The miscible behaviors and mechanism of CO2/CH4/C3H8/N2 and crude oil in nanoslits: A molecular dynamics simulation study

Abstract Using molecular dynamics simulations, we have investigated the miscible behaviors of different gas (CO2, N2, CH4, C3H8) and different crude oils in nanoslits at 413 K and 60 MPa. In this study, the effect of gas type, the polarity and the chain length of crude oil on the miscible process of gas and crude oil is explored. The simulation results show that CO2, CH4, C3H8 and N2 are more miscible with apolar crude oil than polar crude oil due to the stronger interaction between polar crude oil and silica surface. It is worth noting that the solubility of polar crude oil in CO2 phase is higher than that in hydrocarbon gas phase and N2 phase. In addition, it is found that the chain length of crude oil could affect the dissolution of crude oil in hydrocarbon gas and N2. In contrast, it has a negligible effect on the miscibility of crude oil and CO2. The simulation results could provide valuable guidance for enhancing oil recovery in the development of deep and ultra-deep reservoirs.