sequestration in coal - unconventional gas · 1 pds030402(co2 forum).ppt the coal-seq project field...
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PDS030402(CO2 Forum).ppt1
The Coal-Seq Project
Field Studies of ECBM and CO2
Sequestration in CoalPresented by:
Scott R. Reeves
Advanced Resources International
Coal-Seq I Forum
March 14 & 15, 2002
Houston, Texas
PDS030402(CO2 Forum).ppt2
Presentation Outline
• Project Description
• Allison Unit
• Tiffany Unit
• Supporting Studies
• Closing Remarks
PDS030402(CO2 Forum).ppt3
Project Objectives
• Perform Two Detailed (Reservoir Modeling) Field Studies of Long-Term, Multi-Well CO2/N2Injection into Coalseams (Allison & Tiffany Units, San Juan Basin).
• Couple that with Fundamental Understanding of CO2 Sequestration Reservoir Mechanics (“benchtop” studies of sorption behavior, coal swelling, geochemistry).
• Develop Screening Model to Evaluate Potential Coalseam Sequestration Projects
• Assess Potential for Coalseam Sequestration across U.S
• Disseminate Results to Industry
PDS030402(CO2 Forum).ppt4
Unique Project Features
• Studying CO2 sequestration based primarily on the results of long-term, multi-well field tests.
• Laboratory studies play supporting (not primary) role.
• Also look specifically also at N2injection.
PDS030402(CO2 Forum).ppt5
Why Nitrogen?• Power plant flue gases contain mostly nitrogen
– not having to process flue gas to a pure CO2stream has important front-end cost reduction implications.
• Nitrogen is an effective ECBM injectant – early incremental methane production also has important cost implications for lowered net CO2sequestration costs.
• Examining both “end points” will facilitate “unified” understanding of reservoir mechanics and improve reliability of mixed gas injection predictions.
PDS030402(CO2 Forum).ppt6
Two Reservoir Mechanisms
• Methane stripping (nitrogen)• Methane displacement (carbon
dioxide)
Note: BP (Amoco) holds numerous patents on both N2and CO2 injection for ECBM recovery.
PDS030402(CO2 Forum).ppt7
Adsorption Isotherms, San Juan Basin
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Pure Gas Absolute Adsorption on Tiffany coals at 130°F wet coal
PDS030402(CO2 Forum).ppt8
Gas Production ResponseNitrogen Carbon Dioxide
Gas Production Response to CO2 Flooding
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0 30 60 90 120 150 180 210 240Month
Gas
Rat
e, M
scfd
Base Case
CO2 @ 500 McfdCO2 @ 250 Mcfd
1.0 Bcf (2.7 Bcf CO2 sequestered)
@500 Mcfd1.8 Bcf
0.4 Bcf (1.4 Bcf CO2sequestered)
@ 250 Mcfd1.1 Bcf
Incremental CH4 Recoveries
Gas Production Response to N2 Flooding
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Gas
Rat
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scfd
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60.00%
70.00%
Nitr
ogen
Con
tent
Nitrogen Content
Base Case
N2 @ 500 Mcfd
N2 @ 250 Mcfd
Net Methane
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Injection/Production Ratios
Injection/Production Ratios500 Mcfd Inj Rate
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Month
Inj/P
rod
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N2 Inst N2 Cum
CO2 Inst CO2 Cum
PDS030402(CO2 Forum).ppt10
Field Response Expectations
Nitrogen– Immediate gas production increase – Early N2 breakthrough– N2/CH4 ratio reaching minimum of <1 at N2
breakthrough, then gradually increasing
Carbon Dioxide– Delayed gas production increase– Late CO2 breakthrough– CO2/CH4 ratio stabilizing at +/- 2:1
PDS030402(CO2 Forum).ppt11
• Allison Unit• San Juan basin• Upper Cretaceous Fruitland Coal• Burlington Resources• Carbon dioxide injection• 16 producers• 4 injectors• 1 pressure observation well
• Tiffany Unit• San Juan basin• Upper Cretaceous Fruitland Coal• BP America• Nitrogen injection• 34 producers• 12 injectors
Only Two “Commercial-Scale” Field Tests Exist Worldwide
PDS030402(CO2 Forum).ppt12
Field Sites, San Juan Basin
F a r m i n g t o n
A z t e c
B l o o m f i e l d
D u l c e
D u r a n g o P a g o s a S p r i n g s
C O L O R A D O N E W M E X I C O
L A P L A T A C O . A R C H U L E T A C O .
C O A L S i t e
K A O 9 9 1 0 0 . C D R
A l l i s o n U n i t
F A I R W A Y
F l o r i d a R i v e r P l a n t
T i f f a n y U n i t
San Juan Basin Outline
N2 Pipeline
PDS030402(CO2 Forum).ppt13
Presentation Outline
• Project Description
• Allison Unit
• Tiffany Unit
• Supporting Studies
• Closing Remarks
PDS030402(CO2 Forum).ppt14
• Field on primary production in 1989.• CO2 injection commenced in 1995 (four
wells).• Production enhancement program
implemented (recavitation, line pressure reduction, well reconfigurations, onsite compression)
• CO2 injection suspended for 12-months in August, 2001 to carefully study “long-term” effects of ECBM operations.
Field History/Status - Allison
PDS030402(CO2 Forum).ppt15
Allison Unit Base Map
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POW#2
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12M
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PDS030402(CO2 Forum).ppt16
Allison Production HistoryAllison Unit Performance
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Gas Rate, Mcf/mo CO2 Injection Rate, Mcf/mo Well Count
16 producers, 4 injectors, 1 POW
Five wells shutin during initial injection period
Injection suspended, five wells reopened
Line pressures reduced, wells reconfigured, onsite compression installed
Injection resumed
Recavitations, line pressure reduced, wells reconfigured, onsite compression installed
PDS030402(CO2 Forum).ppt17
Data Available for Model
•Skin, delta-skin due to recavitation•Bottomhole injection pressures
“Inferred” Data•Relative permeability•Porosity•Pore-volume compressibility•Permeability exponent
•Isotherms (2 samples each from 3 wells)•Reservoir pressure (POW#2)•PTA – May 2000 - 8 prod wells•CO2 injection data•Surface CO2 injection pressures•PTA – August 2001 – 4 inj wells
“Raw”Data•Gas production•Water production (limited)•Recent casing pressures•Gas composition•Coal depths/thicknesses•Completion/Restimulation info
PDS030402(CO2 Forum).ppt18
Reservoir Model Description
• 16 production wells, 4 injector wells, 1 pressure observation well
• 33 x 32 gridblocks (18,500 ft x 16,800 ft, 7,100 acres)
• 3 (independent) layers (3,168 total gridblocks)
• COMET2 simulator
PDS030402(CO2 Forum).ppt21
Status
Current• Initial history-match achieved.
Next Steps• Review with Burlington, formulate strategy to
achieve final match.• Run “what-if” and economic optimization
cases.• Prepare/publish report.
PDS030402(CO2 Forum).ppt22
Presentation Outline
• Project Description
• Allison Unit
• Tiffany Unit
• Supporting Studies
• Closing Remarks
PDS030402(CO2 Forum).ppt23
• Field on primary production in 1983
• Intermittent N2 injection commenced in 1997 (12 wells).
Field History/Status - Tiffany
PDS030402(CO2 Forum).ppt24
Tiffany Unit Base Map
Producer-to-Injector Conversions
Previous Study Area
PDS030402(CO2 Forum).ppt25
Tiffany Production History
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ate
Gas Rate, Mcf/mo N2 Injection Rate, Mcf/mo Water Rate, Bbls/mo
34 producers, 12 injectors
PDS030402(CO2 Forum).ppt26
Data Available for Model
•Relative permeability•Absolute permeability•Porosity
“Inferred” Data•Results of simulation study performed in 1993 (permeability, permeability anisotropy and orientation, relative permeability, porosity)
•Coal depths/thicknesses•Completion info •Reservoir pressure (injection wells, June 1997)
“Raw”Data•Gas production•Water production•Gas composition
PDS030402(CO2 Forum).ppt27
Reservoir Model Description
• 34 production wells, 12 injector wells• 37 x 73 gridblocks (25,600 ft x 38,900 ft,
22,800 acres)• 4 independent layers (10,804 total
gridblocks)• COMET2 simulator
PDS030402(CO2 Forum).ppt30
Status
Current• Model initialized.
Next Steps• Achieve initial history-match.• Review with BP America, formulate strategy to
achieve final match.• Run “what-if” and economic optimization cases.• Prepare/publish report.
PDS030402(CO2 Forum).ppt31
Presentation Outline
• Project Description
• Allison Unit
• Tiffany Unit
• Supporting Studies
• Closing Remarks
PDS030402(CO2 Forum).ppt32
Benchtop Study Topics
• CO2 sorption behavior near critical point, multi-component sorption modeling:qObtained independent data set from TiffanyqDid not observe abnormal CO2 sorption behavior
(validity of Langmuir model?)qSee work of Oklahoma State University
• Matrix shrinkage/swelling:qAnalyzing long-term CO2 injection behavior at
Allison.qSwelling appears to be an issue, but further
analysis required.
PDS030402(CO2 Forum).ppt33
Benchtop Study Topics (continued)
• Geochemistry:qPerformed equilibrium modeling on
Tiffany water samples.qNo precipitate problems expected.
• Modeling:qRECOPOL project (Appalachian basin analog).qARC ECBM project (mixed gas injection).qModel comparison study.
PDS030402(CO2 Forum).ppt34
Presentation Outline
• Project Description
• Allison Unit
• Tiffany Unit
• Supporting Studies
• Closing Remarks
PDS030402(CO2 Forum).ppt35
Significant Accomplishments• Comprehensive compilation of long-term,
commercial-scale field results; general agreement with laboratory and simulation-based predictions observed.
• Collected independent set of multi-component isotherm data; dispelled abnormal CO2 sorption behavior.
• Collection/analysis of first long-term CO2 injection data in coal to examine existence and magnitude of matrix swelling effects
• Gained insights into potential for precipitates formation with CO2 injection.
PDS030402(CO2 Forum).ppt36
Interim Findings/Conclusions
• Feasibility/economics of CO2 sequestration (or ECBM recovery) in coalseams not established
• Field results providing valuable insights into reservoir processes
• Reservoir mechanics of CO2/N2 injection into coalseams not fully understood:– CO2 sorption behavior– Matrix swelling– Modeling requirements and capabilities
PDS030402(CO2 Forum).ppt37
Near Term• Complete field studies (i.e., final history
matches, forecasts, economics and field practices). Prepare reports & publications.
• Finalize reservoir mechanism studies (i.e., multi-component isotherms, matrix shrinkage/expansion, geochemical studies). Prepare report & publication.
Future Work