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National Assessment of Oil and Gas Fact Sheet

Assessment of Undiscovered Oil and Gas Resources of the Southwestern Wyoming Province, 2002

Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean 84.6 trillion cubic feet of undiscovered natural gas, mean of 131 million barrels of undiscovered oil, a mean of 2.6 billion barrels of undiscovered natural gas liquids in the Southwestern Wyoming Province.
Introduction
The U.S. Geological Survey (USGS) recently completed an assessment of the undiscovered oil and gas potential of the Southwestern Wyoming Province (fig.1). The USGS Southwestern Wyoming Province for this assessment included the Green River Basin, Moxa arch, Hoback Basin, Sandy Bend arch, Rock Springs uplift, Great Divide Basin, Wamsutter arch, Washakie Basin, Cherokee Ridge, and the Sand Wash Basin. The assessment of the Southwestern Wyoming Province is based on the geologic elements of each Total Petroleum System TPS) defi ned in the province, including hydrocarbon source rocks (source-rock maturation, hydrocarbon generation and migration), reservoir rocks (sequence stratigraphy and petrophysical properties), and hydrocarbon traps (trap formation and timing). Using this geologic framework, the USGS defi ned nine Total Petroleum Systems (TPS) and 23 Assessment Units (AU) within these TPSs and quantitatively estimated the undiscovered oil and gas resources within 21 of the 23 AUs (table 1).
Resource Summary
The USGS assessed undiscovered conventional oil and gas and undiscovered continuous (unconventional) oil and gas. The USGS estimated a mean of 84.6 trillion cubic feet of gas (TCFG), a mean of 131 million barrels of oil (MMBO), and a mean of 2.6 billion barrels of total natural gas liquids (BBNGL) in nine TPSs. Nearly all (97 percent, or 82.1 TCFG) of the undiscovered gas resource is continuous and distributed in six Total Petroleum Systems: Mowry Composite TPS (8.5 TCFG); Hilliard-Baxter- Mancos TPS (11.7 TCFG); Mesaverde TPS (25.8 TCFG); Mesaverde-Lance-Ft. Union Composite TPS (13.7 TCFG); Lewis TPS (13.5 TCFG); and Lance-Ft. Union Composite TPS (8.7 TCFG) (table 1). The remainder of the undiscovered gas is associated/dissolved gas in oil accumulations 0.13 TCFG) or is in conventional nonassociated gas accumulations (2.3 TCFG). The Niobrara TPS is estimated to contain a mean of about 103 MMB of continuous oil, or about 79 percent of all undiscovered oil. The Phosphoria TPS contains a mean of 16.6 MMBO, or about 12.5 percent of the undiscovered oil. The remainder of the undiscovered oil is in the Mowry TPS, the Mesaverde TPS, and the Mesaverde-Lance-Ft. Union Composite TPS (table 1). The Niobrara Continuous Gas AU and the Wasatch-Green River Continuous Gas AU were not quantitatively assessed in this study.
For Further Information
Supporting geologic studies of Total Petroleum Systems and Assessment Units, and reports on the methodology used in the Southwestern Wyoming Province assessment are in progress.
Assessment results are available at the USGS Central Energy Team website:
http://energy.cr.usgs.gov/oilgas/noga/
Figure 1. Green River Map - Southwestern Wyoming Province of southwestern Wyoming and northwestern Colorado.

Figure 1. Southwestern Wyoming Province of southwestern Wyoming and northwestern Colorado.


Southwestern Wyoming Province Assessment Team:
Mark Kirschbaum (Task Leader; mkirsch@usgs.gov), Thomas M. Finn, Robert D. Hettinger, Edward A. Johnson, Ronald C. Johnson, Joyce Kibler, Paul G. Lillis, Philip H. Nelson, Laura N.R. Roberts, Stephen B. Roberts, Ronald R. Charpentier, Troy A. Cook, Robert A. Crovelli, Timothy R. Klett, Richard M. Pollastro, and Christopher J. Schenk.
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