反射地震层析成像在海洋天然气水合物储层识别中的应用  

Identification of marine gas-hydrate reservoir using seismic reflection traveltime tomography

作　　者：王明[1] 张建中[1,2] 邓杨[1] 孙运宝[2,3] 赵铁虎[2,3] 

机构地区：[1]海底科学与探测技术教育部重点实验室中国海洋大学海洋地球科学学院,青岛266100 [2]青岛海洋科学与技术国家实验室海洋矿产资源评价与探测技术功能实验室,青岛266061 [3]青岛海洋地质研究所,青岛266071

出　　处：《地球物理学进展》2017年第1期401-407,共7页Progress in Geophysics

基　　金：中国地质调查局国家海洋地质专项(GZH201100308);国家自然科学基金项目(41230318;41074077)联合资助

摘　　要：海底地层速度结构是识别海洋天然气水合物储层的直接依据,本文应用地震反射走时层析成像建立了海底地层速度模型.采用不规则网格对模型进行离散化,使速度单元与反射界面单元完全耦合;利用基于不规则单元波前扩展和走时插值的射线追踪方法,精确确定反射射线路径和反射波走时;在反演中同时使用先验约束、平滑约束、归一化和正则化技术,提高了层析反演的稳定性和结果的可靠性.对南海北部神狐海域SH2井附近的二维地震测线资料,利用多域人机交互法拾取了反射走时,用反射走时层析成像方法获得了SH2井附近含水合物目标区的速度结构.该反演结果与测井声波速度和钻探结果一致,其中的高速带对应水合物储层,表明反射走时层析成像能够有效地得到海洋天然气水合物储层的速度结构,为海洋天然气水合物储层识别提供依据.A velocity structure of submarine strata is a direct evidence for gas hydrate reservoir identification,in this paper we build the velocity model of submarine strata using seismic reflection traveltime tomography. The tomography is based on an irregularly discretized model so that the interface can couple well with the cell boundary. The ray tracing method is based on a bilinear traveltime interpolation and wavefront group marching method and it can calculate the ray path and traveltime accurately. Priori constraint,smoothing,normalization as well as regularization were introduced in the tomographic inversion for stabilization of the inversion process and reliability of the inversion results. We applied the tomography method to the 2-D seismic data near well SH2 in Shenhu area of the South China Sea. For the seismic data,we picked the reflection traveltimes using a human-computer interaction technique in different seismic gathers. Finally the velocity structure of submarine strata along the seismic profile was built. The tomography result is consistent with the drilling and logging data and the high velocity zone in the velocity profile is corresponds to the gas hydrate reservoir. Accordingly,we conclude that the reflection traveltime tomography is an effective technique to obtain the velocity structure of the marine gas hydrate reservoir and can provide direct evidence for its reservoir identification.

关 键 词：天然气水合物 反射走时 层析成像 走时拾取 正则化 归一化 

分 类 号：P631[天文地球—地质矿产勘探] P738[天文地球—地质学]