The Giant Continuous Oil Accumulation in the Bakken Petroleum System, Williston Basin

Transcription

1 The Giant Continuous Oil Accumulation in the Bakken Petroleum System, Williston Basin Stephen A. Sonnenberg Department of Geology and Geological Engineering Colorado School of Mines Williston Basin Conference 2015

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4 Picopore Nanopore Micropore Mesopore Bakken & Three Forks & Niobrara Pore Sizes Nelson, 2009

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6 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

7 CANADA Ambrose Field USA Painted Woods Area Nesson Anticline Ross Field Area Poplar Dome Parshall/Sanish Area Elm Coulee Structure Top Bakken Formation Bakken and Three Forks Producers shown Cedar Creek Anticline Bicentennial Anticline Montana North Dakota Hay Stack Butte Area Billings Anticline Little Knife Anticline St. Demetrius Area Fort Berthold Area Bailey Area

8 Bakken Petroleum System USGS 2013 Bakken PS Assessment 7.4 BBO 6.7 TCFG Modified from LeFever 1992; Anna, 2009

9 Unconventional, Continuous Tight Oil Accumulations Pervasive accumulations that are hydrocarbon saturated Not localized by buoyancy Abnormally pressured (high or low) Commonly lack downdip water Updip contact with regional water saturation Low permeability and low matrix porosity reservoirs Reservoirs may be single or vertically stacked Commonly enhanced by fracturing Associated with mature source rocks that are either actively generating or have recently ceased generation Hydrocarbons of thermal origin Fields have diffuse boundaries Inverted Petroleum Systems

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11 Modified from Smith et al., 1995

12 Canadian Shield Exshaw Sappington Cottonwood Canyon Bakken Englewood Antrim Leatham New Albany Sunbury Pilot Chattanooga Woodford Chattanooga Percha Woodford Late Devonian Early Mississippian black shales (360 Ma) Blakey, 2007, <

13 Bakken Petroleum System Basics Upper & lower black shales World Class Source Rocks Hard, siliceous, pyritic, fissile, organic rich TOC s average wt. 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 & Middle Three Forks dolostones (target of horizontal drilling) Pronghorn dolostones (new target!) Abnormal pressure and hydrocarbon generation (> 0.5 psi/ft)

14 Barrels Oil Per Day Antelope Field Discovery Bakken & Three Forks 1953 Shell Elkhorn Ranch 1961 Billings Nose Vertical Drilling Upper Bakken Shale 1976 Billings Nose Horizontal Drilling Upper Bakken Shale 1987 Elm Coulee Horizontal Drilling Middle Bakken 2000 Parshall & Sanish Fields Horizontal Drilling Middle Bakken MCF Gas Per Day Total US Williston Basin Bakken and Three Forks 1,289,803,891 BO 1,311,105,241 MCFG

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17 What factors influence productivity? Theloy, 2013

18 Bakken Facies G E-F D C B A G False Bakken Scallion U. Bakken Sh. M. Bakken L. Bakken Sh. Pronghorn Upper Three Forks RT Marker Middle Three Forks Lodgepole Bakken Fm. Three Forks DEVONIAN MISSISSIPPIAN

19 CANADA Poplar Dome Nesson Anticline Antelope Anticline Isopach Bakken CI: 20 ft Montana North Dakota

20 Isopach Middle Bakken CI: 10 ft Montana North Dakota CANADA

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23 Sanish Field Parshall Field Non productive False Bakken Scallion Upper Bakken Shale Middle Bakken Lower Bakken Shale Pronghorn Upper Three Forks RT Marker Middle Three Forks Bakken Lodgepole Three Forks Source Beds: Mature Over pressured Source Beds: Marginally mature Highly over pressured Source Beds: Immature Normally pressured

24 Sanish and Parshall Fields

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26 CANADA Isopach Middle Bakken Facies D CI: 10 ft Montana North Dakota

27 CANADA Isopach Middle Bakken Facies E F CI: 10 ft Montana North Dakota

28 Bakken 1 st 90 days Oil/(Oil+Wtr)

29 From Theloy, 2013

30 From Theloy, 2013

31 From Theloy, 2013

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34 Modified from Sandberg et al., 1988

35 Bottineau Anticline Poplar Dome Cedar Creek Anticline CANADA Nesson Anticline Antelope Anticline Montana North Dakota

36 False Bakken Lodgepole Subtidal Intertidal (dolosiltone) Scallion Upper Bakken Shale Pronghorn Upper BAKKEN Intertidal (dolosiltstone) Supratidal/Intertidal Supratidal/Sabkha Chicken-wire anhydrites Middle Lower Three Forks Nisku/Birdbear Modified from Gantyno, 2010

37 Pronghorn Upper Three Forks Middle Three Forks Lower Three Forks Birdbear

38 Bakken Petroleum System

39 Modified from Dumoncaux, 1984; Berwick; 2009; Gantyno, 2010; Franklin and Sonnenberg, 2012

40 CANADA Isopach Lower Three Forks CI: 25 ft Montana North Dakota

41 CANADA Isopach Middle Three Forks CI: 10 ft Montana North Dakota

42 CANADA Isopach Upper Three Forks CI: 10 ft Montana North Dakota

43 Pronghorn Sandstone B A2 Modified from Berwick, 2009; Gantyno, 2010; Johnson, 2013 A1

44 Three Forks 1 st 90 days Oil/(Oil+Wtr)

45 Resistivity Upper Bakken Shale > 100 ohm m Resistivity Lower Bakken Shale > 100 ohm m Limit Lower Bakken Shale >3000 Limit Upper Bakken Shale IP BOPD Structure Bakken, Bakken Shale Resistivity and Three Forks IP Map

46 From Theloy, 2013

47 Conclusions A giant continuous accumulation is present in the Bakken and Three Forks of the Williston Basin Sophisticated completion technology and geological factors have a large impact on productivity Sweetspots influenced by hydrocarbon generation, pore overpressure, inferred oil saturations and productivity, net pay, facies, natural fractures, etc. Optimal completion design depends on area and field maturity 40 stage completions may not be economic in low productivity areas Simpler (cheaper) completions may be preferable for infill wells at late development stage Multistage hydraulic fracturing and horizontal drilling are game changers for tight oil systems

48 Colorado School of Mines Bakken Consortium Mike Johnson & Associates