Gas-Solvent-Assisted CO₂ Injection for Shale Oil Recovery: Modifying Oil Properties and Enhancing Competitive...

Area of Science:

• Petroleum Engineering
• Chemical Engineering
• Materials Science

Background:

• Pure CO2 injection shows limited success in enhancing shale oil recovery from microscopic pores.
• Understanding gas-solvent interactions is crucial for optimizing enhanced oil recovery (EOR) strategies.

Purpose of the Study:

• To investigate the potential of gas-solvent-assisted CO2 injection for improving shale oil recovery.
• To elucidate the interaction mechanisms between gas-solvent-assisted CO2 and shale oil using molecular dynamics simulations.

Main Methods:

• Systematic experimental analysis of gas-solvent-assisted CO2 and shale oil interactions.
• Molecular dynamics simulations to assess oil displacement performance and interaction mechanisms.
• Competitive adsorption experiments to evaluate gas solvent roles in CO2 adsorption.

Main Results:

• Gas solvents reduce shale oil saturation pressure, enhance CO2 solubility, and increase expansion coefficient.
• Significant reduction in viscosity, density, and minimum miscibility pressure (MMP) observed.
• Improved displacement efficiency and faster CO2-oil interactions in displacement models.
• Enhanced CO2 adsorption over CH4 in nanopores, optimizing adsorption profiles.

Conclusions:

• Gas-solvent-assisted CO2 injection is a promising strategy for enhancing shale oil recovery.
• This method offers improved miscibility and displacement efficiency compared to pure CO2.
• Findings advance the understanding of gas-liquid interactions in unconventional reservoirs.