Molecular Dynamics Study of Interfacial Behavior between Crude Oil and Injected CO₂ in a Niger Delta Reservoir

Abstract

As global oil reservoirs mature and conventional recovery methods become less effective, there is growing interest in CO₂-enhanced oil recovery (EOR), especially in regions like the Niger Delta. This study employed molecular dynamics (MD) simulations to investigate the interfacial interactions between injected CO₂ and crude oil under typical reservoir conditions. Octane was selected as a model compound for crude oil and represented using the TraPPE-UA force field, while CO₂ molecules were modeled with the all-atom TraPPE-AA force field to accurately capture electrostatic interactions. The system was simulated at 344 K, reflecting deep reservoir temperatures in the Niger Delta. Results revealed that CO₂ solubility and oil swelling increased with pressure, enhancing oil mobility. Interfacial tension (IFT) declined linearly as pressure rose, with the minimum miscibility pressure (MMP) estimated at approximately 18 MPa. These outcomes underscore the need to operate above the MMP for effective miscible displacement. The study highlights the potential of CO₂ injection for improving oil recovery and demonstrates the value of MD simulations as predictive tools for optimizing EOR strategies in complex reservoir environments.