USGS Releases Assessment of Undiscovered Oil & Gas Resources in Wyoming, Southern Montana

Reston, Va. (March 12, 2025) — The U.S. Geological Survey (USGS) released its assessment of potential for undiscovered oil and gas in formations under Wyoming and parts of southern Montana, as well as parts of western South Dakota and Nebraska, assessing that there are technically recoverable resources of 47 million barrels of oil and 876 billion cubic feet of gas.

Since exploration began in the area in the 1920s, the upper Paleozoic reservoirs of the Wind River, Bighorn and Powder River basins have produced 4 billion barrels of oil — as much oil as the U.S. consumes in six months at the current rate of consumption.

“USGS energy assessments typically focus on undiscovered resources — areas where science tells us there may be a resource that industry hasn’t discovered yet. In this case, after a century of production, the upper Paleozoic reservoirs of the Wind River, Bighorn and Powder River basins have little remaining undiscovered oil,” said Sarah Ryker, acting director of the USGS.

USGS oil and gas assessments began 50 years ago following an oil embargo against the U.S. that signaled a need to understand the occurrence, distribution and potential volumes of undiscovered resources. The embargo led to a mandate for the USGS to use geologic science and data to assess undiscovered oil and gas resources to help meet the nation’s needs. The work continues today, identifying new resources for domestic production, as well as international resources that affect market conditions — an important part of the USGS mission to provide actionable insight to U.S. leaders, other federal agencies, industry and the public.

The range of assessments produced has changed with the technology available to produce oil. In 1995, the USGS began conducting assessments of unconventional, technically recoverable resources. “The shift to horizontal drilling with fracking has revolutionized oil production, and we’ve changed with it,” said Christopher Schenk, USGS geologist, noting that the Bakken Shale deposit in North Dakota had a few hundred vertical wells when the USGS first assessed the area, and that has grown to tens of thousands of wells today.

The USGS Energy Resources Program assesses the potential for undiscovered oil and gas resources in priority geologic provinces in the United States and around the world. Two methodologies are used by the USGS: one for assessing conventional oil and gas resources and one for assessing unconventional (continuous) oil and gas resources (such as shale gas and coalbed gas).

The fact sheet on the upper Paleozoic Oil and Gas Assessment is available here.