After a successful pilot test, a 92-acre surfactant flood expansion project was conducted in the William Berryhill lease of the Glenn Pool field, Creek County, OK. The field had been waterflooded and had an average residual oil saturation of 30% PV. At the end of October 1992, about 1.14 million barrels of incremental oil was produced, which accounted for about one-third of the residual oil. This is the largest amount of oil produced by a surfactant flood.
The Glenn Pool field, discovered in 1905, is located in Creek and Tulsa Counties, OK. Waterflooding started in the 1950's, and the field is nearing depletion. The field covers about 18,000 acres, and the 160-acre William Berryhill lease is located in the south central part of the field. This lease has been waterflooded since 1955. In 1979, a surfactant pilot test was conducted in the northeastern quadrant of the Berryhill lease. The test pattern consisted of four inverted five-spots, comprising 20 acres. With the successful completion of the pilot test, an expansion project was initiated in 1982 in the remaining three quadrants of the lease, comprising 92 acres. The project has had 21 injectors and 32 producers in repeated five-acre five-spot patterns. The east and south boundary wells in the pilot test were converted and used in the project. Figure 1 shows the well location in the project.
During the expansion project, lignosulfonate was evaluated as a sacrificial adsorbate in the northeastern quadrant. The test and control patterns had observation wells, Wells 140 and 141, respectively. In July 1986, an observation well, Well 142, was drilled to monitor the process efficacy. This well is located at 215 ft directly on line from Well 114 toward Well 117, a producer.
The objective of this paper is to summarize and present the technical results of the expansion project. The economic environment, when this project was planned and carried out, was quite different from what it is now; this project would be uneconomic at current conditions.
RESERVOIR AND CORE DESCRIPTION
The reservoir was well described in previous papers, and interested readers are referred to them. The Glenn Pool reservoir sand is a member of the Bartlesville sand group. There are three sands, located at depths between 1490 and 1660 ft, separated by shale streaks. These sands are designated as Upper, Middle, and Lower sands. The Lower sand has lower porosity and permeability than the Middle and Upper sands and contains bottom water. The Middle sand has a net pay thickness of about 50 ft and the Upper sand about 25 ft. Originally, the shale streaks were thought to be continuous.