THE RICHEST OIL SHALE DEPOSIT IN THE WORLD
Mike Priaro, P.Eng.
First uploaded April 3, 2018
OIL SHALE RESOURCE OF THE GREEN RIVER SHALE IN THE WESTERN U.S.
This summarizes the findings of a series of evaluations of the Green River oil shale in the western U.S. conducted by the U.S. Geological Survey (USGS) in 2010-2011.
The USGS estimates for the original-oil-in-place (OOIP) resources of the three basins containing the Green River oil shale in the western U.S. states of Colorado, Utah and Wyoming are summarized below.
Previous estimates of the amount of oil shale that is technically recoverable without considering economics are 45 percent (Taylor, 1987) and 55 to 75 percent (Prien, 1974) of the OOIP using room-and-pillar mining methods, whereas estimates of technically recoverable resource using open-pit mining are as much as 80 percent of the OOIP (Taylor, 1987).
At present, there are no estimates of the percent of the resource that could be recovered using the in-situ methods that are currently being developed.
Note that the percentage of the OOIP that could be technically-recoverable in each basin by surface open pit mining, underground post-and-pillar mining, or in-situ methods is unknown and undefined at present for all three basins.
In addition, the percentage of those methods that could apply to access economically-recoverable reserves in each basin is unknown and undefined at present.
Photo of a sample of Green River Shale. Source: USGS.
The Green River shale was evaluated down to a depth of 6,000 feet below surface. Oil shale content was determined to be 0-40 USgal/ton in the Piceance Basin and 5-20 USgal/ton in the Uinta Basin.
In comparison, Alberta's oil sands surface mines produce syncrude at about 20 USgal/ton from in-place bitumen content of about 30 USgal/ton.
Piceance Basin
The Piceance Basin in Colorado is thought to be the richest oil shale deposit in the world.
The Piceance Basin is one of three large structural and sedimentary basins that contain vast amounts of oil shale resources in the Green River Formation of Eocene age. The other two basins, the Uinta Basin of eastern Utah and westernmost Colorado, and the Greater Green River Basin of southwest Wyoming, northwestern Colorado, and northeastern Utah also contain large resources of oil shale in the Green River Formation;
Estimated total in-place oil in the Piceance Basin is about 1.53 trillion barrels, or about 50 percent larger than the previous in-place assessment of about one trillion barrels, according to An Assessment of In-Place Oil Shale Resources in the Green River Formation, Piceance Basin, Colorado, USGS, 2010.
Almost all of this increase is due to (1) new areas being assessed that had too little data to assess in the previous assessment, and (2) new intervals being assessed that were not assessed previously.
However, much of this previously unassessed resource is of low grade and is unlikely to be developed.
Uinta Basin
The total in-place resource for the Uinta Basin is estimated at 1.32 trillion barrels according to Assessment of In-Place Oil Shale Resources in the Eocene Green River Formation, Uinta Basin, Utah and Colorado, USGS 2010.
The area underlain by oil shale in the Uinta Basin is much larger than that of the Piceance Basin—3,834 sq mi vs. 1,335 sq mi—[but] the average gallons per ton and barrels per acre values for each of the assessed oil shale zones are significantly lower in the ... Uinta Basin when compared to the Piceance.
Green River Basin
The assessed area of the Greater Green River Basin, about 5,500 sq mi , is about 1.4 times larger than the assessed area of the Uinta Basin (3,834 sq mi ) and more than four times larger than the assessed area of the Piceance Basin (1,335 sq mi). Thus, the oil shale deposits of the Greater Green River Basin are the lowest grade of the three basins that contain Green River Formation oil shale.
Total in-place resources are estimated at 1.44 trillion barrels of oil according to Assessment of In-Place Oil Shale Resources of the Green River Formation, Greater Green River Basin in Wyoming, Colorado, and Utah, USGS, 2011.
These are divided among three assessed units in the Green River basin: Tipton Shale Member, Wilkins Peak Member, and LaClede Bed of the Laney Member.
Mike Priaro, P.Eng.
Calgary
403-281-2156
