瞬变电磁法三维拟地震成像信息提取技术  

Information collecting technology in 3-D pseudo-seismic imaging of transient electromagnetics

作　　者：朱宏伟[1,2,3] 李貅[3] 张军[3] 戚志鹏[3] 

机构地区：[1]中国科学院成都山地灾害与环境,山地环境演变与调控重点实验室,成都610041 [2]中国科学院研究生院,北京100049 [3]长安大学地质工程与测绘学院,西安710054

出　　处：《地球物理学进展》2010年第5期1648-1656,共9页Progress in 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)资助

摘　　要：在瞬变电磁法中,为提高对地下电性界面的分辨率,可移植地震勘探中的诸多技术对界面直接成像,以克服反演中的不适定性.首先为使得波形在高低不同的电性基底所产生的虚拟反射波振幅有可比性,在将原有瞬变电磁场逆变换成虚拟波场数据的基础之上,需要求取均衡系数;接着通过对虚拟波场的离散数据求取反褶积,可基本抵消波场变换的展宽作用和大地滤波影响,以达到对电性界面精确定位的效果;然后,对波形做低通滤波处理后运用克希霍夫积分公式,将虚拟地震波场由地面向地下反向逆时偏移成像.把波场分析原理用于对瞬变电磁场的解释,就形成了瞬变电磁偏移方法.从波场角度看,它拓展和丰富了瞬变电磁场的内涵.使用本方法,可更加容易得到从前用常规解释方法处理无法提取的信息.在延拓成像中可更精确的确定界面深度,并为在瞬变电磁法中合理引入拟地震处理解释方法提供重要的理论依据和实验参照.In the field of TEM, we make the imaging underground directly by transplanting lots of technology that is usually used for seismic exploration, to improve the resolution of images electric of interfaces. The ill-posed characteristics will be overcome if doing that. Firstly, balanced coefficient must be calculated based on the suppositional waves transformed from TEM, as the amplitudes of them, which grow out of the interface, have always differences. Secondly, the broadening and earth filtering effects can be proximately countervailed, if the result of deconvolution of discrete data are figured out. Then, it is possible for us that the positions of electrical boundaries are located. At last, the final outcome, that is the extension imaging by inversing time from the surface to underground with fictitious seismic waves, will be obtained if we take above data after low pass filtering into Kirchhoff integral formula. The TEM continuation method has been generated when we put the principle of wave field analysis into the explaining of TEM. It makes the connotation of transient electromagnetics widen and abundant, from the wave field view. It’s easier to get the information that is difficult to obtain without that technique in the past. The depth of the electrical interface that we calculate becomes more accurate after the continuation imaging. At the same time, it provides significant theoretical basis and experimental reference for rational introduction of the seismic treatment method into TEM.

关 键 词：瞬变电磁法 波场变换 偏移成像 克希霍夫积分 均衡系数 反褶积 

分 类 号：P631[天文地球—地质矿产勘探]