Microscopic Mechanism and Fluctuation–Dissipation of Methane Hydrate Decomposition in Oil-Containing Systems

Hydrate blockages in oil and gas pipelines threaten transportation safety and efficiency, underscoring the need to clarify hydrate decomposition mechanisms. This study investigates the microscopic decomposition of methane hydrates in oil-containing systems by constructing four models representing alkanes, aromatics, and asphaltenes based on crude oil composition. By integrating multiparameter analysis with the Green-Kubo and fluctuation-dissipation frameworks, the decomposition mechanisms are examined from kinetic, rheological, and energetic perspectives. Results show that oil molecular structure regulates decomposition: light oils accelerate it (viscosity rise 5.87%), while heavy oils inhibit it (12.69%). Heavy oil systems exhibit stronger dynamic instability and stage-dependent dissipation, with dissipation coefficients 13.03% higher during guest release. Component-dependent van der Waals, electrostatic, and hydrogen bond dynamics further reveal energy-driven differences, with over 80% of hydrogen bond lifetimes concentrated within 10-20 ps. This work elucidates oil structural regulation, quantifies fluctuation-dissipation characteristics, and provides a molecular-scale foundation for understanding hydrate decomposition in complex oil-based environments.