HR: 0830h
AN: OS51B-0841    [PDF]
TI: Experimental Study on Growth Kinetics of Gas Hydrates in Marine Sediments
AU: * Komai, T
EM: koma@ni.aist.go.jp
AF: AIST, Japan, 16-1 Onogawa, AIST-West, Tsukuba, 305-8569 Japan
AU: Sakamoto, Y
EM: sakamoto-yasuhide@aist.go.jp
AF: AIST, Japan, 16-1 Onogawa, AIST-West, Tsukuba, 305-8569 Japan
AU: Kawabe, Y
EM: y-kawabe@aist.go.jp
AF: AIST, Japan, 16-1 Onogawa, AIST-West, Tsukuba, 305-8569 Japan
AU: Kawamura, T
EM: t-kawamura@aist.go.jp
AF: AIST, Japan, 16-1 Onogawa, AIST-West, Tsukuba, 305-8569 Japan
AU: Haneda, H
EM: h.haneda@aist.go.jp
AF: AIST, Japan, 16-1 Onogawa, AIST-West, Tsukuba, 305-8569 Japan
AB: 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 CO2 at the molecular level. This method would be feasible to achieve the sequestration of CO2 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. It was shown that reformation of gas hydrates easily occurred in the quasi-solid structure when the dissociated solution is used. The rate of reformation of CO2 gas hydrate was observed by Raman spectroscopy. The results of the bulk scale experiment showed that replacement of CO2 gas hydrate could be achieved within a period of 12 hours in pure samples of CH4 gas hydrate that had been synthesized as solid crystal, if the pressure and temperature are precisely controlled in the pressure cell. The replacement of guest elements in CO2 and CH4 gas hydrates may be quite innovative from both aspects, the extraction of gas hydrates and sequestration of CO2, to maintain the global environment and stability of marine sediments.
DE: 1055 Organic geochemistry
DE: 1635 Oceans (4203)
DE: 3022 Marine sediments--processes and transport
DE: 4806 Carbon cycling
DE: 4820 Gases
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting