FAQ
What is the Bakken Formation?
The Bakken Formation was initially described by geologist J.W. Nordquist in 1953, and is an immense blanket of rock from the Late Devonian to Early Mississippian age occupying a substantial part of the subsurface of the Williston Basin, Montana, North Dakota, and Saskatchewan. Covering about 200,000 square miles, the Bakken serves as a significant oil reservoir, and until recently has historically frustrated efforts to extract its oil, initially discovered in 1951.
The formation consists of three members: lower shale, middle dolomite, and upper shale. The shales were deposited in relatively deep marine conditions, and the dolomite was deposited as a coastal carbonate bank during a time of shallower water. The middle dolomite member is the principal oil reservoir, roughly two miles below the surface.
© 2008 U.S.G.S.
Porosities in the Bakken average about 5%, and permeabilities are very low, averaging 0.04 millidarcies - much lower than typical oil reservoirs. However, the presence of horizontal fractures makes the Bakken an excellent candidate for horizontal drilling techniques in which a well drills along the extent of the rock layer, rather than punching a hole vertically through it. In this way, many thousands of feet of oil reservoir rock can be penetrated in a unit that reaches a maximum thickness of only about 140 feet. Production is also enhanced by artificially fracturing the rock.
The bulk of Bakken oil production comes from Elm Coulee Oil Field, Richland County, Montana, where production began in 2000 and is expected to ultimately total 270 million barrels. In 2007, production from Elm Coulee averaged 53,000 barrels per day, more than the entire state of Montana a few years ago.
EOG Resources of Houston, Texas reported that a single well it had drilled into an oil-rich layer of shale below Parshall, North Dakota is anticipated to produce 700,000 barrels of oil.
Estimates for ultimate oil contained in the entire Bakken play range from 271 billion to 503 billion barrels, with a mean of 413 billion barrels of technically recoverable and irrecoverable oil. This massive estimate appears to dwarf the estimated 50 billion to 70 billion barrels of technically recoverable and irrecoverable oil in Alaska’s North Slope. A conservative estimate of the Bakken’s technically recoverable oil would be 1% to 3% percent, or between 4.1 and 12.4 billion barrels of oil, due to the fact that Bakken’s shale is so tight. Recoverable oil estimates in the Alaska formation are 30% to 50%, or a mean of 26 billion barrels.
From Wikipedia.com
Where is the Bakken Formation?
© 2006 Walker, et al.