DSC Measurement on Formation and Dissociation Process of Methane Hydrate in Shallow Sediments from South China Sea

Marine methane hydrates exploitation has become one of the hottest research topics in recent years. In this study, we investigated thermodynamic characteristics on methane hydrates in shallow sediments of South China Sea (SCS). The formation and dissociation process of methane hydrate in SCS sediments were conducted by use of a high pressure micro-differential scanning calorimeter ( u DSC). The ice melting peak and hydrate dissociation peak were well distinguished by DSC and the repeated cycles proved the accuracy of DSC measurement. According to the DSC thermograms and pressure profiles, we found the hydrate formation from ice and meltwater respectively in two heating stages. The stage of transformation from ice to hydrate had obvious pressure decrease without little heat effect. Hydrates may come unstable when close to the dissociation temperature and affected the heat flow and pressure irregularly and frequently by a small degree. Comparing the heat flows of different pressures, we also noticed the decrease of ice melting point and the increased of hydrate dissociation point along with the pressure got higher. This study aimed to provide fundamental data for spot exploitation of marine methane hydrate reservoirs. (C) 2019 The Authors. Published by Elsevier Ltd.