Optimization And Experimental Study Of Plugging Agent After ASP Flooding

In the middle and late stage of oilfield development,when the oil field enters the stage of high water cut or ultra-high water cut,the development cost increases,so it is necessary to select layers for water plugging to reduce the ineffective or inefficient circulation of the injection system and improve the development effect.Due to the complex reservoir environment after ASP flooding,it is difficult for conventional plugging agents to form efficient plugging.Therefore,it is necessary to carry out the optimization of plugging agents suitable for the reservoir environment after ASP flooding.According to the reservoir environment after ASP flooding,the performance evaluation experiments of different types of plugging agents were carried out to analyze the influence of temperature,alkalinity and salinity on the gelling stability.The adaptability evaluation of mixed fluid of different plugging agent/ternary production fluid was carried out,and the influence of plugging agent concentration,ternary production fluid type and plugging agent/ternary production fluid ratio scheme on its performance was analyzed,and the long-term stability was evaluated.Physical simulation experiments were carried out to analyze and evaluate the flow performance of the plugging agent,the plugging performance after ASP flooding and the influence of residual oil on the gelling performance.In this paper,three alkali-resistant plugging agents were selected for basic performance evaluation.When the temperature range was 35-65?,the p H value range was 7-12,and the salinity range was 3888-10166mg/L,the performance of the three plugging agents was good.On this basis,using the produced fluid after ASP flooding,mixtures of four kinds of proportional plugging agents/ASP produced fluid were prepared.The experimental results show that the No.2 plugging agent is greatly affected by the ternary production fluid,and the glue is formed first and then broken.When the proportion of No.1 plugging agent is higher than 70%,the mixture can be gummed,and when the proportion of No.3 plugging agent is higher than 60%,the mixture can be gummed.The properties of No.1 and No.3 plugging agents are stable within 60 days after gumming.The indoor physical simulation results show that the plugging rate of No.1 plugging agent is higher than 99.86%.The plugging rate of No.3plugging agent was less than 76.22%.The optimized environment after ASP flooding was simulated and evaluated.The plugging efficiency of different concentrations of No.1 plugging agent was all higher than 99.91%.The No.1 plugging agent is less affected by the residual oil.The effective plugging can be achieved by injecting low concentration of plugging agent from the production end.In view of the complex situation of the reservoir after ASP flooding,the software of well plugging and layer selection after ASP flooding is developed,and the multi-factor comprehensive evaluation method is used to make the decision of well selection and layer selection,which provides guidance for field construction.