Abstract

The Brundage Canyon Field, located in Duchesne County, Utah, produces oil from the Green River Formation in the southern Uinta Basin, along with other fields such as Monument Butte and Antelope Creek. Discovered in 1966, production was established from the Douglas Creek and Garden Gulch units of the Eocene lower Green River Formation. Field development over the last 10 years has expanded production to include the Uteland Butte unit of the lower Green River Formation and limited testing of the underlying Colton Formation. There are currently 410 producing wells in the field, which has produced nearly 10 million barrels of oil and 41 billion cubic feet of associated gas through 2007.

Brundage Canyon is categorized as a fracture-enhanced reservoir, stratigraphically trapped along the gently dipping south flank of the Uinta Basin. The lower Green River Formation has four productive units from oldest to youngest: Uteland Butte; Castle Peak; Douglas Creek; and Garden Gulch. Fractured carbonates in the Uteland Butte and Castle Peak units contribute to production in the field, while in portions of the Castle Peak and throughout the Douglas Creek and Garden Gulch units, discontinuous fluvial sandstones form the reservoirs. Cores taken from the Uteland Butte and Castle Peak units reveal oil-saturated sandstones, argillaceous dolostone, wackestone, and limestone. Sandstone porosity averages 8% and permeability is typically less than 2 millidarcies. The dolostones and limestones exhibit fracturing and microfractures that enhance reservoir connectivity.

The kerogen-rich Black Shale facies in the lower Green River Formation is the primary source of the hydrocarbons in Brundage Canyon. Much of the oil was sourced in the deeper portion of the Uinta Basin to the north of Brundage Canyon and migrated into the field as it was expelled during the generation process. The oil is a combination of black and brown waxy crude with oil gravities ranging from 38 to 42 degrees and wax contents of 20 to 30%. Pour point is approximately 90°F, thus some shallow reservoirs contain solidified oil. The associated gas has a heating value of 1,180 British Thermal Units.

Field development is on 40-acre spacing, and there are no current secondary recovery projects. The limits of the field and the southern Uinta Basin lower Green River oil trend are being expanded to the south and west as exploratory wells are drilled in the Ashley National Forest and the Lake Canyon region of Duchesne County.