Ultra-High-Resolution Seismic Surveys: 3D Sea Trial at Beppu Bay

A 3D high-resolution seismic (3D-HRS) survey was conducted to clearly reveal and map faults and fractures in a shallow-water region of Beppu Bay, Japan. The 3D-HRS was conducted using a dense array of six short streamer cables combined with a single GI gun, which generate the primary pulse and create the main bubble with generator and collapse the main bubble with injector. This high-frequency seismic source and high-density seismic source/receiver point distribution achieved a significant improvement in seismic imaging resolution. Because the 3D-HRS system is compact and lightweight and can be operated by small vessels, its effectiveness and necessity have been demonstrated, especially in shallow coastal waters, where conventional seismic survey using large ships and long streamer cables is difficult. For seismic data processing, pre-stack noise attenuation, de-ghosting, multiple removal, and acquisition footprint removal had essential roles in enhancing seismic imaging quality. Compared to existing 2D seismic survey technology, the 3D-HRS achieved much higher resolution and delineated highly detailed features of the seafloor and subsurface. Following the seismic processing sequence, similarity and thinned fault likelihood attribute workflows were applied to detect and visualize faults and fractures within the 3D-HRS volume. These seismic attributes revealed a network of broadly distributed faults and fractures along an active fault system in Beppu Bay.