A Thermo-Stable Polymeric Surfactant for Enhanced Heavy Oil Recovery via Hot Water Chemical Flooding

Thermal-chemical flooding with hot water is a widely used method for heavy oil recovery, yet its efficiency is often limited by the degradation of conventional viscosity reducers under high-temperature conditions. This study developed a thermo-stable polymeric surfactant (ADA) specifically designed for hot water flooding applications. Synthesized via free radical polymerization of acrylamide (AM), N-[3-(dimethylamino)propyl]methacrylamide (DMAPMA), and sodium α-olefin sulfonate (AOS), ADA demonstrated unique dual functionality in 90 °C hot water flooding: (1) it exhibited significant thermo-thickening behavior, increasing solution viscosity by over 50% at elevated temperatures to improve sweep efficiency while (2) simultaneously reducing heavy oil viscosity by 92.4% through formation of stable oil-in-water emulsions. Comprehensive core flooding tests showed that ADA maintained stability throughout the 90 °C flooding process, ultimately achieving 87.23% oil recovery. The polymer's salt tolerance (40,000 mg/L) and persistent interfacial activity under thermal conditions address critical limitations of existing chemical flooding systems. This work provides an innovative solution in combining thermal thickening and emulsification capabilities specifically optimized for enhancing polymer surfactant thermal stability under hot-flooding operations.