多线源瞬变电磁横磁极化场探测方法及应用

Transient electromagnetic method is an important method for the reconstruction of the geo-electric structure of the earth. Traditionally, the magnetic-source and electric-source transient electromagnetic method mainly observes transverse electric polarized field, and the transverse electric polarized field is sensitive to the conductive target while insensitive to the high-resistivity target. The transverse magnetic polarized field has high resolution on high-resistivity anomaly, but it has not been effectively used. The multi grounded-wire transient electromagnetic method can detect the transverse magnetic field effectively and improve the resolution on the high-resistivity target. Therefore, we will carry out the research of multi grounded-wire transient electromagnetic method based on observation of transverse magnetic field. The response expression is derived and adaptive three-dimensional finite element modeling is researched. Then, response characteristics of several typical models, recording rules, and additional effects problems are studied. Based on regularization algorithm, the joint inversion of axial, equatorial and multi-component data is realized. Application rules and technical specification are founded. The field test is carried out in Liaodong area with rich metal deposits. The research of this project is of great significance for improving the theory of transient electromagnetic detection with transverse magnetic polarized field and realizing the fine detection of high-resistivity target using transient electromagnetic method.

瞬变电磁法是重建地下电阻率等电性结构的重要方法。传统磁性源和电性源瞬变电磁法主要观测横电极化场，横电极化场仅对良导目标敏感，对高阻目标的分辨能力有限。横磁极化场对高阻目标具有较强的分辨能力，但未得到有效利用。多线源瞬变电磁法实现对横磁极化场的有效探测，提升瞬变电磁法对高阻目标的分辨能力。为此，本项目拟开展以横磁极化场观测为主的多线源瞬变电磁探测方法的研究。通过面向目标自适应有限元三维正演模拟，分析典型地电模型的响应特性、记录规则、附加效应等问题；基于正则化算法实现多线源瞬变电磁多数据体的联合反演；建立施工方法与技术规范，并在多种金属矿富集的辽东地区进行野外测试验证和技术集成。本项目的研究对完善瞬变电磁横磁极化场探测理论，实现瞬变电磁法对高阻目标的精细探测具有重要的推动意义。

传统磁性源和电性源瞬变电磁法主要观测横电极化场，横电极化场仅对良导目标敏感，对高阻目标的分辨能力有限。横磁极化场对高阻目标具有较强的分辨能力，但未得到有效利用。开展基于横磁场的瞬变电磁探测方法的系统研究是实现瞬变电磁高精度探测的前提。.本项目提出多线源瞬变电磁法，实现瞬变电磁横磁极化场的有效探测，主要包括如下三个方面的研究内容：1）瞬变电磁横磁场正演模拟及响应特性分析；2）瞬变电磁横磁场数据反演与信息提取技术；3）瞬变电磁横磁场探测示范验证与推广应用。.取得的重要成果包括：1）开发了多线源瞬变电磁面向目标自适应有限元三维正演模拟程序，分析典型地电模型的响应特性等问题；2）研发了数据反演和多参数信息提取技术，包括基于Occam算法的多线源瞬变电磁数据反演和基于深度学习的电阻率、极化率多参数信息提取技术；3）基于示范验证，建立施工方法与技术规范；4）将多线源瞬变电磁探测方法推广应用到岩浆型铜镍硫化物矿床、伟晶岩型稀有金属矿床的实际勘探中，取得显著应用效果。.在本项目支持下，共发表SCI论文11篇，授权发明专利6项，培养博士后1名，博士生4名，硕士生2名。项目负责人入选中国科学院青年创新促进会，项目骨干李海留所任特聘副研究员。.本项目的研究弥补传统瞬变电磁法以横电场观测为主的不足，完善瞬变电磁横磁极化场探测理论，为实现金属矿产、油气资源的精细探测打下坚实理论基础；提出的多线源瞬变电磁探测方法，实现以横磁场观测为主的瞬变电磁探测，提出的数据反演方法和多参数信息提取技术进一步提高瞬变电磁法对高阻目标的分辨能力；将新方法和技术应用于花岗伟晶岩型稀有金属矿、岩浆型铜镍钴矿等关键金属矿床的勘探中，将为保障我国锂钴镍等关键金属矿产安全供给提供技术支撑。