The Bakken and Three Forks formations in North Dakota, South Dakota, and Montana hold an estimated mean of 7.38 billion bbl of undiscovered, technically recoverable crude oil, the US Geological Survey announced.
The updated assessment represents a two-fold increase from the 2008 estimate of 3.65 billion bbl in the Bakken, it noted. The update includes the Three Forks for the first time.
USGS’s latest assessment found that the Bakken has a 3.65 billion bbl estimated mean resource—unchanged from 5 years ago—and Three Forks has an estimated mean 3.73 billion bbl. The formations’ combined estimate ranges from 4.42 million bbl, with a 95% chance of production, to 11.43 billion bbl, with a 5% chance.
Since 2008, however, more than 4,000 wells have been drilled in the 2 formations producing 450 million bbl of crude, and Three Forks activity has increased significantly, warranting its inclusion in the area estimate, the US Department of the Interior agency said.
The new assessment also found mean undiscovered, technically recoverable volumes of 6.7 Tcf of associated/dissolved natural gas, and 0.53 billion bbl of natural gas liquids in the Bakken and Three Forks formations.
Gas estimates ranged from 3.43 Tcf (with a 95% chance of production) to 11.25 Tcf (with a 5% chance) and 0.23 billion bbl (95%) to 0.95 billion bbl (5%) of NGLs. These estimates represent a nearly three-fold increase in mean gas and NGL resource estimates from the 2008 assessment, due primarily to the inclusion of Three Forks Formation, USGS said.
Resource bigger than initial estimates
“These world-class formations contain even more energy resource potential than previously understood which is important information as we continue to reduce our nation’s dependence on foreign sources of oil,” US Interior Secretary Sally Jewell said.
Acting USGS Director Suzette M. Kimball said the agency undertook the assessment of the Bakken and Three Forks formations as part of a nationwide project assessing US petroleum basins using standardized methodology and protocol.
The geological foundation underpinning USGS’s assessment was facilitated by data provided by the North Dakota Geological Survey, North Dakota Industrial Commission, Montana Board of Oil and Gas, and multiple industry groups working in the region, the agency said.
This new information and data allowed it to develop a more robust geologic model and understanding of the two formations’ petroleum system, it indicated.
In a 2010 assessment, North Dakota’s Geological Survey and Department of Mineral Resources estimated that almost 20 billion bbl of oil apparently appeared to be in place within the Three Forks portion of the Bakken pool, with close to 2 billion bbl expected to be produced.
It noted that the state’s oil and gas division, which is part of DMR, generally defined the upper 50 ft of the Three Forks formation as the lowest part of the Bakken pool.
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