齐彦福^1,2,,
李貅¹,
殷长春^2,,,
戚志鹏¹,
周建美¹,
孙乃泉¹,
刘云鹤²,
张博²
1. 长安大学地质工程与测绘学院, 西安 710054
2. 吉林大学地球探测科学与技术学院, 长春 130021

基金项目: 国家自然科学基金重点项目（41530320，41830101），国家自然科学基金面上项目（41774125），陕西省自然科学基础研究计划项目（2018JQ4006），中国博士后科学基金面上项目（2018M643553），中央高校基本科研业务费专项资金（300102268104）联合资助


详细信息

作者简介: 齐彦福, 男, 1989年生, 讲师, 主要从事地球物理电磁正反演理论和方法技术研究.E-mail:jdqiyanfu@126.com

通讯作者: 殷长春, 男, 1965年生, 教授, 国家海外高端人才, 主要从事电磁勘探理论, 特别是航空和海洋电磁方面的研究.E-mail:yinchangchun@jlu.edu.cn

中图分类号: P631

收稿日期:2019-01-19
修回日期:2019-03-11
上线日期:2020-06-05

Three-dimensional adaptive finite-element method for time-domain airborne EM over an anisotropic earth

QI YanFu^1,2,,
LI Xiu¹,
YIN ChangChun^2,,,
QI ZhiPeng¹,
ZHOU JianMei¹,
SUN NaiQuan¹,
LIU YunHe²,
ZHANG Bo²
1. College of Geology Engineering and Geomatics, Chang'an University, Xi'an 710054, China
2. College of Geo-exploration Science and Technology, Jilin University, Changchun 130021, China


More Information

Corresponding author: YIN ChangChun,E-mail:yinchangchun@jlu.edu.cn

MSC: P631

--> Received Date: 19 January 2019
Revised Date: 11 March 2019
Available Online: 05 June 2020


摘要
摘要:各向异性介质模型电性结构复杂，如何进行合理的网格剖分成为获得高精度正演结果的关键，为此本文开展时间域航空电磁各向异性大地三维自适应有限元正演算法研究.通过结合非结构时间域有限元算法和自适应网格优化技术，实现各向异性介质条件下三维时间域航空电磁自适应正演.考虑到时间域航空电磁响应随时间的衰减特性，为了综合评价不同时刻的后验误差，本文将时间作为加权因子，调整各个时刻后验误差的相对权重，进而实现对浅部和深部网格的同步优化.通过与一维解析结果进行对比验证了本文算法的可靠性.数值实验结果显示电导率各向异性对自适应网格影响严重，其最大主轴电导率的数值及其分布特征直接决定了网格加密效果.此外，各向异性对时间域航空电磁三分量响应的分布形态和异常幅值也会产生严重影响，利用全域视电阻率极性图，可以很好地识别各向异性主轴方向.
关键词: 时间域航空电磁/
各向异性/
自适应有限元/
三维正演/
异常识别

Abstract:How to generate a reasonable mesh for the anisotropic medium model with complex electrical structure is the key to obtaining high-precision modeling results. In this paper, we study the adaptive finite-element (FE) method for 3D time-domain airborne EM modeling over an anisotropic earth. By combining the time-domain unstructured FE algorithm and the adaptive mesh refinement technology, we successfully realize the 3D time-domain airborne EM adaptive forward modeling for anisotropic media. To deal with the big difference of EM responses at different time channels, we bring in a temporal weighting to achieve a synchronous refinement of shallow and deep meshes. The reliability of our algorithm is verified by comparing our results with 1D semi-analytic solution. The numerical experiments show that the anisotropic conductivity has a big influence on the mesh refinement. The value of the maximum principal-axis conductivity and its distribution directly determines the mesh refinement. In addition, anisotropic conductivity can also seriously affect the distribution pattern and anomalous amplitude of the three-component EM responses. By using the polarity maps for full-domain apparent resistivity, the direction of the anisotropic principal axis can be well identified.
Key words:Time-domain airborne EM/
Anisotropy/
Adaptive finite element/
3D forward modeling/
Abnormal recognition



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