Decoding the dynamic of CH4 and CO2 displacement for enhanced condensate oil recovery

[Display omitted] •MD simulation is applied to reveal the dynamics of condensate oil recovery.•CO2 demonstrates better performance in condensate oil recovery compared to CH4.•CO2 outperforms CH4 in effectively extracting heavier components.•Pore depth and pore opening size are closely related to the condensate oil recovery. Gas-condensate reservoirs have attracted wide attention owing to substantial gas and high-quality condensate oil. However, the limited research makes the enhanced oil recovery mechanism through gas injection in condensate reservoirs remains poorly understood. This study explores the intricate molecular interactions of gas displacement in condensate oil recovery. The results underscore that CH4 proves more effective in extracting light components, while CO2 excels in extracting both light and heavy components. Microscopic analysis reveals unique displacement mechanisms, with CH4 displacing light components and forming clusters that concentrate in the center of the pore. In contrast, CO2 induces continuous dispersion and expansion of condensate oil components, thereby extracting more oil from the pore. Additionally, the study emphasizes the influence of pore geometry on condensate oil recovery. These insights provide valuable guidance for optimizing strategies for the gas-driven recovery of condensate oil.