US doubles estimate of shale oil reserves

US government officials announced today the Bakken Formation and the Three Forks Formation in the country's central northwestern region contain twice the amount oil reserves than originally thought.

The United States Geological Survey said the combined shale formations contain 7.4 billion barrels of undiscovered, technically recoverable oil.

According to the new USGS assessment for Three Forks, which lies in North Dakota, South Dakota and Montana, it has an estimated mean of 3.73 billion barrels of oil — doubling the previous estimate.

In 2008, the USGS said the Bakken formation had about 3.65 billion barrels of undiscovered oil.

Image: David Gaylor,