Emulsion Characteristics Associated With An Alkaline Water Flooding Process

Abstract

ABSTRACT This paper presents the results of an investigation of emulsions containing an acidic crude oil from Wilmington Field, California, and sodium hydroxide/sodium orthosilicate solutions. The effect of alkaline water formulation on emulsion characteristics was determined. The characteristics of emulsions were evaluated as a function of salinity, alkali type, and alkali concentrations in the aqueous phase. Emulsion stability, as defined by the coalescence rate of oil droplets in water-external emulsions, was determined as a function of salinity and alkali type. Shear viscosity measurements were made for both the oil-external and water external emulsions formed as a result of crude oil/alkaline water interaction. When the emulsions were oil-external, the degree of incorporation of water by the oil was measured in terms of oil phase volume swelling. The effect of divalent ions on shear viscosity and phase volume swelling were also evaluated. The results indicate that there is some optimum salinity in the aqueous phase which needs to be maintained to minimize the problems associated with viscous emulsions. Also the emulsions formed with sodium hydroxide are different from those formed with sodium orthosilicate, especially in the presence of divalent ion salts, so that different salinities are required to minimize the shear viscosity of emulsions for the two systems.