Abstract:

It is proved by the long-term exploration that natural gas hydrate generally occurs within fine-grained sediments, and its stability is controlled by a number of physical, chemical and geological factors, such as temperature, pressure, pore water composition, and so on. Recent experimental studies have shown that the stability of gas hydrate in pore space with various pore structures is distinguished evidently from that of bulk one. Pore structures of host sediments significantly affect the formation and dissociation of gas hydrate, as well as wettability of pore surface. We summarize the latest experiments reported in literatures and discuss the possible influence mechanism of pore structure and wettability of inner surfaces on the stability of gas hydrates confined in pores. It is proposed that establishing an integrated thermodynamics model of methane hydrates in pore spaces with various radii, and investigating the pore structure and surface properties of hydrate-bearing sediments would advance the prediction, exploration and evaluation of gas hydrate resources. At the  same time, it is of importance for methane storage and transportation.

Key words: hydrate, pore structure, stability, surface and interface