Study on the Stabilization Mechanism of Wormlike Micelle-CO2 Foams in High-Temperature and High-Salt Oil Reservoirs

The reservoir environment is complex and variable, and the foam itself is a thermodynamically metastable system. Therefore, the influence of a high-temperature and high-salt reservoir environment on the stability of foams has not been extensively studied in the field of foam flooding. In this study, the influence of high-temperature and high-salt oil reservoir conditions on the stability and stability mechanism of wormlike micelle (WLM)-CO2?foam systems was explored using foam volume, foam half-life, liquid separation half-life, and foam coarsening behavior as the performance indexes. This goal was achieved by characterizing the foam stability, setting a series of temperatures and salinity in the environment where the foam system is located, and applying statistical methods to intuitively recognize the foam and evaluate the foam effect. In addition, the theory of rheology was used to measure WLM-CO2?foam system’s apparent viscosity and the modulus of energy storage and modulus of loss of foams, and the foam effect was evaluated indirectly. The results showed that the higher the temperature of the WLM-CO2?foam in the experimental temperature range, the worse the foam stability was. The effect of salinity on the stability of WLM-CO2?foams is “slightly synergistic, excessively antagonistic”. This paper systematically explored the stability law of WLM-CO2?foams under high-temperature and high-salt reservoir conditions from the microcosmic level and analyzed the attenuation mechanism of the foam by innovative use of rheological theory as to provide a more comprehensive theoretical guidance for the practical application of the WLM-CO2?foam system in enhanced oil recovery.