基于OBS和MCS数据的水合物地层速度特征  

Velocity features of gas-hydrate stratigraphy based on OBS and MCS data

作　　者：李子正 丘学林[1,2,4] 邢磊 LI Zizheng;QIU Xuelin;XING Lei(CAS Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Guangzhou 510301,China;Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences,Guangzhou 510301,China;MOE Key Laboratory of Submarine Geosciences and Prospecting Techniques,Ocean University of China,Qingdao 266100,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院南海海洋研究所,边缘海与大洋地质重点实验室,广东广州510301 [2]中国科学院南海生态环境工程创新研究院,广东广州510301 [3]中国海洋大学海底科学与探测技术教育部重点实验室,山东青岛266100 [4]中国科学院大学,地球与行星科学学院,北京100049

出　　处：《热带海洋学报》2020年第2期25-34,共10页Journal of Tropical Oceanography

基　　金：国家重点研发计划(2018YFC0309801、2017YFC0307401);国家自然科学基金(41674092、41730532)~~

摘　　要：天然气水合物是一种新型的清洁能源,南海北部神狐海域的地质条件有利于水合物的形成和储藏。传统的多道地震(MCS)数据难以得到精确的速度信息,并且只能从时间域上判断地质体纵向分布。海底地震仪(OBS)是一种常用的主动源地震仪器,可以接收到更清晰的气枪信号。相比于MCS,OBS剖面上的折射震相可以揭示较深部的地层速度信息。文章结合MCS和OBS的优势,识别水平叠加剖面上的反射层位,并得到初始模型;将OBS剖面和水平叠加剖面拼合,从而判断OBS剖面上反射震相所对应层位;拾取OBS台站上的反射和折射震相,使用Raylnvr软件正演模拟得到水合物存在区域的二维速度模型,解决了MCS中较为困难的时深转换问题。最终模型显示了水合物、游离气区域的埋深、厚度和速度,以及似海底反射(BSR)下方更深部界面的深度和速度特征。Natural gas-hydrate is a new clean energy resource.The geological conditions in Shenhu area in the northern South China Sea(SCS)are conducive to the formation and storage of gas-hydrate.It is difficult to obtain accurate velocity information from traditional multi-channel seismic(MCS)data,and we can only judge the vertical distribution of geological bodies from the time domain.Ocean bottom seismometer(OBS)is a widely used active-source seismic instrument,which can receive clearer air gun signals.Compared with MCS data,refraction seismic data of OBS profiles can reveal velocity information from deeper layers.In this paper,combining the advantages of MCS and OBS,we determine the reflection interfaces on MCS profile,and then obtain the initial model.The OBS and MCS stacking profiles are merged to determine the reflection interface in the OBS profile.The reflection and refraction phases of OBS stations were picked up,and the two-dimensional velocity model of hydrate region was obtained by forward modeling using Raylnvr,which solved the difficult time-depth conversion problem in MCS.The final model shows the depth,thickness and velocity of hydrate and free gas regions;it also shows the depth and velocity characteristics of the deeper interface below BSR.

关 键 词：天然气水合物 似海底反射 多道地震 海底地震仪 折射波 正演模拟 

分 类 号：P738.4[天文地球—海洋地质] P741.1[天文地球—海洋科学]