By OGJ editors
HOUSTON, Apr. 10 -- The Upper Devonian-Lower Mississippian Bakken formation in North Dakota and Montana, which has produced 105 million bbl of oil through the end of 2007, contains an estimated 3 to 4.3 billion bbl of undiscovered, technically recoverable oil, the US Geological Survey said Thursday.
This is 25 times the USGS 1995 assessment of the amount of oil that can be recovered from the formation. It is "larger than all other current USGS oil assessments of the lower 48 states and is the largest 'continuous' oil accumulation ever assessed by the USGS."
The next largest continuous oil accumulation in the US is in the Austin chalk of Texas and Louisiana, with an undiscovered estimate of 1 billion bbl technically recoverable.
The mean value for the Bakken is 3.65 billion bbl of oil, 1.85 tcf of associated-dissolved natural gas, and 148 million bbl of natural gas liquids. This volume is judged to be producible using available technology and industry practices.
"New geologic models applied to the Bakken formation, advances in drilling and production technologies, and recent oil discoveries have resulted in these substantially larger technically recoverable oil volumes," the USGS said.
Five continuous assessment units (AU) in the southern Williston basin were identified and assessed: Elm Coulee-Billings Nose, Central Basin-Poplar Dome, Nesson-Little Knife Structural, the Eastern Expulsion Threshold, and the Northwest Expulsion Threshold.
At the time of the assessment, a limited number of wells have produced oil from three of the assessment units: Central Basin-Poplar Dome, Eastern Expulsion Threshold, and Northwest Expulsion Threshold.
Elm Coulee field in Montana, discovered in 2000, has produced about 65 million bbl of Bakken oil (OGJ, Dec. 11, 2006, p. 42).
The USGS worked with the North Dakota Geological Survey, a number of petroleum industry companies and independents, universities, and other experts to develop a geological understanding of the Bakken formation.