Dynamic Interfacial Evolution and Miscibility of CO₂-Alkane Systems: The Role of Chain Length

Area of Science:

• Petroleum Engineering
• Chemical Engineering
• Physical Chemistry

Background:

• Carbon dioxide (CO2) injection is vital for greenhouse gas mitigation and enhanced oil recovery (EOR).
• Understanding CO2-oil interfacial dynamics is crucial for optimizing miscibility and displacement efficiency in EOR.
• Molecular-level insights into CO2-alkane systems are needed to guide injection strategies.

Purpose of the Study:

• To systematically investigate interfacial evolution in CO2-alkane systems using molecular dynamics simulations.
• To determine the effects of pressure, temperature, and alkane chain length on CO2-oil interfacial behavior.
• To elucidate the mechanisms governing CO2-oil miscibility and its dependence on alkane chain length.

Main Methods:

• Molecular dynamics (MD) simulations were employed to model CO2-alkane systems.
• Systematic variation of pressure, temperature, and alkane chain length.
• Vanishing Interfacial Tension (VIT) method used to determine Minimum Miscibility Pressure (MMP).

Main Results:

• Alkane chain length significantly influences interfacial behavior, more so than pressure or temperature.
• Increasing pressure enhances mass transfer and decreases alkane bulk density; increasing temperature promotes CO2 escape.
• Long-chain alkanes show weaker pressure sensitivity, narrower interfacial widths, lower CO2 solubility, and reduced oil swelling.
• Long-chain alkanes exhibit higher interfacial stability and lower configurational entropy, increasing resistance to CO2-oil miscibility.

Conclusions:

• Long-chain alkanes require higher Minimum Miscibility Pressure (MMP) due to their structural ordering and interfacial stability.
• Findings provide molecular-level understanding of CO2-oil interfacial dynamics and miscibility.
• Offers theoretical guidance for optimizing CO2 injection pressure and composition in EOR applications.