Numerous oil displacing mechanisms of CO

2

have been widely recognized

but due to reservoir factors

the effectiveness of CO

2

flooding varies significantly under different reservoir conditions. It is necessary to further deepen the research on the micro-interaction mechanisms between CO

2

and crude oil

clarify the CO

2

flooding mode under different reservoir conditions

and maximize the potential of

CO

2

flooding. Molecular dynamics simulation methods have been used to study the effects of components

temperature

and pressure on the interaction between oil droplets and CO

2

. The kinetic parameters were obtained to quantitatively characterize the oil droplets-CO

2

interaction

clarifying the micro-interaction patterns under different conditions. The simulation results show that the dispersion force is the the main driving force of the interaction between CO

2

and alkane molecules

which mainly includes two aspects: one is the dissolution and diffusion of CO

2

molecules into the oil droplets by overcoming the steric hindrance between alkane molecules

and the other is the extraction attraction of CO

2

molecules to the outer layer molecules of the oil droplets. As the chain length of alkane molecules decreases

the temperature decreases and the pressure increases

the solubility parameter of the oil droplets and the coordination number of CO

2

increase

the curvature of the molecules in the outer layer of the oil droplets decreases

and the interaction between the two is enhanced. It is concluded that CO

2

miscible and near-miscible flooding should be realised as much as possible in light and medium-light reservoirs with lower temperatures and higher pressures

while in medium and heavy reservoirs with higher temperatures and lower pressures

the advantages of CO

2

non-miscible flooding in terms of dissolution viscosity reduction

crude oil volume expansion and energy replenishment should be fully exploited. The study results can provide theoretical guidance for laboratorial research and field application of CO

2

flooding.