Technology lies at the crux of understanding aformations characteristics and ultimately de-signing the optimal completion designs, fracturefluid formulas, and shale stimulation strategies fordeveloping unconventional resources. Perhapsnowhere is this truer than in Canadas unconven-tional and shale formations.

The Duvernay Formation has deep reservoirswith high temperatures and pressures as well as athermogenic aspect, all of which results in a verycomplex formation that can be difficult toexploit. A large piece of the Duvernay play, forexample, needs fracturing equipment rated for15,000 psi pressures.

Meanwhile, a very different play is developing inthe Cardium Formation, where an economic fieldredevelopment is taking place thanks to new tech-nology. Although operators have been drilling andproducing in the Cardium Formation since the1950s, they are beginning to exploit the halo aroundthe core-producing areas, which is challenging.Exploitation strategies and completion designs areevolving as the industry begins to understand thesehalo areas while drilling and designing the appro-priate completion systems. The same can be said ofareas in the Montney and Exshaw formations.

Mineralogy servicesOne tool that we have developed to exploit tightshale plays is the Formation Lithology eXplorer(FLeX) elemental spectroscopy wireline loggingtool, said Grant Ferguson, technical support man-ager, Wireline Systems for Baker Hughes in Canada.

It is the first pulse neutron spectroscopy tooldesigned to operate in openhole environments forthat purpose. It quantifies certain elements presentin the formation and allows for the interpretationof the rocks mineralogy.

The wireline logging tool is the only one in theindustry that directly measures carbon, according tothe company. Once the carbon is apportioned intoeach minerals composition to satisfy chemical sto-ichiometry, any excess carbon measured by the toolis quantified into either total organic content (TOC)or liquid hydrocarbons.

The wireline logging tool uses both capture andinelastic neutron spectroscopy to measure andquantify elements such as hydrogen, carbon, silica,oxygen, magnesium, and iron. From the chemistrydata gathered by the logging tool, geoscience inter-pretations are performed by the companys Rock-View service, which begins by computing a generallithology and then breaks that into specific litholo-gies. From that point, it can analyze and quantifymineralogy, such as carbonate minerals like calciteand dolomite.

The company is developing additional measure-ments for the services. For example, when MReX, thecompanys nuclear magnetic resonance service, is usedwith the FLeX services and bulk density, an inde-pendent secondary TOC measurement can be taken.

Openhole completion systemThe FracPoint multistage fracturing system is thecompanys openhole completion technology used inCanadian unconventional and shale formations.

Improved technologies and drilling efficiencies are driving unconventional resource development in several Canadian plays.

Unlocking Canadian Tight Oil Plays

By Jerry GreenbergContributing Editor

CANADA: TECHNOLOGY

Short radius openhole packers and fracturingsleeves isolate intervals in horizontal wells to bettertarget fracture treatments. The system also can usethe companys REPacker openhole packer, which isa self-energizing swelling elastomer packer. The sys-tem works when a reaction with wellbore fluidscauses the rubber element of the packers to swell.

Coiled tubing fracture stimulationOne fracturing method used in Canada with successis the companys OptiPort coiled tubing fracturingsystem. The company brought it to the US in 2011.The technology uses the annulus coil tubing frac-turing method. In Canada, the cemented-in slidingsleeve tool allows the service company to pump thefracturing fluid and proppant into an isolated for-mation. Another feature is the ability to circulatesand out of the well in the event of a sand-off, min-imizing delays.

The OptiPort system uses sliding sleeves likethose found in ball-drop systems; however, thesleeves are cemented in and opened by the SureSetpacker assembly rather than sequentially sized balls.The fracturing process occurs down the annulusbetween the casing and the coiled tubing, ensuringthat the well is isolated from the previous zone.

Because the fracturing fluid is pumped down theannulus, lower pumping horsepower is required.This allows for a virtually unlimited number ofstages and leaves the coiled tubing in the well to per-form a quick cleanout if required after a screenout.

Disintegrating fracturing ballsBaker Hughes developed fracturing balls that arelighter and stronger than those made of phenolic orfiber glass resin material, but the significant differ-ence is that the IN-Tallic fracturing balls disintegratewhen exposed to brine or acid solutions. This elimi-nates the risk of balls not being produced back to sur-face or remaining on corresponding seats, whichcould result in lost production. The fracturing ballscan be used with the FracPoint completion system.

Disintegrating fracturing balls are composed ofcontrolled electrolytic metallic nanostructuredmaterial that is lighter than aluminum and strongerthan some mild steels. The disintegration processworks through electrochemical reactions controlledby nanoscale coatings within the composite grainstructure. The rate of disintegration depends ontemperature and the concentration of the brine.Acid will disintegrate the balls at a much faster rate,allowing the flexibility to pump acid on the ball

IN-Tallic disintegrating fracturing balls are lighter and stronger than those made of phenolic or fiber glass resin material. The signifi-cant difference is they disintegrate when exposed to brine or acid solutions as shown here. (Image courtesy of Baker Hughes)

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after the fracture is complete. It will not disintegratein an oil-based or neutral solution.

We are seeing a growing interest in our IN-Tal-lic fracturing balls, said Marc Carriere, Canadianproduct line manager for Completions with BakerHughes. More operators are considering runningthese tools to avoid having to immediately drill outthe ball seats and at the same time increasing theconfidence of production from each interval.

New cutter technologyThe company recently introduced a new technologyin its cutting structures called Advanced MetalMuncher Technology (AMT). The type of cutter weuse is called the Glyphaloy, Carriere said. It isdesigned carbide used to form cutting structures.They are stronger and made of higher grade carbidethan others currently available.

These cutters are milling out up to 40 compos-ite plugs in one run, he said, which limits fluidexposure to the formation and improves operatingefficiencies.

The cutters are engineered using pressed sin-tered tungsten carbide available in a variety ofshapes and metallurgies. A milling tool can includeseveral types of AMT cutters to optimize variousaspects of the milling operations. The self-sharp-ening cutters are designed to mill high chrome and

nickel-content mate-rials. The technologyincreases millingpenetration rates,extends effective timeon the bottom inhigh-volume millingapplications, andenables greater flexi-bility during themilling process, thecompany said.

Operators havereported as much asa 300% improvementin wear resistanceand longevity withthe inserts, accordingto the company. In

North Dakota, for example, an AMT mill success-fully milled out 79 composite plugs in two hori-zontal wells in one trip per well, achieving a newrecord for fracturing plug removal, the companysaid on its website.

Openhole technologyExploration and development of the Montney andCardium formations have been ongoing the pastfive years. The Duvernay and Exshaw formationshave only been attracting interest for the past 12 to18 months as far as drilling and completing hori-zontal laterals. Calgary-based Packers Plus has beenactive in each formation because of its openholecompletion designs and equipment.

The Exshaw is the least explored of the four for-mations, and information is held tight by the operatorsfor the most part. The formation is considered to bevery complex because it is close to the Canadian Rock-ies with different layers and depths. The geologyrepeats as you drill, said John Zukowski, Canadiansales manager for the company. Sometimes you drillthe same section four times. Still, there arent manydrilling issues, but there are a lot of issues with for-mation stress and subsequent stimulation.

The company has been working in the Montneysince 2007, but activity really took off in 2010 witha doubling of the number of wells over 2009. Thecompany saw a continuing upward trend in com-pletions since then, completing 775 openhole hor-izontal laterals as of the end of July 2012. Thenumbers are even higher in the Cardium Formation.The company became active there in 2007 and by2010 completed six times the number of wells itcompleted in 2009. Activity in the Cardium con-tinues to increase each year, with the company com-pleting 950 openhole horizontal lateral wells as ofthe end of July 2012.

With much less drilling and completion activityin the Duvernay and Exshaw formations, the com-pany completed fewer than 50 openhole horizontallateral wells in these formations as of July 2012.

We are seeing a trend in all four of the areas withoperators trying to complete more stages, saidMike Kenyon, Technical Sales for Packers Plus,partly because our technology has advanced toallow for higher stage numbers, but also because

Advanced Metal Muncher Technology usespressed sintered tungsten carbide and has milled out up to 40 composite plugs in one run.(Image courtesy of Baker Hughes)

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operators see better results with longer laterals anda higher density of fracs.

For example, the company is pumping as manyas 30 stages in both the Duvernay and Montney,with an average of 16 stages in the Montney and 22in the Duvernay.

We worked with an operator on a study com-paring plug and perf completions to open hole (inthe Montney) and found that openhole results inabout 36% more cumulative production after a 12-month period on average, Kenyon said. It was anincentive for operators to move to open hole for asignificant cost savings, but even more so because ofthe production comparisons.

Operators are mainly running 15,000 psi high-pressure tools through the Duvernay just below theMontney, Kenyon said. The company is typicallyrunning its StackFRAC and QuickFRAC TitaniumXV high-pressure systems. All Packers Plus systemsas well as the SF Cementor are available in Tita-nium XV 15,000-psi-rated versions. In addition, thesystems are modular, enabling operators to cus-tomize the system design to deliver the desired stim-ulation program by combining technologies such asthe StackFRAC and QuickFRAC systems.

The trend for the horizontal sections was plugand perf in the beginning until the operator betterunderstood the formations characteristics,Zukowski said. However, the cost [for plug andperf] for the initial wells was about 70% higher thanopenhole completions.

Cardium Formation the most activeIn the early stages of developing the Cardium For-mation, Packers Plus would set casing down to 90and then run liners. Adopting experience gained inthe Canadian Bakken, operators would begin with15- to 17-stage completions in the lateral, but thathas evolved over the years with many operators nowaveraging about 20 stages and some operators exper-imenting with longer length laterals and stage num-bers up to 40.

The other trend is toward openhole monoborewell construction, Kenyon said, especially on thewest Pembina side of the formation where operatorswill set 4-in. casing from surface to toe and cementthe heel and vertical section, leaving the lateral sec-tion uncemented with StackFRAC equipment.

Initially the fracs used oil-based fluids becausemost operators were worried about pumping a

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One stage of a Packers Plus StackFRAC Titanium XV system for HP/HT completions. (Image courtesy of Packers Plus)

water-based frac, but that also has changed,Kenyon said. We started out using foam fracs, andnow almost everyone is using a slickwater frac with10% to 20% nitrogen.

About 90% of the wells drilled into the CardiumFormation are completed openhole, according tothe company. The formation ranges from 1,400 mto 2,100 m (4,600 ft to 6,800 ft) true vertical depth.The comfort level of openhole at that depth wasvery high, Zukowski said, and operators wantedthe efficiency of openhole completions.

Openhole completion systemsThe companys QuickFRAC system is capable offracturing 60 stages while pumping only 15 treat-ments at surface, according to Packers Plus. Usinglimited entry diversion techniques, the systemallows the operator to fracture several isolatedstages at one time through a batch fracturingmethod. For each treatment zone, the systemincludes a number of QuickPORT sleeves flankedby RockSEAL II packers, which creates multiple,individually isolated stages within a single treat-ment zone.

The appropriate size ball is inserted into thestring and pumped down onto the seat. The toolstring is pressured up to activate and open multipleQuickPORT sleeves to allow stimulation fluid toflow into the annulus. A variety of ball sizes areavailable, allowing multiple rounds of fracture treat-ments to be run in sequence. After the stimulationis completed, the balls can be flowed back.

SF CementorThe SF Cementor, a stage collar developed by thecompany and used with any of its openhole com-pletion systems, eliminates the need for intermedi-ate casing, resulting in significant reductions inwell construction costs. The tool is hydraulicallyactivated and designed to close without the use ofa plug or dart, reducing post-cement cleanout oper-ations and lowering the likelihood of issues associ-ated with debris in the completion system.

The tool is assembled in the completion stringabove the openhole stimulation system. When thepackers are set, the tool string is pressured up tohydraulically open the tool. Once the cement ispumped, it is displaced with a high viscous pill and

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Packers Plus QuickFRAC multistage batch fracturing system enables simultaneous stimulation of multiple stages with a single frac-ture treatment at surface. (Image courtesy of Packers Plus)

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spacer fluid, eliminating a wiper plug operation toclean out the casing and the potential challengesassociated with drilling out a plug. When thecementing operation is complete, the tool ismechanically closed and locked by applying com-pression on the tool to isolate the ports.

The efficiencies of the stage collar were tested bya major operator in multiple field trials in the lowerMontney, cementing back 17 wells completed with12- to 14-stage StackFRAC systems. The stage col-lar was run at an average depth of 2,650 m (8,700ft) and the tools were landed between 45 and 90from the vertical. Since then, the operator hascemented back more than 100 wells with 12- to 25-stage StackFRAC systems.

In one well, the tool was run in the Montneyand landed at 3,160 m (10,380 ft )and 56 fromthe vertical. A 15,000-psi-rated stage collar was runabove a 14-stage StackFRAC Titanium XV HPHTsystem. The stage collar was opened at 2,750 psi andcement was placed in the annulus followed by a vis-cous pill and spacer fluid to displace the cementfrom the liner. The tool was closed using set-downcompression in a single attempt and only one drill-out trip was performed.

Geomechanics, stimulation modeling,and flow channel hydraulic fracturing Unconventional reservoirs need out-of-the-boxthinking, said Stan Cena, Canada TerraTek oper-ations manager, Schlumberger. They need inte-gration with other segments to leverage as much information and data from the rock indesigning the programs that will deliver a suc-cessful completion.

TerraTek rock mechanics and core analysis serv-ices measure reservoir quality and completion qual-ity. The reservoir quality looks to how muchhydrocarbon is in the reservoir, where it is in thereservoir, the permeable porosity, and saturation,Cena said. The completion quality speaks to thegeomechanic properties.

Services include geomechanics testing for assess-ment of reservoir geomechanical properties;hydraulic fracture testing, providing simulation foreffective fracturing; and core geology and petro-graphic analysis for describing rock fabric, whichgoes into fluid flow and how the rock will fractureduring stimulation.

Operators are using a certain amount of sci-ence in all of their wells, said Timothy Pope, Stim-

Components of an openhole cemented-back monobore StackFRAC system completion are shown. (Image courtesy of Packers Plus)

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ulation Domain manager, Canada,Schlumberger, although less sciencein the Cardium completions than inthe emerging plays, the Duvernay andExshaw, which tend to be more com-plex than a lot of the plays.

One of Duvernays challenges is frac-ture containment. We can create afairly large fracture height, Pope said.If we pump slickwater treatments weare going to have a nice conductive bedof sand in the bottom 20 m to 30 m [66ft to 98 ft] of the fracture.

We are now pumping hybridtreatments, beginning with slickwater in the beginning of the stimu-lation followed with crosslink fluidsat the end of the treatment, Popesaid, giving better vertical proppantdistribution so we stimulate theentire height of the Duvernay.

There are similar challenges in theMontney Formation, he said. Thisformation can have frac heights twicethe size of what is experienced in the

Duvernay, which makes it important to assure ver-tical proppant distribution. We have done somehybrid treatments in Montney that have been verypromising, Pope said. We pump slickwater treat-ment in a continuous operation followed by ourHiWAY flow-channel fracturing service. In the last12 months, we have pumped the HiWAY service in11 different reservoirs.

The Cardium is an older field where poorer qual-ities on the edges of the field presently are beingexploited through horizontal completion tech-nologies, Pope said. The company has been frac-turing the Cardium with its flow-channel service.The technique requires about 40% less proppantthan a conventional fracturing treatment and about25% less water on average.

With the flow-channel technique, proppantworks as a supporting agent to prevent closurewithin the channels rather than as a conductivemedia as in the case of conventional treatments.Fracture performance becomes independent ofretained proppant pack conductivity. The open

Geoscientists validate a core-to-log correlation for classifying heterogeneous rock types.(Photo courtesy of Schlumberger)

Unstructured gridding of complex hydraulic fracture shows produc-tion simulation pressure depletion over 30 years. (Image courtesy ofSchlumberger)

CANADA: TECHNOLOGY

channels extend from the near-wellbore area to thetip of the fracture, significantly increasing the effec-tive fracture length. The channels are created withinthe proppant pack through a patented techniquethat combines a pulse pumping procedure, perfo-ration scheme, and fiber technology.

Reservoir stimulation modelingThe companys Mangrove reservoir-centric stimu-lation design software enables an integrated work-flow in reservoir characterization to understandunconventional reservoir heterogeneity. It functionsas a plug-in for the Petrel E&P software platform,allowing close integration with geoscience and engi-neering asset teams. Completion and stimulationmodels can be calibrated using microseismic meas-urements in the context of local geology and struc-ture. The calibrated model then is represented in aproduction model for forecasting and optimiza-tion. Field production data are used to calibratethe production model. An operator can determinean optimal number of perforation clusters, designfewer stages if the right spot to fracture (based onlaboratory measurements calibrating log measure-ments) is determined, and pump the right size jobrather than going for the biggest job possible. Thesoftware also can work efficiently if an operatorwants to maintain the number of stages while gain-ing a production improvement.

Mangrove provides the opportunity to modelcomplex fracture networks as well as proppanttransport within these networks, Pope said. Thisbecomes extremely important when the wells con-ductivity is coming from where there is proppant.

We can take this complex hydraulic fracturenetwork and grid it directly into our reservoir sim-ulator to perform production predictions as well astreatment optimization, he said.

A completion advisor is one of the softwares keyelements. It provides an optimal way of placing theperforations and grouping them in a stage by pro-viding automated workflows for specific well ori-entation. There are separate advisors for tight sandsand shale.

The Mangrove software provides rigorous andrepeatable solutions for optimizing staging andperforation design, the company said. The staging

algorithms are linked to fit-for-purpose hydraulicfracture models ranging from Pseudo3D to thenewly developed complex fracture models, the UFMunconventional fracture model and Wiremesh. Thecomplex fracture models are specifically developedfor simulating non-planar complex fractures appli-cable in naturally fractured reservoirs commonlyfound in shale.

The field is a very, very expensive laboratory,Pope said. The Mangrove workflow allows us to per-form complex optimizations that reduce uncertainty.

Fracture fluids in Canadian unconventional formationsExploration in the Montney and Cardium plays inAlberta has been ongoing for about 50 years in theCardium. However, in each of these plays, horizon-tal drilling has been taking place only in the last fiveto six years. Today, much of the drilling taking placein these two formations is developmental, with paddrilling that could contain as many as six wells.

In the less developed Duvernay and Exshaw for-mations, operators are taking their time in order tounderstand them. As a result, Exshaw is experienc-ing little activity, and Duvernay only slightly more.Six months ago there was a big push to see whatthe Exshaw contains and how [operators] weregoing to complete the different wells, said GregHenderson, technical manager, Acid and FracturingServices for Trican Well Service.

Among other things, operators discovered thatthe Exshaw contains poorer quality rock than foundin the eastern portion of what sometimes is referredto as the Alberta Bakken. The situation makes itmore expensive to drill, complete, and stimulate.Part of the higher cost is because of drilling andcompletion services not being readily available dueto the remoteness of the play, according to Hen-derson. Also, the Exshaw is a deeper formation thanmost in Alberta, which also creates certain issues,and water supply for fracing is scarce because itslike a desert down south, he said.

The service companies would come if the rockquality was there, said David Quirk, technical man-ager, Unconventional Resources for Trican. It reallybegins with the reservoir quality, but all of the otherchallenges arent helping the situation.

Trican stimulated fewer than 10 Exshaw wellsdue to the slowdown in drilling and completionactivity in the play. Henderson said operatorsbecame somewhat active about two years ago butit probably didnt take long to find out aboutthe [poor] rock quality.

The Duvernay Formation below the Montneyspreads over most of Alberta. The favored fracfluid is a slickwater system with 40/70 naturalsand. The Duvernay is in the development stage,and the industry has not yet found the right frac-ing formula. We are getting closer every day. Wetypically are using smaller natural sand and inter-mediate strength proppants, Henderson said.

Depth of the Duvernay Formation can varysignificantly depending upon the area. The far-ther north of Calgary the shallower it becomes.The formation can vary from 1,200 m to 3,500 m(4,000 ft to 11,480 ft) deep, although most of theexploration and development activity is in thedeeper portion of the formation, generally rang-

ing from 2,800 m to3,500 m (9,200 ft to11,480 ft) total verticaldepth, according toHenderson. The hori-zontal laterals can beas long as about 1,500m (4,900 ft) but aver-age about 1,200 m(4,000 ft).

The Duvernay is afairly complex reservoir,and a lot of operatorswere comparing it tothe Eagle Ford becauseof its liquid content.We are finding it diffi-cult to fracture and areapproaching the Duver-nay with a similardesign as found in theEagle Ford, Hendersonsaid. Its not all slickwater; we are usingsome crosslink guar-base fluid for viscosity

to place the proppant.As far as completion design, some operators were

using a ball drop openhole system, he said, but thosesystems add more complexity and cost to the opera-tion when working in the harder-to-fracture forma-tion. The industry generally is moving toward theplug and perf method, Henderson said. We canpump higher rates down larger diameter casing and itbecomes easier to work in higher pressure formationsas well.

These days in the Duvernay, we are pumping rel-atively large slickwater treatments, Quirk said.

In the Montney Formation, the company isfracing with smaller proppant due to its depth.Also, it is a fairly easy formation to fracture, Hen-derson said, until an operator drills into areasthat can be highly faulted. Slick water is the for-mula of choice in the Montney, with a foam sur-factant, depending upon which part of theformation is being worked. There is an Upperand Lower Montney and also a Middle and

CANADA: TECHNOLOGY

Trican fracturing operation with frac pumpers is shown. (Photo courtesy of Trican Well Service)

Middle Lower. Different frac fluids are used ineach interval.

Operators in the Cardium recently have beendrilling into the tighter portions of the formationwith openhole horizontal laterals and multistagefracturing systems. The completion system andfluid formula are dictated by the sensitivity of therock to the fluids.

Multistage ball drop systems are used extensivelyin the Cardium, because it is a shallower play, Hen-derson said. We dont see many plug and perf systemsin the typical Cardium due to its depths.

The Cardium Formation ranges between 1,500 mto 2,500 m (4,900 ft to 8,200 ft) total vertical depthwith horizontal laterals ranging between 600 m to1,000 m (2,000 ft to 3,300 ft), although some later-als can be as long as 1,500 m (4,900 ft).

Where specifically the Cardium is drilled alsodictates the frac fluid type. Trican has pumped slick-water systems, surfactant gels, and foam intoCardium as well as crosslink systems, the latter notas often as the other fluid system options. The com-panys slickwater systems are trending to high salt-tolerant additives.

Operators in the Cardium and Montney are inthe cost-reduction stage, Henderson said. Mostoperators by now know which fluids they want touse in a particular area. In those cases, it is a matterof reaching the efficiency on multiwell pads to oper-ate in a 24/7 mode with continuous fracing, whichcan reduce the cost of each frac job.

Trican believes there could be a fourth-quarterslowdown in the pumping business as operatorsspend their budgets near year-end. The companyanticipates a good 1Q 2013 as new budgets areimplemented. However, one potential kink could bean excess of pumping equipment: From the capitalbuild during 2012 that is just wrapping up, Quirksaid, there will be some idle equipment.

Single and multi-array sleeve systems,RFID technologyWeatherford has been active in several Canadianunconventional plays, including, in varying degrees,the Montney, the Cardium, the Duvernay, and theExshaw. The company is more active in the Montneyand Cardium than the other plays with openhole and

cemented casing systems. The Exshaw and Duvernayare in their infancy stage, said Randal Biedermann,sales manager, Completion and Liner Systems forWeatherford in Canada. Operators are walking intothem a little slower with regard to new or advancedtechnologies, especially in the Duvernay because it isa higher-pressure formation.

Biedermann noted that some equipment com-ponents necessary for optimal completion of theDuvernay are not yet available, but the industry iscurrently field testing applicable equipment. Therequirement includes 15,000-psi equipment. Thereis not a large track record for the high-pressureequipment, he noted, so many operators are choos-ing to complete the formation with cemented cas-ing and the plug and perf method. Operators arelearning about the reservoir and how it is stimulatedbefore pursuing an optimization method, like a balldrop system, he said.

As an industry, we are still installing manycemented-in casing strings, Biedermann said. Thetechnology path typically pursued starts with perfo-rating single intervals, stimulating, and successivelyisolating with drillable bridge plugs and plug and perf.

The first optimization step would be to move onto a cluster-style fracing and perforating using lim-ited-entry frac technology, where each perforatedinterval consists of multiple exit points along theformation, he said. The goal is to eliminate thewell intervention operations to minimize the timeto stimulate the well.

Using plug and perf, an operator can readilyproduce each interval and evaluate the productivityand the effectiveness of the stimulation chosen,Biedermann said. With a ball drop system we aretrying to reduce the time that pressure pumpingequipment is on location and minimize nonpro-ductive time once the drilling rig has moved on.

Zone completionsThe company has been using its ZoneSelect systemin the Montney Formation for nearly four years.The modular completion system enables operatorsto choose from a variety of sleeve actuation optionsand zonal isolation methods to create the optimalcompletion for the particular formation. Themethod uses sliding sleeves that can be ball drop

CANADA: TECHNOLOGY

actuated, mechanically shifted, or pressure activatedin the case of the toe sleeve. Zonal isolation isachieved with either swellable or hydraulically acti-vated packers or cement.

The systems sleeves feature up to 40 ball dropsizes that allow segmenting up to 41 zones using4-in. casing. The additional zone is accessed byusing a pressure-activated sleeve at the toe of thewell. A unique feature of the sleeves is their shearrings rather than shear screws or pins, which providemore precise opening pressures and consistentopening pressure indications, the company said.

The system also can be fitted with Multiple ArrayStimulation System (MASS) sleeves in which mul-tiple sleeves can be opened with a single ball size.The MASS sleeve groups up to five sliding sleevesper stimulation stage. Opening the sleeves allows asegmented seat to shift into a recess that in turnreleases the shifting ball, and the ball continues tobe pumped to the next sleeve. This process contin-ues until the ball lands on a solid seat sleeve. TheMASS sleeves system can currently segment a max-imum of 10 stages each consisting of five sleeves ina single installation, the company said.

In one well in the Montney Formation, an operatorwanted to isolate and fracture multiple zones in a

6,130-m (20,111-ft) measured depth horizontal well.The well was kicked off at 1,873 m (6,145 ft). The hor-izontal section was about 4,000 m (13,123 ft). Thewell was cased with 4-in. cemented liner casing.

The ZoneSelect SingleShot sleeves and AREShydraulic openhole packers were successfully deployedto the total depth of the well. Eighteen sleeves and 22packers were used to isolate 21 intervals and stimulate18 intervals. The operator was able to access a signifi-cant portion of the formation and realized a well pro-duction increase of 25% over an 18-month period,according to the companys website.

Additionally, the company said, the completionsystem minimized extraneous time and servicesrequired to stimulate the well, saving associated rigcosts and reducing the overall environmental impact.

Multizone fracturing systemThe company has also acquired a diverter system,the i-ball system, that requires only one ball to acti-vate any number of sleeves one at a time, Bieder-mann said, and it is the same size ball for each sleeve.

We installed a couple of these systems in Canada.They are being pilot-tested here; however, a client inthe US has already installed multiple systems andplans to continue using the technology, he said.

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The MASS sleeves system can currently segment a maximum of 10 stages, each consisting of five sleeves in a single installation.(Image courtesy of Weatherford International)

Traditional ball drop systems for multizoneoperations require the deployment of balls andball seats of successively smaller sizes movingfrom the heel to toe of a well. This contributes toincreased surface pressure pumping requirementsand can limit the accessibility to the toe of thewell in a screenout scenario because the size ofcoil cannot fit through a seat restriction. In somecases, the operator may sacrifice shorter seg-mented interval length to minimize the numberof sleeves required and thus the smallest insidediameter (ID) seat restriction installed.

The companys new i-ball system can be run aspart of the ZoneSelect system. It permits high-ratestimulating at the toe, provides large ID accessthroughout the well, and eliminates quality controlconcerns by using only one ball and seat size. Thenear-drift diameter of the system enables nearly anunlimited amount of zones to be stimulated, andthe zones are fractured one at a time. Once stimula-tion is completed through the sleeve, the seat systemthen retracts back to a size that is close to the ID ofthe host tubing. This feature eliminates the need todrill out and allows the large outside diameter acti-vation balls to easily be recovered at surface during

flowback. The technology has been tested in open-hole and cemented wellbores and is currently rated to10,000 psi. It can be run in temperatures up to 135C(275F). The company said it will be running as manyas 100 i-ball systems during the next few months infive wells for a single operator.

RFID technologyThe company is advancing its use of radio fre-quency indentification (RFID) to activate sleeves.We have undergone numerous field tests andhave successfully proven the technology worksdownhole, Biedermann said.

With RFID technology, an electronic chip ispumped downhole to signal a tool to function asdesired. In conjunction with ZoneSelect, the tech-nology eliminates the need for ball, seats, anddrilling out. It can be used to function sleeves ina sequence other than toe to heel, the only optionwith conventional technology. While the use ofthis technology is new to the oil and gas industry,the company has installed and uses the RFIDtechnology in various downhole applications. n

References available.

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The i-ball system requires only one ball to activate any number of sleeves at one time. (Image courtesy of Weatherford International)

Copyright 2012, Hart Energy 1616 S. Voss, Ste. 1000, Houston, TX 77057 USA +1 (713) 260-6462 Fax: +1 (713) 993-0029 www.hartenergy.com