Surfactant flooding oil recovery process

Abstract

The effectiveness of a surfactant waterflooding oil recovery process employing an aqueous, saline fluid containing an alkylpolyalkoxy sulfate or an alkylarylpolyalkoxy sulfate is increased substantially if the fluid is subjected to a high shear for a predetermined period of time prior to injecting the fluid into the oil-containing formation. The surfactant fluid should be subjected to a shear rate of at least 150 and preferably at least 250 reciprocal seconds for a period of time of at least 0.1 minutes and preferably at least 0.5 minutes. The improvements obtained by shearing the surfactant fluid include increased stability of the solution, i.e., resistance to separation into separate, distinct phases, reduced turbidity of the fluid which provide improved injectivity with reduced well plugging problems, and attainment of significantly lower interfacial tension between the aqueous surfactant fluid and formation petroleum, and more effective oil displacement from reservoir rock.