Research And Evaluation Of Self-generating Foam Flooding System

The self-generating foam flooding system both has the high oil washing capacity of surfactant flooding,and the capacity of gas flooding for blocking and profile control,which can improve the heterogeneity of rock and enhance oil recovery.In this paper,the foam and interfacial tension properties of anionic/amphoteric/nonionic surfactants are studied,mixed and screened,and the foam oil displacement system with the range of ultra-low interfacial tension is obtained.The system is made up of LAS,CTMAB and BC-14 with a proportion of 4:4:2 and a total concentration of 1000 mg/L,with a foaming volume of 110 mL and a half-life of 12 min.In order to improve the foam properties of the system,several foam stabilizer were screened.The results showed that the foam performance of the system was improved most obviously with the addition of 1000 mg/L of HEC,and the half-life increased to 33 min.By studying the effect of temperature on the system,the higher the temperature is,the shorter the half-life of the system is.CO（NH₂）₂ is hydrolyzed by urease to produce（NH₄）₂CO₃,and NaNO₂ is reacted with（NH₄）₂CO₃ to form N₂.The results show that when CO（NH₂）₂ 100 g/L,NaNO₂150 g/L,Tris 22.5 g/L,the initial pH value is 6-7,and the reaction temperature is45℃,the amount of gas is the most.In this paper,the oil displacement effect of the system is evaluated by core displacement experiment.The result shows that the self-generating foam flooding system can increase the recovery rate of 8.06%after water flooding,and has a higher oil displacement capacity than the simple surfactant flooding.