舟山东极岛东侧海底浅层气特征

Characteristics of Sea Floor Shallow Gas in the Eastern Part of Zhoushan Dongji Island

侯志民 张异彪 蔡春麟 廖林燕 胡斌

HOU Zhimin ZHANG Yibiao CAI Chunlin LIAO Linyan HU Bin

中国石化集团上海海洋石油局第一海洋地质调查大队, 上海 201208; 上海石油天然气有限公司, 上海 200041

Shanghai Offshore Petroleum Geophysical Corporation of SINOPEC SOPB, Shanghai 201208, China; Shanghai Petroleum Corporation Limited, Shanghai 200041. China

利用声学剖面仪对舟山东极岛东侧海域进行探测,发现该区存在较为明显的浅层气特征:一是海水中存在云雾状反射;二是侧扫声纳海底影像显示海底存在有三个海底凹陷;三是声学浅地层反射剖面中存在声波反射异常现象,主要表现为反射剖面的声学幕和声学空白。静力触探(CPT)探测显示该区沉积物中有溶解甲烷。经过分析,海水中的云雾状反射是浅层气作用形成的。海底凹陷是由浅层气引起的沉积物不均匀下陷的结果。

Sea floor shallow gas detection has been conducted by using acoustic profiler in the eastern area of Zhoushan Dongji Island.It is found that there are obvious features of the shallow gas in this zone:The first,there are cloudy reflection phenomena in the sea water;the second,it is revealed by side scan sonar image that there are three offshore concaves in the sea bed;the third,there are acoustic reflection anomalies in acoustic reflection profile of shallow strata,mainly for acoustic curtains and acoustic blanket.The result of CPT shows that there is dissolved methane in this zone.It is concluded through the analysis that cloudy reflection phenomena were formed by the shallow gas.Offshore concaves were the result of the uneven subsidence of submarine sediments,which were caused by the shallow gas.

中石化石油工程有限公司科研项目"海底管道高精度综合地球物理探测技术研究"(SG14-20K)

https://doi.org/10.3969/j.issn.1008-2336.2015.03.027