Assessment of Undiscovered Conventional Oil and Gas Resources in Upper Paleozoic Reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces, 2024

Fact Sheet 2024-3049
National and Global Petroleum Assessment
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Abstract

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean conventional resources of 47 million barrels of oil and 876 billion cubic feet of gas in upper Paleozoic reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces.

Introduction

The U.S. Geological Survey (USGS) assessed the potential for undiscovered, technically recoverable conventional oil and gas resources within upper Paleozoic reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces (fig. 1). These basins were formed during the Late Cretaceous to Paleogene Laramide orogeny that resulted in the fragmentation of the Sevier foreland by basement-involved deformation. This process formed intermontane basins, such as the Wind River, Bighorn, and Powder River Basins (Yeck and others, 2014; Yonkee and Weil, 2015). Exploration for oil in structural traps along the margins of these basins began in earnest in the 1920s because many of the contractional structures had obvious surface expression that focused exploration efforts. By the 1960s, most structural fields had been discovered. Since that time, exploration has focused on the pursuit of oil within complex stratigraphic and structural traps in eolian sandstones in the Permian upper part of the Pennsylvanian–Permian Minnelusa Formation in the north-central part of the Powder River Basin Province. The purpose of this report is to provide an assessment of the remaining oil and gas potential in upper Paleozoic reservoirs within structural and stratigraphic traps in these three geologic provinces.

Location of five conventional assessment units in upper Paleozoic reservoirs of the
                     Wind River Basin, Bighorn Basin, and Powder River Basin Provinces.
Figure 1.

Maps showing the location of five conventional assessment units (AUs) in upper Paleozoic reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces.

Total Petroleum Systems and Assessment Units

The USGS defined a Paleozoic–Mesozoic Composite Total Petroleum System (TPS) that encompasses oil generated and migrated from thermally mature Pennsylvanian and Cretaceous organic-rich shales. The geologic model for the Powder River Basin Leo Sandstone Reservoirs Assessment Unit (AU) is for oil generated from Pennsylvanian organic-rich shales and from Cretaceous shales (Clayton and Ryder, 1984) to have migrated into structural traps within the Hartville uplift. Reservoirs are predominantly eolian sandstones of the Pennsylvanian Leo Sandstone Member of the Minnelusa Formation (Tromp and others, 1981; Cardinal and Sherer, 1984; McBane, 1984).

The Phosphoria TPS was defined in the Wind River Basin and Bighorn Basin Provinces to encompass oil that may have been generated from thermally mature organic-rich shales of the Retort Tongue and Meade Peak Member of the Permian Phosphoria Formation in west-central Wyoming and eastern Idaho (Maughan, 1975). Phosphoria-generated oil was ultimately trapped in upper Paleozoic reservoirs in the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces (Donohue and others, 2020), possibly as the result of long-distance eastward migration of oil (Sheldon, 1967; Stone, 1967; Maughan, 1975). Although several scenarios have been proposed for the regional distribution of oil generated from the Phosphoria Formation, the processes and timing of long-distance oil migration relative to ultimate trap formation are not well constrained (Burtner and Nigrini, 1994; Ellis and others, 2017; Kendall and others, 2023). The Wind River Basin Upper Paleozoic Reservoirs AU and the Bighorn Basin Upper Paleozoic Reservoirs AU were defined within the Phosphoria TPS (fig. 1). The geologic model for these two AUs is for Phosphoria-sourced oil to have ultimately migrated into eolian sandstone reservoirs in sandstones of the Pennsylvanian Amsden Formation and into the Pennsylvanian–Permian Tensleep Sandstone, and into carbonates of the Phosphoria Formation within Laramide-age structural and stratigraphic traps (Andrews and Higgins, 1984; Curry, 1984; Carr-Crabaugh and Dunn, 1996). Phosphoria-sourced gas is interpreted to have been generated at depth and trapped mainly within carbonate reservoirs of the Mississippian Madison Group, such as the hydrogen-sulfide-rich gas occurring within the dolomites of the Madison Group of the Madden Deep Field in the Wind River Basin Province (Hawkins and Baugh, 2006).

The Pennsylvanian–Permian Composite TPS was defined within the Powder River Basin Province to encompass oil and gas generated and migrated from organic-rich shales of the Phosphoria Formation (Donohue and others, 2020) and oil possibly generated from organic-rich shales of the Pennsylvanian middle part of the Minnelusa Formation (Clayton and Ryder, 1984; Desmond and others, 1984). The Powder River Basin Minnelusa Sandstone Reservoirs AU and the Powder River Basin Tensleep Basin Margin Reservoirs AU were defined within this composite TPS (fig. 1). The geologic model for the Powder River Basin Minnelusa Sandstone Reservoirs AU is for oil from the Phosphoria Formation and from thin, organic-rich shales of the middle part of the Minnelusa Formation to have migrated into Wolfcamp-age eolian sandstones within a spectrum of stratigraphic and structural traps (Fryberger, 1984; George, 1984; Trotter, 1984; Sheppy, 1986; Jorgensen and James, 1988). The potential for oil in the eolian sandstone reservoirs of the middle part of the Minnelusa Formation (Desmond and others, 1984) and for oil and gas in the carbonate reservoirs of the Madison Group are included in this AU. The geologic model for the Powder River Basin Tensleep Basin Margin Reservoirs AU is for oil to have migrated from the Powder River Basin into structural traps along the western and southern margins of the basin. Reservoirs within the basin-margin structures are eolian sandstones of the Tensleep Sandstone and possibly carbonates of the Madison Group. The assessment input data for five conventional AUs are summarized in table 1 and in Schenk (2025).

Table 1.    

Key input data for five conventional assessment units in upper Paleozoic reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces.

[Gray shading indicates not applicable. AU, assessment unit; MMBO, million barrels of oil; BCFG, billion cubic feet of gas]

Assessment input data—Conventional AUs Powder River Basin Leo Sandstone Reservoirs AU Wind River Basin Upper Paleozoic Reservoirs AU
Minimum Median Maximum Calculated mean Minimum Median Maximum Calculated mean
Number of oil fields 1 2 4 2.1 1 4 12 4.3
Number of gas fields 1 12 48 13.2
Size of oil fields (MMBO) 0.5 0.8 6 1.0 0.5 0.8 10 1.0
Size of gas fields (BCFG) 3 18 1,500 46.0
AU probability 0.95 1.0
Assessment input dataConventional AUs Bighorn Basin Upper Paleozoic Reservoirs AU Powder River Basin Minnelusa Sandstone Reservoirs AU
Minimum Median Maximum Calculated mean Minimum Median Maximum Calculated mean
Number of oil fields 1 20 40 20.5 1 15 30 15.4
Number of gas fields 1 6 24 6.6 1 2 8 2.2
Size of oil fields (MMBO) 0.5 0.8 12 1.1 0.5 0.8 6 1.0
Size of gas fields (BCFG) 3 12 1,000 30.1 3 12 360 20.8
AU probability 1.0 1.0
Assessment input dataConventional AUs Powder River Basin Tensleep Basin Margin Reservoirs AU
Minimum Median Maximum Calculated mean
Number of oil fields 1 4 8 4.1
Number of gas fields
Size of oil fields (MMBO) 0.5 0.8 6 1.0
Size of gas fields (BCFG)
AU probability 0.95
Table 1.    Key input data for five conventional assessment units in upper Paleozoic reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces.

Undiscovered Resources Summary

The USGS quantitatively assessed undiscovered conventional oil and gas resources in upper Paleozoic reservoirs in five AUs in the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces (table 2). The estimated mean undiscovered resources are 47 million barrels of oil (MMBO), with an F95–F5 range from 24 to 76 MMBO; 876 billion cubic feet of gas (BCFG), or 0.9 trillion cubic feet of gas, with an F95–F5 range from 198 to 2,186 BCFG; and 20 million barrels of natural gas liquids (MMBNGL), with an F95–F5 range from 4 to 50 MMBNGL.

Table 2.    

Results for five conventional assessment units in upper Paleozoic reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces.

[Results shown are fully risked estimates. F95 represents a 95-percent chance of at least the amount tabulated; other fractiles are defined similarly. Gray shading indicates not applicable. MMBO, million barrels of oil; BCFG, billion cubic feet of gas; NGL, natural gas liquids; MMBNGL, million barrels of natural gas liquids]

Total petroleum systems and assessment units (AUs) AU prob-ability Accum-ulation type Total undiscovered resources
Oil (MMBO) Gas (BCFG) NGL (MMBNGL)
F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean
Powder River Basin Leo Sandstone Reservoirs AU 0.95 Oil 0 2 4 2 0 1 3 1 0 0 0 0
Gas
Wind River Basin Upper Paleozoic Reservoirs AU 1.0 Oil 2 4 9 4 2 4 8 4 0 0 0 0
Gas 142 497 1,468 610 3 11 34 14
Bighorn Basin Upper Paleozoic Reservoirs AU 1.0 Oil 13 22 34 22 7 12 19 12 0 1 1 1
Gas 37 145 554 200 1 3 9 3
Powder River Basin Minnelusa Sandstone Reservoirs AU 1.0 Oil 9 14 22 15 1 1 1 1 0 0 0 0
Gas 9 33 132 47 0 2 6 2
Powder River Basin Tensleep Basin Margin Reservoirs AU 0.95 Oil 0 4 7 4 0 1 1 1 0 0 0 0
Gas
Total undiscovered conventional oil and gas resources 24 46 76 47 198 694 2,186 876 4 17 50 20
Table 2.    Results for five conventional assessment units in upper Paleozoic reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces.

For More Information

Assessment results are also available at the USGS Energy Resources Program website, https://www.usgs.gov/programs/energy-resources-program.

Upper Paleozoic Reservoirs Assessment Team

Christopher J. Schenk, Tracey J. Mercier, Phuong A. Le, Andrea D. Cicero, Ronald M. Drake II, Sarah E. Gelman, Jane S. Hearon, Benjamin G. Johnson, Jenny H. Lagesse, Heidi M. Leathers-Miller, and Kira K. Timm

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Suggested Citation

Schenk, C.J., Mercier, T.J., Le, P.A., Cicero, A.D., Drake, R.M., II, Gelman, S.E., Hearon, J.S., Johnson, B.G., Lagesse, J.H., Leathers-Miller, H.M., and Timm, K.K., 2025, Assessment of undiscovered conventional oil and gas resources in upper Paleozoic reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces, 2024: U.S. Geological Survey Fact Sheet 2024–3049, 4 p., https://doi.org/10.3133/fs20243049.

ISSN: 2327-6932 (online)

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Assessment of undiscovered conventional oil and gas resources in upper Paleozoic reservoirs of the Wind River Basin, Bighorn Basin, and Powder River Basin Provinces, 2024
Series title Fact Sheet
Series number 2024-3049
DOI 10.3133/fs20243049
Publication Date March 13, 2025
Year Published 2025
Language English
Publisher U.S. Geological Survey
Publisher location Reston VA
Contributing office(s) Central Energy Resources Science Center
Description Report: 4 p.; Data Release
Country United States
State Montana, Nebraska, South Dakota, Wyoming
Online Only (Y/N) Y
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