基于数值模拟的等值反磁通装置勘探效果对比  

The detection capability study of the opposing-coils transient electromagnetic method based on numerical modeling

作　　者：葛虎胜 况锅明 柳建新[2,3] 薛建强 周珂珂 刘嵘 GE Husheng;KUANG Guoming;LIU Jianxin;XUE Jianqiang;ZHOU Keke;LIU Rong(Luoyang Nonferrous Metal Mining Group,Luoyang 471400,China;School of Geosciences and Info-physics,Central South University,Changsha 410083,China;Hunan Key Laboratory of Nonferrous Resources and Geological Hazards Exploration,Changsha 410083,China)

机构地区：[1]洛阳有色矿业集团有限公司,洛阳471400 [2]中南大学地球科学与信息物理学院,长沙410083 [3]有色资源与地质灾害探查湖南省重点实验室,长沙410083

出　　处：《物探化探计算技术》2022年第5期615-624,共10页Computing Techniques For Geophysical and Geochemical Exploration

基　　金：国家自然科学基金资助项目(42130810,42004065,42074165);湖南省重点研发计划项目(2020SK2058)。

摘　　要：等值反磁通瞬变电磁法便捷高效,相较于传统的瞬变电磁法,其旁侧影响小,横向分辨率高,被广泛应用于中浅层高精度电磁探测中。从信号强度、横向分辨力与纵向分辨力等方面对其对称装置和非对称装置进行研究,有利于等值反磁通瞬变电磁法仪器的研发与野外工作装置的优选优化。这里借鉴航空电磁法足迹理论,对两种装置的地下电流分布及其对测量信号的贡献程度进行了比较,并运用截断边界矢量有限元法计算了相应的三维理论模型。数值模拟结果表明,对称装置在时间域具有更高的横、纵向分辨力,而非对称装置可以加强观测点信号幅值,在频率域具有更高的横、纵向分辨力,能够有效提高探测深度和精度。The opposing coil transient electromagnetic method(OCTEM)utilizes two small concentric and parallel current coils to cancel the mutual-induction field,which overcomes the blind region and has been widely applied for near surface prospecting.The asymmetric-coil systems have developed based on the symmetric-coil system.It is essential to evaluate the detection capability by comparing the strength of signals,lateral and vertical resolution between conventional symmetric-coil system and new developed asymmetric-coil system,which is meaningful to instrument development and fieldwork.Rather than using the smoking ring,we applied the footprint from airborne electromagnetic method to describe the EM diffusion of the two different OCTEM systems.Furthermore,we compare the response of three-dimensional models in both frequency domain and time domain for the two different OCTEM systems by applying the compact finite element method and fourier transformation.The numerical results demonstrate that the symmetric-coil system has enhanced the lateral and vertical resolution in the time domain.The asymmetric-coil system has strengthened signals,and then have a better lateral and vertical resolution in the frequency domain,which is conducive to increase the exploration depth.

关 键 词：非对称装置 足迹 截断边界矢量有限元法 横纵向分辨力 

分 类 号：P631.2[天文地球—地质矿产勘探]