Richard M. Pollastro Stephanie B. Gaswirth Michael D. Lewan Paul G. Lillis Laura N.R. Roberts Christopher J. Schenk Ronald R. Charpentier Troy A. Cook Timothy R. Klett Lawrence O. Anna 2008 <p><span>Using a geology-based assessment method, the U.S. Geological Survey estimated mean undiscovered volumes of 3.8 billion barrels of undiscovered oil, 3.7 trillion cubic feet of associated/dissolved natural gas, and 0.2 billion barrels of undiscovered natural gas liquids in the Williston Basin Province, North Dakota, Montana, and South Dakota. (See “Introduction” in Fact Sheet for additional information.)</span></p> application/pdf 10.3133/fs20083092 en U.S. Geological Survey Assessment of undiscovered oil and gas resources of the Williston Basin Province of North Dakota, Montana, and South Dakota, 2008 reports