磁化率对大地电磁响应的影响及其提取方法  

The influence of magnetic susceptibility on MT response and its extraction method

作　　者：王珺璐[1] 王萌[2] 李荡[1] 李建华[1] 林品荣[1] 

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000 [2]中国国土资源航空物探遥感中心,北京100083

出　　处：《物探与化探》2015年第6期1292-1298,共7页Geophysical and Geochemical Exploration

基　　金：国家重大科学仪器设备开发专项(2011YQ050060);国家高技术研究发展计划(2014AA06A610);中国地质科学院地球物理地球化学勘查研究所基本科研业务费专项资金(AS2014D01;AS2013R02)

摘　　要：在电磁探测理论中,电导率和磁导率是两个重要的岩石物性参数。在磁性较强的地区进行大地电磁探测工作时,电磁场信号必然受到介质磁性的影响。将磁化率参数引入到二维大地电磁正演理论中,实现了含磁化率的大地电磁有限单元法数值模拟。建立棱柱体模型计算并分析了磁化率参数对大地电磁的电场、磁场、视电阻率及相位等参数的影响。数值模拟结果表明:高磁性介质导致电场升高,磁场降低,视电阻率增大,相位复杂变化,且随着磁性物质的增多或磁化率的增大,这种影响逐渐变大。引入电导率、磁化率光滑约束与磁化率对数约束,采用改进的特别快速模拟退火法实现了电阻率、磁化率参数一维同时反演。对K型、H型中间层高磁地电模型进行反演试算,反演结果良好。该研究为在高磁性地区开展大地电磁工作提供了基础,对实现"第二找矿空间"内的矿产勘探,具有一定的意义。In electromagnetic theory,conductivity and permeability are two important petrophysical parameters. The electromagnetic signal will inevitably be affected by the magnetic properties of the media in MT detection where magnetism is strong.The authors made the numerical simulation of the electromagnetic finite element method with magnetic susceptibility by introducing the magnetic susceptibility parameter into the two-dimensional MT forward theory.Prism model was established for calculation and analysis of the influence of the magnetic susceptibility parameters on the electric field,magnetic field,MT apparent resistivity and phase parameters.The numerical simulation results show that the high magnetic medium results in increasing the electric field,reducing the magnetic field,increasing the apparent resistivity,and complex changes of phase and,with the increase of the magnetic substance or the increase of the magnetization rate,the effect gradually becomes larger.The inversion results of geoelectric model with high magnetic middle layer are good.The results obtained by the authors provide a theoretical basis for the MT work in the high magnetic area and also have a certain significance for conducting the mineral prospecting in ＂ the second space＂.

关 键 词：磁化率 电阻率 大地电磁 有限单元法 模拟退火法 

分 类 号：P631[天文地球—地质矿产勘探]