Synergistic Effects of Nano-SiO2 and Amphiphilic Polymers on Enhanced Oil Recovery

Abstract

In this study, the polymerizable surfactant monomer DAAC₁₂ and modified nano-silica SiO₂-NHMA were synthesized. These two monomers were then copolymerized with acrylamide (AM) and acrylic acid (AA) via free radical polymerization to produce a quaternary copolymer, PAMDS, which exhibits surface-active properties. The polymers were structurally characterized by FT-IR, ¹H NMR, TG, and SEM, and their characteristic viscosities as well as molecular weights were determined by dilution method. The effects of temperature on the copolymers were investigated, and PAMDS was evaluated for its temperature resistance, salt resistance, shear resistance, emulsification capacity, and oil–water interfacial tension. The results demonstrated that the incorporation of functional monomers significantly enhanced the polymer's temperature resistance, salt resistance, and shear resistance, while also improving its emulsification ability. Furthermore, at a polymer concentration of 3 g/L, the oil–water interfacial tension was reduced to 7.9 mN/m, representing a 75.5% decrease compared to that in pure water. Core flooding experiments were conducted to evaluate the oil displacement efficiency of PAMDS. The results revealed that PAMDS achieved a recovery rate of 22.1% at 65 °C, which was 8.6% higher than that of the HPAM. These findings indicate that PAMDS exhibits superior potential for enhanced oil recovery applications.