ABSTRACT

The dissociation behavior of methane hydrate and the kinetics of gas hydrate formation at the interface between gas hydrate and fluid were investigated experimentally and theoretically. As the behavior of dissociation of methane hydrate is an essential function of the commercial recovery of methane gas, the bulk-scale experiment on dissociation rate was conducted as functions of time, temperature and pressure. Based on the results, the replacement experiment of CO2

INTRODUCTION

Large amounts of gas hydrates, clathrate compounds of water and gases formed under high pressure and low temperature, are found in marine sediments and permafrost. To extract methane gas from its reservoir in a practical method, it is necessary to obtain fundamental information on the mechanism underlying the formation and dissociation of gas hydrates and their properties, including kinetics and crystal growth. We have proposed an advanced method of gas hydrate production, by which methane gas is extracted from the reservoir by replacing methane with carbon dioxide at the molecular level. This method would be feasible to achieve the sequestration of carbon dioxide into the sediments. The main purposes of this research are to elucidate the mechanism underlying hydrate reformation and replacement and accumulate practical data for completing the original concept of the proposed method. We have carried out experiments on the dynamics on reformation and replacement of gas hydrates using an apparatus consisting of a high pressure vessel and a Raman spectroscopy. In this paper we present the experimental results concerning the behavior of gas hydrate reformation and replacement, and some discussion on the dynamics and the mechanism of gas hydrate formation. and methane hydrate was performed to obtain fundamentals of the extraction of methane hydrate. The result suggests that the new concept for mining methane hydrate can be applied to the practical cases, such as marine sediments.

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