BISMARCK, N.D. - The government estimates that about 200 million barrels of oil can be recovered in the Williston Basin, which includes parts of the Dakotas and Montana, using current technology.
The latest U.S. Geological Survey estimate is for an area outside the Bakken shale formation, an oil-rich deposit within the basin. It compares with a 1995 estimate of 150 million barrels using technology at that time.
Lawrence Anna, a USGS geologist and one of the report's authors, said the estimate is separate from an assessment done in April on the Bakken formation. The USGS has estimated that up to 4.3 billion barrels of oil can be recovered from the Bakken in North Dakota and Montana, using current technology.
North Dakota produced 45 million barrels of oil last year, up about 5 million barrels from 2006. Production this year is on pace to exceed the record of 52.6 million barrels set in 1984, state officials say.
Companies will likely continue to focus on oil production in the entire Williston Basin, Anna said.
"I think the Bakken will be the main target, but I don't think everybody is putting their eggs in one basket, either," he said.
The Williston Basin is a 134,000-square-mile-area that includes North Dakota, South Dakota, Montana and the Canadian provinces of Saskatchewan and Manitoba.
The Bakken formation encompasses some 25,000 square miles within the Williston Basin in North Dakota, Montana, Saskatchewan and Manitoba. About two-thirds of the acreage is in western North Dakota, where the oil is trapped in a thin layer of dense rock nearly two miles beneath the surface.
The Geological Survey has called the Bakken formation the largest continuous oil accumulation it has ever assessed.
Rich Pollastro, a USGS geologist, said the USGS reports cover only U.S. portions of the Bakken and the Williston Basin.
Anna said most of newly identified recoverable oil in the Williston Basin comes in North Dakota and Montana. South Dakota has only a negligible amount, if any, he said.
"South Dakota certainly gets the short end of the stick when it comes to new resources," Anna said.