Synergistic thickening mechanism of surfactants and supramolecular inclusion systems

The effectiveness of conventional polymer flooding systems for improving oil recovery (IOR) in high-temperature and high-salt reservoirs is greatly limited. The polymer inclusion system forms a spatial network structure through host–guest inclusion, which can achieve the goal of low concentration and high viscosity in high-temperature and high-salt environments. However, there are few reports on further enhancing the performance of polymer flooding systems based on the inclusion system. In this study, the optimal ratio of erucamide propyl betaine (EDAB) to polymer inclusion system (ABMN) was first investigated. The results showed that the optimal formulation for the synergistic enhanced inclusion system was 2000 mg/L ABMN+2000 mg/L EDAB, which could reach 95.7 mPa·s under 85 ℃ and salinity of 32868 mg/L, and the viscosity was more than twice that of the ABMN system. The wormlike micelles (WLMs) formed by EDAB synergistically interacted with the ABMN, resulting in a larger hydrodynamic radius and a denser spatial network structure. Due to the synergistic effect of supramolecular forces, the system has significantly improved its temperature resistance, salt resistance, and shear resistance, with a viscosity recovery rate of up to 98.9 %. This provides a new oil displacement system for IOR in high-temperature and high-salt reservoirs.