Surfactant adsorption on reservoir rocks or sands is one of the major factors that may significantly reduce the effectiveness of an alkaline/surfactant flooding for heavy oil recovery.It is difficult to determine the surfactant adsorption by measuring the difference in surfactant concentrations between before and after adsorption when water phase contains fine heavy oil drops that cannot be simply separated by using a centrifuge.In this work,an extraction method was used to determine the surfactant adsorption on sand surface. The adsorbed surfactant on sand was first"washed"by using an azeotropic mixture of isopropyl alcohol and deionized water in a Soxhlet apparatus.The amount of surfactant extracted from sands was then measured using two-phase titration after isopropyl alcohol in the mixture is evaporated. The purpose of this study is to quantitatively determine the adsorptions of surfactant on sand and at oil-water interfaces in an alkaline/surfactant flooding for heavy oil recovery.The addition of alkalis in water phase reduced surfactant adsorption on sand.Moreover,the reaction between alkalis and the acidic compounds of the heavy oil resulted in the formation of oil-in-water emulsions,which greatly increased the oil-water interface area in water phase.Experimental results showed that the formation of emulsions dramatically reduced surfactant loss to sand surface.The adsorptions of surfactant on sand and at oil-water interface were determined under various alkaline concentration and salinities.The results provide useful information for evaluating and predicting surfactant adsorption in alkaline/surfactant flooding for enhanced heavy oil recovery.
展开▼
