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Tar Sand Triangle Bitumen Deposit, Garfield and Wayne Counties, Utah

Steven Schamel
GeoX Consulting Inc

The bitumen in the Tar Sand Triangle deposit is reservoired in a several-hundred-foot-thick eolian sandstone, the White Rim Sandstone (Lower Permian). Across an area of 84 square miles, the thickness of the bitumen-impregnated sandstone exceeds 100 ft. The strata are gently dipping and otherwise unstructured. Average porosity and permeability of the sandstone reservoir are in the range 15-20 % and 200-500 md, respectively. The oil saturation is consistently low, averaging 30-35%. The bitumen has an API gravity less than 8º at the surface and just over 10º in core. It has a high asphaltene and sulfur content, and it is saturate-poor. Although very viscous at reservoir temperatures, the bitumen is a few orders of magnitude less viscous than the Uinta Basin heavy oils. This study estimates a total in-place bitumen resource between 4.25 to 5.15 billion barrels in a deposit less than 200 square miles in size. However, at a commercially viable resource minimal threshold equal and greater than 60 MBO/ac, the in-place bitumen resource is estimated to range between 1.30 and 2.46 billion barrels in an area of 30 to 52 square miles, respectively. The Tar Sand Triangle deposit has several drawbacks that will make commercial bitumen recovery operations difficult and expensive, but not impossible. These include the relatively low grade of the resource and the apparent low oil saturations; the generally poor quality of the oil due to high sulfur content and high viscosity at reservoir temperatures; the difficult access by existing unimproved roads, all of which pass through the Glen Canyon NRA; potentially complicated and/or expensive process water access; the lack of petroleum service vendors and other support services in southeast Utah; and the proximity to environmentally-protected and visually stunning public lands.

AAPG Search and Discovery Article #90169©2013 AAPG Rocky Mountain Section 62nd Annual Meeting, Salt Lake City, Utah, September 22-24, 2013