测量磁场水平分量H y的电性源广域电磁测深法  

Wide field electromagnetic sounding using y-component magnetic field with horizontal current dipole source

作　　者：罗维斌 丁志军 高曙德 张星 LUO Wei-Bin;DING Zhi-Jun;GAO Shu-De;ZHANG Xing(Lanzhou Resources&Environment Voc-Tech College,College of Geology and Jewelry,Lanzhou 730000,China;Gansu Nonferrous Geological Survey Institute,Lanzhou 730000,China;Earthquake Administration of Gansu Province,Lanzhou 730000,China)

机构地区：[1]兰州资源环境职业技术学院地质与珠宝学院,甘肃兰州730000 [2]甘肃省有色地质调查院,甘肃兰州730000 [3]甘肃省地震局,甘肃兰州730000

出　　处：《物探与化探》2021年第1期46-56,共11页Geophysical and Geochemical Exploration

基　　金：中国地震局地震科技星火计划项目(XH18047)。

摘　　要：基于层状大地表面水平电偶极源电磁场公式系统,提出了比值法获取H y分量全区视电阻率计算公式。计算了层状地电模型多个收发距的电磁场各场分量E x、H y、H z,并用这三个场分量计算了全区视电阻率,以及E x/H y卡尼亚电阻率,并与模型的MT卡尼亚电阻率频谱曲线进行对比。发现H y全区视电阻率在赤道装置和轴向装置的广大区域对地电模型均有较好的响应,可进行单分量广域电磁测深。轴向装置H y全区视电阻率与赤道装置垂直磁场H z全区视电阻率相似,在低频段与层状模型大地电磁测深卡尼亚电阻率有相似的频率响应特征,在较小收发距条件下对大埋深基底就能有较好的响应。赤道装置和轴向装置测量的水平电场E x分量全区视电阻率在低频区均会进入“饱和”区。对于各电阻率定义方法,合适的收发距是较好地反映出地电特征深度变化的前提,多收发距测量有利于揭示深部电性特征。Based on the formula system of the electromagnetic field of the horizontal electric dipole source on the layered earth surface,this paper proposes the wide field apparent resistivity of y-component magnetic field(H y)using the modulus of impedance.The field components E x,H y,and H z of the electromagnetic field with multiple source-receiver separations on the surface of layered geoelectric model are calculated.The wide field apparent resistivity with these three field components and E x/H y cagniard resistivity are calculated,and compared with the MT Cagniard resistivity spectrum curve of the model.It is suggested that the wide field apparent resistivity of H y has a good response to the geoelectric model in the vast area of the equatorial array and the axial array of the horizontal electric dipole source,and it can be used for single component wide field electromagnetic sounding.The axial array wide field apparent resistivity of H y is similar to that of the equatorial array wide field of the vertical magnetic field of H z.In the low frequency band,the wide field apparent resistivity of H y is similar to that of the Cagniard resistivity of the magnetotelluric sounding of the layered model.Under the condition of small source-receiver separation,the axial array wide field apparent resistivity of H y can have a better response to the deep basement.The equatorial array and the axial array wide field apparent resistivity of the E x component of the horizontal electric field will wholly enter"saturated area"in the low frequency band.For each resistivity definition method,the appropriate source-receiver separation is the premise to reflect the geoelectric characteristics better,and the multi source-receiver separation measurement is more conducive to reflecting the deep electrical characteristics.

关 键 词：水平电偶极源 层状模型 水平磁场H y分量全区视电阻率 垂直磁场H z分量全区视电阻率 水平电场E x分量全区视电阻率 

分 类 号：P631[天文地球—地质矿产勘探]