To most efficiently estimate oil and gas reserves for the State of Colorado, a county-by-county analysis was undertaken. This report is the eighth in a series of oil and gas reserve investigations undertaken for those counties in which oil and/or gas was being produced at that time.
Garfield County, located in northwestern Colorado, is approximately 20 miles north of Grand Junction, within the Piceance Basin. In this county, oil and/or gas are produced from, in descending order of age, the Wasatch Sandstone, Rollins Sandstone, Cozette Sandstone, Corcoran Sandstone, Mesaverde Sandstone, Niobrara Limestone, Mancos Shale, Dakota Sandstone, Buckhorn Sandstone, Morrison Sandstone, and Entrada Sandstone. There are 20 fields considered active producers as of September 30, 1983. Of these, all 20 are classified as gas fields (based on cumulative GOR >15:1).
Production decline curves are plotted for each currently producing horizon within each field (field-horizon). There are 35 production decline curves plotted, one for each field-horizon. Decline rates were calculated where there were sufficient production histories. Estimated oil reserves for Garfield County totaled 17,047 barrels. Estimated gas reserves for Garfield County totaled 51,330,082 MCF. Note that the gas reserve calculations are based on a 20-year projection, therefore they do not account for gas production after the year 2002. These figures also do not account for production increases due to secondary and/or tertiary recovery not already in progress, or account for undiscovered reserves, nor do they reflect changes in economics and demand.
49 pages. Digital PDF download. OF-84-10D