Depositional, Diagenetic Depositional, Diagenetic and and

Tectonic Complexity of the Tectonic Complexity of the San Andres on the Central San Andres on the Central

Basin PlatformBasin Platform

Bob TrenthamBob Trentham

CEED UTPBCEED UTPB

Problem StatementProblem StatementThe Guadalupian on the Central Basin The Guadalupian on the Central Basin

Platform has produced more oil than any Platform has produced more oil than any other reservoir in the Permian Basin (>3.5 other reservoir in the Permian Basin (>3.5 BBO). However, percent recoveries from BBO). However, percent recoveries from primary, secondary and tertiary methods is primary, secondary and tertiary methods is low (ranging from 11 to 50%). low (ranging from 11 to 50%).

In part, this is a function of a “postage In part, this is a function of a “postage stamp” mentality where workers, both stamp” mentality where workers, both geologists and engineers, become experts geologists and engineers, become experts in particular fields.in particular fields.

This leads to an incomplete understanding This leads to an incomplete understanding of the regional which in turn reduces the of the regional which in turn reduces the potential for enhance reserve recovery.potential for enhance reserve recovery.

Naming ConventionNaming Convention Holt on Central Basin Platform = Leonardian 7 Holt on Central Basin Platform = Leonardian 7

and 8 of Kerans = lower Cutoff? Called lower and 8 of Kerans = lower Cutoff? Called lower SA1 and lower SA2 in 2002 Kerans CD. SA1 and lower SA2 in 2002 Kerans CD.

McKnight = Guadalupian 1 & 2 (middle SADR1 McKnight = Guadalupian 1 & 2 (middle SADR1 and middle SADR2) in 2002 Kerans CD. Includes and middle SADR2) in 2002 Kerans CD. Includes McKnight Shale that is probably middle SADR1 McKnight Shale that is probably middle SADR1 equivalent. Ward sees no major karst event at equivalent. Ward sees no major karst event at top of McKnight.top of McKnight.

Intermediate = Guadalupian 3 & 4 (upper Intermediate = Guadalupian 3 & 4 (upper SADR1 & upper SADR 2) in 2002 Kerans CD. SADR1 & upper SADR 2) in 2002 Kerans CD. Brushy Canyon Bypass Surface = top Brushy Canyon Bypass Surface = top Intermediate. Brushy Canyon = Guadalupian 5, Intermediate. Brushy Canyon = Guadalupian 5, 6 & 7 (BR 1, 2 & 3).6 & 7 (BR 1, 2 & 3).

Judkins = Guadalupian 8 (upper SADR3) in 2002 Judkins = Guadalupian 8 (upper SADR3) in 2002 Kerans CD. Major karst surface at top.Kerans CD. Major karst surface at top.

Post Judkins = Guadalupian 9 (upper SADR4) in Post Judkins = Guadalupian 9 (upper SADR4) in 2002 Kerans CD. Major karst surface, base is 2002 Kerans CD. Major karst surface, base is Lovington Sand. Could be called Lovington Lovington Sand. Could be called Lovington Interval or Lovington Equivalent.Interval or Lovington Equivalent.

KeransTrentham

Ward

Guad 2middle SADR

2 McKnight

P - 6 lower

Pay Zones in Howard - Glasscock, Iatan, Diamond M, etc

Guad 1middle SADR

1 McKnight Shale P - 7

Leon 8 lower SADR 2

Holt P - 8

SADR

Leon 7 lower SADR 1

Leon 6 Glorieta 1 Glorieta GlorietaSan Angelo San Angelo

Lower San Andres

Guad 8 upper SADR 3BR 4 Judkins

Pi Marker P-1 P-2 P-3

Slaughter 1 - 3

Cedar Lake, Welch, Moore, & SADR prod in Reagan Co.

Guad 7 BR 3

Guad 6 BR 2

Guad 5 BR 1

Guad 4 upper SADR 2 Intermediate

P - 4

Guad 3 upper SADR 1 P – 5

Middle San Andres

Kerans(2001)Trentham/Ward (2002)

Northwest Shelf Eastern Shelf

Guadalupe Mts., NW ShelfDelBasin

Central Basin Platform NM TX NE Midland Basin

Guad 10GRBG 1

CC 2

lower GRBG

Premier Sand Premier Sand

Guad 9 upper SADR 4 CC 1Post

Judkins

Upper SADR

Evaporitic Facies

Evaporitic Facies

Non-deposited or ErodedLovington Sand Lovington Sand

Upper San Andres

The paradigm has been that all San

Andres reservoirs on the Central Basin

Platform “flood the same” and produce

from the same rocks.

San Andres Structural San Andres Structural HistoryHistoryThe San Andres on the platform has had a on the platform has had a

complex history including multiple karsting complex history including multiple karsting (Low Stand) events.(Low Stand) events.

The model for San Andres deposition on The model for San Andres deposition on the platform are the Guadalupe Mountain the platform are the Guadalupe Mountain outcrops which were deposited in a outcrops which were deposited in a tectonically passive environment.tectonically passive environment.

However…..There is an middle to upper However…..There is an middle to upper San Andres uplift of the southern end of San Andres uplift of the southern end of the Central Basin Platform that is NOT the Central Basin Platform that is NOT seen in the Guadalupe Mts.seen in the Guadalupe Mts.

The San Andres varies from +/-600‘ to The San Andres varies from +/-600‘ to >1600’ on the platform both as a result of >1600’ on the platform both as a result of thickening toward the platform margins thickening toward the platform margins and thinning over pre-existing structures.and thinning over pre-existing structures.

This Leads To:This Leads To:In the southern portion of Crane Co. there In the southern portion of Crane Co. there

are are coal bedscoal beds and reworked coals in the and reworked coals in the middle and upper San Andres. middle and upper San Andres.

The Penwell, Jordan, Waddell and The Penwell, Jordan, Waddell and Keystone Fields produce from Keystone Fields produce from upperupper San San Andres on the flanks and Andres on the flanks and middlemiddle San San Andres on the crest of the structures.Andres on the crest of the structures.

McKnight (lower SADR) production, a McKnight (lower SADR) production, a major producing horizon in Sand Hills major producing horizon in Sand Hills Field, may have been by passed in a Field, may have been by passed in a number of fields. number of fields.

San Andres Sub-ProvincesSan Andres Sub-ProvincesUplift – Ft Stockton Uplift portion of CBP. Mostly in

Pecos Co. 600 to 1000’ SADR.Spine – north to south axis of CBP. Extends thru W.

Crane, W. Ector, E. Ward, E. Winkler, W. Andrews, and E. Lea Counties. 800 – 1200’ SADR

Outboard - Eastern and Western margins of CBP, Crane, Ectro, Andres, Gaines, Ward, Winkler and Lea Counties

North and Northwest Shelves -. Northern Midland Basin Rim and Northwest Shelf of Delaware Basin. 1200 to 1500’ SADR. Better analogs to Guadalupe Mts.

Ozona Arch - More deeply eroded than CBP. Possibly nearer to source of tectonism. 600 to 1100’ SADR.

Eastern Shelf – 0 to 800’. Close to source of tectonism.

Midland Basin – Mix of clastics and carbonates.

San Andres Sub-provincesSan Andres Sub-provincesFIELDS BY THICKNESS AND PROVINCE

0

200

400

600

800

1000

1200

1400

1600

1800

1 2 3 4 5 6 7 8

UPLIFT

SPINE

NW SHELF

OUTBOARD

NORTH SHELF

OZONA ARCH

MIDLAND BASIN

EASTERN SHELF

I 20 CROSS SECTIONI 20 CROSS SECTION

H.S.A.H.S.A. JANELLJANELL PENWELLPENWELL FOSTERFOSTER

LOVINGTONLOVINGTON 243243 E 75E 75 E EE E 250250

JUDKINSJUDKINS 340340 275275 E 237E 237 338338

INTERMEDIATEINTERMEDIATE 243243 235235 236236 255255

McKNIGHT (+ McKNIGHT (+ Holt)Holt) 480480 435435 312312 663663

TOTALTOTAL 13061306 10321032 785785 15061506

San Andres FactoidsSan Andres FactoidsIf >900’ Lovington may be present. If >900’ Lovington may be present. @ ~~ 900’, Judkins, no Lovington. @ ~~ 900’, Judkins, no Lovington. If <600’, no Judkins.If <600’, no Judkins.Contour maps of GRBG and SADR production Contour maps of GRBG and SADR production

is from wells IP’d prior to 1950. The is from wells IP’d prior to 1950. The assumption is that these are natural, acid or assumption is that these are natural, acid or nitro completions with no fracsnitro completions with no fracs..

TThe San Andres in the Foster area is +/- in the Foster area is +/- 1500’ thick. In the Penwell area, 15 miles to 1500’ thick. In the Penwell area, 15 miles to the southwest, the SADR is only ~800’ thick.the southwest, the SADR is only ~800’ thick.

The “boomer wells” (>10,000 BOPD) on the The “boomer wells” (>10,000 BOPD) on the east flank of the McElroy Field are from east flank of the McElroy Field are from karsted upper SADR.karsted upper SADR.

B

B

B

B

A

B

B

C

C

C

CC

D

D

D

D

D 250 – 500 BOPD

D

C 500 – 1,000 BOPD

B 1,000 – 5,000 BOPD

A 5,000 – 10,000 BOPD

B

Waddell

Penwelll

Jordan

Harper

TXL

Goldsmith

Andector

Lawson Donnelly

E. Goldsmith

FosterS Cowden

N. & W. Goldsmith

EmmaEmbar

San Andres production San Andres production in in RedRed overlain on overlain on IsopachIsopach

Note northwest to Note northwest to southeast trend of southeast trend of both isopach and both isopach and production.production.

Note relationship Note relationship between isopach thins between isopach thins and production and production

Western boundary of Western boundary of production is production is controlled by updip controlled by updip permeability barrierpermeability barrier

Work to DateWork to Date

7 cores 2 in Sand Hills; 2 in 7 cores 2 in Sand Hills; 2 in North Ward Estes; 3 in Foster-North Ward Estes; 3 in Foster-South CowdenSouth Cowden

Cross section network in Crane Cross section network in Crane Co.Co.

Correlation of 100 wells in North Correlation of 100 wells in North Ward Estes areaWard Estes area

Ector County San Andres Ector County San Andres ProjectProjectCorrelate units within the San Andres Correlate units within the San Andres

in Ector County. in Ector County. Create Cross section grid.Create Cross section grid.Delineate San Andres production by Delineate San Andres production by

unit.unit.Evaluate depositional history and Evaluate depositional history and

diagenetic overprint of the San Andres.diagenetic overprint of the San Andres.Generate isopach and structure maps Generate isopach and structure maps

of each San Andres unit. of each San Andres unit.

Needed ResourcesNeeded Resources

Digital Data – logs, bases, Scout Digital Data – logs, bases, Scout info, seismicinfo, seismic

Rock Data – Cores, samples from Rock Data – Cores, samples from selected wellsselected wells

FundingFunding