Mechanism And Experimental Study Of Reducing Injection Pressure Using Cationic Gemini Surfactants

Due to the particularity of the molecular structure of the cationic gemini surfactants,the adsorption are stronger than conventional surfactants.Moreover,their surface activity,wetting property and anti-swelling property are more superior,and they also have better temperature and salt resistance compared with the traditional surfactants.However,there are also some questions about the effect of the cationic gemini surfactant structure on its properties,and the relationship between adsorption and changing rock wettability.Therefore,in this paper,cationic gemini surfactants are the main research objects for experimental and applied research.In this paper,by studying the different carbon chain length and linker length of active agent on reducing the interfacial tension of oil and water,the adsorption on quartz sand surface and the ability to change the wettability of rock and the emulsification properties,the optimal carbon chain length and linker length are selected.The effects of temperature and salinity on the properties of the active agent were also studied.Preference is given to suitable anti-swelling agents in combination with active agents to provide a superior system of depressurization and replenishment: C16-2-16(1~3mmol/L)+BSA(150mg/L),The system performance and temperature and salt tolerance were tested.The results show that the system is suitable for the salinity range and reservoir temperature range.The core flooding experiment was used to evaluate the effect of injection system.The results show that the system has a good effect on enhancing injectivity and the optimal pressure drop rate can reach 33.98%.Experiments show that different active agent injection concentration,injection velocities,different injection volumes and core permeability all have impacts on the pressure-lowering rate.Through orthogonal test analysis of variance,the primary and secondary factors affecting the parameters and the optimal injection parameters were obtained.The optimal combination of injection parameters and the most suitable range of formation permeability were obtained.