Quantitative analysis of CO2 miscible flooding in tight formation at pore scale applying nuclear magnetic resonance

Abstract

The CO2 miscible flooding in Baikouquan tight formation was thoroughly investigated under reservoir condition of 37 MPa and 89 °C. The low-field nuclear magnetic resonance (NMR) system was used to measure the real time oil saturation under high-temperature and high-pressure environment. The results show that the recovery factors of large, medium and small pores are 66.18%, 45.71%, and 12.71%, respectively. A complementary investigation of CO2–brine–rock interaction was performed, which indicate that the small pore throats blockage during the displacement process is the main reason for low recovery in small pores.