Study On Emulsion Influencing Factors And Generation Law Of Asp Flooding Produced Fluid

After many years of laboratory research and field experiments in Daqing Oilfield,it has been proved that ASP flooding has obvious effect of increasing oil recovery and water control in the reservoir of No.4 Oil Production Plant.Compared with water flooding,ASP flooding can increase oil recovery by more than 19%.In recent years,emulsification phenomena frequently occur in oilfield produced fluid,resulting in the increase of wellhead pressure,the shortening of pump inspection cycle,the increase of viscosity of produced fluid and the difficulty of post-processing.This has greatly hindered the large-scale popularization of ASP flooding.Therefore,it is of great practical significance to study the influencing factors and generation rules of emulsion in ASP flooding production fluid.The results are as follows:(1)By studying the particle diameter distribution of three emulsion preparation methods at different rotational speeds(power),it is concluded that when the rotational speed of shear emulsifier is 3500 r/min,the particle diameter distribution of the prepared emulsion is the closest to that of the extracted emulsion in the mine.Therefore,this scheme is used as the indoor simulation emulsion preparation scheme.(2)In this paper,different concentration of alkali,surfactant and polymer,different size of interfacial tension,oil-water ratio,temperature and salinity of the emulsion were prepared,and the effects of various factors on the formation of the emulsion were analyzed.The results show that the stability of emulsion increases with the increase of alkali concentration.The critical micelle concentration of surfactant is about 0.5%.When the concentration of surfactant is less than 0.5%,the stability of emulsion increases with the increase of concentration.With the increase of polymer concentration,the stability and viscosity of emulsion will increase.The lower the interfacial tension of the oil-water interface,the more stable the emulsion is,the higher the strength of the oil water interfacial film.The oil-water ratio affects the type of emulsion in ASP system.When the oil-water ratio is less than 5:5,the emulsion is O/W type,and when the oil-water ratio is more than 6:4,the emulsion is W/O type.The higher the temperature,the lower the stability of the emulsion.The ASP system with high salinity will reduce the stability of the emulsion.(3)In this paper,a 6m long,multi-sampling sand-filled pipe core is used to simulate the stratum.Compared with single sampling point and short-distance core,it can better simulate the seepage of ASP system in the stratum and the complex shear action of oil-water two phases in the stratum.Through the ASP flooding experiment,the migration of different components of ASP flooding in reservoirs and the influence of different displacement stages on the law of emulsion formation were explored.The adsorption capacity of alkali,surfactant and polymer in the stratum is 47.3%,82.7% and 68.4% respectively.The concentration of alkali,polymer and surfactant are the main factors affecting the formation of emulsion.With the increase of the concentration of each component in ASP system,the average particle diameter of emulsion formed in reservoir gradually decreases.With the increase of injectedpore volume of displacement ASP slug,the average particle diameter of emulsion formed in reservoir gradually decreases.In the later stage of water flooding,the average particle diameter of emulsion formed in reservoir increases with the increase of injected pore volume.During the migration from near to far from the injection end,the maximum emulsification strength and stability of the produced emulsion will decrease.