| Description |
This report addresses an important need to the State of Utah; to define, tabulate, and document an economic resource which has aroused the interest of industry and academia and which is vastly undeveloped and little understood as to its potential. The need for this report has grown since the last tabulation, the 1979 Utah Geological and Mineral Survey Map No. 47 entitled "Oil Impregnated Rock Deposits of Utah". Much has changed in the domestic energy picture in the intervening ten years. During this time the energy boom of the 1970's have added greatly to a better understanding of this valuable hydrocarbon resource. The energy crisis of the 1970's affected the lives of all Americans. Rapid increases in energy prices and frequent shortages were stark reminders of our growing dependence on foreign energy resources in today's energy-hungry world. Innumerable; studies were conducted on the feasibility for utilizing tar sands as a replacement, far crude oil. Numerous proposals to develop Utah's tar sands were also formulated. But after many years of study and discussion of techniques, factors, and problems, the energy crisis subsided. With the subsidence, the plans for action were put on hold. The need tor a reliable alternative for crude oil, not only for energy but also for petrochemical usage, has not subsided, only the perception that an alternative is no longer needed. Tar sands were defined in 1980 by the U.S. Department of Energy as any consolidated or unconsolidated rock, other than coal, oil shale, or gilsonite, that contains hydrocarbons (bitumen) with a gas free viscosity greater than 10 pascal seconds, or 10,000 centipoise, at original reservoir temperature. Following passage of the 1981 Federal Combined Hydrocarbon Leasing Act, the Bureau of Land Management, for royalty purposes, added the phrase "or is produced by mining or quarrying" to the definition, Tar sand, oil sand, bituminous bearing rock, oil impregnated rock and bituminous sand are terms used interchangeably in describing petroleum-bearing, outcropping deposits. These are distinguished from more conventional crude oil reservoirs principally by the high viscosity of the hydrocarbon which is not recoverable in its natural state through current oil production techniques. The most, common terminology used to describe this resource is "tar sand", however, this term is somewhat of a misnomer. The heavy oil substance contained in these deposits is more accurately called bitumen, a dense viscous substance exhibiting chemical characteristics similar to petroleum and other liquid hydrocarbons found in close proximity to these deposits. In addition, the material containing the bitumen is not always sand or sandstone; limestone and siltstone deposits have also been found to contain these heavy oil deposits. Unlike oil shale which is relatively homogenous over a large areal extent, tar sand deposits are highly heterogenous, consisting of many separate occurrences characterized by noncontiguous beds and variations in point-to-point richness. Despite the inexactness of the term "tar sand" as it refers to domestic deposits, the term is firmly entrenched in the technical and industrial literature as well as legislative documents that it will also be used for the purposes of this assessment. |
