The Ashley Valley field, located in the Uintah basin of northeastern Utah, produces oil from the Pennsylvanian Weber Sandstone in conjunction with a prolific natural water drive. Permeability heterogeneity is extreme. Matrix permeability in the reservoir rock ranges from 1 to 700 md. In addition, a substantial fracture network contributed to premature water breakthrough and the co-production of thousands of barrels of water per day from the underlying acquifer. This paper describes the application of a chromium (III) polyacrylamide gel system (MARCITSM) as a water shut off treatment in the Ashley Valley #2. In addition to conformance control from the reduction of excessive water production, the field exhibited potential for improved oil recovery from the polymer treatment.

A stratified reservoir model quantified a potential incremental target of 500,000 STB or 3.0% of original oil in place (OOIP) from uniform depletion of the lower permeability reservoir matrix by maximum pressure drawdown at the production wells. Production logging with a downhole video camera in the open hole completion interval confirmed that the highest permeability zones were not contributing any oil production.

Following placement of 2,200 barrels of the MARCIT SM polymer system in the Ashley Valley #2, oil production increased 6 BOPD (32%), water production decreased 2,950 BWPD (40%) and relative permeability to water decreased 70%.

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