WASHINGTON, April 11 A shale rock formation
that stretches across Montana and North Dakota could hold about
3.7 billion barrels of oil, the biggest single deposit in the
United States except for Alaska, the U.S. Geological Survey
said this week.
The new USGS study shows the biggest contiguous oil deposit
in the Bakken Shale formation, located in the Williston Basin,
which extends from the U.S.-Canada border down into Montana and
The last time the USGS assessed the area in 1995, it found
151 million barrels of technically recoverable oil, but
drilling technology advances allowed the 25-fold increase in
its potential, said U.S. Sen. Byron Dorgan, the North Dakota
Democrat who requested the study.
"The substantial amount of oil that it estimates is in the
Bakken Shale should attract significant new investment to this
region," Dorgan said.
The Bakken Shale, comprised of thin layers of rock about
two miles down, holds about 3.65 billion barrels of technically
recoverable oil, the USGS said. The Arctic National Wildlife
Refuge (ANWR) in Alaska could hold more than 10 billion barrels
But while ANWR is off-limits due to a congressional
drilling moratorium, Marathon Oil Corp, EOG Resources Inc and
Continental Resources Inc are among the companies already
producing oil in the Bakken Shale.
The area could also hold 1.85 trillion cubic feet of
natural gas and 148 million barrels of natural gas liquids, the
As early as 2000 there was virtually no oil and gas
produced from the Bakken Shale because of its complex geology,
but it now accounts for half of Montana's oil production,
thanks to high-tech advances like horizontal drilling. The area
has turned North Dakota into the No. 8 U.S. oil producer.
As production in conventional oilfields declines, U.S.
energy companies are turning to shale formations, where
hydrocarbons are trapped in layers of rock.
For example, the Barnett Shale in north Texas has yielded
sizable new discoveries in recent years.
(Reporting by Chris Baltimore; Editing by Christian Wiessner)