瞬变电磁法感应电压场与B场探测效果的数值计算对比分析  

A numerical study of transient electromagnetic sounding effect using the induced voltage and the B field data

作　　者：李展辉 杨淼鑫 曹学峰 LI Zhan-Hui;YANG Miao-Xin;CAO Xue-Feng(China Aero Geophysical Survey and Remote Sensing Center for Natural Resources,Beijing 100083,China;Hebei Key Laboratory of Strategic Critical Mineral Resources,Hebei GEO University,Shijiazhuang 050031,China)

机构地区：[1]中国自然资源航空物探遥感中心,北京100083 [2]河北地质大学河北省战略性关键矿产资源重点实验室,河北石家庄050031

出　　处：《物探与化探》2021年第1期114-126,共13页Geophysical and Geochemical Exploration

基　　金：国家重点研发计划重大科学仪器设备开发专项课题(2018YFF01013305)。

摘　　要：本文通过一维和三维正演程序分别生成了回线源瞬变电磁法的感应电压场和B z场数据,并从多个角度对比了二者的探测效果。通过多个模型对比分析了这两种数据在当前主流硬件的数据采集精度下的最长有效延迟时间;通过全时视电导率计算与一维反演对比分析了两种数据的纵向分辨率和横向分辨率。结果表明,在本文采用的仪器精度水平和测量方式下,只有当模型中存在电导率≥0.036 S/m的高导异常体时,B z场的有效观测延迟时间才可能比感应电压场更长;B z场相比感应电压场虽然能够提前感知到地下异常体,但是在横向和纵向分辨率以及对异常体电导率的呈现程度上均比感应电压场差。在实际野外测量时,不建议仅开展B z场测量,而是在有条件情况下,同时采集感应电压场和B z场,充分利用感应电压场和B z场各自的优势,达到最佳的探测效果。In this study,the authors compared the loop source transient electromagnetic sounding effect between the induced voltage data and B z data obtained by one-dimensional and three-dimensional forward modelling.The longest effective delay time of the two types of data under the current data acquisition accuracy of mainstream hardware was analyzed through a comparison of multiple models;the longitudinal and horizontal resolutions of the two types of data were analyzed through a comparison of apparent conductivity and one-dimensional inversion.The results show that,under the data acquisition accuracy presumed in this study,only when an abnormal body with a conductivity≥0.036 S/m exists in the model can the effective delay time of the B z data be longer than the induced voltage data.Compared with the induced voltage data,the B z data can sense the underground anomaly in advance,but are worse in longitudinal and horizontal resolutions.The recovery of resistivity by B z data is also worse than that by the induced voltage data.In the actual field measurement,it is not recommended to record only the B z field.If conditions are allowed,the induced voltage and the B z field could be collected simultaneously to obtain an optimized solution.

关 键 词：瞬变电磁 B场 感应电压 视电阻率 一维反演 分辨率 

分 类 号：P631[天文地球—地质矿产勘探]