Discovered Crude Oil Resources of Wyoming, USA
The geologic characteristics and distribution of the discovered crude oil resources in nine recognized petroleum systems are summarized for 375 oil fields, accounting for 93% of total crude oil production from Wyoming.
Through 2003 the fields analyzed had produced 6.40 billion barrels of crude oil from a total discovered resource base of 22.28 billion barrels (OOIP). Present remaining reserves are estimated to be 462 MMBO. This suggests that current oil production operations in the state will ultimately recover 7.31 billion barrels of oil, or about 32.8% of the original oil in place.
Approximately 54% of the discovered resource base is attributed to the Phosphoria-Minnelusa systems. The Permo-Pennsylvanian Tensleep and Minnelusa formations and their equivalents contain 35% of the resource. The thick high quality sandstone reservoirs of the Pennsylvanian Tensleep Formation exhibit the highest recovery efficiency, 34% to 62% of the OOIP. Recoveries in the Permian Phosphoria and Mississippian Madison carbonate reservoirs are in the range of 12% to 27%.
The Lower Cretaceous Mowry-Belle Fourche systems account for 26% of the discovered resource base, nearly all of which is contained in sandstone reservoirs of the Lakota (Cloverly), Fall River (Dakota), Muddy, and Frontier formations. A bulk of the remaining resource is contained within the Upper Cretaceous sandstone reservoirs within the Cody-Pierre Shale and their equivalents, the Mesaverde Group, and Lewis Formation. In general, the Cretaceous reservoirs exhibit the lowest average recoveries, ranging from 6% to 25% of the OOIP.