Stratigraphic Framework of theWolfcamp – Spraberryof the Midland Basin

Lowell Waite

Department of GeosciencesPermian Basin Research LabUniversity of Texas at Dallas

October 8, 2019

Roswell Geologic Society

Permian Basin Research Lab at UT DallasDr. Robert J. Stern and Mr. Lowell Waite, Co-Directors

Goals:

• Advance understanding of all geologic aspects of the Permian Basin through open applied research,linking academia and industry

• Educate and better prepare students for professional careers in the oil and gas industry

-- established January, 2019 --

• Graduate courses offered:

https://labs.utdallas.edu/permianbasinresearch/

• Geology of the Permian Basin

• Petroleum Geoscience

• Paleo Earth Systems: Global Themes

Stratigraphic framework of Wolfcamp – Spraberry:Objectives

• Review the tectono-stratigraphic framework of the Wolfcamp and Spraberry deep-water units of the Midland Basin, west Texas

Note: although not specifically addressed, the framework outlined here is applicableto the Delaware Basin

• Briefly discuss the facies/characteristics of these rocks

• Highlight the differences between the Wolfcamp shale (A – D) and Spraberry depositional systems

Fold and thrust belt

Basement uplift

Shallow marine shelf

Reef / shoal complex

Deep marine basin

PrecursorTobosa Basin(Ord. to Miss.)

Greater Permian Basin Region

StudyArea

• Confluence of Marathon-Ouachita fold and thrust belt and Ancestral Rockies basement-involved uplifts(Penn. – early Permian)

Permian Basin Stratigraphy and Tectonic History

System

Permian

Pennsylvanian

Mississippian

Devonian

Silurian

Ordovician

Cambrian

Precambrian

Series

Ochoan

Guadalupian

Leonardian

Wolfcampian

Virgilian

Missourian

Desmoinesian

Atokan

Morrowan

Chesterian

Meramecian –

Osagean

Kinderhookian

Upper

Middle

Lower

U. Niagaran

L. Niagaran

Alexandrian

Cincinnatian

Mohawkian

Chazyan

Canadian

Ozarkian

Upper

Delaware BasinFormations

Wolfcamp

Cisco

Canyon

Strawn

Atoka

L. Miss Lm

Woodford

Devonian (Thirtyone)

Upper Silurian (Wristen)

Fusselman

Montoya

Ellenburger

Rustler

Lamar

Cherry Canyon

Brushy Canyon

BromideTulip Crk.

Mclish

Oil Creek

Sim

pso

n

McKee Sd.

Waddell Sd.

Connell Sd.

Joins

Bone

Spring

3rd Sand

Dewey Lake

Salado

Precambrian

Basement

Bell Canyon

Morrow

Barnett

DetritalLime

Cutoff Member /

1st Carb / Avalon

1st Sand

3rd Carb2nd Sand2nd Carb

Stray Sd

Castile

CBP & NW ShelfFormations

Wolfcamp

Cisco

Canyon

Strawn

Atoka

L. Miss Lm

Woodford

Devonian (Thirtyone)

Upper Silurian (Wristen)

Fusselman

Montoya

Ellenburger

Rustler

Tansill

Queen

Seven Rivers

Grayburg

Glorieta

Go

at

Se

ep

Cap

itan

BromideTulip Crk.

Mclish

Oil Creek

Sim

pso

n

McKee Sd.

Waddell Sd.

Connell Sd.

Joins

U. Miss Lm

Dewey Lake

Salado

Precambrian

Basement

Yates

Morrow (NW Shelf Only)

U. BarnettL. Barnett

DetritalLime

Midland BasinFormations

Wolfcamp

Cisco

Canyon

Strawn

Atoka

L. Miss Lm

Woodford

Devonian (Thirtyone)

Upper Silurian (Wristen)

Fusselman

Montoya

Ellenburger

Rustler

Tansill

Queen

San Andres

Seven Rivers

Grayburg

BromideTulip Crk.

Mclish

Oil Creek

Sim

pso

nMcKee Sd.

Waddell Sd.

Connell Sd.

Joins

Sylvan Sh.

Holt /Upper Leonard

Spraberry

Dean

Clear-

fork

U. Miss Lm

Dewey Lake

Salado

Precambrian

Basement

Yates

Wolfcamp D

UpperMiddle

Lwr Jo Mill

Wolfcamp A

Wolfcamp BWolfcamp C1Wolfcamp C2

Morrow

U. BarnettL. Barnett

Bend Lm

DetritalLime

Sh & Detrital

L. SPBY Sh

Bliss AbsentWilberns

Bliss / Hickory / Riley

Wichita / AboLower Clearfork

Yeso /

ClearforkTubb

Middle Clearfork

Upper Clearfork

Holt / Upr LeonardLwr San Andres

Lower San Andres

Upper San AndresDela

ware

Mtn

Gro

up

541

485

444

419

359

323

299

252

Ma

Early WFMP Event

Tectonic Phase

Strawn EventAtokan Event

Morrow Event

Penn. – Early PermianForeland Deformation

Tobosa Basin(Middle Ordovician to

Late Mississippian)

Moderate Subsidence

Post Orogenic Loading Rapid Subsidence;

Onset of HC Generation

Grenville Orogeny (1.3 to 1.0 bya)

Basement assembly and breakup of

Rodinia supercontinent

(~ 150 million yrs. duration)

(~ 30 million yrs.

duration)

( ~ 50 million yrs. duration )

Passiv

e M

arg

inA

ctive M

arg

in

mid – Wolfcamp unconformity

final basin fill/termination

Great American Carbonate Bank(Late Cambrian – Early Ordovician)

TOB

OSA

BA

SIN

PH

ASE

PER

MIA

N B

ASI

N P

HA

SE

(modified fromReed, unpub., 2016)

+5,000

(

Top Precambrian structure (courtesy of Mark George, PXD)

Ft. +5000

0

-5000

-10000

-15000

-20000

-25000

Midland

Basin

Delaware

Basin

Guadalupe

Mountains

datum: sea level0

-5,000

-10,000

-15,000

-20,000

Ft.

Eastern ShelfMidland BasinCentral

Basin

Platform

Delaware Basin

Woodford

Dewey Lake

Triassic

Strawn - Atoka

Woodford

Wichita - Abo

Clear Fork

Queen - Grayburg Tansill – Yates – Seven Rivers

Salado

(WTGS, 1984)

The Permian Basin

(maps: Ron Blakey, NAU/Colorado Plateau Geosystems)

Late Pennsylvanian • Icehouse climate; PB in humid-tropical setting (abundant rainfall)• Numerous high-freq., high-amplitude sea-level changes• Expansion of Penn seaway (long-term rise); stratified water columns• Continued tectonism in west Texas (Marathon-Ouachita FTB, rise of ARM)

A very dynamic time in

Earth history, especially in

west Texas

Wolfcampian – Early Leonardian• Waning icehouse, transition to greenhouse• Northward drift of Pangea• Increasing aridity & expansion of continental desert in western U.S.• Cratonic emergence / contraction of seaway (onset of long-term SL fall)• Culmination of tectonic pulses in W. TX (mid WC); Pacific arc volcanism (Late WC-Leon.);

PB enters rapid subsidence phase (Dean - Spraberry)

LATE PENNSYLVANIAN – EARLY PERMIAN EVOLUTION OF WESTERN PANGEA

2nd-ordercycles

1

T

R

2

T

R

3

T

R

4

T

R

T

5

Chrono-stratigraphy

Sea-levelrise

OperationalUnitsFZ a. b. c.

Gre

enh

ou

se

a. Tectonicpulses

b. Ash beds

c. Climatephase

FZ. Fusulinidzonation

R = RegressionT = Transgression

(Sea-level curve from

Ross and Ross, 2009;

Fusulinid zonation from

Wahlman, 2019)

Numerous 3rd- and higher-order cycles of sea-level change organized into larger 2nd-order trends (5 – 10+ m.y. in duration); from oldest to youngest:

WC D – lowermost WC C2

WC C2

WC C1

WC A - B

Spraberry – L. Clear Fork

1

2

3

4

5

mwu mwu: mid-Wolfcampunconformity

Stratigraphic framework,Wolfcamp - Spraberry

7500

8000

8500

9000

9500

10000

10500

Penn.

Wolfcam

p-

ian

Le

on

ard

ian

Wolfcamp D: Basinal cyclothems (starved basin)

Wolfcamp C: Clay-rich shale(progradation of Eastern Shelf deltas & Glasscock Nose)

Wolfcamp A – B: silty- and calcareous organic-rich mudstones;carbonate percentage increases upward

Spraberry – Dean:silty mudstones and clay-rich siltstones punctuated by multiple deeper-water submarine fan complexes(incl. massive to laminated, fine-grained sandstones)

Lower Strawn: shallow-water platform limestones

mid-WCunconformity

GENERAL DESCRIPTION / DEPOSITIONAL FACIES

C2

C1

A

Jo Mill

Lower

Leonard

Shale

Dean

Lower

Spraberry

Middle

Spraberry

Upper

Spraberry

UpperLeonard

Strati-graphy

WFMP

D

B

Wo

lfc

am

p

Midland Basin Type Log

(modified from Hamlin and Baumgardner, 2012)

MD(ft.)

Lower Strawn Limestone andWolfcamp D (Cline)

Mid Continent / Anadarko Basin

(Gianoutsos et al, USGS, 2014)

AAPG COSUNA chart (1985)Midland Basin

(Reed and Mazzullo, 1987)

Midland BasinFusulinid zonation

Wolfcamp

Formation

Eastern Shelf

Lower Strawn Limestone = Early Strawn

Middle & Upper Strawn =lower portion of WC D

STRAWN GROUP STRATIGRAPHY (DESMOINESIAN SERIES)

Wolf-

camp-

ian

Admiral Fm.

Putnam Fm.

Moran Fm.

Pueblo Fm.

Cisco –

Canyon

Group

Cisco Gp.

Canyon Gp.

Strawn Gp.Strawn

Gp.

Bend Gp.Bend Gp.

Virgil-ian

Miss-ourian

Pe

nn

sylv

an

ian

Des-moine-

sian

Atokan

Morro-wan

Barnett

Shale

Mississippian

Limestone

Mississippian

Limestone

Ches-terian

Mera-mec-ian

Osagean

Mis

sis

sip

pia

n

Lower Desmoinesian Facies (Lower Strawn Limestone)

• Shallow water platform carbonate facies extend across entire Midland Basin and Eastern Shelf region

• Lower Strawn Limestone is generally < 200 ft. thick in Midland Basin

(Wright, 2011)

• Core analyses indicate typical Penn shelf cyclothem deposits: burrowed skeletal wackestones grading upward into phylloid algal packstones and skeletal grainstones, capped by exposure surfaces

• Pre-dates drowning of Midland, Delaware basins

Wolfcamp D (Canyon – Cisco) facies

(Ewing, 2016)

Organic-rich Wolfcamp D (Canyon – Cisco)

black shales in core from the center of Midland Basin

(Saller et al., 1999)

Photomicrographs of

highly porous limestones

of the Horseshoe Atoll

reef complex

2 in.

• Drowning of basins and backstepping of surrounding shelfal regions

1

T

R• Silica – rich shales; relatively high clay content

thin dolomite or LS; highly correlative basin-wide

• Organic content partitioned into multiple thin cycles

Wolfcamp D: Basinal cyclothems

10

0 f

t.

0 150GR 0.2 2000Res.

L. Strawn

1040

010

500

1060

0

• Equivalent to classic “Penn. cyclothems” on shelves

non-porous, thin dolomite or LS

organic-rich, silica-rich shale

clay-rich, low TOC shale

• Each basinal cyclothem = 15 – 45 ft. thick; bounded by

• High pore pressures due to depth, maturity

Wo

lfca

mp

D

Wolfcamp C

• Westward progradation of Eastern Shelf delta systems and platform margins (100 -150 km)

Preliminary correlation of MB tops to Eastern Shelf

• Initial development of Glasscock Nose during WFMP C1 time

(Sinclair et al., 2018)

Wolfcamp C

• Uplift of CBP structural blocks and development of mid-Wolfcamp unconformity

Progradation of Wolfcamp C shelf delta systems across the Eastern Shelf

(Sinclair et al., 2017)

(Sinclair et al., 2017)

SW

Sequential development of the Glasscock Noseprograding, mounded deep-water carb. flows

Possible analog: carbonate delta drift

Indian Ocean/Maldives seismic line

(Reed, 2014)

mid-Wolfcamp unconformity on the CBP

• note diachronous nature of unconformity across Permian Basin region

• last major tectonic pulse prior to middle –late Permian subsidence phase

Wolfcamp A - B

Platform Carbonate

Shelf Edge Carbonate

Slope Sediments & Reef Talus

Carbonate Debris Flows

Carbonate Gravity Flows

Land

Clastic Detrital

Clastic Slope Sediments

Clastic Gravity Flows

Delta

Pelagic Sediments

Silt Cloud in Suspension

Anaerobic Zone

(Organic-rich Sediments)

Basinal Sediments

Wolfcamp A & B Facies Map

Schematic Block Diagram of

Wolfcamp Facies in Midland Basin

San Simon

Channel

North Basin

Platform

Glasscock

Nose

Marathon

Thrust Belt

Fluvial - Deltaic

Platform

Carbonate

Clastic

Slope

Land

Carbonate Slope

Debris

Flow

Carb

Gravity Flow

Clastic

Gravity Flow

Pelagic Sed.

Platform

Carbonate

Land

Land

CBPMidland

Basin

Marathon

Thrust Belt

North

Older

Wolfcamp

Clastics

Wolfcamp A and B Facies & Depositional Model

(Diagram by T. Reed, 2013,

based on Handford, 1981)

(Sinclair et al., 2018)

• 700+ ft. of organic-rich, silica- and calcareous-rich mudstone punctuated by numerous density flows (carb. turbiditesand debris flows)

• Aggradation of carbonate margins during second-order highstand increase percentage of CaCO3 into basin during WFMP A time

Wolfcamp A - B

• Interval currently resides in peak oil window in Midland Basin; remains a main horizontal drilling target

• Six operational sub-units:

• A1

• A2

• A3

• B1

• B2

• B3

L. Leonard Shale

Dean

Wolfcamp B

XRD analyses from core(n = 476)

• WC B are predominantly siliceous mudstones

• WC A are mixed carb-silica mudstones

Wolfcamp A

(Mzee, 2018)

Calcareous mudstone

Wolfcamp B2 Wolfcamp A3

(Murphy, 2105)

Wolfcamp carbonate debris flows

• Flows are thickest and coarsest near the shelf margins; distal portions of flows are thinner and finer grained

• Geometries include sheet-like fans and highly channelized flows

Spraberry - Dean

7500

8000

8500

9000

9500

10000

10500

Penn.

Wolfcam

p-

ian

Le

on

ard

ian

Wolfcamp D: Basinal cyclothems (starved basin)

Wolfcamp C: Clay-rich shale(progradation of Eastern Shelf deltas & Glasscock Nose)

Wolfcamp A – B: silty- and calcareous organic-rich mudstones;carbonate percentage increases upward

Spraberry – Dean:silty mudstones and clay-rich siltstones punctuated by multiple deeper-water submarine fan complexes(incl. massive to laminated, fine-grained sandstones)

Lower Strawn: shallow-water platform limestones

mid-WCunconformity

GENERAL DESCRIPTION / DEPOSITIONAL FACIES

C2

C1

A

Jo Mill

Lower

Leonard

Shale

Dean

Lower

Spraberry

Middle

Spraberry

Upper

Spraberry

UpperLeonard

Strati-graphy

WFMP

D

B

Wo

lfc

am

p

Midland Basin Type Log

(modified from Hamlin and Baumgardner, 2012)

MD(ft.)

• 1st major incursion of submarine fans

• Equivalent to 3rd Bone Spring SsDean

LowerLeonard Sh.

• organic-rich siliceous shales

Jo Mill • 2nd major incursion of submarine fans• Equivalent to 2nd Bone Spring Ss

L. Spraberry • siliceous shales, minor fans

M. Spraberry • silty, shales; minor fan complex

U. Spraberry• 2 major submarine fan complexes

(Floyd and Driver fans)• Equivalent to 1st Bone Spring Ss

whole-rockmineralogy,Dean Ss

(Mzee, 2018)

Qtz45%

Clay22%

Dolomite17%

Dean – Spraberry units of the Midland Basin

• Main facies:

• Massive f.g. sandstones (“Bouma A”)• Laminated siltstones / shales• Burrowed siltstones / shales (O2)

• Black shale (thin caps)

• Provenance? (north vs. south)Depositional model ?

• All fans (Dean, Jo Mill, Middle & Upper Spraberry) are similar in appearance

(a) Poroussandstone

(b) Sandstonecemented w/ferroandolomite

(Hamlin and Baumgardner, 2012)

Mas

sive

san

dst

on

e

Bo

um

a se

qu

en

ce Laminatedsiltstones

(Waite et al., in press)

ZIRCON U-Pb RADIOMETRIC AGE SPECTRA(DEAN – SPRABERRY, CENTRAL & SOUTHERN MIDLAND BASIN)

• Strong age signal (“peaks”)

• Grenville province (1100 Ma)

• Gondwana (600 Ma)

• Appalachia (400 Ma)

• Intermediate signal

• Granite-Rhyolite province (1400 Ma)

• Yavapai – Mazatzal province (1700 Ma)

Strong age signals are from southern-located provinces, indicating a southern source land for Dean – Spraberry sands in central & southern Midland Basin (currently accepted view: all sands were from a northern source)

• Weak signal

Gravity Flow DepositsLow Sea Level

Lowstand and ensuing transgression–• Shelf exposed

• Clastics move across shelf via wind and in wadis

• Clastic gravity flow deposits bypass shelf during

lowstand and are cannabalized during early transgression

Carbonate

Debris FlowsBasinal ShalesHigh Sea Level

Highstand –• Shelf submerged

• Carbonates on shelf

• Carbonate gravity flow deposits and organic-rich

shales in basin

Dean

N S

Wolfcamp A

Shelf Edge

L. Spraberry

Shelf EdgeM. Spraberry

Shelf Edge

Spraberry and shelf equivalents are alternating sand-rich and organic

shale/carbonate-rich packages deposited during alternating high and low sea levels.

Sands are very fine-grained turbidites with partial Bouma sequences

Organic-rich shales highly laminated and not bioturbated; Organic-poor shales bioturbated

Thin dolomitic hard grounds observed in sands and shales

Spraberry & Dean (Bone Spring) Depositional ModelEarly Permian

(based on Hanford, 1981)

Possible modern analog for Dean - Spraberry:Offshore Mauritania, African Sahara

coresample

Core data (Zuhlsdorff et al., 2008)

Summary and Conclusions

• The Wolfcamp – Spraberry interval of the Midland Basin consists of a series of lithologically- and mineralogically-complex facies; each interval is unique

• Wolfcamp A - B: Silty, calcareous terrigenous shales; carbonate % increases upward

• Dean - Spraberry: Argillaceous siltstones, punctuated by numerous submarine-fan complexes (massive & laminated sandstones)

• Wolfcamp D: basinal cyclothems

• Wolfcamp C: clay-rich shales

• Complexity of these rocks reflects changing/evolving geologic conditions (eustasy, climate, tectonics, sediment supply, biota, etc.) along the SW margin of western Pangea during Late Pennsylvanian – early Permian time

• Geologists must work closely with drilling, completion, and reservoir engineers to fully communicate the complexity and uniqueness of each unit / horizontal zone

“Not all shales are created equal”

(Hamlin and Baumgardner, 2012)