Effects of inorganic gel-surfactant synergy on profile control and oil displacement in high-temperature and high-salinity reservoir

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This study systematically investigates the interfacial tension (IFT) behavior between different surfactant systems and crude oil under high-temperature and high-salinity conditions, as well as their combined application with inorganic gels in enhancing oil recovery. The anionic-nonionic and cationic surfactant systems achieve ultra-low IFT (10−3 mN/m) through electrostatic attraction and molecular synergy, outperforming conventional single-surfactant systems. Furthermore, the presence of natural oil sands significantly impacts IFT, and increasing the liquid-solid ratio reduces surfactant adsorption on quartz sand, thereby improving IFT characteristics. The incorporation of sodium silicate, which reacts with acidic crude oil components to generate in situ surface-active agent, enables ultra-low IFT at high salinities. The study demonstrates the combined application of surfactant systems and sodium silicate-based inorganic gels for profile control and oil displacement, revealing a remarkable 24.40% increase in oil recovery compared to water flooding. The breakthrough findings highlight that surfactant addition during gel formation significantly boosts ΔP (differential pressure) and sweep efficiency, offering an approach for enhanced oil recovery in harsh reservoir conditions.