摘要：The heavy oil reservoirs in China have the characteristics of high asphaltene content, low wax content and deep burial. During the steam flooding development, the wellbore has large heat loss and low thermal efficiency. In the hot water injection development process, the water viscosity is lower than the viscosity of heavy oil, which induces viscous fingering effect and results in low recovery of the heavy oil. Considering that supercritical CO2 has the permeability close to gas permeability and self-diffusion coefficient much higher than that of liquid, we tried to use supercritical CO2 to improve the recovery of heavy oil. The heavy oil viscosity and ultimate recovery of displaced heavy oil were measured under different supercritical CO2 injection pressures. The experimental results show that with the increase of supercritical CO2 injection pressure, the viscosity of heavy oil gradually decreases, and the magnitude of viscosity reduction gradually decreases. The recovery of heavy oil increases first and then decreases during the displacement process. It is shown that the development of supercritical CO2 flooding heavy oil cannot simply consider viscosity reduction. It must also consider the effects of swelling and extraction to determine the optimal supercritical CO2 injection pressure for thermal recovery of heavy oil.
