THREE-DIMENSIONAL RESERVOIR CHARACTERIZATION OF THE BAKKEN GEOLOGIC SYSTEM Project DE-NT0005672 TECHNOLOGY STATUS ASSESSMENT 1) CURRENT STATE OF TECHNOLOGY A) Initial Assessment of Bakken Petroleum System The Mississippian-Devonian Bakken Petroleum System of the Williston Basin is characterized by low porosity and permeability reservoirs, organic rich source rocks, and regional hydrocarbon charge. This unconventional play is the current focus of exploration and development activity by many operators. Estimates of oil generated from the petroleum system range from 10 to 400 billion barrels (1.6 to 63.9 billion m3 ) (Dow, 1974; Meissner and Banks, 2000; Flannery and Kraus, 2006; LeFever and Helms, 2006; Webster, 1984; Schmoker and Hester, 1983). The USGS mean technologically recoverable resource estimates for the Bakken are 3.65 billion barrels (0.58 billion m3 ) of oil and 1.85 trillion cubic ft (52.3 billion m3 ) of associated/dissolved natural gas, and 148 million barrels (23.5 million m3 ) of natural gas liquids (USGS, 2008). Previous workers in the Bakken have suggested the significant source rock potential of the Bakken (Meissner, 1978; Dow, 1974; Williams, 1974; Pitman et al., 2001; Price et al., 1984). The Williston Basin is a large, intracratonic sedimentary basin that occupies parts of North Dakota, South Dakota, Saskatchewan, and Manitoba (Fig. 1). The basin is semi-circular in shape and prominent structural features are the Nesson, Billings and Cedar Creek anticlines (Fig 1). The Nesson Anticline is the location of the first oil discoveries in the 1950s. Many of the structural features have a documented ancestral origin and influenced Paleozoic sedimentary patterns (Gerhard et al., 1990). The Elm Coulee Field is located in the western part of the Williston Basin in Montana (Fig. 1). The field is a recent giant discovery in the middle Bakken. Horizontal drilling began in the field in 2000, and to date over 500 wells have been drilled. The estimated ultimate recovery for the field is over 200 million barrels (31.8 million m3 ) of oil. Horizontal drilling and fracture stimulation of the horizontal leg are key technologies that enable a low permeability reservoir to produce. A detailed understanding of trapping mechanisms and reservoir properties will aid in the exploration and discovery of other areas in the Bakken petroleum system.