Pressure Maintenance Operations in the Sharon Ridge Canyon Unit, Scurry County, Tex.

Abstract

Abstract The Sharon Ridge Canyon Unit is a pressure maintenance project using fresh surface water injected on a peripheral pattern. Canyon Reef limestone of Pennsylvanian age, occurring at approximately 6,700 ft, comprises the producing reservoir. The original producing mechanism was that of an undersaturated solution-gas drive. Rapid pressure decline and the threat of climbing gas-oil ratios pointed toward the need for pressure maintenance. Performance to date under the influence of water injection has been very encouraging. During six years of water injection, the volumetric average reservoir pressure has increased 338 psi, from 1,583 to 1,921 psi. The producing gas-oil ratio has been reduced from about 1,300 to about 900 cu ft/bbl. Before water injection, it was necessary to withdraw approximately 2.3 reservoir bbl in order to place 1 bbl of oil in the stock tank. Now, 1 bbl of stock-tank oil requires a withdrawal of only 1.8 reservoir bbl. Peripheral portions of the reservoir which have experienced encroachment by the injected water have performed better than predicted. Based on this history and recovery predictions, ultimate recovery as a result of this water injection will be at least 50 per cent of the original oil in place. This is twice the predicted recovery without pressure maintenance. Introduction With the completion of Humble Oil and Refining Co.'s R. E. Bishop 1 (now known as Tract 35, Well 1) in March, 1949, the Sharon Ridge Canyon field was discovered. This field is located approximately 20 miles southwest of Snyder, Tex., and its Pennsylvanian reef reservoir was divided from the Kelly Snyder and Diamond "M" fields by means of arbitrary lines. In Nov., 1951, the Sharon Ridge Canyon field was combined with the Diamond "M" field. Less than two years after the discovery well had been completed and with the field only 75 per cent developed, the operators met and formed the "Sharon Ridge Canyon Engineering Committee". A great amount of work and study directed toward a conservation program resulted in the formation of the Sharon Ridge Canyon Unit, with 100 per cent of the operators signing the agreement. On May 1, 1955, unitized operations commenced with a peripheral water-injection pressure maintenance program. JPT P. 645^