Undiscovered Oil and Gas in the Wyoming Thrust Belt, 2017 USGS Assessment

Using a geology-based method, the U.S. Geological Survey estimated that the Wyoming Thrust Belt Province of Wyoming, Idaho and Utah holds these undiscovered, technically recoverable conventional resources (means):

F95 means a 95 percent chance of at least that amount; F5, a 5 percent chance.

The province, its one conventional assessment unit and its major thrust faults. Base map from the National Park Service. USGS.

A belt of stacked thrust sheets

The province lies west of the Southwestern Wyoming Province, east of the Eastern Great Basin, south of the Idaho–Snake River Downwarp and north of the Uinta–Piceance Basin.

• How it formed: east-directed compression during the Sevier Orogeny (Late Jurassic to Late Cretaceous), driven by steeply dipping subduction, piled up thrust sheets that get younger toward the east.
• The major thrusts: Paris-Willard, Meade, Crawford, Absaroka, Hogsback-Darby and Prospect.
• Discoveries: exploration in the mid-1970s found more than 30 oil and gas fields, most on the Absaroka sheet; the others have been largely unsuccessful.
• The timing of thrust loading and deformation gave the province's petroleum systems a complex history.

The petroleum system

The USGS defined the Paleozoic–Mesozoic Composite Total Petroleum System and, within it, one assessment unit: the Wyoming Thrust Belt Conventional Oil and Gas AU.

The geologic model

• Phosphoria oil left early: the Phosphoria shales matured for oil before most thrust structures formed, and much of their oil migrated east into what are now the Laramide basins of Wyoming, Montana and Colorado. Oil left behind was cracked to dry gas as the thrusts loaded the rock; most Phosphoria shale in the belt is now in the dry-gas window or past it.
• Aspen timing was right: the Aspen Shale matured as the thrust sheets moved, making it the main source of oil in the belt's reservoirs, along with some gas.
• Traps: oil and gas migrated into conventional reservoirs in structural traps.
• Reservoirs: mostly carbonates — the Ordovician Bighorn Dolomite, Mississippian Madison Group, Pennsylvanian Amsden Formation, Lower Permian Phosphoria Formation, Lower Triassic Thaynes Formation and Middle Jurassic Twin Creek Limestone — plus the Pennsylvanian Weber and Tensleep sandstones and the Jurassic Nugget Sandstone.

Input data

Results by accumulation type

Fully risked estimates; for gas accumulations all liquids are counted as NGL.

Sources

Based on Assessment of Undiscovered Conventional Oil and Gas Resources in the Wyoming Thrust Belt Province, Wyoming, Idaho, and Utah, 2017, U.S. Geological Survey Fact Sheet 2017–3091 (publication page), by the Wyoming Thrust Belt Province Assessment Team (Christopher J. Schenk, Tracey J. Mercier, Marilyn E. Tennyson, Cheryl A. Woodall, Michael E. Brownfield, Phuong A. Le, Timothy R. Klett, Stephanie B. Gaswirth, Thomas M. Finn, Kristen R. Marra and Heidi M. Leathers-Miller). The map and both tables are restored from the fact sheet's PDF. More results: USGS Energy Resources Program. A work of the United States government in the public domain.