Occam Inversion of Transient Electromagnetic Data in a Layered Medium with Azimuthal Anisotropy

Wangwang Wang,Honglei Liu,Handong Tan,Chang-Hong Lin

doi:10.4236/ijg.2016.77068

Abstract

In recent years, the anisotropic study has become a hot topic in the field of electromagnetics. Currently, inversion technologies of transient electromagnetic sounding data are mainly based on the case of an isotropic medium. However, the actual underground electrical structure tends to be complicated and anisotropic. It is often found that the isotropic inversion technologies do not lead to good results for field transient electromagnetic sounding data. We have developed an algorithm for calculating the transient electromagnetic response in a layered medium with azimuthal anisotropy. An occam inversion algorithm has also been implemented to invert the transient electromagnetic data induced by a grounded horizontal electric dipole in a layered medium with azimuthal anisotropy. Synthetic examples demonstrate the stability and validity of the inversion algorithm. Experimental results show different data for inverting have great influence on the inversion results.

Highlights

Electrical anisotropy in the Earth has recently gained attention as a significant linking factor between electrical models and underlying structural and tectonic patterns
The following conclusions can be drawn: a) When only inverting the horizontal electric field which is parallel to the source, we can get better inversion results than inverting any of the other single response. b) When the more synthetic data are used in the inversion, the better inversion results we can achieve
We have developed an algorithm for calculating the transient electromagnetic response in a layered medium with azimuthal anisotropy

Summary

Introduction

Electrical anisotropy in the Earth has recently gained attention as a significant linking factor between electrical models and underlying structural and tectonic patterns. This factor has motivated more and more studies into the anisotropic electrical structures. For the direct current resistivity method, Herwanger and Pain (2004) proposed. (2016) Occam Inversion of Transient Electromagnetic Data in a Layered Medium with Azimuthal Anisotropy. A rapid finite element resistivity modelling algorithm for 3D arbitrary anisotropic structures was presented [3]. Wang et al (2013) developed a 3D direct current anisotropic resistivity modelling method using a finite-element method [4]

Methods

Results

Conclusion