To most efficiently estimate oil and gas reserves for the State of Colorado, a county-by-county analysis was undertaken. This report is the fifth 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. 58 pages. Digital PDF download. OF-84-07D
Arapahoe County, located in northeastern Colorado, is just southeast of Denver, within the central portion of the Denver Basin. In this county, oil and/or gas are produced from, in descending order of age, the D Sand, J Sand and Niobrara Limestone. There are 35 fields considered active producers as of September 30, 1983. Of these, 33 are classified as oil fields (based on cumulative gas-oil ratio (GOR) of 15:1).
Production decline curves are plotted for each currently producing horizon within each field (field-horizon). There are 43 production decline curves plotted, one for each field-horizon. Decline rates were calculated where there were sufficient production histories. Estimated oil reserves for Arapahoe County totaled 3,285,087 barrels. Estimated gas reserves for Arapahoe County totaled 12,817,272 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.