网格层析速度反演方法在准三维西沙水合物中的应用  

The application of grid tomography method to quasi three-dimensional of Xisha hydrate

作　　者：薛花[1] 杜民[1] 文鹏飞[1] 张宝金[1] 张如伟[1] 

机构地区：[1]广州海洋地质调查局,广东广州510075

出　　处：《物探与化探》2017年第5期846-851,共6页Geophysical and Geochemical Exploration

基　　金：国家自然科学基金面上项目(41176056)

摘　　要：天然气水合物横向速度分布不均匀,且与断层、碳酸岩盐、渗流和盐底辟等构造有密切关系,由时间偏移得到的地质成像不准确,因此必须通过深度偏移得到深度域的地质成像。利用层析成像手段优化深度域的速度模型,因其精度高和可靠性大,目前被广泛应用。文中应用高精度网格层析速度反演方法来优化叠前深度偏移速度模型,阐述了剩余曲率分析(RCA)原理,详细介绍了利用高精度网格层析速度反演方法来优化深度域层速度模型的步骤和方法。对实际采集的准三维西沙水合物地震资料速度模型建立的应用效果表明,此种方法不仅运算效率高,而且从偏移剖面上可以看出:断层带内的成像精度明显提高,断裂结构更加清楚,波组特征明显变好,还能为研究断层与天然气水合物的关系提供基础资料,以及为后续优选有利钻探目标、评价天然气水合物资源潜力提供依据。Natural gas hydrate lateral velocity distribution is not uniform, and has a close relationship with the faults, carbonate rock, seepage and salt diapir structure;therefore, geological imaging obtained by the time offset is not accurate.It is hence necessary to obtain geological imaging in the depth domain by depth migration.The velocity model in the depth domain is optimized by tomography, which is widely used at present because of its high accuracy and reliability.In this paper, a high precision grid tomography method is used to opti- mize the pre-stack depth migration velocity model.The residual curvature analysis （RCA） principle is described.The steps and methods of using high precision grid tomography velocity inversion method to optimize interval velocity model in the depth domain are introduced in detail.The application effect of the actual acquisition of quasi three-dimensional Xisha hydrate seismic velocity model shows that this method has high operation efficiency, significantly improves imaging accuracy within the fault zone, shows fracture structure more clear- ly, and obviously changes wave group characteristics for the better, as can be seen in the migration profile.

关 键 词：天然气水合物 断层 叠前深度偏移 层析成像 高精度网格层析速度反演 剩余曲率分析 速度建模 准三维西沙水合物 

分 类 号：P631.4[天文地球—地质矿产勘探]