Seismic identification of gas hydrate and its distribution in Shenhu Area,South China Sea

Shenhu Area of Northern South China Sea has favorable conditions for the occurrence and formation of gas hydrate, which was discovered in drilling cores and disseminated evenly within the hydrate stable zone (HSZ). Based on 3-D seismic data of marine geophysical investigation of gas hydrate, a variety of methods on gas hydrate identification were introduced, including high-resolution seismic imaging, impedance inversion, seismic attribute cluster analysis and neural network analysis. The applicability of various techniques was discussed and comprehensive interpretation of the results indicates that seismic attribute cluster analysis is the optimal technique for gas hydrate identification, by which the 3-D distribution of free gas and gas hydrate is presented and is identical with the drilling cores. Integrating the drilling cores with geological conditions, various geophysical information was used to analyze the geological cause of formation and the distributing model of free gas and gas hydrate, from which it can be concluded that faults and fractures are the important if not dominant factor in the formation and distribution of gas hydrate in Shenhu Area.