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Fact Sheet 2009-3012

Oil Shale Assessment Project Fact Sheet

Assessment of In-Place Oil Shale Resources of the Green River Formation, Piceance Basin, Western Colorado

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The U.S. Geological Survey (USGS) recently completed a reassessment of in-place oil shale resources, regardless of richness, in the Eocene Green River Formation in the Piceance Basin, western Colorado. A considerable amount of oil-yield data has been collected after previous in-place assessments were published, and these data were incorporated into this new assessment. About twice as many oil-yield data points were used, and several additional oil shale intervals were included that were not assessed previously for lack of data. Oil yields are measured using the Fischer assay method. The Fischer assay method is a standardized laboratory test for determining the oil yield from oil shale that has been almost universally used to determine oil yields for Green River Formation oil shales. Fischer assay does not necessarily measure the maximum amount of oil that an oil shale can produce, and there are retorting methods that yield more than the Fischer assay yield. However, the oil yields achieved by other technologies are typically reported as a percentage of the Fischer assay oil yield, and thus Fischer assay is still considered the standard by which other methods are compared.

First posted April 2, 2009

Supporting geologic studies of the oil shale-bearing units, assessment units, oil shale analysis, and the methodology used in assessing the oil shale resources in the Piceance Basin are in progress.. Assessment results are available at the USGS Central Energy Team website:

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Suggested citation:

Johnson, R.C., Mercier, T.J., Brownfield, M.E., Pantea, M.P., and Self, J.G., 2009, Assessment of in-place oil shale resources of the Green River Formation, Piceance Basin, western Colorado: U.S. Geological Survey Fact Sheet 2009–3012, 6 p.

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