Structure and Reservoir Characterization of Farnham Dome Field, Carbon County, Utah

Craig D. Morgan¹, Kevin McClure¹, Thomas C. Chidsey, Jr¹, and Rick Allis². (1) Utah Geological Survey, P.O. Box 146100, Salt Lake City, UT 84114-6100, phone: 801-537-3370, fax: 801-537-3400, [email protected], (2) Utah Geological Survey, UT

Farnham Dome in east-central Utah is an elongated surface anticline associated with ramp-style thrusting of a Sevier-aged decollment in the Jurassic Carmel Formation. Farnham Dome field includes a much broader Laramide-aged anticline along the northern plunge of the San Rafael uplift. Pennsylvanian-aged reverse faulting associated with the Uncompahgre uplift resulted in local thickening of the Pennsylvanian section creating potential stratigraphic traps.

Drilling along the crest of Farnham Dome in the 1920s and 1930s resulted in the discovery of a significant deposit of carbon dioxide (CO2)in the Jurassic Navajo Sandstone and smaller accumulations of CO2 in Triassic, Permian, and Pennsylvanian reservoirs. More recent additional drilling and seismic data revealed the surface anticline was a shallow feature on the west flank of the broader anticline that forms the trap for the CO2. Most of the CO2 may have migrated into the trap between 10 and 58 Ma. The gas accumulation is hydrodynamically displaced to the northwest resulting in a lower gas/water contact on the northwest side of the structure. Nearly 5 BCF of CO2 was produced before field abandonment in 1979 for lack of a market. Currently, a newly drilled well is shut-in prior to construction of a plant to process the gas to food-grade liquid CO2.

The UGS studied Farnham Dome field as an analogue for sequestration of CO2 in Rocky Mountain aquifers. Farnham Dome field is a good example of the potential for long-term sequestration of CO2 in Rocky Mountain aquifers.