Experimental Research of Gas Hydrate Dissociation in Sediments by Depressurization Method

Abstract

Abstract:

Experimental investigation of methane hydrate dissociation process in sediments using depressurization method was carried out based on an selfdeveloped experimental setup for gas hydrate exploitation. The TDR (timedomain reflectometry) technique was applied to measure hydrate saturation during gas hydrate dissociation. The materials used in this study are natural sand (0.18-0.35 mm), 0.03% sodium dodecyl sulfate (SDS) solution and highpurity methane. The results show that during gas hydrate dissociation, the temperature and hydrate saturation vary in different parts of sediments, suggesting that hydrates dissociate earlier on the surface and in outer layer of the sediments than those in inner layer. The TDR waveforms arent affected by rapid depressurization. The changes of TDR curve is just due to gas hydrate dissociation so that the measured hydrate saturations arent affected by pressure changes. Moreover, the cumulative volume of dissociation gas is also used to calculate the hydrate saturation for comparison, and the result is well consistent with that of TDR method. It indicates that TDR method can be used to measure the variation of hydrate saturation and exactly demonstrate the hydrate dissociation process.

Key words: gas hydrate, sediment, depressurization dissociation, TDR, saturation

CLC Number:

TE311

SUN Jian-Ye, YE Yu-Guang, LIU Chang-Ling, ZHANG Jian, DIAO Shao-Bo. Experimental Research of Gas Hydrate Dissociation in Sediments by Depressurization Method[J]. Geoscience, 2010, 24(3): 614-621.

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