Multi-scale 2-D and Pseudo 3-D Seismic Approaches for the Detection of Sea-bottom Fault Deformation at a Gas Hydrate Site

We identified faults on a typical 2-D seismic section acquired for gas hydrate exploration in the Ulleung Basin, East Sea, using a 1,035 in3 air-gun array and 240-channel streamer. To determine the possible sea-bottom deformation by a fault for the preparation of future gas hydrate test production, we performed the multi-scale 2-D and pseudo 3-D marine seismic explorations. The 2-D chirp sub-bottom profiler (SBP) section confirmed the vertical offset of the sea-bottom by the fault. To investigated the fault extension in detail, we conducted an experimental pseudo 3-D survey using a 1,500 J sparker and a single-channel streamer in 360 × 1,000-m area with a water depth of 2,150 m. The optimal processing sequence consisting of 2-D first phase and 3-D second phase data processing was specifically designed to process a pseudo 3-D seismic data set. We easily determined the amplitude variation around the fault on the time slice from the final pseudo 3-D seismic volume.