DISTRIBUTION OF GAS HYDRATE IN SHENHU AREA: IDENTIFIED WITH WELL LOG AND SEISMIC MULTI-ATTRIBUTES

High quality gas hydrate samples have been successfully recovered from the Shenhu area, the northern slope of South China Sea. The spatial distribution of gas hydrate varies greatly owing to the complex fluid movement caused by lateral migration of canyons and gas chimneys. In this paper, we identified the BSR and erosional canyon surface with well logging and seismic data and the extracted multiple seismic attributes along the theoretical base of the gas hydrate stability zone (BGHSZ). It is found that the amplitude type of attributes are sensitive to gas hydrate after optimization of all extractable seismic attributes. Description of gas hydrate bodies suggests that the distribution pattern of gas hydrate changes from site to site. It is horseshoe-shaped at Site W19 and U-shaped and point-shaped at Site W18 respectively, depending upon the topography of the local structural high. Gas hydrate occurrences are inconsistent with lithology according to well log data. It is mainly distributed at the top of a large gas chimney structure. Fluid flow is an essential element for gas hydrate deposition in this area, and thermogenic gas contributes to higher gas hydrate saturation.