东沙岛西南泥火山区的地震烃类检测  

Seismic Detection for Hydrocarbon in Mud Volcano-Rich Area Southwest to the Dongsha Island

作　　者：王潇[1,2,3,4] 阎贫 于俊辉[1,2,3] 王彦林 Wang Xiao;Yan Pin;Yu Junhui;Wang Yanlin(Key Laboratory of Ocean and Marginal Sea Geology of Chinese Academy of Sciences,South China Sea Institute of Oceanology,Guangzhou 510301,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;Key Laboratory of Marine Geology and Environment of Chinese Academy of Sciences,Qingdao 266071,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院边缘海与大洋地质重点实验室,南海海洋研究所,广东广州510301 [2]南方海洋科学与工程广东省实验室,广东广州511458 [3]中国科学院海洋地质与环境重点实验室,山东青岛266071 [4]中国科学院大学,北京100049

出　　处：《地球科学》2021年第2期621-631,共11页Earth Science

基　　金：“科学”号高端用户项目(No.KEXUE2019G10);中国科学院海洋地质与环境重点实验室开放基金课题(Nos.MGE2018KG14,MGE2020KG01);中国科学院特别研究助理资助项目;国家自然科学基金项目(Nos.U1901217,91855101,41876052);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(No.GML2019ZD0104);广东省特支计划(No.2019BT02H594)。

摘　　要：近年来通过多道地震、浅剖及海底采样调查在东沙岛西南海域发现了大量喷溢甲烷的泥火山,通过研究泥火山可能会发现含气层,具有重大的油气资源指示意义.一条多道地震剖面显示,在该海域一泥火山MV3附近存在一个具有极性反转的埋藏背斜构造,其振幅绝对值随偏移距增大而增大.为探究该背斜是否含有烃类气体,开展了速度分析、AVO反演和频率吸收衰减分析.结果表明:该极性反转下方存在纵波低速层;该带在截距P及梯度G剖面表现为负值,在P、G交会图中落入第三象限,在横波反射率剖面中表现为正值,在泊松比变化率剖面中表现为高负值;该带高频成分快速衰减,低频成分相对增加.以上多属性特征预示着该带含气,可能与深部甲烷泄露有关.In recent years,a number of methane-venting mud volcanoes have been found in the southwest area of the Dongsha waters from multi-channel seismic,sub-bottom profiling and dredging survey.Studying mud volcanoes has great significance for oil and gas reserves.In this paper,a buried anticline was found near a mud volcano,MV3,with reversed polarity on a multichannel seismic profile,where the absolute amplitude increases with offset.To detect whether it contains natural gas,velocity analysis,AVO inversion and frequency absorption attenuation analysis were carried out.There is a low P-wave velocity layer under the reflector of reversed polarity.AVO inversion shows that the polarity reversal zone features negative values in intercept and gradient sections,and falls in the third quadrant in P and G cross-plot.The polarity reversal zone features positive in S-wave reflectivity section,and is highly negative in Poisson ratio change rate section.Frequency absorption and attenuation analysis shows rapid energy loss of high frequency and relative increase of low frequency.Multiple attributes point to gas accumulation there,likely associated with the methane seepage from deep.

关 键 词：东沙西南 泥火山 多道地震 极性反转 烃类检测 石油地质 

分 类 号：P618.13[天文地球—矿床学]