The US Geological Survey said western Colorado’s Piceance basin has an estimated 1.525 trillion bbl of in–place oil shale.
USGS added that no economic extraction method currently is available in the US so it’s unknown how much of the assessed resource is recoverable.
The latest assessment is 50% larger than the 1989 assessment of 1 trillion bbl. USGS said the increase stems from assessments of additional geographic areas and subsurface zones.
The Piceance basin contains one of the world’s thickest and richest oil shale deposits (OGJ, Oct. 20, 2008, p. 22).
The USGS said it has not yet assessed the uppermost oil shale interval exposed on high ridges and plateaus in the southern Piceance basin, which includes some oil shale that could be potentially developed.
“In order to assess this interval, we would have had to digitize the detailed geologic mapping that was done by the USGS in that area in the 1970s and 1980s, and we simply ran out of time,” a USGS spokesman told OGJ.
“We were mandated by Congress to assess all the Green River oil shales in 2 years, and we had to move on to the other two Green River oil shale basins, the Uinta basin in Utah, and the Greater Green River basin in Wyoming,” he said. “In addition, there is a thin oil shale interval underneath Grand Mesa in the extreme southern part of the Piceance basin that was not assessed. This oil shale zone underlies about 163 sq miles of Grand Mesa, but it is highly unlikely that it will ever be developed.”
API responds
The American Petroleum Institute said the new estimate demonstrates the need for continued oil shale research and development efforts.
“That is why we were disappointed that the Interior Department recently delayed issuing a second round of oil shale research and development leases,” API said.
The study also found an estimated 43.3 billion tons of in–place nahcolite resources in the Piceance basin. Nahcolite is embedded with oil shale, and produces large quantities of carbon dioxide when heated in oil shale processing.
Oil shale does not contain crude oil but instead contains kerogen, which is an organic precursor to oil that must be heated for oil production.
