U.S. oil shales are concentrated in the western United States in the states of Colorado, Utah, and Wyoming, but sizable quantities also exist in the eastern United States. The most economically attractive deposits, containing an estimated 1.5 trillion barrels of oil equivalent, are found in the Green River Formation of Colorado in the Piceance Creek Basin, in Utah in the Uinta Basin, and in Wyoming in the Green River and Washakie Basins.

In particular:

  • Colorado has 1.2 trillion barrels of oil shale resources, and five RD&D projects are currently being reviewed for Environmental Impact Statements (EISs) by the Bureau of Land Management (BLM) under their oil shale RD&D program. Shell has three projects, Chevron/Texaco has one, and EGL has one. The EIS is also under way for commercial leasing in 2007 or 2008.

  • Utah has substantial oil shale resources and BLM has recently granted one company the right to proceed to a pilot project. The USGS has had an oil shale data compilation project in Utah for the last 2 years.

  • In the eastern United States, oil shale underlies the Appalachian, Illinois, and Michigan Basins, predominantly in Devonian age deposits covering hundreds of thousands of acres from Illinois to New York to Alabama, and it is estimated that there are 189 billion barrels of oil equivalent in Eastern oil shale.3 Kentucky has the largest outcrop of oil shale in the eastern United States and also has the largest amount of surface and near-surface oil shale. A two county area in eastern Kentucky was investigated in detail in the 1980s and was estimated to contain 4.4 billion barrels of oil equivalent with 1.3 billion barrels in a stripping ratio of 2.5:1.

The extent and characteristics of U.S. western oil shale resources, and particularly those in the Green River Formation, are well known and documented.4 More than a quarter million assays have been conducted on core and outcrop samples for the Green River oil shale, and results have shown that the richest zone, known as the Mahogany zone, is located in the Parachute Creek member of the Green River Formation. This zone can be found throughout the formation.

A layer of volcanic ash several inches thick, known as the Mahogany marker, lies on top of the Mahogany zone and serves as a convenient stratigraphic event that allows oil shale beds to be correlated over extensive areas. Because of its relatively shallow nature and consistent bedding, the resource richness is well known, giving a high degree of certainty as to resource quality. By assay tech-


Dyni, op. cit.


Anton Dammer, Office of the Deputy Assistant Secretary for Petroleum Reserves, Office of Naval Petroleum and Oil Shale Reserves, U.S. Department of Energy Washington, D.C., Strategic Significance of America’s Oil Shale Resource, Volume II, Oil Shale Resources, Technology and Economics, March 2004, pp. 2-5.

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