Mechanism of the CO₂ flooding as reservoirs containing high water

Aiming at problems of low or no efficiency of water flooding in high water cut reservoirs or stagnant zones, the present paper studied the mechanism of supercritical CO₂ miscible flooding, migration characteristics of oil film and the mass transfer process between CO₂ and oil by using a high-speed, advanced and visualized camera micro-simulation model, by which the displacement mechanism of transient blind side was observed, and the film migration phenomenon and the mixed phase were also seen. The results have shown that the wax in crude oil continues to be deposited at pore throats and chock up throats, while supercritical CO₂ can surpass water hindrance in pores and further flood the residual oil away in the form of both the cylindrical and columnar flow. Supercritical CO₂ has a strong ability to dissolve oil due to the occurrence of molecular aggregation within it. What is more, it could extract not only light hydrocarbon components but also certain heavy hydrocarbon components from crude oil. Thus, supercritical CO₂ is a kind of good miscible agents for flooding crude oil.