Observation of the Self-preservation Effect of Methane and Ethane Hydrate

摘要

We investigated surface changes of methane and ethane hydrates during depressurization using optical and confocal scanning microscopes. The dissociation of methane hydrate above 242 K and ethane hydrate above 267 K resulted in the formation of clear ice sheets on the hydrate surface. The ice sheets that formed at 252 K were the thickest of those from 242 to 262 K, indicating that methane hydrate stability may be greatest around 252 K. Our results reveal that the formation of ice sheets is closely related to the mechanism of the self-preservation effect of methane hydrate and ethane hydrate. Practical transportation and storage of methane hydrate and ethane hydrate should be undertaken at 250 and 270K at atmospheric pressure. Dissociation control of methane hydrate by the self-preservation effect based on ice sheet formation may be helpful for research into methane hydrate resources, and thus our results are of value.