Key Findings of the World’s First Offshore Methane Hydrate Production Test off the Coast of Japan: Toward Future Commercial Production

Marine methane hydrate in sands has huge potential as an unconventional gas resource; however, no field test of their production potential had been conducted. Here, we report the world’s first offshore methane hydrate production test conducted at the eastern Nankai Trough and show key findings towar...

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Bibliographic Details
Published in:Energy & Fuels
Main Authors: Konno, Yoshihiro, Fujii, Tetsuya, Sato, Akihiko, Akamine, Koya, Naiki, Motoyoshi, Masuda, Yoshihiro, Yamamoto, Koji, Nagao, Jiro
Format: Article in Journal/Newspaper
Language:English
Published: American Chemical Society 2017
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Online Access:https://oceanrep.geomar.de/id/eprint/40165/
https://oceanrep.geomar.de/id/eprint/40165/1/Konno.pdf
https://doi.org/10.1021/acs.energyfuels.6b03143
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Summary:Marine methane hydrate in sands has huge potential as an unconventional gas resource; however, no field test of their production potential had been conducted. Here, we report the world’s first offshore methane hydrate production test conducted at the eastern Nankai Trough and show key findings toward future commercial production. Geological analysis indicates that hydrate saturation reaches 80% and permeability in the presence of hydrate ranges from 0.01 to 10 mdarcies. Permeable (1–10 mdarcies) highly hydrate-saturated layers enable depressurization-induced gas production of approximately 20,000 Sm3/D with water of 200 m3/D. Numerical analysis reveals that the dissociation zone expands laterally 25 m at the front after 6 days. Gas rate is expected to increase with time, owing to the expansion of the dissociation zone. It is found that permeable highly hydrate-saturated layers increase the gas–water ratio of the production fluid. The identification of such layers is critically important to increase the energy efficiency and the technical feasibility of depressurization-induced gas production from hydrate reservoirs.