Large-Scale Field Application of Micellar-Polymer Flooding

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Abstract
This paper describes the development and operation of a 113-acre (457 x 10 to the 3rd m2) micellar-polymer flood in the Robinson sand of southern Illinois. Production increased from 40 BOPD (6.4 m3/d) at the beginning of the project to 536 BOPD (85 m3/d) in August 1977. Current production is averaging more than 120 BOPD (19.2 m3/d). Recovery from this project is expected to be between 27 and 33% of the oil in place. Introduction The Maraflood- oil-recovery process is a fluid-injection process in which a slug of a micellar system is injected process in which a slug of a micellar system is injected into a formation and displaced toward production wells by a mobility buffer. The mobility buffer (typically a solution of polymer and water) in turn is displaced by water. The micellar system displaces both oil and water through the formation.Marathon Oil Co., alone and with other companies, has conducted about 20 field tests of the Maraflood oil-recovery process. Since 1962, these projects have produced more than 900,000 bbl (143 088 m3) tertiary produced more than 900,000 bbl (143 088 m3) tertiary oil. Most test results were reported previously. While developing the Maraflood process, Marathon conducted laboratory sulfonation work. As a result of that work, the cost of the process fluids was reduced by developing a crude-oil sulfonate slug (COSS). Consequently, a commercial-sized manufacturing unit was constructed at the Robinson, IL, refinery to provide COSS for large-scale field projects.We began the 219-R Project to continue testing the capability of the micellar-polymer process for recovering oil from a previously waterflooded reservoir. Specific evaluations includedthe use of a crude-oil sulfonate system,the use of old vs new wells, andthe economics of the recovery method. Fig. 1 shows the location of the 113-acre (457 x 103 m2) project in Crawford County, IL. Ninety-four wells (39 injectors and 55 producers) are used in a 3-acre (12 x 10 to the 3rd m2) five-spot pattern. Drilling for the tertiary project began in Fall 1974. Slug injection started Oct. 1, 1975, and continued until April 5, 1976. Polymer injection followed the slug and continues today. We expect to complete the project in 1980. Project Development Project Development The 219-R Project is located in the Robinson sand of early Pennsylvanian age and lies near the crest of the La Salle anticline. The Robinson sand occurs from 750 to 1,000 ft (229 to 305 m) throughout Crawford County, IL. The sand was named after the town of Robinson, which is about 6 miles (9.65 km) east of the project site.The Robinson sand was deposited by a meandering river with migrating point bars. Considerable variation in sand thickness occurring over short lateral distances is characteristic of point-bar-type deposits. Single sand bodies are seldom more than 30 ft (9.1 m) thick. The lens underlying the project area is a finely grained, relatively clean quartz sand. The sand varies from 10 to 25 ft (3.05 to 7.62 m) thick and averages 16.6 ft (5.06 m). Fig. 2 shows a net sand isopach map.Production from the lens of the Robinson reservoir, where the project is located, was developed first in the early 1990's. The original reservoir production mechanism was solution-gas drive. This was depleted and air and gas injection were applied in addition to the already widespread practice of vacuum assistance. During primary production, about 606,000 bbl (96 346 m3) Oil was production, about 606,000 bbl (96 346 m3) Oil was produced [323 bbl per acre-foot (0.028 m3/m3)]. produced [323 bbl per acre-foot (0.028 m3/m3)]. JPT P. 690

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