2005 Fiscal Year Final Research Report Summary
Methane hydrate investigations on sediment core samples obtained in the Sea of Okhotsk
| Project/Area Number |
14254003
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
エネルギー学一般
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| Research Institution | Kitami Institute of Technology |
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Principal Investigator |
SHOJI Hitoshi Kitami Institute of Technology, New Energy Resources Research Center, Professor, 未利用エネルギー研究センター, 教授 (50201562)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Nobuo Kitami Institute of Technology, Materials Science, Professor, 工学部, 教授 (20108187)
MAEDA Hiroyuki Kitami Institute of Technology, Civil Engineering, Professor, 工学部, 教授 (00003202)
MINAMI Hirotsugu Kitami Institute of Technology, Instrumental Analysis Center, Associate Professor, 機器分析センター, 助教授 (40241426)
HACHIKUBO Akihiro Kitami Institute of Technology, New Energy Resources Research Center, Associate Professor, 未利用エネルギー研究センター, 助教授 (50312450)
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| Project Period (FY) |
2002 – 2005
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| Keywords | Methane Hydrate / Clathrate Hydrate / Sea Sediment Core / Offsore Sakhalin, Okhotsk Sea / Methane Seep / Seepage Structure / Gravity Corer / Sea Bottom Survey |
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| Research Abstract |
Side-scan-sonar survey with high-resolution seismo-acoustic profiling was performed offshore Sakhalin, Okhotsk Sea by the members of CHAOS (hydro-Carbon Hydrate Accumulations in the Sea of Okhotsk) Project lead by Kitami Institute of Technology in 2003. The survey results revealed characteristic distributions of gas hydrate accumulations with unique images of gas seepage structures and vertical fluid channel at/near sea bottom. More than 40 seepage structures were found within a 10 x 20 km survey area. The maximum size of seepage structure observed is about 600 m in diameter. Methane gas released from the seepage structures into the above water was detected as flare images by hydro-acoustic profiling. Gas hydrate and sediment core samples were obtained from those seepage structures and transported to Kitami Institute of Technology for laboratory studies by gas chromatography, liquid chromatography, oxygen/hydrogen/carbon isotopes, 13C-NMR, thermal analysis, physical analysis and other analytical techniques. Methane hydrates of massive forms, layers and/or small pieces were observed in silty-clay, sea sediment cores within a depth of 2-3 meter below the sea floor. Gas hydrates samples were stored in a liquid-nitrogen-temperature container immediately after core recovery, preventing hydrate samples from the dissociation. Main results obtained are summarized as below. Guest gases trapped in hydrates are mainly of methane and only small amount of ethane, propane and others. Crystal structure of hydrates is of clathrate hydrate structure I, and the hydration number is close to six, showing very high quality of gas hydrates. The results of carbon isotope and gas composition measurements show the methane gas in gas hydrates is of microbial origin. Latent heat of gas hydrate measured is found to be quite close to that of artificial, pure methane hydrate.
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