Study and Application of Influencing Factors on Sweep Coefficient of CO2 Miscible Flooding in Low Permeability Reservoir

Due to deep burial depth and high pressure, CO2 can achieve miscible flooding in Jidong Oilfield, and the oil displacement efficiency can reach more than 90%.Thesweep coefficient is the key to restrict the implementation effect of this technology. Inorder to greatly improve the recovery efficiency, the numerical simulation and field statistics were combined to study the influencing factors of CO2 miscible flooding sweep coefficient from five aspects, such as reservoir heterogeneity, formation dip Angle, injection-production well pattern and injection-production speed. Heterogeneity, injection-production parameters and injection-production well spacing are the main controlling factors restricting the sweep coefficient of CO2 miscible flooding in low permeability reservoirs, and a calculation model of CO2 miscible flooding sweep coefficient is established. It has guided the formulation of CO2 miscible flooding scheme of G fault block, which is expected to increase the oil recovery rate by more than 30 percent. This paper explores a new model of water flooding to carbon flooding to greatly improve oil recovery in complex fault block strong heterogeneous multilayer sandstone reservoirs.