南海西沙海域天然气水合物识别与分布预测  

Distinguishing and Forecasting the Distribution of Gas Hydrates in the Sediments of Xisha Area,South China Sea

作　　者：杨志力 王彬 李丽 李东 张强[1] 吴敬武 孙国忠 YANG Zhili;WANG Bin;LI Li;LI Dong;ZHANG Qiang;WU Jingwu;SUN Guozhong(Petrochina Hangzhou Research Institute of Geology, Hangzhou 310023, China)

机构地区：[1]中国石油杭州地质研究院

出　　处：《重庆科技学院学报（自然科学版）》2019年第4期33-38,共6页Journal of Chongqing University of Science and Technology：Natural Sciences Edition

基　　金：国家科技重大专项“南海中建海域深水油气地质条件及目标评价”(2017ZX05026-006)

摘　　要：西沙海域在烃源岩、运移通道、盖层条件、保存条件等方面都具备发育天然气水合物的条件,西沙海域海底发育可能由水合物分解而形成的麻坑。根据海底地貌特征圈定天然气水合物的潜在发育区,并根据西沙海域天然气水合物的似海底反射(BSR)、与BSR伴生的空白反射带、高纵波阻抗等地球物理特征对这些潜在发育区的天然气水合物进行识别,预测西沙海域天然气水合物的发育区。在西沙海域天然气水合物发育区的地震剖面上,具有在BSR之下的低阻抗、含水合物地层,在叠前地震道集上具有3类AVO响应等地球物理特征。这表明在天然气水合物稳定底界之下存在游离气,在西沙海域有广泛分布的天然气水合物,资源潜力较大。The Xisha area has the conditions for gas hydrate developed in terms of source rocks, migration channels, caprock conditions and preservation conditions, and pots that may be formed by hydrate decomposition during seabed development in Xisha sea area. The potential area of gas hydrate developed is delineated according to the geomorphological characteristics of pockmark. And in the potential area, the gas hydrate developed area in Xisha area is predicted by the geophysical characteristics of gas hydrate such as bottom simulating reflectors (BSR), blank zone associated with BSR and high p-impedance. The seismic profiles also have other geophysical characteristics, such as low p-impedance under BSR and type III AVO response on pre-stack seismic gathers, which indicate that free gas exists under the stable bottom of gas hydrate. Gas hydrate is widely distributed in Xisha area, which has great resource potential.

关 键 词：西沙海域 似海底反射 天然气水合物 AVO 地震反射特征 

分 类 号：P631[天文地球—地质矿产勘探]