Tar sand: Technology status report

Tar Sand is defined as any consolidated or unconsolidated rock, exclusive of coal, gilsonite, or oil shale, that contains a hydrocarbonaceous material with a gas-free bitumen viscosity greater than 10,000 centipoise (cP) at reservoir temperatures. Figure 1 graphically relates tar sand to heavy and light oil (Kuuskraa 1985). The tar sand resource base of the United States is composed of approximately 550 occurrences broadly distributed over 22 states, with the major deposits located in Utah, Alaska, Alabama, Texas, California, and Kentucky. Figure 2 (Marchant 1985) illustrates the geographic scatter and implies the geologic diversity of the deposits. In addition, hydrocarbon and mineralogical properties vary widely between deposits. The total tar sand resource base was estimated by Lewin and Associates (Kuuskraa 1985) to include measured and speculative resources of 61.7 billion barrels of oil in place, and may approach 100 billion barrels with additional resource characterization. Figure 3 (Kuuskraa 1985) illustrates the distribution of tar sand resources by state; measured versus speculative resources are also shown. Since tar sand has had no significant commercial development in the U.S., little effort has been expended to discover and evaluate resources. Tar sand bitumen is solid at room temperature. Most domestic tar sand is consolidated. In general, the mineral matrix is nearly all fine-grained quartz, or modified quartz, with 50% by weight being less than 0.3 mm (300 |xm) . Grains are normally cemented by a carbonate (e.g., calcite or dolomite). References to clays in tar sand literature may refer to fines, not to illite or kaolinite. Some tar deposits in California are in diatomaceous earth but these are exceptional cases.