Influence Of Emulsification On Recovery In ASP Flooding And Its Mechanism

ASP flooding has achieved good effect of increasing oil and precipitation,but the problems of scaling in the injection end and the extraction end and the high cost of the produced fluid have restricted the economic effect of the ASP technology.In addition,the reacting of alkali and reservoir fluid,the resulting of chemical dissolution,emulsification and effect of oil displacement were also plagued the engineers,in order to explore the formation mechanism of these problems and put forward corresponding methods for the improvement of ASP has important theoretical value.According to the actual demand of the mine production,in this paper,took reservoir engineering,physical chemistry and analytical chemistry as the theoretical guidance,took instrument detection,chemical analysis and physical simulation technology as the technical means,the emulsion type,chemical concentration,distribution ratio,resistance coefficient and residual resistance coefficient and the recovery rate as the evaluation index,the reservoir fluid and material of strong-alkali and weak-alkali ASP test area were taken as the research object,carried out the research on the mechanism of recovery and the effects emulsion on ASP flooding.The results showed that: Contacted with crude oil,some surfactant and alkali in the ASP flooding system would be dissolved into the oil phase,and some of the surfactants can also enter the aqueous phase from crude oil,this is the main reason for emulsification in ASP flooding.Compared with the ASP system,the ratio of alkali and surfactant distribution to crude oil in the SP system was larger.Compared with the surfacant solution,the surfactantt in the SP system was dissolved in crude oil a lot.It can be seen that the alkali can increase the solubility of the surfactant in the crude oil,and the polymer can reduce the solubility of the surfacant and alkali in the crude oil.The emulsification type of the extracted liquid was closely related to the water content,and when the water content was low,it was easily to form W/O type emulsion.On the other hand,it was easily to form O/W type emulsion.The critical water content of the two types of emulsion was about 60%.When weak-alkali ASP system contacted with crude oil,it would cause emulsification.When emulsion flowed in porous media,it would produce "Jia Min effect",which would lead to increasing of seepage resistance and liquid flow diversion effect.The emulsification and the additional seepage resistance or pressure difference of ASP in the length of the core were different.The pressure increasing rate in the front area was 72%,the central area was 84.6%,and the rear area was only 12.5%.It can be seen that the emulsification in the middle part of the injection well was stronger,which was mainly due to the higher concentration of alkali and surfactant and the higher oil saturation.In the oilfield practice,the "Jia Min effect" caused seepage resistance increasing,on the one hand,it would cause the injection pressure increased and improved the recovery.On the other hand,it would also cause the residual pressure of produced liquid flow pressure reduced,then reduced the reservoir production capability.Through the fracturing of the middle and low permeability layers in the mining end,the the emulsification could further release liquid flow,and improved the effect of ASP flooding.