LI Songyan1, WANG Lin1, HAN Rui1, LI Lun2, LI Aiying2, LI Zhaomin1

1. School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, Shandong, China;

2. Engineering Technology Research Institute, Tuha Oilfield Company, PetroChina, Hami 839009, Xinjiang, China

Abstract: The supercritical CO2 foam can effectively reduce the mobility of CO2, increase the plugging strength, and inhibit the channeling of CO2 in fractured tight cores. By evaluating eight kinds of foaming agents under conditions close to the reservoir, we selected a foaming agent with the best stability. The core percolation characteristics of the supercritical CO2 foam flooding under different gas–liquid ratios, fracture openings, and injection modes were studied, and the laws of the supercritical CO2 foam flooding after water flooding and gas flooding were analyzed. The results show that the foaming agent HY-2 has the best stability when the mass fraction is 0.5%; when the gas–liquid ratio is equal to 1.0, it has the best plugging effect on the fractured tight cores and the good adaptability to the cores with the fracture openings of 39.80–82.67 μm. The simultaneous injection of gas and liquid is more conducive to improving the plugging effect of the supercritical CO2 foam flooding. There is an increase in oil recovery of more than 20% with supercritical CO2 foam flooding compared that with water flooding or gas flooding. Therefore, the supercritical CO2 foam flooding under certain conditions has a significant effect on improving the oil recovery of the fractured tight reservoirs.