El Dorado Micellar-Polymer Demonstration Project. Second annual report, July 1975--May 1976

Laboratory oil displacement tests were conducted using Shell Oil Co. and Union Oil Co. chemical formulations in both Berea and El Dorado Admire Sandstone cores. Total relative mobility of the oil-water bank created during chemical flooding was measured in Admire Sandstone cores. The values ranged from 0.018 to 0.065 reciprocal centipoise. Four observation wells were drilled, cored, and logged during the year. They were cased with fiberglass and are now being used to monitor fluid properties. A tracer test was conducted by injection of chemical tracers into each of the 18 injection wells. Results indicate that there is no gross channeling in the reservoir. The same conclusion was drawn from results of interference tests. Performance forecasting was utilized to show that maintaining the bottom-hole injection pressures at 400 psia and the producing pressures at 30 psia would increase throughput rates and result in acceptable project life for the 6.4-acre, five-spot patterns. Injection well rates relative to the central injector were computed. These rates will be used as a guide for the operation of injection wells. This plan corresponds to operation at constant bottom-hole pressures for a homogeneous reservoir of uniform thickness. Construction of the fresh water system and injection plant was completed. The injection plant has performed satisfactorily. Injection of pretreatment fluid was started in both patterns on November 18, 1975.Severe loss of injectivity was experienced during the first week of injection. Several likely causes were identified and corrective actions taken. More moderate injectivity problems have continued throughout this reporting period. Additional preventive measures have been undertaken to improve the quality of injected fluids. A procedure was developed to stimulate and clean-up wells damaged by the injection fluid. A preliminary evaluation indicates that combination solvent-acid treatments will increase injection rates to the desired level.