Second Ripley Surfactant Flood Pilot Test

Abstract

ABSTRACT A second successful surfactant flood pilot test was conducted by Exxon on the Lewis Ripley lease in a watered-out portion of the Weiler sand, Loudon Field, Illinois. The salinity-tolerant, micellar/polymer process tested in this pilot incorporated several process modifications developed since a previous test was conducted in 1980. These changes included using a 25% smaller microemulsion bank size and addition of formaldehyde to injected fluids to inhibit bacterial degradation of biopolymer. The pilot was performed in a single, 0.71-acre [2873 m2], 5-spot operated to approximate a confined pattern. Extensive data on flood performance were obtained from a comprehensive pilot monitoring program, including use of fluid tracers, observation wells, and post-test cores. Approximately 68% of the waterflood residual oil present in the test pattern was recovered. This actually exceeded the oil recovery achieved in the first pilot, despite using a smaller microemulsion bank. Improved mobility control and lower surfactant retention contributed to enhancing process performance. Formaldehyde was effectively transported and prevented bacterial degradation of biopolymer. It appears to be an effective biocide for use in subsequent surfactant flooding operations at Loudon. During the pilot, an inexpensive and efficient method was developed to separate produced oil-water-surfactant emulsions. While all test objectives were met, the effect of well spacing on oil recovery and chemical transport was not addressed.