Basin-wide evaluation of the uppermost Green River Formation's oil shale resource, Uinta Basin, Utah and Colorado
Michael D. Vanden Berg, Utah Geological Survey
Presented at the AAPG Annual Conference, Denver, CO, June 2009
Due to the recent increase in crude oil prices and concerns over diminishing conventional reserves, the Utah Geological Survey has reexamined the Uinta Basin’s oil shale resource, primarily in the Mahogany zone of the Green River Formation. We created conversion equations by correlating available Fischer assays with corresponding density and sonic measurements as a way to predict oil yield from geophysical logs. In addition to the core-based Fischer assays obtained from 107 wells drilled specifically for oil shale, 186 oil and gas wells with oil yields calculated from digitized bulk density or sonic logs were used to create a basin-wide picture of the oil shale resource in the Uinta Basin. These widespread data were used to map oil shale thickness and richness and create isopach maps delineating oil yields of 15, 25, 35, and 50 gallons of shale oil per ton (GPT) of rock. From these isopach maps, new basin-wide resource numbers were calculated for each richness grade.