浅剖资料在南海北部东沙西南海域水合物调查中的应用

南海北部东沙海域陆坡已经被证实为天然气水合物前景分布区,浅地层剖面数据以其高效率采集过程和浅表层高分辨率的特点被国内外学者应用到天然气水合物调查中并取得了很多成果。以南海北部东沙西南海域的两条浅剖测线为例,分析了该区浅表层沉积物的声学特征,并在浅剖剖面上发现了浅层含气带以及气体泄露现象,初步推测为深部的天然气水合物分解后通过断层运移到浅层中形成了浅层含气带,部分浅层气体还通过泄露点喷射到海水中从而形成了剖面中的气体泄露现象。最后,进一步通过对研究区域的沉积及气源条件、温压条件、地质及生物证据的讨论,证实该区具有天然气水合物发育的基本条件,因此,可以证实上述浅剖资料解释中关于天然气水合物的推测。

THE APPLICATION OF SUB-BOTTOM PROFILE TO GAS HYDRATE INVESTIGATION IN SOUTHWEST DONGSHA SEA AREA,NORTHERN SOUTH CHINA SEA

It has been confirmed that the continental slope of Dongsha area in the northern South China Sea(SCS)is a prospecting area for gas hydrate.Sub-bottom profiling,due to its efficiency and high resolution,is widely applied in the investigation of gas hydrate by domestic and foreign scholars.In the paper,we selected two sub-bottom profile survey lines from the southwest Dongsha area in the northern SCS to reveal acoustic characteristics of shallow sediments.Shallow gas strata were divided and gas seepage phenomena observed from the sub-bottom profiles.It is speculated that there was deep gas hydrate decomposition and migration vertically or horizontally along faults.Shallow gas escaped around the gas seepage points.According to the availability of gas source,temperature and pressure combination and geological and biological evidence from the research area,it is inferred that the research area is favorable for gas hydrate formation.