HR: 1340h
AN: OS33B-1476    [Abstracts]
TI: Delineation of Gas Hydrate-Bearing Sediments by Multi-Seismic Attributes Using 3D Seismic Survey in the Eastern Nankai Trough
AU: * Inamori, T
EM: inamori-takao@jogmec.go.jp
AF: JOGMEC, 1-2-2, Hamada, Mihama-ku, Chiba, 2610025 Japan
AU: Saeki, T
EM: saeki-tatsuo@jogmec.go.jp
AF: JOGMEC, 1-2-2, Hamada, Mihama-ku, Chiba, 2610025 Japan
AB: In 2000, the occurrence of gas hydrates was confirmed by corings and borehole log measurements in the Eastern Nankai Trough. It gave us so big impact to the view of Japanese future energy resources and other scientific interests. METI, Ministry of Economy, Trade and Industry of JAPAN, started _gJapan_fs Methane Hydrate Exploitation Program" since the autumn of 2001. We conducted the 3D seismic survey in this area in 2002, we decided well sites and drilled thirty-two boreholes in 2004. We had gotten several logs and cores which indicated the occurrence of gas hydrate below the sea floor. Bottom Simulating Reflectors (BSRs) were widely found on the marine seismic data acquired offshore Japan, especially in the shelf-slope in the Eastern Nankai Trough area. If we will explore and exploit the gas hydrate, we have to get the information of hydrate-bearing sediments, such as its concentration, porosity or thickness. BSRs indicate the existence of gas hydrates. However, we cannot estimate detail reservoir information from BSRs. In order to estimate the amount of gas hydrates accurately, we need to get the more detailed reservoir parameters from seismic data. We apply the seismic attributes analysis to 3D seismic survey data to delineate hydrate-bearing sediments. We calculate seismic attributes of the P-interval velocity using the NMO velocity analysis, P-impedance, S-impedance, and Poisson's ratio change from pre-stack (AVO) analysis and the attenuation. And we delineate of gas hydrate bearing-zones at borehole locations. High P-interval velocity, High P and S impedance, low Poisson_fs ratio and high-attenuated layers are corresponding to the hydrate bearing-zones.
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3004 Gas and hydrate systems
DE: 3025 Marine seismics (0935, 7294)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005