Influence of Surfactant and Weak-Alkali Concentrations on the Stability of O/W Emulsion in an Alkali-Surfactant–Polymer Compound System

Emulsions have emerged as advanced materials for wide industrial applications because of their unique properties. In the actual application in oilfields, emulsions can significantly enhance oil recovery. In the present study, the stability test shows that the concentrations of a surfactant and alkali and salinity have a great influence on the stability of the emulsion, but the addition of excessive chemical agents may adversely affect the emulsion stability. The addition of excessive alkali causes the phase inversion behavior of the emulsion to be discovered, which is also the main reason for the destabilization of the oil-in-water emulsion. Rheological experiments reveal that the emulsion produced by the chemical-flooding fluid is a pseudoplastic fluid, and the apparent viscosity decreases with the increase of the shear rate. Core-flooding experiments were conducted to study the effect of the emulsion stability on enhanced oil recovery, and the results indicate that the system with a better emulsion stability has higher oil recovery and displacement pressure.