Petroleum Reservoir Evaluation and Development ›› 2024, Vol. 14 ›› Issue (1): 26-34.doi: 10.13809/j.cnki.cn32-1825/te.2024.01.004

• Methodological Theory • Previous Articles     Next Articles

Molecular dynamics simulation on interaction mechanisms of crude oil and CO2

LI Jianshan1,2(),GAO Hao1,2(),YAN Changhao1,2,WANG Shitou1,2,WANG Liangliang3   

  1. 1. Research Institute of Oil and Gas Technology, PetroChina Changqing Oilfield Company, Xi’an, Shaanxi 710018, China
    2. National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields, PetroChina Changqing Oilfield Company, Xi’an, Shaanxi 710018, China
    3. School of Petroleum Engineering, China University of Petroleum(East China), Qingdao, Shandong 266580, China
  • Received:2022-11-18 Online:2024-02-26 Published:2024-03-05


Numerous oil displacing mechanisms of CO2 have been widely recognized, but due to reservoir factors, the effectiveness of CO2 flooding varies significantly under different reservoir conditions. It is necessary to further deepen the research on the micro-interaction mechanisms between CO2 and crude oil, clarify the CO2 flooding mode under different reservoir conditions, and maximize the potential of CO2 flooding. Molecular dynamics simulation methods have been used to study the effects of components, temperature, and pressure on the interaction between oil droplets and CO2. The kinetic parameters were obtained to quantitatively characterize the oil droplets-CO2 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 CO2 and alkane molecules, which mainly includes two aspects: one is the dissolution and diffusion of CO2 molecules into the oil droplets by overcoming the steric hindrance between alkane molecules, and the other is the extraction attraction of CO2 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 CO2 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 CO2 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 CO2 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 CO2 flooding.

Key words: CO2 flooding, microscopic interaction mechanism, molecular dynamics simulation, dispersion force, dissolution and diffusion

CLC Number: 

  • TE357