台湾西南海域地震数据处理及天然气水合物地震属性

对台湾西南海域增生楔部位长排列多道地震数据进行地震成像、速度分析、AVO分析、AVO反演处理,获得了天然气水合物多属性地震特征.在偏移剖面上,BSR与海底近似平行,极性与海底相反,穿越沉积层.AVO分析显示,强BSR振幅部位,BSR振幅随偏移距增大而增大.精细速度分析表明强BSR振幅下方存在纵波低速层.对应于强BSR振幅部位,AVO反演的P波、G波为相对高负值区,位于P、G交会图的第三象限,该部位泊松比变化率为负值,横波反射系数接近于零.以上多属性地震特征均预示着该区域可能存在天然气水合物层,且天然气水合物层下方可能存在游离甲烷气层.

Seismic data processing and seismic attributes of gsa hydrate offshore southwestern taiwan

Various seismic attributes of gas hydrate were obtained in the acretionary prism of the southwest Taiwan Waters by seismic imaging,velocity analysis,AVO analysis and AVO inversion with the long streamer seismic data.BSR is found with reversed polarity,compared with the seabed,and to cut across the sediments reflectors in the migrated profiles.AVO analysis shows that the amplitude of the BSR increases with the offset The low p-wave interval velocity layer is present below the strong BSR according to detailed velocity analysis.The BSRs value is relative high negative and lies in the third quadrant in the crossplot of the P and G profiles within the strong BSR.The BSRs value is also negative in the P G profile and it is approximate zero in the P-G profile in the same strong BSR.All the seismic characters above suggest that the gas hydrated layer and the free gas layer below it may be in existence in the southwest Taiwan Waters.