Seismic Attribute Analysis of the Indicator for Gas Hydrate Occurrence in the Northwest Ulleung Basin, East Sea

Based on the interpretation of 3D seismic profiles, the shallow sediments consist of five seismic units. BSRs and acoustic blanking are located within the gas-hydrate stability zone as indicators for the presence of gas hydrate. Seismic-attribute analysis shows that if gas hydrates are underlain by free gas, high reflection strength and low instantaneous frequency are displayed below the BSR. Whereas, if not, reflection strength is low and instantaneous frequency is continuously high. Four models for the occurrence of the gas hydrate are suggested, considering the slope of sedimentary layers as well as the presence of gas hydrate or free gas.