| Description |
The P.R. Spring oil-impregnated sandstone (tar sand) deposit is located in the southeastern portion of the Uinta Basin, approximately 50 miles northwest of Grand Junction, Colorado. These oil impregnated sandstones are in the Eocene Green River Formation and five zones have been identified. These zones consist of one or more lenticular beds of lacustrine sandstone, separated by intervals of barren lithologies. The degree of impregnation of individual beds within the five zones is controlled by the lateral extent of the bed, its porosity and permeability, and the distance the oil has migrated within the bed. The degree of saturation varies both laterally and vertically. The purpose of this report was to 1) determine the total hydrocarbon content of each zone in blocks of 640 acres or less, and 2) relate this data to current economic and mining feasibility. This study incorporates the results of 38 measured sections and 26 core holes. The oil extracted from the P.R. Spring tar sands is a naturally occurring, brown to black, highly viscous or solid mixture of hydrocarbons. Its composition indicates that the oil was formed in situ or migrated only a short distance. The author has calculated the total barrels of oil in place for the deposit to be approximately 3.3 billion barrels. This is less than other published calculations of 3.7 and 4.0 to 4.5 billion barrels (Byrd, 1967; Ritzma, 1974). Problems associated with the method of economic recovery of the oil remain to be solved. Only the southeastern corner of the field is strip rninable. Other areas will probably have to be exploited by in situ recovery methods and several are being tested. The only known active operation in P.R. Spring is by Bighorn Oil, located in the southeastern part of the deposit. Their operation consists of an open-pit mine and a 200-barrel-per-day extraction plant utilizing a solvent solution process. Surface water availability in the area is limited, but may be sufficient if storage, reuse and ground-water potential are considered. Oil extraction will require a fuel supply, possibly from generated coke and other byproduct fuels generated by the tar refining process or by local natural gas or coal production. Further work is needed in the area, specifically more core holes and associated analyses. Strategic drilling in T. 11 S., R. 22 and 24 E., and T. 12 S., R. 22 E., could be used to verify assumed saturation. |
