任意形态场源可控源电磁法各向异性介质三维数值模拟

Three-Dimensional Controlled-Source Electromagnetic forward Modeling with Complex Source Geometries in General Anisotropic Media

介质的电各向异性特征在层理发育区表现得尤为明显,在该类区域开展资料解释时介质的各向异性特征不容忽视。为了更好理解和掌握电各向异性特征,对任意各向异性介质条件下任意形态场源三维可控场源电磁法(CSEM)问题开展研究。研究工作利用非结构化四面体进行区域离散以避免复杂异常体刻画不准确带来的数值误差,采用Delta函数和局部加密技术来完成任意形态场源加载,最终完成了三维CSEM各向异性介质算法研究和模型算例分析。单一模型的数值解对比结果表明,本研究开发的算法精度高且可靠性高。同时,分析了有限长导线源和大回线源各向异性介质地电响应,各向异性介质会导致电磁场各分量的响应产生明显差异。各向异性介质的电性主轴沿欧拉旋转角变化会导致电磁场异常的中心发生严重偏转,严重影响三维CSEM资料解释的准确性。本研究工作可为层理发育区三维可控场源电磁法各向异性介质资料解释提供参考。

The anisotropic characteristics of media often occur in areas with obvious bedding development,and the influence of anisotropy in data interpretation in this area can not be ignored.In order to understand the anisotropic characteristics,this paper focuses on the forward modeling of three-dimensional controllable source field source electromagnetic method under arbitrary anisotropic media conditions,using unstructured tetrahedron for regional dispersion can effectively avoid numerical errors caused by inaccurate characterization of complex anomalies.This method improves the accuracy of forward modeling effectively.The method of field source loading based on delta function and the technique of local grid encryption are used to load any shape of field source and reduce the loss of forward accuracy caused by the singularity of field source.Finally,the numerical simulation of the controlled source electromagnetic method of the arbitrary anisotropy model of the complex field source is realized.Firstly,the line electrical source is analyzed and designed in the corresponding geo-electric model,which verifies the accuracy and correctness of the algorithm in this paper.Then,the electromagnetic response characteristics of finite-length wire source and large-loop source in anisotropic medium are designed,and the variation characteristics of electric spindle along Euler rotation angle are discussed.The research results of this paper will play a positive role in the interpretation of 3D electromagnetic anisotropic media data with controllable field sources in the regions with well-developed bedding.