瞬变电磁虚拟波场的三维曲面延拓成像  

Three dimensional curved surface continuation image based on TEM pseudo wave-field

作　　者：李貅[1] 戚志鹏[1] 薛国强[2] 范涛[1] 朱宏伟[1] 

机构地区：[1]长安大学地质工程与测绘学院,西安710054 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《地球物理学报》2010年第12期3005-3011,共7页Chinese Journal of Geophysics

基　　金：国家自然科学基金面上项目(40774066);国家自然科学基金重点项目(50539080);中国科学院知识创新工程重要方向项目(KZCX2-YW-Q04-07)联合资助

摘　　要：根据瞬变电磁场扩散方程与波动方程间存在的数学对应形式,将已知瞬变电磁场数据转换为虚拟波场数据,在此基础上,提出了用克希霍夫积分法将所转换的波场从地面向地下反向延拓的方法.在延拓的数值计算中,为提高计算效率,采用三维边界元技术,把边界积分分解为诸三角单元积分的积分之和,建立了曲面延拓方程式;通过地面测点的波场值,求出地下某一点的波场值,实现了地表为曲面的向下延拓成像计算.通过对理论模型计算和实际资料处理,证明了该方法可以增强瞬变电磁法识别地下电性分界面的能力,使瞬变电磁法对地下目标体的三维精细探测成为可能.Based on the relationship between the wave equation, the data of time domain field is transient electromagnetic diffusion equation and transformed into a pseudo wave-field. We then propose that the transformed wave can be extended from surface into ground by the Kirchhoff integral method. During the numerical calculation of surface extension, in order to improve the computing efficiency, three-dimensional boundary element method has been used. The equations of surface extension have been established after separating the boundary integral into lots of Triangle unit integral. The wave-field corresponding to underground point has been reached by the wave-field value of surface point. The continuation imaging at the curved surface has been realized at last. The theoretical model and the real application both show that the method can strengthen the capacity of the transient electromagnetic method to identify the underground electrical interface, and make the transient electromagnetic method in 3-D fine exploration possible.

关 键 词：瞬变电磁场 波场变换 曲面延拓 成像 

分 类 号：P631[天文地球—地质矿产勘探]