电性源瞬变电磁发射源形变对观测结果影响分析  

Analysis on the influence from the shape of electric source TEM transmitter

作　　者：陈卫营[1] 薛国强[1] 崔江伟[2] 

机构地区：[1]中国科学院地质与地球物理研究所 [2]东华理工大学核工程与地球物理学院

出　　处：《地球物理学进展》2015年第1期126-132,共7页Progress in Geophysics

基　　金：国家重点基础研究发展计划(973计划)(2012CB416605);国家重大科研装备研制项目"深部资源探测核心装备研发"(ZDYZ2012-1)-05子项目"多通道大功率电法勘探仪"-04课题"M-TEM资料处理及偏移成像软件研制";中国科学院地质与地球物理研究所矿产资源重点实验室开放基金联合资助

摘　　要：电性源瞬变电磁法的基本理论是建立在水平电偶极子的基础之上的,但是实际生产中发射源常为接地长导线,随着短偏移距观测方式的实现,一方面发射源的尺寸不能忽略,偶极子条件不再成立,需要新的方式计算电磁场响应;另一方面,受制于场地条件,发射源可能无法水平、笔直地铺设,这种源形态上的改变必然会对接收点处的响应带来影响,并最终影响到数据解释.本文从电性源一维正演理论出发,研究了发射源发生偏移和弯曲给电磁响应和视电阻率带来的影响,并以某金矿探测为实例做出了验证和说明.研究认为源形态的改变对电磁响应和视电阻率造成的影响随着偏移距的改变而改变,对于电磁响应,偏移距越大影响越小,而对于视电阻率,偏移距越大影响越大.因此在实际生产中应尽量保证源的正规铺设,详细记录实际源的坐标位置与形状,并尽量在偏移距较小的区域内观测.The electric source transient electromagnetic method is based on the dipole theory,while in practice the source is usually a long grounded wire source which can not be regarded as a dipole.On the other hand,it is very hard to set a horizontal and straight wire source limited by the terrain in field work.This change of source will lead to distortions to the signal and data processing.In this paper,we studied the influence on the signal and apparent resistivity from an incline source and a bent source based on the ID forward theory whereafter validated by a practical field work in gold mine.Results indicate that the influence on the signal will decrease but increase on the apparent resistivity with the increase of offset.We give an explanation on this phenomenon and strongly suggest the necessary of laying a normal source and recording the precise location and shape of the source.

关 键 词：电性源 瞬变电磁法 发射源 电磁响应 视电阻率 

分 类 号：P631[天文地球—地质矿产勘探]