Simulation study on methane hydrate formation rule and influencing factors in simulated wellbore

ABSTRACT: Natural gas hydrates possess significant reserves and potential energy value. Understanding the formation mechanism of hydrates is crucial for the exploration and development of natural gas hydrate resources, as well as for research in environmental geology. Therefore, to clarify the formation characteristics and influencing factors of methane hydrates in an experimental wellbore hydrate system, laboratory-scale simulation experiments were conducted. The study investigates the effects of key factors such as temperature, pressure, and stirring speed during methane hydrate formation. Additionally, molecular dynamics (MD) simulations were employed to explore the molecular-level growth behavior of methane hydrates under varying temperature and pressure conditions. The results demonstrate that: (1) The macroscopic experimental results show that increasing pressure, lowering temperature, and increasing stirring speed significantly shorten the induction time for methane hydrate formation, while both the final hydrate formation and pressure drop are significantly enhanced; (2) The molecular simulation results indicate that as pressure increases and temperature decreases, free methane and water molecules at the microscopic level form cage-like methane hydrate structures more rapidly, which correlates with the shorter induction times observed in the macroscopic experiments. This study utilizes MD simulations to complement the macroscopic experimental findings and provides valuable insights into the molecular mechanisms underlying methane hydrate formation.