The North Burbank Unit, Tract 97 Surfactant/Polymer Pilot Operation and Control

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Abstract
Trantham, J.C., SPE-AIME, Phillips Petroleum Co. Phillips Petroleum Co. Patterson Jr., H.L., SPE-AIME, Patterson Jr., H.L., SPE-AIME, Phillips Petroleum Co. Phillips Petroleum Co. Boneau, D.F., SPE-AIME, Phillips Petroleum Co. Phillips Petroleum Co. JULY 1978 Careful control of fluid rates, injection pressures, volumetric balance, and quality control of injected chemical solutions are key factors in chemical flooding in the fractured, oil-wet North Burbank Unit reservoir. Fluid diversion treatments based on radioactive tracer studies helped maintain reservoir control. After 18 months of operation, pilot performance is encouraging. performance is encouraging. Introduction: Fresh-water preflush injection began in the North Burbank Unit surfactant/polymer pilot in Osage County, Okla., on Dec. 1, 1975. This was followed by a sequence of slugs, including controlled salinity preflush, surfactant solution, and a graded viscosity-mobility buffer that is now about 60 percent complete. A description of the oil recovery process was presented in an earlier paper. This study reports the field operations involved when mixing and injecting the fluids, control of fluid composition, efforts to optimize the movement of fluids within the reservoir, and techniques used when analyzing the progress of the pilot's different phases for the past 19 months. Pilot Layout and Equipment Pilot Layout and Equipment Pilot Pattern and Water Supply Pilot Pattern and Water Supply The pattern (Fig. 1) was composed of an array of nine inverted five-spots of approximately 10 acres each (5 acres/well). Injection wells were fed by two gas-driven, triplex pumps located at the flow station adjacent to the chemical blending building at the southwest corner of the tract. Fresh water used for preflushing and for preparing all chemical solutions was obtained from wells completed in the alluvium of the Arkansas River. The only required treatment of the supply water was the addition of a corrosion inhibitor at the water supply station. An oxygen scavenger also was added to assure that no oxygen was present to form iron-containing corrosion products that would plug the formation and interfere with the products that would plug the formation and interfere with the oil-displacing chemical processes. The water contained about 1,000 ppm total dissolved solids, including less than 100 ppm total hardness. This contrasted strongly with the 80,000-ppm (total solids) formation water that allowed fresh-water production to be used as a continuously injected tracer for supplementing the radioactive tracers. Equipment: Fig. 2 shows a simplified flow diagram of the chemical blending system. Three basic assemblies make up this system: the brine maker, the surfactant blender, and the polymer mixing system. Air was excluded from all three polymer mixing system. Air was excluded from all three of the chemical mixing systems, using a nitrogen blanket. Brine Maker. A brine averaging 31-weight-percent sodium chloride was prepared continuously by percolating fresh water through a bed of salt crystals. percolating fresh water through a bed of salt crystals. This concentrated solution was blended to the desired concentration by a proportioning pump that injected it into the fresh water fed to the injection pumps or to the surfactant blender. The concentrated brine varied no more than +/- 1 weight percent in concentration. This system was used during the injection of saline preflush and surfactant blending. P. 1068

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