New USGS oil and gas assessment for Bakken and Three Forks formations boosts estimates of recoverable oil two-fold, natural gas three-fold
The United States Geological Survey (USGS) released an updated oil and gas resource assessment for the Bakken Formation and a new assessment for the Three Forks Formation in North Dakota, South Dakota and Montana, resulting in a two-fold increase in the estimated technically recoverable oil, and a three-fold increase in estimated natural gas.
Technically recoverable resources are those producible using currently available technology and industry practices. USGS is the only provider of publicly available estimates of undiscovered technically recoverable oil and gas resources of the US onshore and state waters.
Oil. The USGS assessment found that the Bakken Formation has an estimated mean oil resource of 3.65 billion barrels of oil (BBO) and the Three Forks Formation has an estimated mean resource of 3.73 BBO, for a total of 7.38 BBO, with a range of 4.42 (95% chance) to 11.43 BBO (5% chance). This assessment of both formations represents a significant increase over the estimated mean resource of 3.65 billion barrels of undiscovered oil in the Bakken Formation that was estimated in the 2008 assessment.
Since the 2008 USGS assessment, more than 4,000 wells have been drilled in the Williston Basin, providing updated subsurface geologic data. Previously, very little data existed on the Three Forks Formation and it was generally thought to be unproductive. However, new drilling resulted in a new understanding of the reservoir and its resource potential.
The primary source of oil for the Bakken and Three Forks Formations are the Upper and Lower Bakken Shale Members of the Bakken Formation. USGS assessed the Bakken and Three Forks Formations for both continuous and conventional resources. Unlike conventional oil accumulations, continuous oil remains in or near the original source rock, and instead of occurring in discrete accumulations is dispersed heterogeneously over large geographic areas.
Natural gas. In addition to oil, these two formations are estimated to contain a mean of 6.7 trillion cubic feet of undiscovered, technically recoverable natural gas and 0.53 billion barrels of undiscovered, technically recoverable natural gas liquids. Gas estimates range from 3.43 (95% chance) to 11.25 (5% chance) trillion cubic feet of gas and 0.23 (95% chance) to 0.95 (5% chance) billion barrels of natural gas liquids.
This estimate represents a nearly three-fold increase in mean natural gas and a nearly threefold increase in mean natural gas liquids resources from the 2008 assessment, due primarily to the inclusion of the Three Forks Formation.
The geological foundation that underpins the assessment was facilitated by data provided by the North Dakota Geological Survey, North Dakota Industrial Commission, Montana Board of Oil and Gas, and multiple industry groups working in this region. This new information and data allowed USGS to develop a more robust geologic model and understanding of the petroleum system of the Bakken and Three Forks Formations.
Gaswirth, S.B., Marra, K.R., Cook, T.A, Charpentier, R.R., Gautier, D.L., Higley, D.K., Klett, T.R., Lewan, M.D., Lillis, P.G., Schenk, C.J., Tennyson, M.E., and Whidden, K.J. (2013) Assessment of undiscovered oil resources in the Bakken and Three Forks Formations, Williston Basin Province, Montana, North Dakota, and South Dakota, 2013: U.S. Geological Survey Fact Sheet 2013–3013, 4 p., http://pubs.usgs.gov/fs/2013/3013/