Molecular Dynamics Mechanism Study of CO₂ Dissolution in Crude Oil Systems

Area of Science:

• Petroleum Engineering
• Environmental Science
• Computational Chemistry

Background:

• Carbon dioxide (CO₂) emissions pose environmental risks, necessitating effective sequestration strategies.
• CO₂ flooding is a promising technique for both enhanced oil recovery (EOR) and underground CO₂ storage.
• Understanding CO₂ dissolution in crude oil is crucial for optimizing CO₂ flooding operations.

Purpose of the Study:

• To investigate the molecular-scale mechanisms of CO₂ dissolution in a multicomponent crude oil model.
• To analyze the pressure dependence of CO₂ solubility and its relationship with adsorption models.
• To provide a theoretical foundation for the practical application of CO₂ flooding technology.

Main Methods:

• Construction of a multicomponent crude oil model representing its fundamental chemical constituents.
• Application of molecular dynamics (MD) simulations to study CO₂ dissolution behavior.
• Analysis of microscopic characteristics including CO₂ conformation, isosteric heat of dissolution, and bond/angle variations.
• Comparison of intermolecular interaction energies between gas-free and CO₂-saturated systems.

Main Results:

• CO₂ solubility in crude oil exhibits pressure dependence consistent with the Langmuir adsorption model.
• The Langmuir equation provides an effective empirical fit for describing CO₂ solubility.
• Microscopic analysis elucidated the dissolution mechanism, including CO₂ conformational changes and energetic interactions.
• Intermolecular energy comparisons offered molecular-level insights into CO₂ solubility variations.

Conclusions:

• The Langmuir model accurately describes CO₂ solubility in crude oil under varying pressures.
• Molecular dynamics simulations provide valuable insights into the mechanisms of CO₂ dissolution in complex oil systems.
• This research offers a theoretical basis for enhancing the efficiency and effectiveness of CO₂ flooding for EOR and carbon sequestration.