The kinetic law of natural gas hydrate (NGH) growth is highly significant for the application of NGH technology. In this work, we observed the process of methane hydrate film thickening at the gas-liquid interface by X-ray Computed Tomography (X-CT). Our results showed that the methane hydrate film growth process at the gas-liquid interface can be divided into three stages. Firstly, the methane hydrate film formation process was controlled by heat transfer; secondly, the thickening process was controlled by mass transfer. Above all, the transport of water below the hydrate film caused fractures in the hydrate film, and new hydrate grows at the fractures. The proposed hydrate film formation and growth mechanism at the gas-liquid interface in this study provided theoretical support and research methodology for future studies of the gas-liquid interface growth process of NGH.
Keywords natural gas hydrate, hydrate film, X-ray CT, mass transfer control, heat transfer control