The U.S. Geological Survey announced Tuesday that the Bakken and Three Forks Formations in North Dakota, South Dakota and Montana have about 7.4 billion barrels of undiscovered, technically recoverable oil.
The upper end of the estimate is 11.4 billion barrels, said Sen. John Hoeven, R-N.D., who had pressed for the new assessment.
The assessment of both formations, the largest unconventional oil resource the agency has ever assessed, is more than twice the previous estimate of 3.65 billion barrels for just the Bakken Formation which as identified in a 2008 assessment.
Technically recoverable oil resources are those producible using currently available technology and industry practices.
The U.S. Geological Survey's new report found that the Bakken Formation has an estimated 3.65 billion barrels of oil and the Three Forks Formation about 3.73 billion barrels for a total of 7.38 billion barrels.
In addition to oil, the two formations are believed to contain 6.7 trillion cubic feet of undiscovered, technically recoverable natural gas and 0.53 billion barrels of undiscovered, technically recoverable natural gas liquids.
"This is clearly great news for North Dakota and great news for the nation," said Hoeven. "It will further serve to enhance our state's role as an energy powerhouse for the nation.
Hoeven had initially contacted Brenda Pierce, coordinator for the Energy Resources Program at the USGS to do the new study early in 2011.
He followed up with now former Interior Secretary Ken Salazar in March 2011 to initiate a new USGS study of the Williston Basin that would encourage more private-sector investment in infrastructure like housing, hotels, retail stores and other services to meet the needs of a rapidly growing western North Dakota.
"This new USGS study further confirms and reinforces the fact that the Williston Basin is a sustainable, long-term play warranting strong private-sector investment for decades into the future," Hoeven said.
Sen. Heidi Heitkamp, D-N.D., said, "The findings released today by the USGS are an affirmation that North Dakota is going to continue to play a major role in America's oil and gas development and production for decades to come. We are in an excellent position to use our resources to improve the lives of North Dakotans with smart investments, while also helping our nation become energy independent.
"This assessment is yet another reminder that increased oil and gas development in North America requires critical infrastructure, like the Keystone XL pipeline, in place to handle increased and sustained production. Pipeline infrastructure is crucial to the safe and efficient transport of oil and natural gas," Heitkamp said. "Among many issues, we need to ensure that there are adequate roads, housing units, and schools in the Bakken communities to support long-term growth."
Secretary of the Interior Sally Jewell said during a teleconference Tuesday that the new assessment is the first USGS assessment in the region since 2008, and part of a nationwide project for the USGS to assess U.S. petroleum basins.
She said the assessment released Tuesday shows an even greater amount of potential resources in the region which is important to better understand the nation's domestic energy portfolio.
"Combined with recent declines in oil consumption, foreign oil imports now account for less than 40 percent of the oil consumed in America the lowest level since 1988," she said.
Jewell said the North Dakota Geological Survey, North Dakota Industrial Commission, Montana Oil and Gas and others provided data for the assessment.
Lynn Helms, Bismarck, director of the North Dakota Department of Mineral Resources, said, "Assessments like these are typically more conservative because technology changes so rapidly. We agree with the range of numbers and think the high estimate of 11 billion barrels is a reasonable target as technology and exploration of the Three Forks continues."
Suzette Kimball, acting director of the USGS, said the Three Forks was not included in the 2008 assessment, and the increase in the undiscovered, technically recoverable oil in the new assessment is primarily due to including the Three Forks information.
The primary source of oil for the Bakken and Three Forks Formations are the upper and lower Bakken shale members of the Bakken Formation.
State Geologist Ed Murphy said the assessment shows the importance of Three Forks development, something that companies are just beginning to explore. "This is an evolving oil play, and we will continue to evaluate the results as more wells are drilled into the deeper Three Forks benches," he said.
Kimball said the increase in natural gas estimates is due primarily to the inclusion of the Three Forks Formation in the assessment.
Since the 2008 assessment, more than 4,000 wells have been drilled in the Williston Basin that provided updated subsurface geologic data.
Previously, very little data existed on the Three Forks Formation and it was generally thought to be unproductive, officials said. However, new drilling resulted in a new understanding of the reservoir and its resource potential.
To warrant a revised study the U.S. Geological Survey needed current data from the oil companies regarding production curves, recovery rates, new technologies they are employing and any new geological analyses they have available, according to information from Hoeven.
Seven companies producing oil in the state provided data to the U.S. Geological Survey about the latest technologies and recovery rates in the Williston Basin, including XTO Energy, Continental Oil, Cornerstone Energy Resources, Marathon Oil, United Energy Corp., Sinclair Oil Corp., and Whiting Oil and Gas. The N.D. Department of Mineral Resources also shared geological data with the USGS.
The full assessment can be found at (pubs.usgs.gov/fs/2013/3013/).