Depositional setting and preliminary oil-shale resource potential, southwestern Uinta Basin, Utah

This report characterizes the potential oil-shale resources underlying those lands west of the Green River in the southwestern Uinta Basin, Utah. The principal evaluation technique has been the calculation of oil yield from oil-well sonic and density log data available in this area. Subsurface correlations have demonstrated the continuity of several oil-shale zones across much of the report area and have isolated a nearly east-west, narrow depositional axis of Lake Uinta that existed during the deposition of the Mahogany oil-shale zone. Several troughs of thick oil-shale accumulation were identified in the Mahogany zone. One trough in the western portion of the study area may contain an average oil yield of 25 gallons per ton continuously through 70 vertical feet. Oil-yield estimates are presented, based on a relationship between acoustic velocity and bulk density, as functions of kerogen content; however, basic parameters that may bias the log interpretations, such as formation-fluid content, porosity, and lithology can, at present, only be assumed from existing geophysical data, outcrop studies, and core data in the eastern basin. The isopach and oil-yield data should be considered as a maximum expected resource potential and the calculation of reserve estimates remains, at present, premature. Regional Tertiary east-west depositional trends are also discussed and similarities notes with the Sheep Pass and Elko Basins of Nevada.