Leigh Price, a scientist with the U.S. Geological Survey, published a study in 1999 that estimates the Bakken shales formation, which underlies much of several western and northwestern counties, may hold up to 400 billion barrels of oil.
By comparison, the Arctic refuge oil reserve is estimated at 16 billion barrels.
Now, Sen. Byron Dorgan, D-N.D., is pushing the federal agency to complete scientific work on Price's paper as part of a national inventory of the nation's oil resources.
The Bakken formation is being developed to some extent in North Dakota, but with better success so far on the Montana side of the formation.
Recently, Marathon Oil, a major national and international oil developer, acquired 200,000 mineral acres from Billings to McKenzie counties and plans to drill as many as 300 wells into the Bakken in the next five years.