Gas Hydrate Research Review
ByShirish Patil
Associate ProfessorPetroleum Development Laboratory
University of Alaska Fairbanks
Alaska Gas Hydrate Planning WorkshopAnchorage, AK
August 17-18, 2005
Energy Technology DivisionArgonne National Laboratory
PDL-UAF 1987
Gas Hydrate Research at UAF(1983-2005)
Gas Hydrate Phase Behavior
S. PatilV.Kamath
A.DandekarS. Paranjape
W. ChenJ. Westervelt
Gas Hydrate Relative Permeability
S. PatilA. DandekarN. Jaiswal
Gas Hydrate Production Modeling
S. PatilN. Nanchary
D. OgbeA. Dandekar
C. BaenaR. Roadifer
V. SrivastavaD. ScottS. Howe
V. Gandibhan
Gas Hydrate Production TechniquesS. Patil
A.DandekarV. KamathM. NademP. Mutalik
J. Sira
Gas Hydrate Formation Damage
S. PatilA. Dandekar
P. Kerkar
Gas Hydrate Production Economics
S. PatilA. DandekarD. Reynolds
S. HoweS. Omenihu
18 M.S. ThesisOver 70 Papers and Reports
Government-Academia-Industry PartnershipLeading to Technology Transfer and Resource Development
PNNL, LBNLANL
UAF
BPXA
CPAlaska
NETL
Experimental &
Modeling Tasks
FieldApplications
TechnologyTransfer
Applications to ANS ShallowResource Development-
State of AlaskaTrained UAF Graduates
(Industry)
(University+Government)
Resource Development
USGS DGGS
UAF Facilities- Petroleum Dev. Lab.
Composite of A-F Hydrates
Milne Pt 3D Survey
Collett et al 1-2004
Milne Point Gas Hydrate Accumulation
Resource Characterization and Quantification of Natural Gas-Hydrate and Associated Free-Gas
Accumulations Prudhoe Bay – Kuparuk River Area, North Slope of Alaska
BP Exploration (Alaska), Inc.Principal Investigator: Robert Hunter
University of Alaska FairbanksPrincipal Investigator : Shirish PatilUnited States Geological Survey
Principal Investigator : Timothy CollettUniversity of Arizona-Tucson
Principal Investigator : Mary PoultonU.S. Department of Energy
Project Manager: Ray Boswell
Gas Hydrate Research Projects at UAF
Alaska Methane HydrateProject
BPXA, UAF, UAz, USGSFunded By
NETL, USDOEHunter, Patil, Casavant, Collett
Poulton &Dandekar(2002)Injection of CO2 for Recovery of
Methane From Gas Hydrate Reservoirs
UAF-PNNL-BPMcGrail, Zhu, Patil, Hunter, Bush
Funded By AETDL (2002)
Novel Chemically Bonded Phosphate Ceramic Borehole Sealants
for Arctic EnvironmentUAF-ANL-BJ ServicesPatil, Wagh, Dawson
Funded by AETDL(2004)
Compliments Recovery/Sequestration
Compliments Completions/Cementing/Infrastructure
Resource Characterization/ Reservoir Engineering/Drilling & Production research potentially leading to successful Pilot Project
Engineering research laboratories
Unique location
Over 20 years of proven research capabilities
Strong industry/Government partnerships
Gas Hydrate Research Focus Groups
Phase Behavior Studies- Jason WesterveltShirish Patil, Abhijit Dandekar
Relative Permeability Studies-Namit Jaiswal
Shirish Patil,Abhijit Dandekar
Reservoir Modeling and Economics- Stephen HoweShirish Patil, David Ogbe, Abhijit Dandekar
Drilling Fluids & Formation Damage- Prasad KerkarShirish Patil, Abhijit Dandekar
BPXA
USGSPHASE 2
PHASE 1
Examples of Hydrate Stability CurvesDepth of Hydrate Stability
Zone for the NW Eileen State 2 Well
0
200
400
600
800
1000
1200260 270 280 290
Temperature (K)
Dep
th (m
)
Geothermal Gradient
Run 1
Run 2
Top of HSZ - 175 m
Base of Permafrost
Base of HSZ - 710 m
Depth of Hydrate Stability Zone for the NW Eileen State 2
Well0
200
400
600
800
1000
1200260 270 280 290
Temperature (K)
Dep
th (m
)
Geothermal GradientRun 1Run 2Run 3
Top of HSZ - 180 m
Base of Permafrost
Base of HSZ - 705 m
Depth of Hydrate Stability Zone for the NW Eileen State 2
Well0
200
400
600
800
1000
1200260 270 280 290
Temperature (K)
Dep
th (m
)
Geothermal GradientRun 1Run 2Run 3
Top of HSZ - 195 m
Base of Permafrost
Base of HSZ - 715 m
Without Porous Media (h=535) Synthetic Porous Media (h=525) Field Sample (h= 520)
Phase Behavior Studies
Hydrates Without Porous MediaHSZ for the Dissociation of Bulk Hydrates
0
200
400
600
800
1000
WK-11 WK-14 WK-17 NW Eileen NHST
Dep
th (m
)
2% Brine 4% Brine
(Hydrates in Presence of Anadarko Hot Ice #1 Core Sample)
HSZ for the Dissociation of Anadarko Sample
0
200
400
600
800
1000
WK-11 WK-14 WK-17 NW Eileen NHST
Dep
th (m
)
2% Brine 4% Brine
• Arco and Exxon Core (1972)– Depth 577 to 776 m
(Red)
• Log Data (Collett 1993)– Depth 575 to 675 m
(Blue)
• This study – Depth 190 to 740 m
(Green)
Depth of Hydrate Stabiltiy Zone for the NW Eileen State
2 Well0
200
400
600
800
1000
1200260 270 280 290
Temperature (K)D
epth
(m)
Geothermal GradientRun 1Run 2Run 3
Top of HSZ - 190 m
Base of HSZ - 740 m
Base of Permafrost
Objectives of Study
Formation Damage Assessment through Drilling Fluids Dynamic Filtration for the Production of
Gas Hydrates on the North Slope of Alaska
• Evaluate Drilling Fluid to assess Formation Damage• Permeability impairment data for near well bore formation
to predict production data, recovery factor and economics• Filtrate loss amount to formation for various mud
composition to simulate on whole length of well
Conceptual Design: Dynamic Filtration
Gap
vn
rr
vn
DD
vn
OHOHw .2
)12(8.0
)(2
)12(8.0).12(8.0 +=
−
+=
−
+=γ
Overburden fluid
Coolant in
Coolant Out
Filtrate Core sample
Drilling Mud StorageDiaphragm Pump
Air
Floating Piston Accumulator
Refrigerated Circulator G-L Separator 1
G-L Separator 2
SR4J-580
N2
SR4J-580
N2
SR4J-350
CH4
BP50 BP50
GMFM1 GMFM2
A
Drilling Fluid Recirculation System
Drain Mud Face
Mud Vent Valve
Vent Mud Face
Bypass
B
Mud Fill Valve
Bypass
DFCH
N2
SR4J-580
Vacuum
Drilling Fluid Drain
Air
P1
P4
P2
P5
P6
P3
Drain
Exhaust
Q
Refill Valve
ISCO 500DX PUMP
Q
System Design and Development
Procedure• Core sample preparation & porosity
measurement • Preparation of recirculation system • Measurement of initial absolute permeability• Dynamic filtration at Overbalance
Pressure• Measurement of damaged permeability in
wellbore to reservoir direction • Measurement of return permeability in
reservoir to wellbore direction
Drilling Fluids RheologyBM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel
Composition n klbf.secn/100 ft2
PVcp
Shear Ratesec-1
Flow Rategpm
Linear Velocity
ft/min30 0.3503 10.9
40 0.4671 14.3
80 0.9342 28.8
30 0.3087 9.5
40 0.4116 12.7
80 0.8231 25.4
30 0.3626 11.2
40 0.4835 14.9
80 0.9671 29.8
30 0.3626 11.2
40 0.4835 14.9
80 0.9671 29.8
BM + 50 gm + 50 gm Q-Broxin
0.7365 0.03037 2
BM + 50 gm + 15 gm Dextrid
0.7365 0.04555 3
BM + 50 gm KCl
0.5142 0.1417 1.5
BM 0.6777 0.03653 1.5
Effect of Shear Rate and Overbalance on Base Mud
Damage
BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel
0.0
0.2
0.4
0.6
0.8
1.0
30 sec-1 40 sec-1 80 sec-1 40 sec-1 200 psi
k/ko
(ko-
initi
al p
erm
eabi
lity)
Damaged Return
Effect of Shear Rate and Overbalance on Flocculated Mud Damage
0.0
0.2
0.4
0.6
0.8
1.0
30 sec-1 40 sec-1 80 sec-1 40 sec-1 200 psi
k/ko
(ko-
initi
al p
erm
eabi
lity)
Damaged Return
BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite+ 0.5 gm KOH + 3 gm Quickgel
Effect of Shear Rate and Overbalance on Mackenzie Mud Damage
BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel
Effect of Filtration Control Agent
0.0
0.2
0.4
0.6
0.8
1.0
30 sec-1 40 sec-1 80 sec-1 40 sec-1 200 psi
k/ko
(ko-
initi
al p
erm
eabi
lity)
Damaged Return
Effect of Shear Rate and Overbalance on Dispersed Mud Damage
0.0
0.2
0.4
0.6
0.8
1.0
30 sec-1 40 sec-1 80 sec-1 40 sec-1 200 psi
k/ko
(ko-
initi
al p
erm
eabi
lity)
Damaged Return
BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel
Static and Dynamic Filtration (40 sec-1) of Mackenzie Mud
BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel
0
20
40
60
80
100
120
140
0 10 20 30 40 50 60
Cumulative time, min
Cum
ulat
ive
Volu
me,
ml
Static Filtration Dynamic Filtration
Static and Dynamic Filtration (80 sec-1) of Dispersed Mud
050
100150
200250
300350
400
0 10 20 30 40 50 60
Cumulative time, min
Cum
ulat
ive
Vol
ume,
ml
Static Filtration Dynamic Filtration
BM: 1 liter water + 0.3 gm Na2SO3 + 0.3 gm Barite + 0.5 gm KOH + 3 gm Quickgel
Conclusions• Annular fluid velocity or shear rate has pronounced effect on
dynamic fluid loss; however, the addition of filtration control agent gives reverse trend.
• Greater overbalance pressure causes more fluid leak-off and more damage. Damage at 200 psi overbalance was severe.
• Permeability impairment is strongly dependent on the state of dispersion of mud. The defloculated mud with lignosulfatecauses more damage by invading deeper with samllerparticles. The floculated mud gives poor quality filter cake, with more filtrate loss into the formation. The drilling fluid formulation giving a low permeability, high strength external mud cake would be ideal to minimize formation damage.
• Presence of filtration control agent (Dextrid) reduces the spurt loss and subsequent filtration rates significantly. The return permeability is found to be 94% after mud circulation at 80 sec-1 shear rate.
Schematic of laboratory set-up for formation of hydrates and relative permeability measurements
BR: Back pressure regulator G.F.M: Gas flow meterP.G: Propylene glycol C: Piston cylinderM. Cyl.: Measuring vessel P: Differential pressure transducer
Relative Permeability Studies
Measured water and gas relative permeability data for different hydrate saturations in Oklahoma 100 mesh sand
sample and Hot-Ice Samples
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Gas saturation, fraction
k rw
, fra
ctio
n
5%10%17%23%29%36%
0
0.01
0.02
0.03
0.04
0.05
0.06
0.0 0.2 0.4 0.6 0.8 1.0
Gas saturation, fraction
k rg,
frac
tion
5%10%17%23%29%36%
0.0
0.2
0.4
0.6
0.8
1.0
0 0.2 0.4 0.6 0.8 1
Gas saturation, fraction
k rw
, fra
ctio
n
7%2131
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.0 0.2 0.4 0.6 0.8 1.0
Gas saturation, fraction
k rg,
frac
tion
7%21%31%
Water and Gas relative permeability as a function of hydrate saturation for different iso-gas saturation values for Oklahoma 100 mesh sand and Hot-
Ice Samples
0.01
0.1
1
0 5 10 15 20 25 30 35 40
Hydrate saturation, %
krw
, fra
ctio
n
Sg=20%Sg=40%Sg=60%
0.0001
0.001
0.01
0.1
0 10 20 30 40
Hydrate saturation, %
k rg,
frac
tion
Sg=20%
Sg=40%
Sg=60%
0.001
0.01
0.1
1
0 10 20 30
Hydrate saturation, %
k rw
, fra
ctio
n
Sg=20%Sg=40%Sg=60%
0.0001
0.001
0.01
0.1
0 10 20 30
Hydrate saturation, %
k rg,
frac
tion
Sg=20%Sg=40%Sg=60%
Relative Permeability- Conclusions• Thus from the results in this study it is confirmed that the type of hydrate
growth not only depends on a number of sediment parameters, including grain size, porosity, structure, but also on parameters such as non-uniform dissociation, fluid parameters such as viscosity and the method of forming hydrates.
• Relative permeability inferred from unsteady state core floods conducted in this study is a lumped parameter which not only includes hydrate saturation but also the effects of dissociation instabilities caused by fluid flow, fines migration due to gas production and local compaction in porous media at low temperature.
• The relative permeability curves generated in the laboratory for sand samples and Anadarko field samples, to a great extent describe the field behavior of two phase flow in the presence of hydrates and would help in effective reservoir modeling for gas production from hydrate formations.
Initialization of Simulation
Reservoir Characterization
Porosity 36%
Permeability 300mD
Hydrate Saturation 0.7
Gas Saturation (hydrate zone) 0.1
Gas Saturation (gas zone) 0.8
Water Saturation 0.2
Max. Well Flow Rate 25 mmscfd
¾ of block hydrate, ¼ free gas
Scenario ran for 15 years
Production Modeling & Economic Evaluation of a Potential Gas Hydrate Pilot Production
Program on the North Slope of Alaska
Gas Production• The production remains on
plateau at a rate of 50 mmscfd for over three years. The main contributor during the plateau is likely to be the free gas and when this is depleted the rate quickly diminishes
• After the rate fall, the decline is steadier, as the dissociation of the hydrate supports production.
• Total Cumulative Production = 161.5 bcf
Daily Gas Production Rate
0
10
20
30
40
50
60
0 2000 4000 6000
time (days)
mm
scfd
Movement of Dissociation Front
At start of Simulation
After 6 months of production from the free gas zone, first signs of dissociation are seen
3 years: dissociation at margins has moved over 1 mile up dip
Cross Section of Reservoir at 6 years shows complete dissociation 400 meters up dip of the well and partial dissociation up to 1 mile distant8 Years
13 years: partial dissociation throughout most of reservoir
15 years: signs of dissociation in all areas of reservoir
Reservoir Cooling
Start of Simulation, temperatures equal geothermal gradient
After 1 year of production, the free gas zone has cooled slightly due to gas expansion. The area of hydrate beginning dissociation has also cooled
3 years: The area of dissociation has cooled to near freezing10 years and low temperature zone expands
At end of simulation (15 years), majority of hydrate zone is near freezing. The section near the well, which by this time is free of hydrate increases in temperature as heat flows from surrounding rocks
Economic Evaluation - SensitivityTornado Diagram +/- 10% Variation
-12.4
-25.1
3.7
3.7
4.2
22.3
32.7
6.3
6.3
5.8
-30 -20 -10 0 10 20 30 40
Gas Price
AK Gas Line
Capex
Lifting Costs
Royalty
NPV ($mm)
Conclusions• While recognizing this study had limitations, this was best
way forward at that time. This research has been refined to a great deal at present.
• The volumes of gas produced in base case scenario are sufficient to produce a ROR on investment cost of the project, though this is very dependent on gas price and transportation tariff. A reduced permeability results in an economic loss, though it can be overcome by expanding the project to reduce the burden of pipeline capital costs.
• Area of concern is the lowering of reservoir temperature, leading to freezing of water and plugging the formation and preventing efficient depressurization.
• Substantial depletion of a reservoir using depressurization alone would be a lengthy process and as such, methods to increase the rate of dissociation should be investigated for effectiveness and economic impact.
Partnership for Economic Development
Alaska
Impact to UA, UAF, StateUA Strategic PlanGoal 3: Research Excellence Goal 5: Responsiveness to State NeedsConduct research that solves problems of importance to the state, the nation, the north, and the world.Meet the educational, cultural, and economic needs of the diverse peoples of Alaska.Increase opportunities for undergraduate and graduate student participation in research.Capture Alaska-specific opportunities for the State and the University.Establish strong research relationships with the private sector and government agencies that address issues of importance to Alaska.Communicate the value of University research in terms of the University’s educational quality and Alaska’s economy
Trained UA/UAF GraduatesNew reserves to declining productionEconomic Development
UAF Petroleum Engineering Hydrate Research Group Student Success at National Competitions
Phillip Tsunemori (B.S.)1st Place 2004 SPE WRM
Namit Jaiswal (M.S.)-3rd Place 2004 SPE WRM
Sudiptya Banerjee (M.S.)-1st Place 2005 AADE, and3rd Place 2005 SPE WRM
Prasad Kerkar(M.S.)- 3rd Place
2005 AADE
UAF- In Communication With All Hydrate Resource Development Projects
India
Japan
Gulf of Mexico
Alaska Canada
Acknowledgement
• Robert Hunter and Scott Digert, BPXA• Brad Tomer and Ray Boswell, NETL, US DOE• Tim Collett, USGS• Brent Sheets and Jim Hemsath, AEO, US DOE• Scott Wilson, Ryder-Scott
Thank you.