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Prestack Depth Migration for Gas Hydrate Seismic Data of the East Sea  

Jang, Seong-Hyung (Korea Institute of Geoscience and Mineral Resources, Petroleum and Marine Resource)
Suh, Sang-Yong (Korea Institute of Geoscience and Mineral Resources, Petroleum and Marine Resource)
Go, Gin-Seok (Chosun University, Resource Engineering)
Publication Information
Economic and Environmental Geology / v.39, no.6, 2006 , pp. 711-717 More about this Journal
Abstract
In order to study gas hydrate, potential future energy resources, Korea Institute of Geoscience and Mineral Resources has conducted seismic reflection survey in the East Sea since 1997. one of evidence for presence of gas hydrate in seismic reflection data is a bottom simulating reflector (BSR). The BSR occurs at the interface between overlaying higher velocity, hydrate-bearing sediment and underlying lower velocity, free gas-bearing sediment. That is often characterized by large reflection coefficient and reflection polarity reverse to that of seafloor reflection. In order to apply depth migration to seismic reflection data. we need high performance computers and a parallelizing technique because of huge data volume and computation. Phase shift plus interpolation (PSPI) is a useful method for migration due to less computing time and computational efficiency. PSPI is intrinsically parallelizing characteristic in the frequency domain. We conducted conventional data processing for the gas hydrate data of the Ease Sea and then applied prestack depth migration using message-passing-interface PSPI (MPI_PSPI) that was parallelized by MPI local-area-multi-computer (MPI_LAM). Velocity model was made using the stack velocities after we had picked horizons on the stack image with in-house processing tool, Geobit. We could find the BSRs on the migrated stack section were about at SP 3555-4162 and two way travel time around 2,950 ms in time domain. In depth domain such BSRs appear at 6-17 km distance and 2.1 km depth from the seafloor. Since energy concentrated subsurface was well imaged we have to choose acquisition parameters suited for transmitting seismic energy to target area.
Keywords
gas hydrate; prestack depth migration; MPI_PSPI; bottom simulating reflector;
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