Emulsification And Demulsication Mechanism Of Alkalescent ASP Flooding

Nowadays, the research was mainly focused on the water-in-oil crude oil emulsion in initial exploitation of oil field. Whereas, little research was carried out to investigate the emulsification, stability and demulsication of alkalescent crude oil emulsion produced by ASP flooding. So it is necessary to develop the research on this aspect.In this paper, the effect of residual alkali, surfactant and polymer in crude oil emulsion produced by ASP flooding on emulsion strength, oil-water separation property, oil phase rheology, water phase rheology and oil-water interfacial property has been studied and the mechanism of Emulsification, stability and demulsication of oil-in-water crude oil emulsion produced by ASP flooding was developed. The conclusion was as flows.(1) Alkali, surfactant and polymer in the crude oil emulsion produced by ASP flooding influence the oil-water interfacial property remarkably. When the content by weight of surfactant was 0.06%, equilibrium interfacial tension descended to 1~5mN/m. Interfacial shearing elastic modulus and interfacial shearing viscosity increased to 4.958mN/m and 3.9244mN ? s/m with thecontent by weight of surfactant was 0.04%.(2) The molecular weight and content of polymer has remarkable influence on the viscosity and elastic modulus of ASP flooding produced water, the higher the content of polymer become, the higher the viscosity increase. A general correlation (Y = 1.1381X) between the viscosity and dynamics viscosity stands for ASP flooding produced water. Dynamics viscosity characterized the rheological behavior better than apparent viscosity.(3) When the content by weight of polymer was 0.04%, surfactant was 0.01%, alkali was 0.15%, water content in oil increased to 6.93%. Oil content in water increased to 1400mg/L with polymer free, surfactant (0.03%), alkali (0.15%). Interfacial tension was descended, for surfactant created in the system of alkali, pectin and pitch. Interfacial membrane changed because of the surfactant adsorbing. Polymer increased the water phase apparent viscosity. Alkali, surfactant and polymer made the stability of crude oil emulsion produced by ASP flooding enhance, as the water content in oil and oil content in water increasing.(4) The stability of crude oil emulsion produced by ASP flooding debased when ASPD- Y was added, Oil content in water decreased from 2920mg/L to 418.3mg/L, with polymer, alkali and surfactant free, Oil content in water decreased from 1565.7mg/L to 987.9mg/L, with polymer0.02%, alkali 0.04% and surfactant 0.05%. The stability of crude oil emulsion debased because of the demulsifier substituting surfactant, fatty acid, naphthene acid and natural surfactant.