二维TI介质非结构网格弹性波矢量逆时偏移  

Vector elastic reverse time migration based on unstructured mesh for 2D tilted TI medium

作　　者：芦永明 张剑锋[1,2] 杨凯 胡锦银[4] 

机构地区：[1]中国科学院地质与地球物理研究所中国科学院油气资源研究重点实验室,北京100029 [2]中国科学院地球科学研究院,北京100029 [3]中国科学院大学,北京100049 [4]中国石油东方地球物理公司物探技术研究中心,河北涿州072751

出　　处：《地球物理学报》2017年第12期4776-4789,共14页Chinese Journal of Geophysics

基　　金：自然科学基金重点项目(41330316);国家科技重大专项(2017ZX05008-007)资助

摘　　要：波场延拓得到的多分量波场中既包含纵波信息也包含横波信息,能否在全波场中实现纵横波的分离对各向同性和各向异性逆时偏移都有非常重要的意义.传统的散度旋度分离只适应于各向同性介质而对各向异性介质却无效.在非规则、非结构网格的弹性波数值模拟方法的基础上,发展了一种适应于各向异性介质的波场分离方法.该方法通过求解Christoffel方程,得到相角和极化角的关系,再利用群角和相角的关系,直接得到群角和极化角的关系.该方法与现存的各向异性波场分离相比,获得的计算效率改进更显著,而且存储量小.用简单各向异性模型和SEG各向异性Hess模型进行测试,都得到了较好的效果,证明了本文方法的有效性.The extrapolated multi-component wavefields contain both compressional waves and shear waves. Whether these two wave modes can be separated from the wavefields makes differences for isotropic and anisotropic elastic reverse time migration. The separation methods based on divergence and curl operators only perform perfectly in isotropic media, whereas do not work well in anisotropic medium. On the basis of elastic wave numerical simulation scheme of irregular and unstructured grids, a wave-mode separation approach which is suitable for anisotropic media is developed. This method firstly extracts the relationship between the phase angle and polarizing angle by solving the Christoffel equation, then directly obtains the relationship between group angle and polarizing angle through hridging group angle and phase angle. Compared with the existing methods, the computational efficiency of this producer is improved with a small storage capacity. By testing the simple anisotropicmodels and SEG anisotropic Hess model, the validity of our scheme proposed in this paper is proved.

关 键 词：非规则网格 各向异性 弹性逆时偏移 波场分离 

分 类 号：P631[天文地球—地质矿产勘探]