rockfalls, and debris flow typical encountered in this locality . the new park bridge, which was completed in 2007, is 350 m long and has a maximum height of 100 m, formed an integral part of the upgrades . the bridge was constructed under a design-build-finance-operate contract, with very tight construction schedules with limited site investigation work done before construction stated . this paper highlights the results of more conventional methods used for the rock socket design for pier 5 of the bridge, and then describes briefly how the edge effect was dealt with, particularly in light of the discovery of a very unfavorably orientated joint set that provided potential for sliding of the entire pier downslope . these limit equilibrium-driven results are compared with numerical modeling results using phase 2 for the same pier . the modeling helped demonstrate and confirm - post construction – the suspected sliding failure mechanism governed and that the actual design was suitably conservative .

ARMA 13-415

Susceptibility analysis of earthquake induced landslide-Dam based on GiS Yanan Fan, Guangqi Chen, Kiyonobu Kasama and Yange Li Civil and Structure Engineering, Kyushu University, Fukuoka, Japan

some significant hazards may occur due to large landslide-dams formed by earthquake induced landslides . it presents serious threats to both life and property from possible upstream flooding as the impounded lake water level rises, possible dam failure and downstream flooding as rapid release of impounded water . in order to prevent those secondary disasters, we made an assumption that the landslide dam is only formed when a large amount of landslide deposits directly rush into a river with moderate or high-velocities, and then presented a practical prediction method to extract the dangerous slopes as sources of earthquake induced landslide-dam formation . the prediction procedure consists of the following steps: (1) identification of all the slopes using spatial statistics; (2) the extraction of potential slopes according to our assumption using three spatial relation filters; (3) stability analysis to determine landslide prone slopes and volume estimation of potential landslide deposits using limit equilibrium analysis . (4) production of susceptibility map by ranking the exact slopes . this method has been used to extract slopes those have potential to collapse and form landslide-dams in the catchment of tongkou river based on the data from 2008 Wenchuan earthquake . the results show that the proposed method is effective and efficient .


ARMA 13-637

flow and transport of fines in Dams and embankments Ezzedine, S.M. and Glascoe, L.G. CED, Lawrence Livermore National Laboratory, NSED, Livermore, CA, USA Kanarska, Y., Lomov, I.N. and Antoun, T.h. AEED, Lawrence Livermore National Laboratory, AEED, Livermore, CA, USA

understanding the flow of fines in porous media and fractured media is significant for industrial, environmental, geotechnical and petroleum technologies to name a few . several models have been proposed to simulate the flow and transport of fines using single or two-phase flow approaches while other models relies on mobile and immobile transport approaches . however, to the best knowledge of the authors, all the proposed modeling approaches have not been compared to each other in order to define their limitation and domain of validation . in the present study, several models describing the transport of fines in heterogeneous porous and fractured media will be presented and compared to each other . furthermore, we will evaluate their performance of the same set of published experimental sets of data .

SeSSiOn 37: reServOir geOmeChaniCS iiWednesday, 26 June, 11:00 am – 12:30 pmChairs: Peter Connolly, Karim Zaki

ARMA 13-100

a new Modeling approach to natural fracturing processChukwudozie, C. and Bourdin, B.Louisiana State University, Baton Rouge, LA, USAYoshioka, K., Buchmann, T. and Connolly, P.Chevron Energy Technology, Houston, TX, USA

robust understanding of natural fracture distribution and connectivity is crucial in hydrocarbon and geothermal energy development . unfortunately, such characterization of the fractured formation remains a major challenge to the industry . We propose the variational approach to fracture modelling, which provides a unified framework for studying fracture nucleation and initiation, autonomous propagation and the growth of an arbitrary number of fractures . in this study, we model fracture nucleation and the sequential infill fracturing of an entire brittle layer, as reported by several authors of out-crop based studies . in addition, the relationship between mechanical stratigraphy and fracture density is captured by studying the effect of the mechanical properties of the fracturing and non fracturing layers on the distribution of fractures within the brittle layers . from a parametric analysis, it is found that the mechanical properties and geometry have a strong effect on the density, spacing and overall distribution of fractures and the initiation of bedding parallel slip .

ARMA 13-275

Quantifying Reservoir compaction in an Unconsolidated pliocene Reservoir Using time-lapse Seismic, continuous Downhole pressure Monitoring, and 3D finite element ModelingLee, D.W., Adachi, J.*, Waggoner, J., holicek, J. and Flack, B.Schlumberger, Houston, Texas, USA


Fauquier, M. and holland, J.W&T Offshore, New Orleans, Louisiana, USA*now with Chevron ETC, Houston, Texas, USA

this paper examines the use of multiple, time lapse data types and a 3d finite element model to quantify compaction effects on the matterhorn field . initial development at matterhorn was based on a geological model of pressure-connected, highporosity , and unconsolidated turbiditic pliocene sandstone reservoirs . however, early production results and additional data acquisition showed a much different reservoir of pressure-separated, compartmentalized sand bodies . a 3d finite-element model was built using geological and reservoir simulation models . model initialization and calibration included laboratory mechanical property core testing, mini-frac closure tests, and continuous downhole reservoir pressure measurements . the finite-element model was calibrated using time-lapse seismic data, time-lapse pressure transient analysis, production data, and recorded failure events . modeling results were used as inputs to the field development plan .

ARMA 13-740

predictive Modeling of the evolution of fault Structure: 3-D Modeling and coupled Geomechanical/flow Simulation Thornton, D.A.Rockfield Software Ltd., Swansea, Wales, UK Crook, A.J.L .Three Cliffs Geomechanical Analysis, Swansea, Wales, UK

reconstruction of geological structures has the potential to provide additional insight into the effect of the depositional history on the current day geomechanical and hydro-geologic state . accurate modeling of the reconstruction process is however complex, necessitating advanced procedures for the prediction of fault formation and evolution within fully coupled geomechanical, fluid flow and temperature fields . in this paper, a 3-d computational approach is presented that is able to forward model complex structural evolution with multiple intersecting faults that exhibit large relative movement within a coupled geomechanical/flow environment . the approach adopts the lagrangian method, complemented by robust and efficient automated adaptive meshing techniques, an elasto-plastic constitutive model based on critical state concepts, and global energy dissipation regularized by inclusion of fracture energy in the equations governing state variable evolution . the proposed model is validated by comparison of 2-d plane strain and 3-d thin-slice predictions of a bench-scale experiment, and then applied to two conceptual coupled geomechanical/fluid flow field-scale benchmarks .

ARMA 13-536

Geomechanical, hydraulic and Seismic properties of Unconsolidated Sediments and their applications to Shallow Reservoirs Grande, L.Norwegian Geotechnical Institute, Oslo, Norway Mondol, N.h.University of Oslo and Norwegian Geotechnical Institute, Oslo, Norway

in this study a series of synthetic clays and unconsolidated sands of different textural and mineralogical compositions have been tested using triaxial cell under uniaxial (one-dimensional) strain conditions applying high effective vertical stresses (up to 30-50 mpa) . a highly specialized setup with combined measurements of axial and radial deformation, acoustic velocity and hydraulic properties was developed to achieve the test program . results from tests show that the constrained modulus, k0, acoustic velocity


and permeability anisotropy versus effective stress relationships were dependent on the mineralogical and textural compositions of rocks . these data are valuable input for parametric studies and uncertainty analysis of shallow reservoirs in general and especially when there is lack of site specific data . for areas with more detailed knowledge of mineralogical and textural compositions more exact predictions can be made and uncertainty span can be reduced . examples of applications towards compaction and fracturing evaluations are given and the effect of drainage of clay units on the overall compaction is also demonstrated in case of a complex reservoir .

ARMA 13-219

field-Scale Geomechanical Modeling of an intensely faulted Gas Reservoir Fischer, K. and henk, A. Technische Universität Darmstadt, Darmstadt, Hesse, Germany

the optimal exploitation of conventional and unconventional reservoirs is strongly dependent on the local tectonic stress field . amongst others, wellbore stability, orientation of hydraulically induced fractures and - especially in fractured reservoirs - permeability anisotropies depend on the recent in situ stress . the workflow presented in this paper can be used to build 3d geomechanical models based on the finite element method (fem) and ranging from field-scale models to smaller, highly detailed submodels of specific fault blocks . this approach is successfully applied to an intensely faulted gas reservoir in the north german basin, for which a field-scale model was built . the stresses predicted by the geomechanical fe model are calibrated against well data actually observed, like borehole breakouts and extended leak-off tests . finally, the validated model can provide insights into the stress perturbations in the inter-well space and undrilled parts of the reservoir . in addition, the tendency of the existing fault network to slip or dilate in the present-day stress regime can be addressed .

ARMA 13-461

analytical Model of fault Reactivation for future Water injection in a Deepwater turbidites oil field, offshore brazilGalarraga, M.A.Shell Brasil Petroleo Ltda, Rio de Janeiro, RJ, Brasil

the aim of this study is to investigate deterministic and probabilistic slip tendency to assess the reactivation potential of a pair of pre-existing normal faults present in a deep water turbidite oil field, where water is planned to be injected at in-situ virgin reservoir condition . the methodology used is fully analytical, and has served to estimate the critical pressure perturbation that induce shear slip along the pre-existing faults which are still under a normal faulting stress regime, therefore, helping to define the operational envelope during the water injection phase . this piece of work also considers the rebound of stresses upon injection using the finding by santarelli et al ., 1998, where basically none or little increment of the minimum horizontal stress was observed during injection . a monte carlo simulation approach has been used for the probabilistic analysis, accounting for the uncertainties associated with some of the input variables . the use of the valuable pole of the stress circle concept also helped to validate some of the results to some extent .


SeSSiOn 38: tunnelS anD CavernS iiWednesday, 26 June, 11:00 am – 12:30 pmChairs: Sarah Wilson, Jonathan Friedman

ARMA 13-374

a comparison of Viscous Material Model Mechanics and boundary conditions Paraskevopoulou, C. and Diederichs, S.M. Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, Ontario, Canada

in underground projects time-dependent deformations can occur and subside during the construction process or continue over a long period of time . the nature and impact of time-dependent behavior is related in part to the particular combination of rockmass mechanical properties, in-situ stresses and local boundary conditions (for a particular element of rock) . considered simply, this behavior can occur either under sustained loading (constant stresses) and manifests as creep strain or it can occur as a relaxation process under conditions of fixed strain . numerous models are available in commercial software that are combinations of visco-elastic, visco-elasto-plastic and truly visco-plastic models . an additional case of strength degradation (without impact on transient stress or strain) is also possible . the long-term behavior of the excavation damage might be affected by these boundary conditions both in a tunnel or a shaft environment . thus, it is crucial to analyze and further understand the mechanics of the different constitutive viscous models being used and adopted for time-dependent simulations . this paper serves to investigate and illustrate the individual mechanical analogues of these visco-models utilizing both 2d and 3d analysis methods . a sensitivity analysis is presented of a rock specimen that is being subjected under stress-controlled and strain-controlled conditions under both uniaxial and triaxial tests . in addition, a tunnel case analyzed and examined in 2-dimensions in order to understand the various mechanisms of the models in tunneling conditions . drawing on the results, this paper highlights the mechanisms of the viscous models and the implications that may arise from the different space conditions by giving practical guidelines .

ARMA 13-412

effectiveness of advancing horizontal boring for the tunneling in the complex Geological formationKamemura, K.Fukada Geological Institute, Tokyo, Japanokazaki, K. and Ito, Y.Civil Engineering Research Institute for Cold Region, Sapporo, Hokkaido, Japan

despite bad geological condition due to a poor and complex geological formation, many mountain tunnels have been constructed in Japan . generally prior to the tunnel construction, a rock mass is classified based on the result of preinvestigation . then supports and excavation method corresponding to the rock class are decided . however, there are many cases where an additional reinforcement of supports and a change of excavation method are necessary because of unexpected rock condition . in the worst case, it is necessary to re-excavate . a large amount of extra cost is needed as a result . in order to avoid this situation, it is very important to evaluate accurately the information about geological condition and tunnel behavior which is obtained in the tunnel face . if the detailed geological information is obtained before next excavation of tunnel face, the evaluation of geological condition may become more accurate . in this paper, geological classification results which have been evaluated in 16 tunnels (total length 31km and 661 sections) of hokkaido Japan were examined in detail, and the effect of the advancing boring from tunnel face was examined . as a result, the effectiveness of advancing boring for the rational tunnel construction was shown .


ARMA 13-148

pre-injection Versus post-injection Grouting – a Review of a case from the himalayaPanthi, K.K.Norwegian University of Science and Technology (NTNU), Trondheim, Norway

safety and stability are important issues in underground excavations . making tunnels water tight plays an important role in this respect . in general, most of the rocks are significant barrier against groundwater movement and have very low porosity, with the exception of certain young sedimentary and volcanic rocks . however, existence of discontinuities in the rock mass increases the permeability . the himalaya rock mass are in general deeply weathered, faulted and fractured . this leads to an increase in the rock mass permeability in the region . if the purpose of tunnel excavation is to transport (convey) water, two issues must be addressed during tunnel excavation . the first one is to secure tunnel against instability . the second is to make tunnel water tight so that risk of water loss through unlined tunnels is kept to a minimum during operational life of the project . this paper discusses the use of pre-injection and post-injection grouting in controlling water leakage from a shotcrete lined/unlined headrace tunnel used to convey water for hydropower generation . pre-injection data are evaluated and strength and weaknesses of the pre-injection and post-injection grouting are discussed . the effectiveness of grouting in controlling construction costs and completion time are also briefly highlighted .

ARMA 13- 397

Modification of the Supported longitudinal Displacement profile for tunnel face convergence in Weak Rockoke, J., Vlachopoulos, N. and Diederichs, M.S. GeoEngineering Centre, Queen’s-RMC, Kingston, Ontario, Canada

the employment of convergence-confinement analysis as a preliminary support design aid is an industry standard . the longitudinal displacement profile (ldp), a component of the convergence confinement method [1-4], relates the normalized profile displacement to a normalized location along the tunnel’s axis with respect to the tunnel’s face location . however, current versions of the ldp do not take into consideration the interaction of the support with the other convergence-confinement components (i .e . the ground reaction curve and the support reaction curve) . the authors investigated the support interaction influence on the ldp, and this resulting paper proposes a modification of the calculation of the displacement at the tunnel face to current ldp approaches . this modification is a function of the plastic radius or the final tunnel convergence . furthermore, this modification will lead to a more accurate approximation of the ldp in front of the tunnel face (within the rock mass) . this increase in accuracy will result in a better estimate of the stresses acting on pre-support structural support members .

ARMA 13-532

Ultra-long-term Geomechanics Design for a Deep Geological Repository in Sedimentary Rock Diederichs, M. GeoEngineering Centre, Queen’s University, Kingston, Canada Damjanac, B. Itasca Consulting Group, Minneapolis, USA Jensen, M. and Lam, T. Nuclear Waste Management Organization, Toronto, Canada Derek Martin University of Alberta, Edmonton, Canada


Dougal McCreath Laurentian University, Sudbury, Canada

a deep geologic repository (dgr) for the long-term management of low and intermediate level radioactive waste, generated by ontario power generation (opg), is currently in the licensing phase . the repository itself is to be located with the argillaceous cobourg limestone formation at a depth of approximately 680m beneath the bruce nuclear site in the municipality of kincardine, ontario . the limestones are overlain by 200m of massive and undisturbed ordovidian shale . above these shales are numerous other formations which host regional aquifers . this paper summarizes the work done to assess the long-term geomechanical behavior of the repository and the shafts after the 100 year operational life of the facility . the primary concern regarding long-term performance of the unbackfilled emplacement rooms is their degradation over time subjecting to different loading conditions including time-dependent strength degradation, seismicity, gas generation within the repository and multiple glacial loading/unloading cycles . this paper describes a series of analyses performed to explore rock mass stability and geological barrier integrity .

ARMA 13-352

tunnel Stress analyses in 3-D using equivalent continuum and Discontinuum procedures Kulatilake, P.h.S.W. and Wu, Q. University of Arizona, Tucson, Arizona, USA

deformation and stability around a tunnel in a limestone rock mass is investigated using both (a) an equivalent continuum/discontinuum model and (b) a fully discontinuum model through three-dimensional stress analyses . in model (a), the representative elementary volume (rev) mechanical properties estimated in a previous paper are used to represent the combined behavior of intact rock and 4 of the 5 fracture sets that had significantly smaller sizes compared to the fifth fracture set (bedding planes) . to this system, the bedding plane fractures were added according to its statistical geometric properties . in model (b), all 5 fracture sets were generated according to the obtained fracture geometry statistical models . using model (a), effect of several factors, such as rev property values, bedding plane modeling method, the average horizontal stress to the vertical stress and tunnel depth, on the geotechnical behavior around the tunnel was studied in detail . a comparison is made between the stress analyses results obtained through the aforementioned two models .

SeSSiOn 39: high perfOrmanCe COmputing: the Challenge Of harneSSing hpC fOr rOCk meChaniCSWednesday, 26 June, 11:00 am – 12:30 pmChairs: Scott Johnson, Stuart Walsh, Tarabay Antoun

ARMA 13-584

Multi-Scale fracture creation and network Generation during hydraulic fracturingJohnson, S. and Settgast, R.Lawrence Livermore National Laboratory, Livermore, California, USAArson, C.Georgia Institute of Technology, Atlanta, Georgia, USA

here we describe both a sequential, hierarchical multi-scale approach for designing scale-dependent constitutive models at different levels of refinement in the problem as well as an open-source, massively


parallel software platform (geos) used for implementing the approach . general cross-scale coupling is achieved through a variety of terms, which are tailored to the specific physical mechanisms involved . the focus in this paper is on the specific state of fracture and damage propagation under fluid forcing, including seismic source generation, directionality and criteria for nucleation and growth, especially in the presence of multi-scale discontinuities . to address computational complexity issues, we discuss strategies for handling under-resolution at the crack tip and the design of phenomenological models based on finer scale considerations in two dimensions . We also discuss progress on approaching the three dimensional case as well as preliminary results of simulations to predict the evolution of microseismicity resultant from progressive damage under changing subsurface stress and hydrological conditions .

ARMA 13-475

a Mortar Method based on nURbS for curved 3-D interfacesFlorez, horacio A.ConocoPhillips, Houston, Texas, USA

in order to tackle general non-conforming sub-domains problems in geomechanics, a mortar finite element method (mfem) on curve 3-d interfaces represented by non-uniform rational b-splines (nurbs) surfaces is presented in this paper, which extends the approach already published in arma paper 12-313 [1] to three-dimensional problems . the goal is providing a robust geometrical representation for mortar spaces that allows gluing non-conforming interfaces on realistic geometries . the resulting mortar saddle-point problem is decoupled by means of standard domain decomposition techniques such as dirichlet- neumann and neumann-neumann, in order to exploit current parallel machine architectures . the mfem becomes very attractive when dealing with large problems, such as those arising in reservoir compaction and subsidence computations, as it avoids propagating tensor-product meshes emanating from the extension of the reservoir towards its surroundings, which reduces the computational burden associated with these simulations . a detailed benchmark between the conforming and mortar or non-conforming solutions, for the same problem, is performed in order to validate the procedure . two examples demonstrate that the proposed mfem can definitively handle field scale problems .

ARMA 13-703

block caving induced instability analysis using fDeMLei, Z., Rougier, E. and Knight, E.E., Geophysics Team, Los Alamos National Laboratory, Los Alamos, NM, USA Munjiza, A. School of Engineering and Material Sciences, University of London, London, UK

World-wide mining operations utilize block caving as one of the most cost-effective techniques for ore extraction . block caving has been addressed in the past by numerous discontinua methods to include discrete element method (dem), discontinuous deformation analysis (dda), combined finite-discrete element method (fdem), etc . however, most of these analyses were either limited to 2d or to elastic material representation . in this paper a representative 3d block caving problem is simulated using fdem . los alamos national laboratory’s geophysics team conducted the modeling utilizing their in-house fdem code, munrou . munrou is a fully parallel, 2d/3d fdem code which utilizes material models that account for a number of plasticity effects, as well as has the capability to model explosive effects, irregular shapes and fracture initiation and propagation . previously problems of this nature and size were un-tractable in 3d . however, the recent performance improvements seen in munrou through the implementation of state of the art parallelization algorithms (see computational mechanics of discontinua, Wiley 2011), have prompted our team to begin intensive efforts to address real world problems, such as block caving . the code’s inherent capability to address fracture and fragmentation


processes at laboratory scale level has been consistently proven in the past . in this paper the feasibility of extending munrou to large space scales in 3d is demonstrated . With this improved capability it is now expected that future analyses efforts can concentrate on 3d phenomenological considerations such as jointing, frictional fault behavior, etc .

ARMA 13-717

efficient Solution of large-Scale Displacement Discontinuity problems using the fast Multipole MethodVerde, A. and Ghassemi, A.Mewbourne School of Petroleum & Geological Engineering, The University of Oklahoma, Norman, OK, USA

the displacement discontinuity method (ddm) is frequently used in geothermal and oil industry applications for modeling the behavior of fractures embedded in linear-elastic rocks . the dd method requires O(N2) memory and O(N3) floating point operations (where N is the number of degrees of freedom) to construct the coefficient matrix and solve the linear system of equations by direct methods . therefore, the conventional implementation of ddm is not computational efficient for very large systems of cracks, often limiting its application to small-scale problems . this work presents an approach for solving large-scale fracture problems using the fast multipole method (fmm) . the approach uses both the ddm and a kernel-independent version of the fmm along with a preconditioned generalized minimal residual algorithm (gmres) to accelerate the solution of linear systems of equations using desktop computers . using the fundamental solutions for constant displacement discontinuity in an elastic medium, several case studies involving fracture networks representing naturally fractured reservoirs are treated . results show a good agreement with analytical solutions and demonstrated the efficiency and accuracy of the fmm implementation of the dd for large-scale situations .

ARMA 13-226

analyzing the effect of large pressure changes on the operational Stability of large-Diameter caverns for the Strategic petroleum Reserve Sobolik, S.R. Sandia National Laboratories, Albuquerque, New Mexico, USA

this paper presents a case study of how large-scale computational analyses may be used in conjunction with site data to make recommendations for safe depressurization and repressurization of oil storage caverns in domal salt with unusual geometries and close proximity . these recommendations were developed in response to a wellbore casing failure, and further utilized to assess ongoing cavern storage operations . two caverns at West hackberry present such concerns due to their unusual shapes and close proximity to each other . cavern 6 at West hackberry has an unusual dish-like shape with a large rim around the circumference . the diameter of cavern 6 at the ceiling ranges from 340 to 380 meters . because of the shape of the cavern and the creep behavior of salt, cavern 6 is prone to wellbore casing failures caused by tensile strains . in addition, cavern 6 has a greater potential for tensile cracking of salt at the perimeter of the cavern during a period of increasing pressure, such as at the end of a workover procedure . cavern 6 is in close proximity to cavern 9, which is hourglass-shaped . the analyses presented here were used to develop guidance for general pressurization procedures for the operation of these two caverns .


ARMA 13-363

cfD-DeM Simulation for Grout injection test using parallel plate fracture Koyama, T. and Sakakibara, S. Department of Urban Management, Kyoto University, Kyoto, Japan Shimizu, h. Institute of Fluid Science, Tohoku University, Sendai, Miyagi, Japan

grouting is a widely used method to seal and/or reduce hydraulic conductivity of fractured rock masses around underground structures . recently, the efficient and effective grouting has been required from environmental and economical points of view . however, injection parameters such as injection pressure and water/cement ratio (W/c) are usually determined empirically by technical experts, because the filtration and penetration mechanism of cement-based grout have not been clarified sufficiently yet due to complicated physical and chemical processes of grout . in this paper, to better understand the penetration and filtration mechanism of cement-based grout through rock fractures, the two-dimensional numerical model of coupled computational fluid dynamics and the distinct element method (cfd-dem) was developed . the interaction between fluid and particles was evaluated by using immersed boundary (ib) method . the simulation results were compared with the laboratory injection test so-called “short slot” experiment to verify the applicability of the newly developed cfd-dem code . the simulation results agree qualitatively well with experiments and the filtration and clogging process during cement-based grout injection was successfully reproduced by the cfd-dem . moreover, the effect of the injection pressure, W/c and particle size distribution on the filtration and penetration mechanism of grout was significant .

SeSSiOn 40: fraCture StatiStiCS anD rOCk maSS meaSureSWednesday, 26 June, 11:00 am – 12:30 pmChairs: Paul La Pointe, Cortney Palleske

ARMA 13-501

impacts of limited Data collection Windows on accurate Rockmass Simulation using Discrete fracture networks Palleske, C.K., hutchinson, D.J. and Diederichs, M.S. Queen’s University, Kingston, Ontario, Canada Elmo, D. University of British Columbia, Vancouver, B.C., Canada

this paper examines the effect of a limited data set on model generation, focusing on truncated mapping windows . the influence of limited sampling of persistence data in particular is examined to quantify typical discrete fracture network input parameters . the resulting data sets from the truncated windows are then compared and used in model generation to quantify the impact this limited data would have on a larger scale project . the effects that limitations of common data collection techniques have on the reliability of numerical model of discrete fractures are discussed . suggestions are given with respect to future work that might be required to allow a better understanding of data limitations and generation of more accurate and realistic representations of synthetic fracture networks .


ARMA 13- 189

Semi-analytical procedure for considering Roughness effect on hydraulic properties of Standard JRc profiles Mahdi Zoorabadi, Serkan Saydam, Wendy Timms and Bruce hebblewhite School of Mining Engineering, The University of New South Wales, Sydney, Australia

in most practical applications, water flow within the rock joints (rough surfaces) is simulated as laminar flow through two smooth parallel plates and cubic law is used for estimating flow rate . in this simulation, a constant opening is assumed between upper and lower parallel surfaces (hydraulic aperture) that will allow passing of the same volume of water flow through real joints . roughness on rock joints produces variable aperture across the joints and increases the flow path length . these facts affect water flow within rock joints . therefore, the validity of cubic law is in dispute and depends on accuracy of the hydraulic aperture estimation . in this study, the concept of local true aperture and tortuosity is applied to assumed joints where surfaces are matched to each other and correspond with standard Joint roughness coefficient (JRC) profiles . the local true aperture through the joint profile is computed for each JRC profile . a new equation is introduced between mechanical and hydraulic aperture for different JRC values .

ARMA 13- 381

Spatial Modeling of Discontinuity intensity – challenges and considerationsCepuritis, P.M. and Villaescusa, E.Western Australian School of Mines, Curtin University, Kalgoorlie, WA, Australia

it is generally understood that discontinuity intensity can control a number of rock mass characteristics, such as rock mass strength and rock mass modulus, and influence rock mass response and behavior . three-dimensional modeling can provide useful insights into the spatial variability of rock properties, however, there still are a number of aspects that hinders its full andcomprehensive inclusion into rock mechanics applications . in contrast to traditional spatial modeling, where parameters are typified by scalar values (e .g . grade, density, etc .), one-dimensional discontinuity linear intensity parameters are vector variables and are unique to the borehole’s orientation . the validity of spatial modeling of one-dimensional discontinuity linear intensity is therefore dependent on both the sampling direction and the degree of rock mass anisotropy . this paper describes some of the difficulties and considerations in the spatial modeling of discontinuity intensity from one-dimensional data . the paper also presents a threedimensional test method to spatially quantify the degree of rock mass anisotropy . the method also allows practitioners to identify regions of the rock mass that have been isotropically sampled by drilling and where the spatial modeling of discontinuity intensity may be confidently applied .

ARMA 13-465

estimation of hoek-brown parameter Mi using brazilian tensile test Richards, L.R. Rock Engineering Consultant, Akaroa, New Zealand Read, S.A.L GNS Science, Lower Hutt, New Zealand

the intact rock constant, mi, is one of the three basic input parameters required for the widely used hoek-brown failure criterion . an earlier paper by the authors (arma 2011) analysed existing databases on rock material properties (sheorey, douglas and rocscience) and demonstrated a very poor correlation between lithology and mi values . a feature of the databases was a lack of results with tensile strength determinations


by both direct and indirect methods . in this paper we firstly investigate the relationship between indirect and direct tensile strengths based on a literature search, finding that the direct tensile strength is less than that of the indirect tensile strength . secondly we examine the relationship between r (the ratio of uniaxial to tensile strength) and mi using the rock material databases and our own testing results . these investigations show that, in the absence of a full suite of laboratory testing, r provides a better estimate of mi than guideline charts . further work is required to confirm the relationship between direct and indirect tensile strengths and the appropriate tensile strength to use in the calculation of r and mi .

ARMA 13-322

Spatial Distribution of young’s Modulus, poisson’s Ratio and eDZ around tbM and D&b tunnels in hard crystalline RockSiren, T.Posiva Oy, Eurajoki, Finland

in order to test a new overcoring based lvdt-cell stress measurement technique measurements, testing campaigns were conducted in known stress conditions in ÄspÖ hard rock laboratory in sweden between 2010 and 2012 . overcoring based methods require a detailed knowledge on rock deformation properties . in order to define the elastic young’s modulus and poisson’s ratio, the pilot cores are biaxially tested in a biaxial chamber . a total of 26 pilot cores from tbm and d&b tunnels were tested both near the excavation surface and deeper from the rock mass . only in d&b tunnel an excavation damage zone near the excavation surface was expected but the results raised a question of edZ also in the tbm tunnel . the spatial distribution of young’s modulus around the tbm tunnel perimeter indicated that there could be an edZ type of behavior in the roof of tbm tunnel . the results indicated a lower young’s modulus in the roof compared to the wall measurements . a new conceptual model of a relationship between young’s modulus and tangential stress is presented in this paper to explain the observations .

ARMA 13-485

the importance of Specifying Rockmass failure Mechanisms in Geotechnical baseline Reportsvan der Pouw Kraan, M.C., hutchinson, D.J. and Diederichs, M.S.Queen’s University, Kingston, Ontario, Canada

in recent examples of early reference designs, the rock mass quality along a tunnel alignment is specified in a geotechnical baseline report (gbr) using a rock mass classification system (such as the Q system) and intact rock laboratory results . designing a tunnel and rock support based on these two items is limited in scope, as it does not consider the specific rockmass failure mechanisms . to determine the importance of including the failure mechanism and specific structural or stress controls during design, the impact of five different behavioral models with identical rockmass classification parameters on a standardized tunnel and rock support design were assessed . the standardized design was inadequate for the majority of the behavioral models . in design-build projects, the failure mechanism and the structural controls on failure (ground behavior) should be specified in a gbr in addition to the rock characteristics or rock quality, as a proper design can mitigate the failure mechanism and magnitude .


SeSSiOn 41: unCOnventiOnalS iiWednesday, 26 June, 12:30 pm – 2:00 pmChairs: Azra Tutuncu, Don Lee

ARMA 13-716

an initial assessment of the impact of Varying perf cluster Design on hydraulic fracture effectivenessElmo, D. Golder Associates Ltd, Burnaby, BC, CanadaInstitute of Mining Engineering, University of British Columbia, Vancouver, CanadaRogers, S. Golder Associates Ltd, Burnaby, BC, CanadaDunphy, R. and Bearinger, D.Nexen Inc, Calgary, Alberta, Canada

there is an increasing search for the optimization of hydraulic fracture development and in particular, the generation of fracture complexity (increased effective fracture surface area) during the stimulations . in trials in the horn river basin, switching to perf clusters proved to provide a clear and positive influence upon initial production, presumed because the multiple fracs interact, resulting in greater complexity, effective surface area and therefore production . to test this assertion, the growth of hydraulic fractures for various perf cluster configurations was simulated using am hybrid fdem geomechanical modelling approach . a key observation from these initial simulations has been the apparent limited impact of increasing the number of perf clusters within a single stage on the overall stimulated reservoir volume (srv) . however adding more fracs does increase fracture complexity and also shows enhanced matrix damage relative to simpler perf configurations . this enhanced damage zone appears to be primarily developed in the nearer wellbore area as a result of the suppressed hydraulic fracture lengths, an observation borne out by micro-seismic observations . the current work suggests that more effort should be placed into defining the effective stimulated surface area of a fracturing job, rather than simply measuring the srv .

ARMA 13-173

Simulating Geomechanical evolution of fractured Shale Reservoir using a poro-Viscoelastic constitutive Model Jian huang & Ahmad Ghassemi Mewbourne School of Petroleum & Geological Engineering, The University of Oklahoma Norman, USA

in most reservoir simulators for gas shale, only the elastic deformation of reservoir rock and fractures is modeled . however, many experimental studies and field investigation indicated that shale experience viscoelastic deformation . in this work, a numerical model is constructed by implementing a poro-viscoelastic model into a dual permeability (dpm)-finite element model (fem) to investigate the coupled time-dependent viscoelastic deformation, fracture network evolution and compressible fluid flow in gas shale . the viscoelastic effect is addressed in both deviatoric and mean effective stresses to emphasize the effect of shear strain localization . in the strain damage model, shear viscosity is set to be proportional to the second invariant of the strain-rate for viscous rheology . the mechanical model is first verified with an analytical solution in a simple consolidation problem and then compared with the poroelastic solution under the same conditions . comparing the case of poroelasticity and poroviscoelasticity show that the pore pressure difference throughout the domain is small; however, the stress evolution is quite divergent, especially for the area close to the loading boundary . this numerical model is applied to different data cases to understand the long term viscoelastic effects on the gas production in gas shale . the numerical results indicate that the mechanical response of the fracture is very sensitive to the creep behavior of the reservoir rock .


ARMA 13-604

characterization of anisotropic Dynamic Mechanical Rock properties in Shale Gas plays hows, A.M., hofmann, R. and Gonzalez, E.F. Shell International Exploration and Production, Houston, TX, USA

organic- and clay-rich shale gas reservoir rocks typically have anisotropic mechanical rock properties that can be modeled as transversely isotropic with a vertical symmetry axis . understanding the mechanical rock properties and in situ stress models based on these properties is essential for predicting the initiation, propagation and long-term conductivity preservation of hydraulic fractures . since determining mechanical rock properties from well logs relies on sonic data, it is necessary to develop a robust method for measuring and modeling acoustic anisotropy . We demonstrate how to use a single pad, multi-well, multi-azimuth sonic dataset to develop an empirical, play-specific model for vti acoustic anisotropy parameters . this data driven methodology then allows for modeling vti acoustic anisotropy in subsequent vertical pilot wells .

ARMA 13-626

analysis of intra-Reservoir Stress Variations in Shale Gas Reservoirs based on the Variation of Viscoelastic propertiesSone, h. GFZ German Research Centre for Geosciences, Potsdam, Germany Zoback, M.D. Stanford University, Stanford, CA, USA

We studied the time-dependent deformation of various shale gas reservoir rocks through laboratory triaxial creep experiments . upon stepwise loading of axial differential stress, samples exhibit instantaneous elastic deformation followed by time-dependent creep behavior . the total elastic and creep strain response is approximately linear against the applied differential stress which evokes a linear viscoelastic behavior against differential stress . We find that the total strain response can be expressed by a power-law creep compliance function, ε=btn, where b and n are characteristic constitutive parameters . b and n range between 0 .015-0 .06 [gpa-1] and 0 .01-0 .08, respectively, thus viscoelastic behavior of these rocks vary significantly between and within reservoirs . using linear viscoelasticity, we attempt to obtain a profile of horizontal stress difference along a vertical well from barnett shale assuming a simple tectonic loading history . the profile of b along the well was estimated from sonic logs and the profile of n was estimated from an empirical relationship between b and n we observed from barnett shale samples . results suggest that the horizontal stress difference along the well can vary by up to 10 mpa within the shale reservoir, consistent with fluctuations in stress difference inferred from observations of wellbore failures in the same well .

ARMA 13-349

permeability Model of Shale Gas Rock With Variable Solid Mass Geilikman, M.B., Karanikas, J.M. and Wong, Sau-Wai Shell International Exploration and Production Inc., Houston, TX, USA

the stress and pore pressure dependence of permeability of shale gas rock is considered for the case of two-solid constituents porous medium . it is done for a generalized model of composite sphere phases each of them being gas/fluid saturated . it is shown that the total mean stress in each of the phases is different from the confining stress even for homogeneous state . this leads to a more complicated dependence of permeability rather than that of exclusively effective (terzaghi) stress, i .e . confining stress minus pore pressure as in the case of one-solid constituent porous medium . additional dependence of permeability on pore pressure is captured by taking


into account knudsen and slip flow contributions . another cause of pore pressure dependence of permeability arises due to the fact that variation of pore pressure even at the same effective (terzaghi) stress is able to shift thermodynamic equilibrium between methane gas state and its solid adsorbed state . because depletion-induced variation of pore pressure leads to variation of eigen-strain, the resultant strain and stress exerted at the reservoir by surrounding country rock is found by using eshelby inclusion model . the depletion-induced evolution of reservoir permeability is expressed as a function of pore pressure .

ARMA 11-557

Microseismicity and Surface Deformation of a heavy oil Reservoir Undergoing cyclic Steam StimulationWalters, R.J., and Zoback, M.D.Stanford University, Stanford, CA, USA

understanding how a heavy oil reservoir undergoing cyclic steam stimulation responds to stress perturbations through microseismic events and surface deformation may lead to enhanced casing integrity and improved reservoir productivity . this project is unique because the data was acquired beginning with the first instance of steam injection, which resulted in the initial stress perturbation to the untouched reservoir . for the first cycle of steam injection, we have tilt data, in addition to microseismic data for the first and second cycles . this study includes a spatial and temporal analysis of the microseismic events and surface deformation that occurred as a result of steam injection into the reservoir . We have seen many microseismic events occur within the high viscosity oil reservoir interval and that the surface region above the reservoir experiences measurable deformation or ‘heave .’ in the future, we plan to explore the mechanisms that might cause the surface deformation we observe, including the reactivation of shallow faults, brittle failure of more rigid “stringers” within the reservoir, the partial translation of movement through slip planes, or some combination of factors . as a first step, we have modeled the steam injection into the reservoir as an inflation of a cylindrical reservoir .

SeSSiOn 42: eXperimental rOCk meChaniCS iii – nOvel rOCkS anD teSting methODSWednesday, 26 June, 12:30 pm – 2:00 pmChairs: Lance Roberts, Russ Ewy

ARMA 13-251

Discontinuum modelling of vuggy carbonate specimens: impact of vugs on strength and stiffness ornés, A.I., Deisman, N.L. and Chalaturnyk, R.J. University of Alberta, Edmonton, Alberta, Canada

the prediction of geomechanical properties for carbonate rocks has become a topic of increasing interest due to existing unconventional hydrocarbon resources in carbonate reservoirs . however the heterogeneity of carbonates presents a challenge in providing accurate estimates applicable to the wide variety of textures and porosities . an example of such heterogeneity is found in the grosmont formation in alberta, canada, which has an estimated 64 .5 billion m3 of in-place bitumen resources . vuggy dolostone lithofacies present some of the most promising areas for bitumen extraction in the grosmont reservoir; thus knowledge on the geomechanical behaviour of this material is relevant for future developments . an approach used for evaluation of geomechanical properties uses pfc3d, a discontinuum modelling software, to evaluate the effect of vug volume and shape on the uniaxial compressive strength (ucs) of carbonate rocks . the


impact of the vugs on the stiffness of the material is also evaluated . the results are then compared with empirical correlations found in literature, which have been previously used to predict the ucs and stiffness of carbonate reservoirs . this study hopes to progress the methods for understanding the geomechanical behavior on heterogeneous carbonate reservoirs, for use in wellbore stability problems and changes due to production activities .

ARMA 13-534

impact of acidizing-induced Wormholes in chalk on Rock StrengthBauer, A., Walle, L.E., Stenebråten, J. and Papamichos, E.SINTEF Petroleum Research, Trondheim, Norway

one way to stimulate oil production from chalk reservoirs is to inject acid into the formation which results in the formation of wormholes that act as flow channels . the aim of this study was to investigate the mechanical stability of wormholes in chalk and the impact of the acidizing process on the rock strength . to this end, we have performed compaction tests with oil and brine-saturated mons outcrop chalk containing wormholes produced by core flooding with hcl acid . acidizing was stopped after acid breakthrough, and the wormholes were imaged by ct scanning prior to the compaction tests . hydrostatic compaction tests reveal wormhole collapse a few mpa below the onset of pore collapse, with the pore-collapse pressure being significantly larger for oil-saturated samples as compared to brine-saturated samples . comparison with hydrostatic compaction measurements carried out with intact core plugs also indicates a reduction of pore-collapse pressure .

ARMA 13-393

Mechanical evolution of an altered limestone using 2D and 3D Digital image correlation (Dic)Zinsmeister, L. and Dautriat, J.IFP Energies nouvelles, Rueil Malmaison, FranceDimanov, A. and Raphanel, J.Ecole Polytechnique, Palaiseau, FranceBornert, M.Ecole des Ponts ParisTech, Champs sur Marne, France

in the context of long term co2 sequestration, we present an original laboratory workflow which allows a multi scale analysis of the effect of chemical alteration on both petrophysical and mechanical properties of a carbonate . the relationship between the mechanical behavior and the micro-structural evolutions is investigated using digital image correlation methods . for this purpose we imaged intact and altered samples during uniaxial and triaxial mechanical tests using optical microscopy, scanning electron microscopy (sem) and 3d x-ray micro-tomography . the porosity increase induced by homogeneous alteration leads to lower elastic moduli and critical stress at sample failure . furthermore, at similar confining pressures we observed a transition from brittle to ductile failure mechanisms with the alteration level . these observations are verified by digital image correlation . altered samples indicate early strain localization which was not observed in the intact ones . these early localization events induce more compaction at the macroscopic scale and tend to initiate early fracturing .


ARMA 13-701

Split hopkinson pressure bar experiment Simulation using MUnRoU Knight, E.E., Rougier, E. and Sussman, A.J. Geophysics Team, Los Alamos National Laboratory, Los Alamos, NM, USA Broome, S.T. Geomechanics Team, Sandia National Laboratory, Albuquerque, NM, USA Munjiza, A. School of Engineering and Material Sciences, University of London, London, UK

the next generation of 3d combined finite-discrete element method (fdem) capabilities has been developed at los alamos national laboratory (lanl) . these include state of the art contact detection, contact interaction, lanl’s constitutive material, and fracture models all combined in a grand scale parallel computing framework called munrou . in this paper a full scale 3d analysis of a split hopkinson pressure bar (shpb) experiment on granite material is modeled using the fdem method, and compared to the experiments performed at sandia national laboratory .

ARMA 13-186

a Modified failure criterion with Scale effect parameterMasoumi, h., hagan, P. and Saydam, S. School of Mining Engineering, University of New South Wales, Sydney, NSW, Australia

the design of structures on or within a rock mass requires an estimate of the strength of the intact rock blocks within the mass . these blocks of rock can be many orders of magnitude greater in scale than the core samples typically tested . including the scale effects into a failure criterion is important for better estimation of the rock strength . in this paper a modified failure criterion with scale effect parameter was developed based on the model proposed by christensen [1] . the modification process was conducted based on the scale effect equations proposed for ucs and point load results and it was shown that for one particular sandstone the strength parameter of the modified failure criterion is scale independent .

ARMA 13-391

continuous core thermal properties Measurements and analysisPopov, Y., Parshin, A., Chekhonin, E., Popov, E. and Miklashevskiy D.Schlumberger Research Center, Moscow, RussiaSuarez-Rivera, R. and Green, S.Schlumberger Innovation Center, Salt Lake City, Utah, USA

a new technique has been developed for non-contact, optical scanning, of rock cores to provide simultaneous, continuous, high resolution, and precision measurements for evaluation of thermal conductivity, thermal diffusivity, and volumetric heat capacity . the technique is rapid and does not damage the core . new and valuable information from the continuous thermal scanning are the direct measurement of thermal heterogeneity and thermal anisotropy . the measured thermal heterogeneity reflects variations in rock fabric and composition (mineral, organic content and pore fluids) that also drive the variability of other rock properties (e .g ., porosity, permeability, cementing, particle contact, saturation, etc) . measurements of continuous thermal properties and thermal heterogeneity provide a direct indication about scale dependence, and the variability in thermal properties from the millimeter scale to the length of the core (hundreds of meters or feet) . the measurements help also identifying thermal behavior of rock classes defined at the core and log scale . the application of this new technique contributes to rapid reservoir thermal characterization and subsequent modeling . it provides a workflow for evaluating reservoir thermal conditions, thermal losses, mass transfer in the reservoir, and the overall efficiency of recovery methods .


SeSSiOn 43: unCertainty QuantifiCatiOn anD parameter eStimatiOn in geOmeChaniCSWednesday, 26 June, 12:30 pm – 2:00 pmChair: Souheil Ezzedine

ARMA 13-291

parameter estimation for the coupled biot-lame-navier problem in Subsurface ModelingWick, Thomas, Elsheikh, Ahmed h. and Wheeler, Mary F.Center for Subsurface Modeling, The Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas, USA

We present a parameter estimation method for a quasi-stationary multiphysics problem in subsurface modeling . specifically, the modeling part for the state equation is based on the coupled biot-lame-navier system in order to describe the interaction between some pay-zone and a non-overlapping non-pay regime . the coupled system for the state is formulated within a variational monolithically-coupled framework . We propose an iterative stochastic ensemble method (isem) to estimate material coefficients such as permeability coefficients in the pay-zone or lame parameters in the non-pay zone . isem is based on stochastic estimation of gradients using an ensemble of directional derivatives within a gauss-newton iteration . the resulting update equation resembles the update step in ensemble kalman filter . however, the inverse of the output covariance matrix in the update equation is regularized using standard truncated singular value decomposition . the proposed algorithm treats the forward simulator as a blackbox and avoids explicit derivation of the adjoint equations, which is major task for nonstationary systems . our forward formulation and parameter estimation method are validated by some numerical tests including an extension of mandel’s problem .

ARMA 13-459

evaluating uncertainty in intact and rockmass parameters for the purposes of reliability assessment Langford, J. Connor and Diederichs, Mark S. Queen’s University, Kingston, Ontario, Canada

uncertainty plays a critical role in geotechnical design projects . in addition to the natural variability of geomaterials, knowledge based uncertainty involving testing, transformation and modeling errors must also be considered to develop an accurate geomechanical model . While such sources of uncertainty can be dealt with subjectively through the use of conservative parameters, this typically leads to overdesign and unnecessary support costs . conversely, by directly incorporating material variability into the design process through the use of reliability based design methods, a greater understanding of system performance can be obtained . this includes greater knowledge about the range of possible failure mechanisms and the variability in rockmass strength . this paper discusses challenges associated with evaluating uncertainty in intact and rockmass parameters for hoek-brown materials . reliability methods are also discussed and a new reliability based design approach is presented . an example of a circular excavation in a silty sandstone under hydrostatic loading conditions is then used to illustrate this process .


ARMA 13-462

Seepage characterization in high Rock Slopes using Remote SensingVivas, J., Stead, D. and Wolter, A.Simon Fraser University, Burnaby, BC, CanadaTuckey, Z.Coffey Mining, Melbourne, AustraliaElmo, D.University of British Columbia, BC, CanadaD’Ambra, S.Golder Associates Ltd., Burnaby, BC, Canada

this paper outlines a preliminary methodology for the use of remote sensing in the characterization of seepage zones in major open pit and natural slopes . the application of a range of techniques is discussed focusing on digital photogrammetry, ground based lidar and infrared thermography (irt) . the definition of seepage zones and preliminary hydrogeological domains can be based on a combination of both remote sensing and field based mapping of discontinuity geometry, geological structures and rock mass quality . the application of discrete fracture network engineering principles to rock slope characterization is demonstrated with the combined use of fracture and seepage intensity methods . sources of parameter uncertainty in hydrogeological mapping of rock slope faces are discussed . data from two open pits where ground-based photogrammetry has been used to characterize the influence of rock mass structure on groundwater seepage is presented along with the results of ground-based lidar and infrared thermography on high natural rock slopes .

ARMA 13-550

a comparison of bayesian techniques and non-probabilistic Models in Rock engineering DesignBedi, A.Imperial College, London, United Kingdomharrison, J.P.University of Toronto, Ontario, Canada

in this paper we examine the fundamental errors that may result from adopting a bayesian approach to characterise and propagate uncertainty when undertaking design using empirical rock mass classification schemes . We suggest that these errors are due to the philosophical difficulty in assigning a prior probability when presented with either limited or no objective information, or when the information is inherently imprecise . We show how this may lead to either misinformed decisions or overconfidence in the accuracy of the resulting conclusions drawn from such analyses . the paper commences with a discussion on the need to characterise the type of uncertainty through a quantitative and qualitative review of the available information . We show how this approach allows the section of an appropriate uncertainty model when the data are imprecise and/or sparse . We present example calculations using non-probabilistic models and bayesian techniques, and draw conclusions regarding the appropriate calculation model for particular degrees of uncertainty .


ARMA 13-590

bayesian analysis of earthquake Seismology Models under UncertaintyCruz-Jimenez, h. and Mai, P.M.King Abdullah University of Science and Technology (KAUST), Thuwal , Kingdom of Saudi ArabiaPrudencio, E.E.Institute for Computational Engineering and Sciences (ICES), The University of Texas at Austin, Austin, TX, USA

in this paper we apply a rigorous bayesian methodology to quantitatively assess and compare, under uncertainty, rupture modeling hypotheses for computational earthquake seismology and advanced ground-motion simulations . reliable ground motion predictions, with quantified uncertainty, are critical for designing large civil structures and response plans, thus helping to mitigate human and economical losses during earthquakes . With the advent of hpc and state-of-the-art parallel statistical algorithms, comprehensive uncertainty quantification of the expected shaking levels is now becoming possible . to demonstrate the potential of bayesian methodology for the analysis of earthquake ground-motion simulations, this feasibility study proposes just two “simple” rupture modeling hypotheses, denoted m1 and m2, which treat as random some of the physical parameters describing the fault properties . for each modeling hypothesis, ground-motions are computed at a dense virtual seismic network . such ground motions are compared against a chosen empirical ground-motion prediction equation (gmpe, the reference data 𝑑) . the ranking returns the hypothesis that best reproduces, among the proposed candidates m1 and m2, peak ground velocities with respect to 𝑑 .

ARMA 13-632

Uncertainty Quantification of thMc processes in a Dynamically Stimulated fracture network Ezzedine, S.M. CED, Lawrence Livermore National Laboratory, NSED, Livermore, CA, USA Ryerson, F.J. AEED, Lawrence Livermore National Laboratory, AEED, Livermore, CA, USA

a major issue to overcome when characterizing a deep fractured reservoir is that of data limitation due to accessibility and affordability . moreover, the ability to map discontinuities in the rock with available geological and geophysical tools tends to decrease particularly as the scale of the discontinuity goes down . geological characterization data include, but not limited to, measurements of fracture density, orientation, extent, and aperture . all of which are taken at the field scale through a very sparse limited number of deep boreholes . these types of data are often reduced to probability distribution functions for predictive modeling and simulation in a stochastic discrete framework . stochastic discrete fracture network models enable, through monte carlo realizations and simulations, for probabilistic assessment of flow and transport phenomena that are not adequately captured using continuum models . despite the fundamental uncertainties inherited within the probabilistic reduction of the sparse data collected, very little work has been conducted on quantifying uncertainty on the reduced probabilistic distribution functions . using nested monte carlo simulations, we investigated the impact of parameter uncertainties of the probability distribution functions of fracture network on the flow using topological measures such as fracture connectivity, physical characteristics measure such as effective hydraulic conductivity tensor .


SeSSiOn 44: rOCk maSS Strength anD DefOrmaBilityWednesday, 26 June, 12:30 pm – 2:00 pmChairs: Eunhye Kim, Bill Dershowitz

ARMA 13-175

Strength of intact Rock containing flawsYun Lu, C. Derek Martin and hengxing LanDept. of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada

there are two contributors to rock mass strength: (1) the strength of the intact rock and (2) the strength of the fractures or flaws . the flaws in a rock can occur at several scales: (1) centimetre scale where the micro-defects are healed with infilling that is usually weaker than the intact rock and (2) metre-scale where the fractures generally lack infilling and are classed as open . a number of numerical simulations were used in this study to establish the effect of flaws on uniaxial rock strength . the flaw arrangements varied from (1) a single flaw at various orientations relative to the applied load; (2) uniformly distributed discontinuous flaws, and (3) randomly distributed discontinuous flaws . for uniformly distributed discontinuous flaws the distance of the flaw to the free boundary plays a significant role in the uniaxial strength . and, for randomly distributed discontinuous flaws, the uniaxial strength decreases as the fracture intensity, expressed as p21, increases . there appears to be a threshold fracture intensity where the strength rapidly decreases but this threshold value is non-unique but related to flaw length .

ARMA 13-377

accounting for Rockmass Structure in Underground and open pit Mine Design Day, J.J., Duran, F.I., Diederichs, M.S. and hutchinson, D.J. Geological Sciences and Geological Engineering, Queen’s University, Kingston, Ontario, Canada

the overall strength of a rockmass, as determined by traditional rockmass characterization methods, typically involves an assessment of the intact rock strength and rockmass structure . this paper investigates a variety of approaches to account for the effect of intrablock structure (veins) on rockmass strength . triaxial and direct shear test data were generated numerically for a theoretical andesitic tuff using fem . the triaxial results were applied to a deep underground mine drift design case . direct shear results were compared to an open pit slope case . the approach previously developed by the authors to account for intrablock structure using gsi was compared to a new approach that degrades the intact strength parameters of the material based on ucs and triaxial tests . the gsi and intact parameter approaches were found to be comparable, with only slight differences near zero confining stress . the numerical simulation of direct shear tests showed the importance of veins in the way failure initiates and propagates under that particular loading condition .

ARMA 13-561

Viscoplastic behavior of fine-Grained Geological Units and its applicability to compressed Gas cavernsNopola, J.R. and Roberts, L.A.RESPEC, Rapid City, SD, USA

time-dependent deformation is an important, but often neglected, aspect in evaluating the geomechanical behavior of fine-grained geological units . triaxial compression creep tests were performed on samples of laminated siltstone and shale from the kanawha formation . creep tests were conducted at a temperature


of 25°c and a confining pressure of 20 mpa . specimens were tested at differential stresses of 7, 13, and 18 mpa, and these conditions were maintained for over 30 days while the axial strain of the specimen was monitored . strain-time curves for these specimens indicate time-dependent behavior comparable to halite rocks at similar stress differences . a power law function was used to fit the creep test data . after the creep tests were completed, triaxial compression strength tests were performed on the specimens and a strength criterion was developed for plastic failure . the viscoplastic behavior was incorporated into a numerical model to evaluate the suitability of a mined storage cavern . the numerical modeling indicated that creep will allow redistribution of stress over time . this redistribution of stress results in an increase in factors of safety against plastic failure in areas . the implication is that compressed gas storage caverns in shale may be plausible at depths greater than previously considered .

ARMA 13-601

Damage plasticity Model for Rock MassUnteregger, D. and hofstetter, G.University of Innsbruck, Institute for Basic Sciences in Engineering Science, Innsbruck, Austria

in the field of rock mechanics the finite element method (fem) is frequently used for numerical simulation of various construction processes, e .g . deep tunnel excavations . the fem allows for analyzing complex 3d problems, but obtaining reliable estimates of displacements and stresses for complex 3d rock mechanical problems is a difficult task . Within this task modeling the constitutive behavior of rock mass involved is a key feature . in the present contribution an advanced 3d constitutive model for intact rock, based on a combination of plasticity and damage theory, is proposed . the required material and model parameters are identified using an optimization procedure, based on experimental data . the proposed model for intact rock is validated for different types of intact rock by numerical simulation of laboratory experiments, i .e . triaxial compression tests at various levels of lateral confinement . the intact rock model is found to be capable of capturing key features of the constitutive behavior of intact rock . furthermore, the model is extended for modeling rock mass, based on the geological strength index, and the behavior of the resulting rock mass model is illustrated .

ARMA 13-182

Visual enhancement of 3D images of Rock faces for Rock Mass characterization Lai, P. School of Computer Science, Carleton University, Ottawa, ON, Canada Samson, C. Department of Earth Sciences, Carleton University, Ottawa, ON, Canada Bose, P.School of Computer Science, Carleton University, Ottawa, ON, Canada

this paper investigates how 3 dimensional (3d) laser images of rock faces can be processed to highlight several characteristics of the rock mass in three different geological environments . the first scene features large cubic quartzite rock blocks from a road cut . the second scene shows a layered sedimentary sequence composed of massive limestone and more friable dolostone from a quarry . the third scene exhibits shatter cone structures imprinted in an outcrop in the subdury impact crater, in northern ontario . images are acquired using a triangulation laser camera with a 30° × 30° field of view, mounted on a tripod, at distances ranging from 1 to 3 m . epsilon nets (ε-nets) are used to downsample the point cloud data with little loss to the overall structure that they represent . a 2 .5d triangular irregular mesh (tin) is constructed from the 3d point cloud data using a delaunay triangulation and smoothed using a few iterations of the geometric laplacian . three different processing strategies are tested to enhance the visual perception of fracture orientation and surface roughness: color-coding of strike and dip, curvature analysis and outer normal planar clustering .


ARMA 13-663

Discontinuity Mapping using Ground-based lidar: case Study from an open pit Mine Tiruneh, h.W. and Stetler, L.D. Department of Geology and Geological Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA oberling, Z.A., Morrison, D.R., Connolly, J.L. and Ryan, T.M. Call and Nicholas, Inc., Tucson, AZ, USA

discontinuity data of rock masses are critical for the characterization, design, and analysis of rock fabrics as related to small- and large-scale slope stability . they present the most common challenges in the design of open pit mines as adverse rock fabric orientations may impart instabilities that have the potential to cause losses of life, infrastructure, and decrease in productivity . therefore, accurate and precise characterizations of discontinuities are a crucial step in successfully designing stable slopes . terrestrial lidar scanning coupled with high resolution images can be used for virtual mapping of discontinuities . the benefits of implementing lidar as concerned with discontinuity mapping include ease of operation, improved safety, ability to collect data in inaccessible areas, short data acquisition time relative to manual data collection, and most importantly, pertinent rock mass data may be collected in much greater detail . a case study from an open pit mine was performed to evaluate if correlations exist among discontinuity properties collected using different methods including (1) traditional cell mapping, (2) optical and acoustic borehole imaging (obi and abi, respectively) with sampled core and, (3) high resolution lidar scanning . the advantages and disadvantages of these techniques are discussed and recommendations based on the results are presented in this study . abell, b .c . - 54


abousleiman, y .n . - 89abu el-ela, a .a . - 176adachi, J . - 178adachi, Jose - 49admassu, y . - 58ahmed, m . farooq - 86ahsan, r . - 78akbari, b . - 160akgun, a . - 57akl, s .a . - 39alam, a .k .m . b . - 67alpern, J .s . - 111alqahtani, adel a . - 102alramahi, b . - 39amann, f . - 40ameli, p . - 55amundson, a .l . - 125an, k . - 92anovitz, l . - 92antoun, t .h . - 178araya, m . - 108argüello, J . guadalupe - 94argüello, J .g . - 94arson, c . - 67, 70, 149, 183avila, J .l . - 61aydan, Ö . - 48, 155aydin, a . - 99ayers, William J . - 135bahrani, n . - 175bai, m . - 80bajpayee, t .s . - 125bakhtiary, e . - 70bakk, a . - 84ballantyne, s . - 114bares, paul - 72baroni, a . - 107bauer, a . - 84, 158, 192bautmans, p . - 123bearinger, d . - 189bedi, a . - 195benson, steve - 82benson, steven a . - 145bingham, p . - 92birch, k . - 143birkholzer, J .t . - 66blair, neil - 147blaisonneau, a . - 133blanco martín, l . - 66

blöcher, g . - 91bobet, a . - 106, 130boomsma, e .b . - 56boonnumma, a . - 42borgos, h . - 148bornert, m . - 192bose, p . - 198bourcier, W . - 118bourdin, b . - 178bowders, J .J . - 176brannon, r .b . - 117brenna, a . - 60brezovski, r . - 101bromhal, g . - 72broome, s .t . - 193brown, l . Jamie - 135brückner, d . - 120bubach, bailey - 82buchanan, m . - 103buchmann, t . - 178bui, binh - 146bunger, a . - 105burghardt, J . - 100buscarnera, g . - 64busetti, s . - 149caceres, c . - 114cai, m . - 150callahan, g .d . - 95cao, J .t . - 140cappa, f . - 45, 70, 164carlsson, anders - 154carmichael, J . - 92carrera, J . - 66carroll, s .a . - 55carter, t .g . - 42, 132carvalho, J .l . - 143catalan, a . - 172cavender, t .W . - 113cepuritis, p .m . - 187cerasi, p . - 83chalaturnyk, r .J . - 160, 191chan, a .W . - 123chang, chandong - 51changani, hossein - 157chaparro, c . - 58, 115, 170chekhonin, e . - 193chen, b .k . - 134chen, f .f . - 151

authOr inDeX


chen, guangqi - 177chen, Zhaowei - 141chen, Zhongwei - 143chenevert, martin e . - 76cheng, m .h . - 149cheng, yi - 98cheon, d .s . - 88chertov, m . - 116chiaramonte, l . - 44choi, b .h . - 150choi, m .k . - 106chok, hamed - 147chou, Queena - 147christensen, h .f . - 50christiansson, r . - 132christiansson, r . - 154, 167chukwudozie, c . - 178chuprakov, d . - 111cladouhos, trenton t . - 163clayton, m .a . - 47clennell, m .b . - 105collins, daniel - 71colovos, J .W . - 117connolly, J .l . - 199connolly, p . - 111, 178constable, k .c . - 123corkum, a .g . - 103cornet, f .h . - 92cosma, c . - 69couzens-schultz, b .a . - 123crandall, d . - 72crawford, b . - 39crook, a .J .l - 179cruz-Jimenez, h . - 196cui, a . - 101cui, f . - 140cundall, p .a . - 173curtis, mark - 102damani, a . - 129d’ambra, s . - 195damjanac, b . - 164, 173, 182danjo, t . - 65darcis, m . - 160dautriat, J . - 192davatzes, n . - 93davids, andrew - 49day, J .J . - 197de mello franco, J .a . - 86dedontney, n . - 39dee, s .J . - 122deen, J . - 104dehn, k .k . - 41

deisman, n .l . - 191delle piane, c . - 105dempsey, d . - 93deng, h . - 72derode, b . - 164dessieux, l . - 92detwiler, r .l . - 55dewhurst, d .n . - 105diederichs, m .s . - 68, 98, 132, 152, 181, 182, 186, 188, 194, 197dight, p . - 156dimanov, a . - 192dobbs, m .r . - 99dobson, p .f . - 163dokhani, v . - 124dontha, l . - 96donzé, f .v . - 47dorion, Jean-françois - 41du, W . - 150dunphy, r . - 189dupray, fabrice - 96duran, f .i . - 197dusseault, maurice b . - 52, 81, 144düsterloh, u . - 94, 154duzgun, s .h .b . - 57dyskin, a .v . - 156eckert, a . - 80edelman, e . - 100, 129elkhoury, J .e . - 55ellenberger, J .l . - 125elmo, d . - 120, 172, 177, 186, 189, 195elsheikh, ahmed h . - 194elsworth, derek - 65, 90, 111, 143emam, s . - 175enescu, n . - 69esteban, l . - 105esterhuizen, g .s . - 62, 125ezzedine, s .m . - 73, 118, 178, 196fakhimi, a . - 119fallahzadeh, s .h . - 169fan, yanan - 177fauquier, m . - 178favero, v . - 74, 97feng, x .t . - 45, 156ferrari, a . - 74, 97ferster, m . - 104figgs, m . - 176fischer, k . - 180fitts, J .p . - 72fjær, e . - 38, 84, 158, 169flack, b . - 178flemings, p .b . - 59


florez, horacio a . - 174, 184florez-guzman, Jorge - 174flynn, J .W . - 128fokker, p . - 91fontoura, s .a .b . - 79, 91franca, l .f .p . - 173frash, l .p . - 92, 133friedman, J .p . - 166fujii, y . - 67fujiia, yoshiaki - 85funatsu, t . - 135furui, k . - 48gadde, murali m . - 63gährken, a . - 94gaines, s . - 152galarraga, m .a . - 180gamwell, c .g . - 101gan, Q . - 111gao, feng - 142gao, y . - 152garcia, J . - 163garcia, x . - 170garduno gallo, amanda - 151garvey, r . - 167gates, W .c .b . - 57gathogo, p . - 129ge, x .r . - 155ge, xiurun - 47ge, yunfeng - 157geel, c .r . - 49geilikman, m .b . - 190geir vaaland, d . - 148gens, a . - 96gentier, s . - 133gentier, s . - 93george, m .f . - 121geraili mikola, roozbeh - 109ghassemi, a . - 185, 189ghazvinian, e . - 68, 98gheibie, s . - 57glascoe, l .g . - 73, 178glaser, s .d . - 107, 130glover, k . - 101goddard, a . - 81goldberg, david s . - 71gonçalves, clemente José - 84gong, x . - 40gonzalez, e .f . - 190goodfellow, s .d . - 128, 145goodrich, r . - 176goto, J . - 53gracie, r . - 43

graham, c .c . - 99gran, k . - 60grande, l - 179grasso, kyla - 163gray, g . - 123green, s . - 193greene, p . - 83greene, s . - 117grindhaug, gaute - 164gu, r . - 63guglielmi, y . - 70, 156, 164guillon, t . - 133guimarães, l . - 96, 159günther, r .m . - 94guo, l . - 141guo, m .W . - 155guo, mingwei - 47gutiérrez, g . - 100gutierrez, m . - 92, 133, 134guy, n . - 107haege, m . - 116hagan, p .c . - 97, 193hagiwara, i . - 109hahn, p . - 95haimson, b . - 159håkansson, ulf - 131hamdi, p . - 120hampel, a . - 94hampton, J .c . - 92, 133han, gang - 49han, k .c . - 150han, yanhui - 161han, Zengqiang - 52, 87handwerger, d . - 116, 148hanna, k . - 125, 176hansen, f .d . - 94, 95hao, y . - 44hareland, g . - 81harrison, J .p . - 195harthong, b . - 47hartline, c . - 163hashimoto, r . - 108hata, t . - 65hatzor, y .h . - 46, 108haug, k .m . - 83hauser, m . - 123hazzard, J .h . - 174heasley, k .a . - 77heath, r . - 171hebblewhite, bruce - 187hedayat, a . - 130hedegaard, k . - 77


heidari moghadam, m . - 79heikkinen, e . - 69helstrup, o .a . - 123heng, shuai - 99henk, a . - 180henry, p . - 164herchen, k . - 94herring, s . - 116, 148hettema, m .h .h . - 159hickman, s . - 93higashi, yukihiro - 153himmelberg, n . - 80hiorth, a . - 50, 78hiyama, michiharu - 113hocking, g . - 113hodges, s . - 125, 176hoedeman, g .c . - 50hoek, e . - 132hofmann, r . - 190hofstetter, g . - 198hol, s . - 89, 118holicek, J . - 178holland, J . - 178holmberg, m . - 132holt, r .m . - 84, 158hossain, m . - 162hosseini, koohmareh - 160hosseini, s . mehran - 148hosseini, Zara - 41houseworth, J .e . - 66hows, a .m . - 112, 190hsi, J .p . - 56hsieh, a . - 156hu, mengsu - 110hu, Qian - 87hu, sheng - 52, 87huang, Jian - 189huang, m .W . - 149hudec, m .r . - 59hudson, J .a . - 156hughes, p .b . - 104humphries, r . - 177hunt, c . - 58, 115hunt, J . - 118hunter, t . - 113husain, taha - 65hutchinson, d .J . - 186, 188, 197hutton, l .d . - 56hwang, J . - 90inoue, n . - 79, 91isago, n . - 153ito, t . - 113, 144

ito, y . - 181ittner, h . - 132iwasaki, y . - 108izadi, ghazal - 90Jabbari, hadi - 145Jansma, pamela - 65Javadi, m . - 73, 74Jeanne, p . - 45, 163Jeanne, pierre - 70Jense, m . - 182Jiang, fuxing - 42Jiang, yingjian - 141Jiang, yujing - 152, 153Jin, s . - 144Jocker, J . - 54Johnson, s . - 183Josh, m . - 105Ju, hongyang - 42Ju, yang - 142Juang, c .h . - 121Jung, chang min - 76Jung, y .b . - 88kaiser, p .k . - 40, 52kallu, r . - 103kamemura, k . - 181kanarska, y . - 178kantia, p . - 69karanikas, J .m . - 190karasaki, k . - 53karekal, s . - 126, 165kasama, kiyonobu - 177katsaga, t . - 174kawasaki, s . - 65kelkar, s . - 43, 93kemppainen, k . - 69keneti, s .a .r . - 58, 115keppetipolaa, s .s .s .s .m . - 85kias, e .m .c . - 63kikumoto, m . - 108kim, eunhye - 157kim, honggyun - 85kim, Jong-oh - 85kim, seung-hyun - 85kinakin, d . - 47kinoshita, n . - 75kirkham, m .p . - 99kishida, k . - 75knauth, m . - 120knight, e .e . - 184, 193knoll, s . - 41knott, david l . - 132koch, c .d . - 137


kodamab, nariaki - 85kong, daqing - 151koo, h-bon - 85korsnes, r . - 50kothamasu, r . - 136kovacevic, m .s . - 166kovalyshen, y . - 79koyama, t . - 108, 109, 110, 186kulatilake, p .h .s .W . - 68, 183kumar, vikas - 102kusaka, a . - 153, 167kushwaha, a . - 64labrie, d . - 98labuz, J .f . - 76lai, p . - 198lai, x .p . - 140laloui, l . - 72, 74, 96, 97lam, t . - 68, 182lan, hengxing - 138, 197langford, J . connor - 194larson, m .k . - 62latham, J .-p . - 141lautenschläger, c .e .r . - 91lavrov, a . - 83lee, b . - 100, 168, 170lee, d .W . - 122, 178lee, Jong-hyun - 85lee, Jung-yup - 85lee, t .J . - 88leelasukseree, c . - 42, 104lehtimäki, t . - 69lei, Q . - 141lei, Z . - 184levine, J .s - 43lewis, k . - 93li, b . - 152, 153li, chao - 72, 96li, chengxue - 151li, g . - 113, 161li, l . - 72li, n . - 151li, nianyin - 142li, tianbin - 138li, yange - 177li, yinping - 99liao, J .J . - 149lim, s .s . - 167lima, a . - 159lin, J .s . - 121lin, Jeen-shang - 135linde, björn - 154lins, c .m .m .s . - 159

liu, fei - 142liu, Jishan - 143liu, pingli - 142liu, Q .s . - 155liu, W .c . - 121liu, Wei - 99loehr, J .e . - 176lokajíεek, t . - 107lomov, i .n . - 178loubaud, m . - 93louis, l . - 39lu, yun - 197lund, h .k . - 169luo, g . - 59luo, y . - 102, 126luo, Zhifeng - 142lux, k .-h . - 94, 154ma, pengpeng - 141ma, x . - 159macciotta, r . - 46madjdabadi, b .m . - 52madland, m .v . - 50, 78mahbaz, s .b . - 81mai, p .m . - 196majdi, a . - 127makhnenko, r .y . - 76maleki, h . - 171mallman, e .p . - 51manca, d . - 97mannon, t .p . - 124manzanilla-morillo, raul - 174marcic, d . - 166marino, s . - 116, 148marone, c . - 111martin, c .d . - 46, 138, 154, 167, 182, 197mashimo, h . - 153masoumi, h . - 97, 193mastalerz, m . - 117masuda, k . - 128mattioli, glen - 65matzar, l .a . - 101mavong, n . - 104mawson, s . - 114mcclure, mark W . - 88mccreath, dougal - 182mcintire, h . - 53mckinnon, s .d . - 171mcnab, W .W . - 73megawati, m . - 78mei, s . - 83mejia camones, luis arnaldo - 86melchaeva, o . - 111


mellegard, k .d . - 95memarian, h . - 137mengjiao, y . - 160merrell, m .p . - 59miki, s . - 109, 110miklashevskiy, d . - 193min, k .-b . - 61minkley, W . - 94, 120mishra, b . - 77miska, s .Z . - 82, 124, 160missal, c . - 94, 95mito, yoshitada - 87mohamadi, m . - 40mohanty, s . - 166moinfar, a . - 78mokhtari, mehdi - 102mollajan, a . - 137mondol, n .h - 179moore, michael - 163moos, d . - 93moritoshi, a . - 135morris, J .p . - 54, 55morrison, d .r . - 199mostofi, m . - 173müller, andré luís - 84munjiza, a . - 184, 193murphy, m .m . - 62, 125muzzio, m .e . - 145nadeem, m . - 144nagel, n .b . - 100, 168, 170nagy, Z .r . - 122nakagawa, s . - 106nakashima, s . - 75, 135narasimhan, santhosh - 38narendranathan, s . - 139nasseri, m .h .b . - 128, 145naumann, m . - 159nauroy, J .-f . - 107nejati, morteza - 69nermoen, a - 50nes, o .-m . - 38, 60newcomen, h .W . - 103newman, robert - 49niioka, m . - 67nikolinakou, m .a . - 59nishiyama, s . - 110nishizawa, o . - 128nolte, d .d . - 161nolte, J . - 176nopola, J .r . - 197nordin, yini - 163nordlund, e . - 172

oak, young-suk - 85oar, trevor - 147oberling, Z .a . - 199ohnishi, y . - 108, 109, 110okazaki, k . - 181oke, J . - 182olabode, a .o . - 75oldenburg, c .m . - 163olivella, s . - 66olofsson, i . - 132olson, J .e . - 168olson, l . - 171oluyemi, g .f . - 162omori, y . - 144onishi, c .t . - 53oo, n .t . - 56orlic, b . - 44, 49ornés, a .i . - 191orozco, s .o . - 79osorio, J .g . - 145ostadhassan, mehdi - 82oyeneyin, m .b . - 162ozbay, u . - 63, 167ozbayoglu, mehmet e . - 82, 160paddock, d . - 116, 148padilla mejía, carlos - 151paiangle, meghana - 38pakalnis, r . - 104, 114palladino, r . - 125palleske, c .k . - 186paluszny, adriana - 51, 69pan, p .Z . - 45pan, y .W . - 149panthi, k .k . - 182panton, b . - 177papamichos, e . - 48, 192paraskevopoulou, c . - 181park, b . - 61park, b .y . - 59park, d . - 150park, e .s . - 88parshin, a . - 193peng, J . - 150perkes, s . - 171perras, m . - 68, 98peter-borie, m . - 93peters, c .a . - 72petrovitch, c .l . - 161petružálek, m . - 107pettitt, W .s . - 174petty, susan - 163petunin, v .v . - 169


pfeiffer, J . - 125pfeiffer, t . - 123pierce, m .e . - 174pinsky, p .m . - 117pinto, m . - 136polsky, y . - 92popov, e . - 193popov, y . - 193porathur, J .l . - 126pradhan, s . - 169pradhan, s .p . - 139preston, r .p . - 53prioul, r . - 54, 111profit, m .l . - 122prudencio, e .e . - 196pudewills, a . - 94, 167purvance, m . - 175pyrak-nolte, l .J . - 54, 56, 106, 130, 161Qi, shengwen - 138Qiu, b . - 102, 126raaen, a .m . - 159, 162rachez, x . - 93, 133radonjic, m . - 75rahe, J .h . - 166rahman, mashuqur - 131rahnama, ali - 105rai, a .r . - 103, 115, 140rai, chandra s . - 102, 129rajbal, singh - 153rance, J .m . - 122ranjith, p .g . - 71, 134raphanel, J . - 192rasouli, v . - 169rath, Jonathan s . - 94ray, anil k . - 63raysoni, n . - 112, 136razavi, mehrdad - 105read, s .a .l - 187rector, J . - 107reeves, h .J . - 99reyes-montes, J .m . - 128rezaei, m . - 127rezaei, saeedeh - 105riahi, a . - 164ribeiro, l .h . - 162richard, t . - 173richards, l .r . - 187righetto, g .l . - 91rinaldi, a .p . - 45rinaldi, antonio pio - 70ringrose, p . - 44rios, a .m . - 100

roberts, d .p . - 53roberts, d .t . - 122roberts, l .a . - 197roberts, s . - 118rodriguez-herrera, a . - 116, 148roehnert, m . - 95rogers, J . david - 86rogers, s . - 172, 189roggenthen, W .m . - 137rokahr, r . - 94rong, g . - 150rosen, richard - 38rougier, e . - 184, 193roworth, m . - 114roy, p .p . - 126russell, s . - 143rutenberg, m . - 154rutqvist, J . - 45, 66, 70, 110, 163ryan, t .m . - 199ryerson, f .J . - 73, 196ryu, d .W . - 150saasen, a . - 60safari, m . reza - 147sakakibara, s . - 186salehi, s . - 124salzer, k . - 94samson, c . - 171, 198sanaee, r . - 162sánchez, m . - 96sanchez-nagel, m . - 100, 168, 170sandbak, l .a . - 103, 115sarkarfarshi, m . - 43sarmadivaleh, m . - 169sarout, J . - 105sasaki, t . - 109, 110satoh, t . - 128saydam, s . - 193saydam, serkan - 187sayers, c .m . - 122schieber, J . - 117schlotfeldt, p . - 177schmid, c .J . - 103schneider, c .l . - 83scholtès, l . - 47selnes, knut .sigve - 164selvadurai, p .a . - 130sepehrnoori, k . - 147settgast, r . - 183shahri, mojtaba p . - 82shakoor, a . - 58shao, s .s . - 134sharf-aldin, munir - 38


sharifzadeh, m . - 73, 74sharma, a . - 129sharma, m .m . - 76, 90, 162sheibani, f . - 168shen, xinpu - 60sherman, c .s . - 107sherpa, m .d . - 97shi, gen-hua - 119shimizu, h . - 113, 186shimizu, n . - 135shin, sang-hee - 85shu, couxian - 42shukla, priyavrat - 102siczkar, leah - 52silva, o . - 66silvestro, J .l . - 122singh, n . - 139singh, raghwendra - 64singh, s .k . - 64singh, t .n . - 71, 139singh, v .k . - 127sinha, a . - 64siren, t . - 188sitar, n . - 109, 121sjöberg, J . - 172skurtveit, e . - 158smith, m .m . - 55sobolik, s .r . - 185soltanzadeh, h . - 136sondergeld, c .h . - 102, 129sone, h . - 112, 190song, l . - 81sonneland, l . - 116sønstebø, e .f . - 169spearing, anthony J .s . - 63spiers, c .J . - 118spokes, John - 49stahlmann, J . - 94, 95stanchits, s . - 100, 129staudtmeister, k . - 94stauffer, p .h . - 43stead, d . - 47, 53, 120, 195steed, c .m . - 143stenebråten, J . - 84, 169, 192stetler, l .d . - 199stevens, k . - 116, 148stille, håkan - 131stroisz, a .m . - 169suarez-rivera, r . - 100, 116, 117, 129, 148, 193surdi, a . - 100, 129sussman, a .J . - 193

sveinbjornsson, b .m . - 165svitek, t . - 107swoboda, g . - 151swyer, michael W . - 163szynakiewicz, t . - 125, 176taguchi, k . - 135tajer, e . - 78takahashi, m . - 75tamagawa, tetsuya - 113tang, huiming - 157tang, xuhai - 51tano, h . - 155tarokh, a . - 119terheege, J .h . - 50tesarik, d .r . - 62tezuka, kazuhiko - 113thepjun, a . - 104thomas, d . - 176thomas, r .d .h . - 139thompson, a .g . - 114thorhallsson, s . - 165thornton, d .a . - 179tien, y .m . - 121timms, Wendy - 187tiruneh, h .W . - 199tokashiki, n . - 155tomac, i . - 134torabi, a . - 158trads, n . - 50tran, m .h . - 89tsuji, masakuni - 131tuckey, Z . - 195tutuncu, azra n . - 102, 146uddenberg, matt - 163umar, s .b . - 172Ündül, Ö . - 40uno, mutlu - 147unteregger, d . - 198urpi, l . - 91utsuki, shinji - 87valley, b .c . - 42valley, benoît - 52van der pouw kraan, m .c . - 188van Wees, J .-d . - 91vargas Jr ., e . - 84, 86varun, - 173vasco, d .W . - 163vaughn, ben - 49verde, a . - 185verma, c .p . - 126vessley, m . - 176vilarrasa, v . - 66


villaescusa, e . - 114, 187vishal, v . - 71, 139vivas, J . - 195vlachopoulos, n . - 182voight, barry - 65Waggoner, J . - 178Walle, l .e . - 192Walsh, s .d .c . - 55Walters, m . - 163Walters, r .J . - 191Wan, r .g . - 40Wang, bingwu - 99Wang, bohua - 52Wang, chuanying - 52, 87Wang, h .W . - 140Wang, houyu - 151Wang, J .s .y . - 156Wang, Jinbo - 142Wang, liangqing - 157Wang, Qian - 141Wang, s .l . - 155Wang, shugang - 143Wang, shuilin - 47Wang, yuan - 110Wassing, b .b .t . - 49Weaver, J . - 112Webb, g . - 172Westhoff, d . - 140Wheeler, mary f . - 194White, J .a . - 44Whyatt, J .k . - 62Wick, thomas - 194Wishart, J . - 58Wolter, a . - 195Wolters, r . - 154Wong, louis ngai yuen - 98Wong, sau-Wai - 190Wu, Q . - 68, 183Wu, y .p . - 140Wu, yingkui - 42Wu, yu - 143xiang, J . - 141xie, p .s . - 140xiong, chengren - 157xu, gancheng - 151xu, h . - 67, 149xu, ma - 142yaghoobi rafi, J . - 131yagoda-biran, g . - 46, 108yamada, s . - 108yan, f . - 45yang, chunhe - 99

yang, Jinyong - 151yang, l . - 152yang, yi - 112yang, yongming - 142yasuhara, h . - 75yildirim, s . - 94yin, yongming - 42yoshioka, k . - 178young, aaron - 157young, r .p . - 128, 145yu, m . - 82, 124yu, W . - 147yu, Zhengxing - 42yuan, conghua - 47Zaka, khalid - 170Zakharova, natalia v . - 71Zamiran, siavash - 82Zapata, t .r . - 122Zapf, d . - 94Zemach, e . - 93Zhang, f . - 100, 168, 170Zhang, p . - 77Zhang, Q .b . - 76Zhang, Wu - 135Zhang, Z .Q . - 151Zhao, liqiang - 142Zhao, xi - 142Zheng, h . - 155Zheng, Jiangtao - 142Zhou, c .b . - 150Zhou, Junhao - 76Zhou, yaneng - 135Zhu, c . - 67Zhu, hengyin - 52Zhu, Quanjie - 42Zimmerman, r .W . - 51, 69Zimmermann, g . - 91Zinsmeister, l . - 192Zoback, m .d . - 51, 88, 89, 112, 190, 191Zoorabadi, mahdi - 187Zou, chunjiang - 98

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