STATUS OF CAUSTIC AND EMULSION METHODS.

Abstract

There are now several proposed mechanisms by which caustic waterflooding may improve oil recovery. These include (1) emulsification and entrainment, (2) wettability reversal (oil-wet to water-wet), (3) wettability reversal (water-wet to oil-wet), and (4) emulsification and entrapment. Each mechanism requires somewhat different initial conditions with respect to reservoir oil, rock, and injection water properties, and each process is designed to improve oil recovery in a somewhat different manner. Oil-in-water emulsion injection as a means for improving waterflood efficiency is related to caustic flooding, but its development and field application is less advanced. The proposed mechanisms by which these oil recovery processes operate, the conditions required for successful application, recommended laboratory screening methods, and the published results of field testing are reviewed.