Molecular Dynamics Mechanism Study of CO₂ Dissolution in Crude Oil Systems

Given the environmental hazards posed by CO₂ emissions, carbon sequestration represents a key approach to reducing emissions. CO₂ flooding serves the dual purpose of improving oil recovery and facilitating underground CO₂ sequestration. Changes in crude oil mobility following CO₂ dissolution warrant a thorough investigation of the gas dissolution behavior. A multicomponent model of crude oil, comprising its fundamental components, was constructed. Molecular dynamics simulations were then applied to investigate CO₂ dissolution within this system. The simulation data show that the pressure dependence of CO₂ solubility follows the Langmuir adsorption model, this indicates that the Langmuir equation can serve as an empirical fitting relationship to describe CO₂ solubility. The dissolution mechanism of CO₂ in crude oil was analyzed using microscopic characteristics such as the conformational distribution of dissolved CO₂, isosteric heat of dissolution, and changes in CO₂ molecular bond lengths and angles. Furthermore, by comparing the intermolecular interaction energies in gas-free and CO₂-saturated crude oil systems, this provides molecular-level insights into the variation of CO₂ solubility in crude oil. The results of this work analyze the molecular-scale mechanisms underlying CO₂ dissolution in crude oil, providing a theoretical basis for the implementation of CO₂ flooding technology.