--> Utah's Undeveloped Oil Sand Resource

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Utah's Undeveloped Oil Sand Resource

Abstract

With an estimated 16 billion barrels of bitumen and heavy oil, Utah holds the largest oil sand resource in the United States. At least fifty deposits are known flanking and within the petroliferous Uinta and Paradox Basins in eastern Utah, but fewer than ten are of potential commercial consequence. During the three decades preceding the collapse in oil price in the mid-1980s, Utah “tar sands” were the object of continuous exploration activity by the petroleum industry and development research by U.S. Department of Energy laboratories and DOE-funded university teams. Since then, this significant domestic energy resource largely has been neglected. To date, there has been no commercially-viable extraction of the oils for fuel. A majority of the deposits are in heterogeneous fluvial sandstones, giving rise to large spatial variability in oil resource-in-place. The very extensive lower Eocene fluvial deposits on the south flank of the Uinta Basin have average oil concentrations less than 50 thousand barrels/acre (MBO/ac), but one small portion of the Sunnyside deposit holds more than 300 MBO/ac. On the north flank of the basin at Asphalt Ridge, Cretaceous-age stacked channel sands contain 120–190 MBO/ac. A small north flank deposit hosted in Triassic-Jurassic eolian sandstone, Whiterock, is even richer, 450–485 MBO/ac. The 4.3 to 5.2 BBO Tar Sands Triangle bitumen deposit covering an area of nearly 200 square miles in south-central Utah is in a Permian-age eolian sandstone reservoir. This deposit is quite lean having an average OOIP of just 37 to 42 MBO/ac. Unfortunately, Utah's oil sand deposits present numerous technical challenges to commercial exploitation. The reservoirs are sandstone, not unconsolidated sands, and they tend to be “oil-wet”. The bitumen and heavy oils are highly viscous. Many deposits are in regions with exceptional scenic quality and high environmental/conservation values presenting added regulatory and legal obstacles. New solvent-based extraction technologies may prove successful unlocking this very large, but elusive, oil sand resource.