Study Of Numerical Simulation And Characteristics Of Response Of Electromagnetic Field In Layered General Anisotropic Media

Recently, the study of anisotropic media has become the focus of geophysical applications. The properties of anisotropy can be utilized to geophysics and military such as ground-penetrating radar and marine controlled source electromagnetic method and Logging etc. For the ground penetrating radar, which is towards the high frequency applications, and marine controlled source electromagnetic method or Logging, which are applications that use low and middle frequencies. This paper presents a method for calculating the electromagnetic field from a dipole source in stratified media with general anisotropy. And some useful theoretical and applicable achievement has been obtained. Concrete contents are following.In Chapter 1, it mainly summarizes the significance and current development status of anisotropy. And chief research contents and methods are also summed up in the paper.In Chapter 2, Maxwell's equations in the time domain were transformed into the frequency-wavenumber domain by using Fourier transformation. Thus, the resulting set of ordinary differential equations consists of a field vector, a system matrix, and a source vector. The source in the general anisotropic media was considered as infinitesimal electric dipole or magnetic dipole. In each piecewise homogeneous region, the system matrix is given by the material properties and the horizontal slownesses. The vertical slownesses are the eigenvalues of the system matrix. A diagonalization of the system matrix transforms the field vector into a model-field that contains upgoing and downgoing field constituents. Furthermore, the expressions for the reflection and transmission coefficients at arbitrary interface or a stack of layers can be derived by using the recursive relations.In Chapter 3, in order to obtain the expression of the mode-field, propagation matrix method was introduced. But, the propagation matrix method is dependent on the ability to calculate eigenvalues and eigenvectors of the system matrix for all layers. So, it's very important to calculate eigenvalues and eigenvector. In this chapter, a method for calculate eigenvalues and eigenvectors has been presented. In simple cases with isotropy or transversal isotropy in the direction of medium variation, the eigenvalue problem can be solved explicitly. The expression of mode-field corresponding to four type sources can be derived latterly.In chapter 4, according to the expression of mode-field, the expression of electromagnetic field in general anisotropic media can be derived. Then, the conclusion was extended in layered general anisotropic media. Finally, we use inverse Fourier transform to obtain expression of electromagnetic field in layered general anisotropic media. We implement the 2-D Fourier transform using adaptive Gauss-Legendre quadrature. By changing the conductivity value, we can obtain the response curve of electromagnetic field. Analyzing and comparing the influence to electromagnetic field by variation of conductivity, and obtain the corresponding conclusion. And the conclusion is useful to theoretical research and practical work.