Formation of nanobubbles generated by hydrate decomposition: A molecular dynamics study

Abstract

Natural gas hydrate is estimated to have huge reserves. Its exploitation can solve the global oil and gas shortage problem. Hydrates decompose into water and methane, and methane molecules are supersaturated to form nanobubbles. Methane nanobubbles can affect the decomposition efficiency of hydrates. They can provide abundant methane sources for the re-nucleation of hydrates. Molecular dynamics is employed in this study to investigate the decomposition process of type I methane hydrate and the formation of methane nanobubbles generated during decomposition under different methane mole fraction, pressures, and temperatures. The results indicate that external pressure inhibits the diffusion of methane molecules, thereby preventing the formation of nanobubbles. A higher mole fraction of methane molecules in the system requires a higher external pressure to generate stable nanobubbles after the decomposition of the hydrate structure. At 330 K, it is easy to form a nanobubble structure. Results of this study can help provide ideas for the study of efficient extraction and secondary nucleation of hydrates.