Study On Stability And Solar Demulsification Of Emulsion From ASP Flooding

With the development and application of oil recovery technology in oil fields,a large number of alkali,surfactant and polymer are used in ASP flooding,which enhances the oil washing effect of formation crude oil.However,in the process of crude oil separation,the water phase contains a lot of residual chemicals,and the emulsification phenomenon is serious.These produced water will cause damage for example casing corrosion,formation gap plugging in the process of reinjection.This not only affects the subsequent mining,but also easy to cause environmental pollution.Therefore,it must be further demulsified and dehydrated before the produced water is injected back into the ground,so as to minimize its corrosion to the soil and equipment.Solar energy is a clean and reliable new energy,which is widely distributed and abundant in China.As a kind of renewable energy,the development and utilization of solar energy is an inevitable way of energy sustainability.This subject uses solar-driven photo,thermal and electrochemical process to demulsify the produced water in the oil field,and organically combines the photoelectric,photothermal,photochemical conversion,so as to achieve the purpose of efficient utilization of solar energy.In the experiment,diesel emulsion was used to simulate the produced water of ASP flooding from Daqing Oilfield,and the demulsification process of photo,thermal,electric single field and composite field was studied successively.Firstly,the factors affecting the stability of emulsion were investigated through single factor experiments.The effects of oil concentration,alkali concentration,surfactant concentration,polymer concentration,emulsifying shear rate and emulsifying time on the stability were investigated.The results showed that the stability of emulsion was mainly determined by viscosity,interfacial tension and the strength of the interfacial film.Secondly,the solar-driven photo,thermal and electrical demulsification experiments were carried out.The viscosity,particle size and distribution,Zeta potential and interfacial tension of the emulsion were monitored in real time.The results show that the solar-driven photo,thermal and electrical treatment can achieve good demulsification effect for ternary emulsion by reducing viscosity,reducing surface charge density and increasing interfacial tension.Thirdly,the oil content of the emulsion after single field demulsification test and compound field demulsification test were determined by uv-vis spectrophotometry,and the results showed that the synergistic effect of photothermal and electric field demulsification was the best.Finally,it is concluded that the demulsification mechanism of the solar-driven photo,thermal and electrical process mainly includes photo/thermal chemical degradation,viscosity reduction,electrochemical oxidation,air flotation,dipole coalescence,and electrophoretic coalescence.Demulsification of ASP flooding produced water is an important part of the development and application of ASP flooding technology.This subject provides a new green and energy saving method for the treatment of produced water by ASP flooding based on the theory of solar energy.