层状介质中大地电磁场信号时域阻抗分析  

Time-domain Impedance Analysis of Electromagnetic Signals In Layered Media

作　　者：吴鸿卿 严家斌[1,2] 王慧[1,2] 李大雁[3] Wu Hongqing;Yan Jiabin;Wang Hui;Li Dayan(School of Info-physics and Geomatics,Engineering Central South University,Changsha Hunan 410083,China;Key laboratory of Non-ferrous Resources and Geological Hazard Detection of Hunan Provincial,Central South University,Changsha Hunan 410083,China;Nuclear Industry Institute of Twenty-Three,Changsha Hunan 410007,China)

机构地区：[1]中南大学地球科学与信息物理学院,湖南长沙410083 [2]中南大学有色资源与地质灾害探查湖南省重点实验室,湖南长沙410083 [3]核工业二三零研究所,湖南长沙410007

出　　处：《工程地球物理学报》2020年第1期9-18,共10页Chinese Journal of Engineering Geophysics

基　　金：国家自然基金项目(编号:40874055);湖南省自然科学基金项目(编号:14JJ2012)。

摘　　要：在大地电磁测深中观测得到的电磁场信号十分微弱,具有非稳定特性,观测信号易受到噪声的干扰,使用基于稳定电磁信号稳定的频率域阻抗张量的估计方法,导致计算的电阻率准确度差。为了能保证非稳定信号阻抗的准确性和可靠性,从频率域传递函数出发并对其求解,利用傅里叶变换得到时域传递函数,经过推导得到时间域中求解阻抗的表达式。最后模拟得到了层状介质中时域大地电磁测深曲线,并与频率域大地电磁理论曲线对比分析。结果表明:时域比频域估算阻抗或电阻率更准确。The electromagnetic field signals observed in the magnetotelluric sounding are very weak and have non-stable characteristics.The observed signals are susceptible to noise interference.Using the estimation method based on the impedance tensor in frequency domain where the electromagnetic signals are stable leads to poor accuracy of the calculated resistivity.In order to satisfy the accuracy and reliability of the unsteady signal impedance,this paper starts from the frequency domain transfer function and solves it.The time domain transfer function is obtained by using the Fourier transform,and the expression of the time domain impedance is derived.Finally,the time-domain magnetotelluric sounding curves in layered media are simulated and compared with the frequency-domain magnetotelluric sounding curves.The results show that it is more accurate to estimate impedance or resistivity in time domain than in frequency domain.

关 键 词：大地电磁法 时域 信号分析 时域传递函数 

分 类 号：P631.3[天文地球—地质矿产勘探]