2.5维各向异性介质直流电法异常场的正演模拟  

Forward modeling of anomalous field in 2.5D anisotropic medium by DC resistivity method

作　　者：柯颂颂 宋滔 刘云 KE Songsong;SONG Tao;LIU Yun(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry Chinese Academy of Sciences,Guiyang 550002,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵阳550002 [2]中国科学院大学,北京100049

出　　处：《物探化探计算技术》2019年第6期745-754,共10页Computing Techniques For Geophysical and Geochemical Exploration

基　　金：国家重点研发专项(2016YFC0600505)

摘　　要：为了提高二维直流电阻率法的数值模拟精度,这里实现了2.5维各向异性介质点源直流电场异常场的数值模拟。首先推导出2.5维各向异性介质总场和异常场满足的变分问题;然后采用矩形内三角网格的方式进行单元剖分,三角单元内二次场值和异常电阻率均设计为线性变化。为了简化背景场的计算,将背景介质的电性主轴与观测坐标系的夹角设计为零,从而避免了直接计算任意各向异性介质电位的傅里叶变换步骤。同时对计算中点源波数的选择和适用情况进行了讨论。最后通过对简单层状模型的计算,与解析解进行对比,验证了本数值算法的正确性和可靠性。比较常规各向同性介质模拟方式,本数值模拟发现直流电阻率法对横向电阻率的变化更为明显。In order to improve the numerical simulation accuracy of the two-dimensional DC resistivity method, the simulation of electric field anomaly field for 2.5-dimensional anisotropic point source DC is carried out in this paper. First, the variational problem of the total field and abnormal field of 2.5 dimensional anisotropic medium is derived. Then, the element is divided by a rectangular triangular mesh, and the two field values and the abnormal resistivity are designed as linear changes in the triangular element. In order to simplify the calculation of the background field, the angle between the electrical principal axis of the background medium and the observed coordinate system is designed to be zero, thus avoiding the Fourier transform directly calculating the potential of arbitrary anisotropic medium. At the same time, the selection and application of the point source wavenumbers in the calculation are discussed. Finally, the validity and reliability of the numerical algorithm are verified by comparing with the analytical solution of the simple layered model. Comparing with the conventional isotropic medium simulation method, it is found that the change of lateral resistivity by DC resistivity method is more obvious.

关 键 词：2.5维各向异性 直流电法 异常场 有限单元法 正演模拟 

分 类 号：P631.3[天文地球—地质矿产勘探]