The effect of gas injection velocity and pore morphology on displacement mechanisms in porous media based on CFD approach

Because of the unique advantages such as easy miscibility, high temperature resistance and so on, hydrocarbon gas flooding has proved to be a promising technology for enhanced oil recovery in deep reservoirs. In order to reveal the potential mechanism of miscibility and displacement of crude oil and hydrocarbon gas, an innovative two-dimensional physical field model is constructed by coupling Navier-Stokes equations and mass transfer equation. Accordingly, the effect of gas injection velocity and pore morphology on fluid transport and miscibility properties is investigated based on computational fluid dynamics approach. The simulation results demonstrated that the residual oil (RO) content is lower at low gas injection velocity than that at high gas injection velocity due to the better miscibility of fluids. For pore morphology, the RO content increases with increasing pore throat ratio and pore throat angle, which are not related to the gas injection velocity. The blocked pore structure has a negative effect on hydrocarbon gas flooding, resulting in the higher RO content. In addition, the influence of the pore throat length on the RO content is related to the gas injection velocity, which means the RO content increases at low gas injection velocity and decreases at high gas injection velocity with increasing pore throat length.