Effect of the Water Film Rupture on the Oil Displacement by Supercritical CO2 in the Nanopore: Molecular Dynamics Simulations

: It is proved that injecting CO2 to displace the residual oils trapped in nanopores with water barriers can achieve the purpose of improving the oil recovery. In the present work, we find that the rupture of the water film has a significant effect on the velocity of the displacement. At first, the whole displacement processes under different water film thicknesses are fully demonstrated by snapshots of molecular dynamics simulations. It is found that the recovery factor is directly related to the case whether the water film is ruptured. The rupture time of the water film is a key factor in the displacement process, which is greatly influenced by three parameters including the water film's thickness, the CO2 injection pressure, and the depth of the dead-end pore. The simulation results are verified by the method of dimensional analysis. Our study may help reveal the effect of the water film rupture on residual oil displacement from the nanoscale pores, and the results can provide new ideas on the application of CO2 flooding in engineering