Review on Molecular Dynamics Simulations for Understanding Mechanisms of Enhanced Heavy Oil Recovery: Recent Progress, Challenges, and Prospects

Heavy oil accounts for more than 70% of the remaining oil reserves and is regarded as a highly promising and accessible resource to meet the energy needs of humanity. However, for conventional heavy oil, enhanced oil recovery (EOR) technologies face significant challenges, such as polymer degradation, surfactant adsorption, high costs and mobility of injected fluids, considerable energy and water consumption, huge solid waste production, significant emissions of CO2, SOx, and NOx, and the need for robust equipment. Recently, molecular dynamics (MD) simulations have offered unprecedented opportunities due to their advantages of investigation of molecular-level EOR mechanisms, multiscale simulation, dynamics simulation, low costs, and environmental friendliness. This paper provides a comprehensive overview of recent advancements in the application of MD simulations for heavy oil recovery and helps researchers obtain valuable insights into molecular-level EOR mechanisms underlying various EOR applications. First, recent research progress on MD simulations for chemical EOR methods including surfactant flooding, polymer flooding, their compound systems, and nanoparticle-enhanced chemical techniques is summarized. Second, applications of MD simulations for gas EOR techniques are highlighted in terms of force field, oil components, and molecular-level EOR mechanisms. Third, recent research advances in MD simulations for thermal EOR methods are comprehensively discussed from various molecular-level mechanisms and the molecular-level interfacial interactions between heavy oil and injected fluids. Finally, challenges and future perspectives are identified for the applications of MD simulations for improving heavy oil recovery.