The Bakken Petroleum System

Stephen A. Sonnenberg

Colorado School of Mines

Colorado School of Mines

Bakken Consortium

Mike Johnson

Consulting Geologist

Oil Shale Gas Hydrates

Tight

Gas Sands;

CBM;

Gas Shales

Tight

Oil;

Heavy Oil;

Bituminous

Sands

Oil Gas

Conventional Reservoirs:

Small Volumes,

Easy to Develop

Unconventional Reservoirs:

Large Volumes,

Hard to Develop

Huge

Volumes,

Difficult

to Develop

Incre

asin

g P

roduct

Price

Impro

vin

g T

echnolo

gy

Province Resource Size

The Resource Pyramid

Unconventional, Continuous Tight

Oil Accumulations

Pervasive petroleum saturation

Mature source rocks

Abnormally pressured

Generally lacks down-dip water

Up-dip water saturation

Low porosity and permeability reservoirs

Fields have diffuse boundaries

Enhanced by fracturing and partings

Structure Base Miss

The Bakken Petroleum System of the Williston Basin:

a Tight Oil Resource Play

Stephen A. Sonnenberg

Colorado School of Mines

WYOMING

SOUTH

DAKOTA

NORTH

DAKOTA

MANITOBASASKATCHEWAN

MONTANA

Limit of

Bakken Fm.

-5000

0 50 miles

Elm

Coulee

Cedar Creek

Anticline

Nesson

Anticline

ParshallArea

ViewfieldArea

Billings

Nose

B-SD Area

NISKU

CHARLES

MISSION

CANYON

LODGEPOLE

BAKKEN

THREE FORKS

DE

VO

NIA

NM

ISS

ISS

IPP

IAN

MA

DIS

ON

GR

OU

P

+++++

++++++

+++

Bakken

Petroleum

System

Modified from Webster, 1984

NDIC (2010) estimated ultimate

production

Bakken Petroleum System:

Bakken: 2.1 Billion barrels

Three Forks: 1.9 Billion barrels

Blakey, 2007, <http://jan.ucc.nau.edu/~rcb7/namD360.jpg>

Bakken

Exshaw

Woodford

Cottowood

Canyon

Leatham

Sappington

Antrim

New Albany

Woodford

Chattanooga

Sunbury

Canadian

Shield

Chattanooga

Percha

Pilot

Late Devonian-Early Mississippian black shales (360 Ma)

0 50

MILES

Lower Bakken

Middle Bakken

Upper Shale Mbr.

Middle Siltstone Mbr.

Lower Shale Mbr.

WEST EAST

NESSON

ANTICLINE ANTELOPE

FIELD

XX

X

Isopach BakkenMeissner, 1978 after Sanberg, 1962

MTND

SD

CANADA

USA

Bakken Petroleum System

Reservoirs:

Middle Bakken & Three Forks

Source Beds:

Upper & Lower Bakken Shales

“what was made in the Bakken, stayed in the Bakken PS”

Bakken Petroleum System Basics

• Upper & lower black shales– „World Class‟ Source Rocks

• Hard, siliceous, pyritic, fissile, organic rich

• TOC‟s as high as 40 wt% (average 11%)

• High OM indicates anoxic conditions (amorphous-sapropelic OM)

• HC Generation: 10 to 400 B bbl oil

• Middle member (target of horizontal drilling)– Dolomitic siltstone to a silty dolomite

– Low porosity and permeability

• Upper Three Forks dolostones (target of horizontal drilling)

• Abnormal pressure and hydrocarbon generation (> 0.5 psi/ft)

Modified from LeFever, 2005

Permeability/ Porosity

0.01

0.1

1

10

100

1000

10000

0 10 20 30

Porosity

Perm

eab

ilit

y

K/PHI 1

K/PHI 10

K/PHI 100

K/PHI 1000

Bakken EC

Wattenberg

Peoria

Morrow Sorrento

D SS Sooner

megapores

macropores

mesopores

micropores

submicroporesBakken

1970-80s

Upper Bakken Shale Play

Post 1987

Horizontal Play

Antelope

Field

Sanish & Bakken

1953

Elm Coulee

2001-P

Horizontal Middle Bakken

Structure

Bakken Fm.

Bakken

Three Forks

Parshall\Sanish

Field - 2006

Ross

Bailey

Willmen

St. Demetrius

Nesson

Anticline

Brigham

“Painted Woods”

Total GOR: 957 cf/bbl

WILLISTON BASIN - 3365 Grouped Wells (Daily Rates)

53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 1 4 7 1012OIL=243,950,345 (BBL)

106

105

104

103

102

GAS=233,515,457 (MCF)

106

105

104

103

102

GOR (CUFT/BBL)

105

104

103

102

10

BO

PD

MC

FG

PD

100

1000

100000

1000000

100000

1000000

1000

100

Williston Basin Bakken and Three Forks Production

10000 10000

1000 GO

R

100

Antelope

1953

Billings Nose

1976

Horizontal Drilling

Upper Bakken Shale

Billings Nose

1987

Horizontal Drilling

Middle Bakken

Elm Coulee

2001

Horizontal Drilling

Middle Bakken

Parshall Field

2006

Factors Related to Bakken/Three

Forks Oil Production

• Source beds - UB, LB, FB; Reservoirs-MB, TF

• Reservoir-favorable facies and diagenetic history (matrix permeability)

• Mature source rocks form continuous oil column (pervasive saturation)

• Favorable history of fracture development: folds, faults, solution of evaporites, high fluid pressures, regional stress field (fracture permeability)

• Drilling and completion technology

Lear Pet Expl Parshall SD 1

Sec. 3-T152N-R90W

Lodgepole

Ba

kk

en

Upper Shale

Middle Mbr.

Lower Shale

Upper

Three Forks

“False Bakken”

Scallion

C

D

E

BA

F

Facies after Canter et al., 2008; LeFever, 2007; Berwick, 2009

TF-A

TF-B

UBS

LBS

TF-C

Kennedy F-32-24P

Sec. 24-149N-93W

AB

C

D

E&F

False Bakken

Scallion

UBS

M-B

LBS

TF

LDGPL

10570

10575

10580

10585

10590

10595

10600

0 5 10 15 20

10506

10508

10510

10512

10514

10516

10518

10520

10522

0 5 10 15 20

Facies after Canter and Sonnenfeld, 2008; LeFever, 2007; Berwick, 2009

TF-A

TF-B

TF-C

Van Krevelen HI/OI

0

100

200

300

400

500

600

700

800

900

1000

0 20 40 60 80 100

OI (mg CO2/gm OC)

HI

(mg

HC

/gm

OC

)

0-4000

4001-6000

6001-8000

8001-10000

10001-12000

TYPE I

TYPE II

TYPE III

Type I

Type II

Type III

Depositional Setting:

Lower and Upper Bakken Black Mudstone

Modified from Smith and Bustin, 1996; Meissner et al., 1984

Isopach Lower Bakken Shale

Isopach Upper Bakken Shale

High Paleogeothermal

Gradient Area

Lower Bakken Res

Upper Bakken Res

Limit Middle

Bakken

Limit Lower

Bakken Shale

Limit Upper Bakken ShaleCCA

Structure

Bakken Formation

50 miles

Resistivities Bakken Shales

4000 8000

Modified from Meissner, 1978

• Bakken/Sanish/UTF

abnormal pressured

• Regarded by Meissner

(1978) to be due to

hydrocarbon

generation which

results from excess

volumes of oil in

shales

FORMATION PORE-FLUID PRESSURE - psi

2000 6000

14000

12000

10000

8000

6000

4000

2000

0

DE

PT

H -

FE

ET

Normal or Hydrostatic fluid

pressure based on average

Paleozoic Formation water

salinity of 325,000 ppm and a

related fluid pressure gradient

of 0.53 psi\ft

Lodgepole 0.46

Bakken/Sanish 0.73

Nisku 0.47

Mission Canyon 0.46

Kibby 0.47

Silurian 0.46

Formation fluid

pressure psi/ft

Isopach

Middle Bakken

Kennedy F-32-24P

Sec. 24-T149N-R93WF

E

D

C

B

Facies after Canter and Sonnenfeld, 2008; LeFever, 2007

A

False Bakken

Scallion

UBS

M-B

LBS

LDGPL

E&F

D

C

B

A

GR Res

UTF

TF-A

TF-B

TF-C

Depositional Environment

after Walker and Plint (1992) from Smith and Bustin, 1996

A

B

C

D

sea level drop

sea level rise

F

E1

E

A

B

C

D

E

E1

F

Three Forks

Lower Bakken

A

B

C

D

E & F

Upper Bakken

Lodgepole

Mid

dle

Bakken

L. Texel #21-35 API: 3306100187 State: North Dakota County: Mountrail

Facies after Canter and Sonnenfeld, 2008; LeFever, 2007

XRD Data

Modified from Whiting, 2010

Overview of Upper Three Forks

• Upper Three Forks Facies

– A. Silty dolomite; highly deformed and brecciated: tidal

mud flat to sabkha

– B. Silty dolomite, dolomitic siltstone, and shale (green)

deposited in tidal mud flat

– C. burrowed dolomitic unit deposited in subtidal

environment

• Sanish Sandstone

– Fine-grained and burrowed

– Locally developed

– Sharp contact with upper Three Forks

Structure

Three Forks

50 Miles

Modified from Blakey, 2005

Late Devonian

360 m.a.

THREE FORKS

Supratidal

Modified from Berwick, 2009; Gantyno, 2010

Sanish

(~5 ft)

Upper

Three

Forks

(~40 ft)

Supratidal/

Intertidal

Mudflat

Intertidal

Subtidal

Supratidal

Gantyno, 2010

Isopach

Upper

Three Forks

Jorgenson 1-15H

Sec. 15-T148N-R96W

Jorgenson 1-15

0% 20% 40% 60% 80% 100%

10970

10972

10976

10979

10989

11000

11041

11045

11049

11053

11060

11068

11077

11082

Quartz

Feldspar

Calcite

Dolomite

Pyrite

Chlorite

Illite

Jorgenson 1-15

0% 20% 40% 60% 80% 100%

10970

10976

10989

11041

11049

11060

11077

Quartz

Feldspar

Calcite

Dolomite

Pyrite

Chlorite

Illite

Jorgenson 1-15

0% 20% 40% 60% 80% 100%

10970

10972

10976

10979

10989

11000

11041

11045

11049

11053

11060

11068

11077

11082

Quartz

Feldspar

Calcite

Dolomite

Pyrite

Chlorite

Illite

XRDLodgepole

U Bakken

M Bakken

L Bakken

Sanish

Upper

Three

Forks A

B

C

Isopach

Lower Bakken

CI: 10 ft

Resistivity lines from Hester and Schmoker, 1985

50 Mi

Origin of Bakken Fractures

• Folding and faulting

• High fluid pressures

• Solution of evaporites

• Geologic history: recurrent

movement on basement shear

zones

• Regional stress field with open

fracture direction

Regional Fractures

Bakken Petroleum System

• A low perm, „tight oil‟ system

• What makes it work?

– Technology

• Horizontal drilling

• Fracture stimulation

– World class source rocks

– Large “kitchen” area

– Abnormal pressure

– Middle Bakken facies, Three Forks facies

– Matrix and fracture permeability

Summary

• Unconventional tight oil resource plays are

„changing the game‟

• It all starts with good to excellent source beds

• Source beds mature over large areal extent

• Natural fracturing enhances tight reservoirs

• Horizontal drilling and fracture stimulation

technology important in tight oil plays