(1)origin of hydrocarbons and depth of hydrocarbon generation (2)migration conduits of hydrocarbon-bearing fluids (3)phase of hydrocarbons (hydrate or gas) (4)kinds of chemical and biological reactions in sediment (5)geothermal structure
MH21 Research Consortium conducted high-resolution 3D seismic survey to explore methane hydrate reservoir in the eastern Nankai Trough. As the high-resolution 3D seismic survey was designed for shallow formation where methane hydrate exists, we could obtain excellent information about some of above-mentioned terms.The high-resolution 3D seismic data provided us information about migration conduits of hydrocarbon-bearing fluids, and also phase of hydrocarbons. Bathymetric chart and seafloor reflection intensity map constructed by reflected waves from seafloor provided us detailed information about relationships between methane hydrate reservoir and seafloor manifestations. Because occurrences of methane hydrate is strongly restricted by temperature, pressure and other physicochemical environments, BSR (Bottom Simulating Reflector) which is considered as the base of the hydrate stability zone, is represented as not geological event but physicochemical event on seismic sections. We estimated geothermal structure near BSR by anomaly map showing difference of predicted BSR depth by laboratory data and observed BSR depth by high-resolution 3D seismic data.
MH21 Research Consortium will continue to conduct seafloor geochemical survey based on the geological and geochemical model constructed using 3D seismic data in the future. In this presentation, we introduce -Fusion on 3D seismic exploration and seafloor geochemical survey- applying to exploration of methane hydrate reservoir in Japan.