Study On Emulsification Mechanism And Oil Displacement Effect Of ASP Flooding

At present,ASP flooding has become the core technology of precipitation and oil enrichment in the old area of Daqing Oilfield.During ASP flooding,the interaction between agent and fluid in reservoir pore and the resultant dissolution and emulsification of agent have a certain influence on oil displacement effect.Therefore,the study of the emulsification mechanism of ASP flooding has important theoretical value and practical significance for improving the effect of ASP flooding oil enrichment and precipitation.In this paper,the emulsification of crude oil is described firstly,and the emulsification and stabilization mechanism of ASP flooding produced fluid in Apricot Twelve Area is obtained through the influence of residual alkali,surfactant and polymer on the emulsification strength,oil-water separation characteristics and oil-water interface properties of ASP flooding produced fluid.Then,taking the reservoir fluid and physical properties of weak alkali and strong alkali ternary test area in Apricot Twelve Area as the research object,the effect of emulsification on recovery factor of ASP flooding and its mechanism are studied.The results show that after contacting with crude oil,some surfactants and alkalis in ternary system will dissolve into oil phase,and some surfactants can also be removed from crude oil.The main reason for emulsification in ASP flooding is re-entry into water phase,and the type of emulsification is closely related to water content.Low water content is easy to form W/O emulsion.On the contrary,O/W emulsion is easy to form.The critical water content of transition of two types of emulsification is about 60%.Finally,the oil displacement effect of the test block is analyzed.When the weak alkali ternary system contacts with crude oil,it will cause emulsification and the formation of emulsion.When the emulsion seeps through porous media,it will produce "Jiamin effect",which will lead to the increase of seepage resistance,the increase of injection pressure,the difference of suction pressure between medium and low permeability layers and the increase of suction volume,and the effect of liquid flow diversion will be enhanced.Volume and enhanced oil recovery,but at the same time,it will also cause the residual pressure of produced fluid,i.e.flow pressure,to decrease and the reservoir productivity to decrease.