三维大地电磁响应各向异性特征研究  

Study on anisotropic properties of three-dimensional magnetotelluric response

作　　者：王磊 岳明鑫 杨晓冬 李勇[2] 吴小平[1] WANG Lei;YUE Mingxin;YANG Xiaodong;LI Yong;WU Xiaoping(School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026,China;Key Laboratory of Geophysical Electromagnetic Probing Technologies of Ministry of Natural Resources,Institute of Geophysical and Geochemical Exploration, CAGS, Langfang 065000,China;Anhui JiaoHui Technology Co.,Ltd, Hefei 230040,China)

机构地区：[1]中国科学技术大学地球和空间科学学院,合肥230026 [2]中国地质科学院地球物理地球化学勘查研究所,自然资源部地球物理电磁法探测技术重点实验,廊坊065000 [3]安徽国科骄辉科技有限公司,合肥230040

出　　处：《物探化探计算技术》2021年第3期340-351,共12页Computing Techniques For Geophysical and Geochemical Exploration

基　　金：国家重点研发项目(2018YFC0603500,2018YFE0208300);国家自然基金(U2039206,41874084);自然资源部地球物理电磁法探测技术重点实验室开放课题基金(KLGEPT201902);安徽蒙城地球物理国家野外科学观测研究站联合开放基金(MENGO-202003);中央高校基本业务基金(WK2080000129)。

摘　　要：大地电磁法是岩石圈深部结构探测的重要方法之一,现阶段大地电磁的数据处理多是基于电导率各向同性理论,当地下介质存在电导率各向异性时会对解释结果带来较大偏差。因此,发展三维大地电磁各向异性正演算法,并研究各向异性参数对于大地电磁响应的影响有重要意义。这里推导了各向异性介质中二次电磁场的变分方程,并利用三维非结构矢量有限元法进行求解,通过与COMMEMI等已有模型的计算结果对比,验证了该算法的正确性。在此基础上,进一步通过垂直板状体和球体模型,详细讨论了各向异性参数对视电阻率的影响。结果表明,与之前的认识不同,视电阻率形态的旋转现象并不能准确反映各向异性参数走向角的大小,其还与水平各向异性系数的大小有关。The magnetotelluric method is one of the important ones for detecting lithosphere.The data processing of magnetotelluric is mostly based on the theory of isotropic conductivity at present,which will cause large deviations in interpretation results for anisotropic media.Therefore,it is of great significance to develop a three-dimensional magnetotelluric anisotropy forward algorithm to estimate the effect of anisotropy on the apparent resistivity.In this paper,the variational equation of the secondary electromagnetic field in anisotropic media is derived,and it is solved by using the unstructured vector finite element method.Compared with the calculation results of several existing models such as COMMEMI,the accuracy of the algorithm is verified.On this basis,the vertical plate and spherical anomaly models are further designed,and the effect of anisotropy on the apparent resistivity is discussed in details.The results show that the rotation angle of the apparent resistivity morphology does not reflect the magnitude of the anisotropic parameter heading angle,but it is also affected by anisotropy coefficient which is different from the previous understanding.

关 键 词：电各向异性 二次场 矢量有限元 大地电磁 

分 类 号：P631.2[天文地球—地质矿产勘探]