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