Significant New “Learnings” Significant New “Learnings” From An Integrated Study Of An From An Integrated Study Of An Old Field, Foster/South Cowden Old Field, Foster/South Cowden Field (Grayburg & San Andres), Field (Grayburg & San Andres),
Ector County, Texas.Ector County, Texas.
Robert C. Trentham, DGSCenter for Energy and
Economic DiversificationUniversity of Texas of the
Permian Basin
Project ResultsProject Results
• 290,000 BO Incremental Production 1996 to present
• >650,000 BO Incremental Reserves• 3 Re-entries• 4 New Drills• >12 Workovers• Economic life of field extended from 9
to 16 years
Sec 36 Production 1977 to Sec 36 Production 1977 to 19931993
Bottom Line
““Learnings” Came in All Learnings” Came in All AreasAreas
•Reservoir Characterization•Well Testing•Re-completions •Production
INTEGATED STUDYINTEGATED STUDY
•GEOLOGICAL MODEL•3D SEISMIC / INVERSION
MODELING •FLOW MODELING•HISTORY MATCH•SIMULATION•WELL WORK, TESTING, AND
MONITORING
PROCEEDURESPROCEEDURES
•PRODUCTION TESTING•PRESSURE TRANSIENT TESTING
•WATER CHEMISTRY•WELL WORK
Type LogType Log
• Queen
• Upper Grayburg –Main Pay
• Lower Grayburg – Minor Pay
• San Andres – Large OOIP
FOSTER FIELD
INTEGATED STUDYINTEGATED STUDY
• GEOLOGICAL MODEL
• 3D SEISMIC / INVERSION MODELING
• FLOW MODELING• HISTORY MATCH• SIMULATION• TESTING, WELL
WORK, MONITORING
• OLD WATERFLOOD• CROSS FLOW
BETWEEN ZONES• NO FRACTURE
STIMULATIONS• BHP DISCREPANCIES• LOW PERMEABILLLTY• WHERE DID THE OIL
COME FROM AND WHERE DID THE WATER GO?
• OPEN HOLES / CASED HOLES
ProblemsProblems SolutiSolutionsons
•Discovered 1939•40 Acre spacing•Nitro Open Holes•Waterflood 1962•20 Acres 1979•Laguna 1992•DOE 1994•Oxy 2002
Reservoir CharacterizationReservoir Characterization
• San Andres Reservoir – Over Estimates and Under Achievement
• Barriers to vertical flow• Inversion Modeling to porosity
maps• Seismic Velocity related to Neutron
Density Porosity
Porosity vs. PermeabilityPorosity vs. Permeability
Seismic Inversion Seismic Inversion ModelingModeling
Porosity - Inversion vs. logPorosity - Inversion vs. log
Seismic Inversion Well Log
Well TestingWell Testing• Water Chemistry
– Inefficient sweep– Backup for well testing & workover
results– Carryover and Makeup water
• Bottom Hole Pressure Test results– Complex layering of reservoir– Cross flow– Low permeability = Longer test
duration• Production tests
– 3 day minimum
HC03 S04 CL CA MG NA TDS
UPPER GRAYBURG
170 2990 13500
1530 450 7750 26390
LOWER GRAYBURG
386 2632 20295
1889 664 11245
37332
SAN ANDRES 980 3881 33846
2507 762 19855
61831
INJECTION WATER
793 3100 32000
2646 947 17757
57244
CANYON 329 1104 76532
5880 692 42193
126693
ELLENBURGER
439 1459 63917
3840 972 36064
106691
LOWER GRAYBURG Na, Cl, TDS
FP#11 WH#2 WH#2
0
10000
20000
30000
40000
50000
60000
70000
0 1 2 3 4 5 6 7 8 9 10 11 12 13
PP
M
NA
CL
TDS
FS#11
SAN ANDRES Na, Cl, TDS
FS#11 WH#2 WH#12
0
10000
20000
30000
40000
50000
60000
70000
0 1 2 3 4 5 6 7 8 9 10
PP
M
NA
CL
TDS
0
20000
40000
60000
80000
8/28/76 2/18/82 8/11/87 1/31/93 7/24/98
DATE
PPM
TDS
NA
CL
PRODUCED WATER TOTAL DISSOLVED SOLIDS, SODIUM, CHLORIDE
INJECTION WATER TOTAL DISSOLVED SOLIDS, SODIUM, CHLORIDE
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
100000
9/15/65 3/8/71 8/28/76 2/18/82 8/11/87 1/31/93 7/24/98DATE
PP
M
TDS
NA
CL
History Match
1939 Discovery 1961 Waterflood
1979 20 Acre Infill 1996 Simulation
BOTTOM HOLE PRESSURE TESTINGBOTTOM HOLE PRESSURE TESTING
AND AND
THE IMPACT OF PERMEABILITY THE IMPACT OF PERMEABILITY ON ON
PRESSURE DISTRIBUTIONPRESSURE DISTRIBUTION
Upper Grayburg wells 1320’ Upper Grayburg wells 1320’ apartapart
544 #
1534 #
2124 #
955 #
Dual Zone TestDual Zone Test
After CIBPAfter CIBP
Same Well After Re-fracSame Well After Re-frac
Recompletions/WorkoversRecompletions/Workovers
• 1955 to 1982 Fracture Stimulation are closed, healed or scaled over
• Acid Stimulations unsuccessful in contacting reservoir
• Success rate can be estimated and candidates ranked by Bottom Hole Pressure, Water Chemistry and Production Tests
Brock Lease Workover Brock Lease Workover ResultsResults
Well Work Date $$ BOPD MCFPD BWPD
BR #5
Re-Frac
8/98 58.5 6 1 6
Post-Frac
72 10 200
6/02 13 3 71
BR#6 Re-Frac
8/98 68.6 3 1 9
Post-Frac
38 10 220
6/02 9 2 62
BR#7 Re-Frac
8/98 77.2 6 2 5
Post-Frac
44 6 242
6/02 15 5 178
ProductionProduction• Outcome of fracture stimulation is
proportional to bottom hole pressure and Oil/Water production rates prior to treatment
• Flowing water recoveries do not condemn a well. Some wells produce many times load and have to have fluid level drop below 1000’ from surface before producing OIL!
Bottom LineBottom Line
$ucce$$ful Project?$ucce$$ful Project?• PRODUCTION BEFORE WELL WORK
(UPPER GRAYBURG ONLY) 37 BO, 9
MCF, 181 BW• INITIAL PRODUCTION AFTER WORK
467 BO, 145 MCF, 3167 BW
• CURRENT PRODUCTION RATE 280 BO, 65 MCF, 2323 BW
AcknowledgementsAcknowledgements
• Dick Weinbrandt• Bill Robinson• DOE Tulsa office• The Staff of Laguna Petroleum • Baker-Hughes (previously Scientific
Software Intercorp)• Paul Laverty