The Bakken Petroleum System of
the Williston Basin
Presented By:
Steve Sonnenberg
Colorado School of Mines
Bakken Consortium
The Bakken Petroleum System of the Williston Basin:
a Tight Oil Resource Play
Structure Base MissStephen A. Sonnenberg
Colorado School of Mines
WYOMING
SOUTHDAKOTA
NORTHDAKOTA
MANITOBASASKATCHEWAN
MONTANA
Limit of
Bakken Fm.
-5000
0 50 miles
Elm
Coulee
Cedar CreekAnticline
NessonAnticline
Sanish/Parshall
Area
ViewfieldArea
BillingsNose
B-SD Area
RoughRider
Blooming Prairie
Oil Shale Gas Hydrates
TightGas Sands;
CBM;Gas Shales
TightOil;
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
Incr
easi
ng P
rodu
ct P
rice
Impr
ovin
g Te
chno
logy
Province Resource Size
The Resource Pyramid
Oil Shale Gas Hydrates
TightGas Sands;
CBM;Gas Shales
TightOil;
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
Incr
easi
ng P
rodu
ct P
rice
Impr
ovin
g Te
chno
logy
Province Resource Size
The Resource Pyramid
Blakey, 2007, <http://jan.ucc.nau.edu/~rcb7/namD360.jpg>
Bakken
Exshaw
Woodford
CottowoodCanyon
Leatham
Sappington
Antrim
New Albany
Woodford
Chattanooga
Sunbury
CanadianShield
Chattanooga
Percha
Pilot
Late Devonian-Early Mississippian black shales (360 Ma)
NISKU
CHARLES
MISSIONCANYON
LODGEPOLE
BAKKENTHREE FORKS
DE
VO
NIA
NM
ISS
ISS
IPP
IAN
MA
DIS
ON
GR
OU
P+++++
++++++++
+
BakkenPetroleum
System
NDIC (2010) estimated ultimate production
Bakken Petroleum System:
Bakken: 2.1 Billion barrelsThree Forks: 1.9 Billion barrels
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”
Meissner, 1978
“Relationship between source-rock maturity, hydrocarbon generation, geopressuring and fracturing suggest an opportunity in exploration for unrecognized and unlooked-for “unconventional” accumulations of potentially very large regional extent”
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
1970s-80sUpper Bakken Shale Play
Post 1987Horizontal Play
AntelopeField
Sanish, Three Forks& Bakken
1953
Elm Coulee2000-P
Horizontal Middle Bakken
Structure Bakken Fm.
Bakken
Three Forks
Parshall\SanishField - 2006
Ross
Bailey
Willmen
St. Demetrius
NessonAnticline“Rough Rider”
“Blooming Prairie”
Antelope Field
“Unusual Characteristics”
• Very high reservoir pressure• High productivity of several wells• Production associated with steepest
dip in central part of basin• Nebulous, ill-defined reservoir• Almost complete absence of water• Porosities 5-6%• Permeabilities < 0.1 md
Murray, 1968
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
FGP
D
100
1000
100000
1000000
100000
1000000
1000
100
Williston Basin Bakken and Three Forks Production
10000 100001000 G
OR
100
Antelope1953
Billings Nose1976
Horizontal DrillingUpper Bakken Shale
Billings Nose1987
Horizontal DrillingMiddle Bakken
Elm Coulee2000
Horizontal DrillingMiddle BakkenParshall Field
2006
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-C
TF-D
UBS
LBS
TF-E
Factors Related to Bakken/Three Forks Oil Production
• Source beds - UB, LB; 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
Kennedy F-32-24PSec. 24-149N-93W
AB
C
DE&F
False BakkenScallion
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-C
TF-D
TF-E
Murray, 1968Comments on the Bakken shales:
“Any restricted reservoir in direct contact with either of the two shale units should be productive anywhere in the deeper part of the basin, regardless of structural position”
“One of the most important conclusions is the recognition that the upper and lower Bakken shale beds are supercharged oil shales and that they probably are the immediate source of most of the oil”
Depositional Setting:Lower and Upper Bakken Black Mudstone
Modified from Smith and Bustin, 1996; Meissner et al., 1984
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 (m
g HC
/gm
OC)
0-40004001-60006001-80008001-1000010001-12000TYPE ITYPE IITYPE III
Type I
Type II
Type III
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
380 400 420 440 460 480 500
Tmax
Pro
du
ctio
n I
nd
ex 0-40004001-60006001-80008001-1000010001-12000
Immature
Oil Zone
High Paleogeothermal
Gradient Area
Lower Bakken Res
Upper Bakken Res
Limit MiddleBakken
Limit LowerBakken Shale
Limit Upper Bakken ShaleCCA
Structure Bakken Formation
50 miles
Resistivities Bakken Shales
Change in pore-
fluid volume
(porosity) and pore-
fluid species which
may accompany
hydrocarbon-
generation
(maturity) in source
rocks
Meissner, 1978
Water Wet
Oil Wet
2000 4000 8000
Modified from Meissner, 1978
• Bakken/Sanish/UTFabnormal 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
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
Lear Pet Expl Parshall SD 1
Sec. 3-T152N-R90W
Lodgepole
Ba
kk
en
Upper Shale
Middle Mbr.
Lower Shale
Three Forks
“False Bakken”
Scallion
L-M
M-M
U-M
D
B
A
E-F
C
B - Bioturbated, argillaceous, calc. poorly sorted, vfg, sandstone/siltstone with helminthopsis/sclarituba.A - Intraclastic-skeletal lime wackestone, 1-4 ft thick.
D - Bioturbated, argillaceous, calc. poorly sorted, vfg, sandstone/siltstone with helminthopsis/sclarituba.E - Intraclastic-skeletal lime wackestone, 1-4 ft thick.
L1 – Siltstone, gray-green massive, bioturbated (Nerites ichnofacies), fossiliferous.
C - Rhythmic, varve-like, mm to cm laminated, well sorted, v.f.g. sandstone and siltstone with calcite cement, hummocks and wave ripples.
C - Rhythmic, varve-like, mm to cm laminated, well sorted, v.f.g. sandstone and siltstone with calcite cement, hummocks and wave ripples.
L2 - Interbedded dark-gray shale and buff, silty sandstone, moderate to intense bioturbation (Cruziana ichnofacies), fossiliferous.
A – Siltstone, gray-green, argillaceous, abundant bioturbation, Nerites & Phycosiphon.
D - Highest energy, coarsest grained alternating cross-bedded bioclast, v.f.g. sandstone.
B1 - Highest energy, coarsest grained alternating cross-bedded bioclast, v.f.g. sandstone.B2 - Muddy calcareous sandy/silty disturbed facies, synsedimentary microfaults, slumps.
L3 – Sandstone, upper & lower wavy to flaser silty sandstone, Skolithos ichnofacies. Middle coarse-grained, massive to xbedded.
B – Sandstone, fg, sharp basal contact, from base upwards, massive to xbedded to laminated. Rare Planolites.
F - Calcitic, whole fossil, dolo-to lime wackestones: fossil-rich beds.E - Thin-bedded dolo-mud/wackestone, more dolomitic.
A1 - Calcitic, whole fossil, dolo- to lime wackestones: fossil-rich beds.A2 - Thin-bedded dolo-mud/wackestone, more dolomitic.A3 - Thin organic-rich mudstone, gamma ray marker.
L4 – Interbedded dark-gray shale and buff, silty sandstone, coarsens upward, moderately bioturbated (Cruziana ichnofacies).
C – Siltstone, laminated, argillaceous, & vfg sandstone, bioturbated, soft sediment deformation. Phycosiphon, Planolites & Teichichnus.
F1 - Pyritic dolostones.A0 - Patterned pyritic dolostones.
L5 – Siltstone, gray-green, massive, mottled, dolomitic, Nerites ichnofacies.
MIDDLE BAKKEN LITHOFACIESNickel & Kohlruss, 2009 LeFever & Nordeng, 2008 Canter & Sonnenfeld, 2009 CSM, 2010
ts
SB
mfs
TST
LST
HST
Skeletal wackestone
Bioturbated siltsone,Vfg ss
Laminite, vfg ss-siltstone
X-bedded bioclast, SS
Thin bedded, dolo-mud, wackestone
Blakey, 2007, <http://jan.ucc.nau.edu/~rcb7/namD360.jpg>
WillistonBasin
CanadianShield
Late Devonian-Early Mississippian black shales (360 Ma)
Depositional Environment-Shallow Shelf
Erosion
XLayer-Cake Shelf Model:
high O2 high productivity
anoxic
rapid subsidence or fast rise in sea levelLBS silty
LBS A B C
D E
F UBS
NS
Uplift?
~ 50 m
Siliciclastic sediment input
slow subsidence or slow rise in sea level
carbonate production
sedimentation rates > rate of sea level rise
sedimentation rates < rate of sea level rise
anoxic
high O2
After Theloy, 2010
Overview of Upper Three Forks
• Upper Three Forks Facies– Silty dolomite; highly deformed and brecciated: tidal mud
flat to sabkha – Silty dolomite, dolomitic siltstone, and shale (green)
deposited in tidal mud flat– burrowed dolomitic unit deposited in subtidal environment
• Sanish Sandstone– Fine-grained and burrowed– Locally developed– Sharp contact with upper Three Forks– Sharp contact with Lower Bakken Shale
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
QuartzFeldsparCalciteDolomitePyriteChloriteIllite
Jorgenson 1-15
0% 20% 40% 60% 80% 100%
10970
10976
10989
11041
11049
11060
11077
QuartzFeldsparCalciteDolomitePyriteChloriteIllite
Jorgenson 1-15
0% 20% 40% 60% 80% 100%
10970
10972
10976
10979
10989
11000
11041
11045
11049
11053
11060
11068
11077
11082
QuartzFeldsparCalciteDolomitePyriteChloriteIllite
XRDLodgepole
U Bakken
M Bakken
L Bakken
Sanish
Upper
Three
Forks
Modified from Berwick, 2009
Sanish(~5 ft)
UpperThreeForks
(~40 ft)
IntertidalMudflat
Intertidal-Supratidal
- Contact between Facies C and B. Bounding Discontinuity (Paleobathymetric shift)
- Contact between Facies D and C. Flooding Surface
Fresh Water Recharge
Hypersaline Sea Water Recharge
Saline Tidal flat-Sabkha (precipitation of evaporites)
Facies B
Intertidal - Supratidal
Fresh Surface Water Recharge (dissolution of
evaporites)
Fresh Water Recharge(dissolution of evaporites)
Hypersaline Water Recharge
10‟s of miles (?)
Desiccation features
Parallel Laminations
Algal structures/laminations
Facies D
Facies C
Facies B
12
12
1
2
* Not to scale
10‟s of feet (?)
Bi-directional cross-laminations
Uni-direction cross-laminations
Tidal Creek
Berwick, 2009
Origin of Bakken Fractures
• Folding and faulting• High fluid pressures• Solution of evaporites• Recurrent movement on
basement shear zones• Regional stress field with open
fracture direction
• Vertical fractures, bedding plane partings
(i.e., horizontal fractures) all play a role
Bakken & Three Forks Fractures
Working Hypothesis
Carus FeeUpper Bakken Shale
11293NDIC
Maxus Shapiro 13-3Sec. 3-T142N-R102W Little Knife Field
Narr and Burrus
Fidelity 43-28H DCRSec. 28-T154N-R92W
Nesson State 42X-36HSec. 36-T156N-R95WCarus Fee 21
Sec. 19-T147N-R96W
Regional Fractures
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
Colorado School of Mines
Bakken Consortium
Mike Johnson
Consulting Geologist