HR: 1340h
AN: OS33B-1477    [Abstracts]
TI: Analysis of time-structure of BSRs using 3D seismic data in the Eastern Nankai Trough, Japan
AU: * Nagakubo, S
EM: nagakubo-sadao@jogmec.go.jp
AF: JOGMEC, 1-2-2, Hamada, Mihama-ku, Chiba, 261-0025 Japan
AU: Inamori, T
EM: inamori-takao@jogmec.go.jp
AF: JOGMEC, 1-2-2, Hamada, Mihama-ku, Chiba, 261-0025 Japan
AU: Kobayashi, T
EM: kobayashi-toshiaki@jogmec.go.jp
AF: JOGMEC, 1-2-2, Hamada, Mihama-ku, Chiba, 261-0025 Japan
AU: Fujii, T
EM: fujii-tetsuya@jogmec.go.jp
AF: JOGMEC, 1-2-2, Hamada, Mihama-ku, Chiba, 261-0025 Japan
AB: According to the result of METI Exploratory Wells "Tokai-Oki to Kumano-nada" conducted in FY2003 in Japan, it is suggested that methane hydrate bearing layers in the Eastern Nanakai Trough distribute heterogeneously above BSRs (Bottom Simulating Reflectors). To understand the heterogeneity of distribution of methane hydrate bearing layers and explore concentrated hydrate bearing layers, we conducted a detailed analysis of time-structure map of BSR using 3D seismic survey data acquired in the Eastern Nankai Trough. Since P-wave velocity of hydrate bearing layers are high, it was expected that two-way-time from sea bottom to BSR is short above concentrated hydrate bearing layers compared to hydrate bearing zones. Although significant anomalies are recognized on time-structure map, it seems that anomalies are corresponding to heterogeneous thermal-structure in preference to distribution of hydrate bearing layers around surveyed area. It should be considered that these thermal anomalies are depending on fluid migration with hydrocarbons through faults, unconformities and permeable sand layers from deeper formations. Since occurrences of methane hydrates are strongly restricted by temperature and pressure, analysis of time-structure of BSR acquired by seismic data could be helpful to understand the accumulation mechanism of methane hydrates in sediments.
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3004 Gas and hydrate systems
DE: 3015 Heat flow (benthic)
DE: 3025 Marine seismics (0935, 7294)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005