Mechanism underlying initiation of migration of film-like residual oil

Abstract

To study the migration conditions of film-like microscopic residual oil, microscopic visualization flooding experiments and Polyflow numerical simulations were conducted. Furthermore, we calculated the adhesion work of oil displacement systems and cores under different conditions. The results revealed that polymer flooding relies on an increase in the horizontal stress differential for systems with film-like residual oil. The results also indicated that a higher viscosity of the polymer corresponds to a larger contact angle with the core and a smaller amount of adhesion work. Additionally, with a lower interfacial tension of the alkali–surfactant–polymer (ASP) system, the contact angle with the core is smaller, and the amount of adhesion work is larger. Under the same viscosity conditions, weaker interfacial tension corresponds to a larger deformation amplitude, larger advancing angle, and smaller receding angle. Under the same interfacial tension conditions, as the viscosity of the displacement fluid increases, the deformation amplitude of the oil film increases, the advancing angle gradually increases, and the receding angle gradually decreases. When the polymer viscosity exceeds 40 mPa·s, the viscosity of the ASP system exceeds 20 mPa·s, and the interfacial tension is <0.3 mN/m. Under these conditions, the oil film ruptures.