West Burkburnett Waterflood-A Successful Shallow Project In North Texas

Abstract

Abstract The West Burkburnett field is located about two miles west of burkburnett in Wichita County, Tex. Waterflooding of the field began nearly 22 years ago. The project has been so successful that expansion has ultimately covered the entire reservoir, although initial plans were to flood only about half of the area. Recoveries are given showing that 50.5 per cent of the original stock tank oil in place will ultimately be recovered and that secondary recovery of 35.3 per cent of the original stock tank oil in place will be 2.3 times greater than total primary. Mobil Oil Corp. is the major operator in the field and has gained much valuable experience in waterflooding through operation of the project. Pertinent data concerning the development, operation, characteristics and success of the project are given, and general conclusions are drawn concerning certain engineering techniques used in waterflood operations. Introduction Waterflooding has long been recognized as an important method of increasing oil recovery from shallow reservoirs in North Texas, The West Burkburnett project, a water injection operation in the 1,750-ft Gunsight sand, was one of the first major secondary recovery projects to be developed in the area. Information gained in the operation of the project has been profitably applied in the project itself and in other reservoirs. In most shallow Cisco Sand waterfloods in North Texas, secondary oil recovery has been less than primary oil recovery except where primary recovery was less than 15 per cent of the original stock tank oil in place. Primary recovery from the West Burkburnett project was 15.2 per cent. Secondary ultimate will be more than twice the total primary. The J. G. Goins lease, which served as a pilot for the project, had a primary recovery of 24.3 per cent, Secondary ultimate recovery for the pilot area was about 1.6 times the total primary. This project has been far more successful than the average North Texas project. Ultimate total recovery from Mobil leases, which comprise about 85 per cent of the field. will be more than 20 million bbl. The West Burkburnett field is situated between the old Burkburnett Townsite and Clara fields, about two miles west of Burkburnett, Wichita County, Tex. Geology and Reservoir Properties The Gunsight sand of the Cisco series and Pennsylvanian age is found in the West Burkburnett field from a depth of 1,550 ft at the south edge of the field to 1,850 ft at the north edge. Sand thickness averaged 10.6 ft for the primary area and 11.6 ft for the secondary area. The structure is monoclinal, dipping about 120 ft/mile from south to north. The reservoir is formed as the sand grades into shale on all sides. Shale is also interspersed in the sand body throughout the reservoir, but is not found in any continuous beds. The sand is also associated with a limestone which lies immediately above it and is almost always known to be present. Thin lime streaks are also commonly present, but are not believed to be continuous. The sand is fairly uniform in porosity and permeability distribution, and in sand thickness. The primary recovery mechanism was solution gas expansion. Primary productive limits on Mobil leases contained more than 3,100 acres, about 2,600 of which have been included in the waterflood project. Approximately 700 core samples were taken from new development wells on Mobil leases. Analyses of these core samples and supplemental data from electrical logs were considered in determining reservoir properties. Comparison of properties from individual leases showed that the sand was of such uniformity that, after the initial development, averages were compiled for the total reservoir (Table 1). History of Development The field was discovered in June, 1912, when Corsicana Petroleum Co., a predecessor of Mobil, completed its Chris Schmoker No. 1 for 85 BOPD. Corsicana owned several other leases in the field amounting to about 85 per cent of the primary productive area. Development of the field continued between 1912 and 1926, and virtually all the locations were drilled on regular 10-acre spacing. Several inside locations on Mobil's leases were not drilled. Initial potentials varied between 5 and 125 BOPD (pumping) with the average being approximately 30 BOPD and no water. A vacuum of 18 in. of mercury was pulled on the casing-tubing annulus of most wells early in their lives. Gas was transported to the Burkburnett gasoline plant, which was constructed in 1918. JPT P. 919ˆ