U.S. Geological Survey: Bakken has more oil and gas than previously estimated. The USGS released a new survey finding that the Bakken shale play and the nearby Three Forks Formation contain nearly double the oil and gas than the agency previously calculated in 2008. The Three Forks shale formation underlies North Dakota, South Dakota, and Montana. Combined, USGS estimates the formations hold 7.4 billion barrels of undiscovered, technically recoverable crude oil. Slightly more than half lies in the Three Forks formation, which has not yet been exploited as it is deeper than the Bakken and more costly to develop. The formations are also estimated to hold 6.7 trillion cubic feet of recoverable natural gas.