Research on minimum transmit-receive distance of tensor CSAMT in layered media
Chao ZHANG1,2, Da-Lei CHEN1,2, Yang WANG1,2, Hong-Jun WANG1,2
1. Shandong Geophysical and Geochemical Exploration Institute, Jinan 250013, China 2. Shandong Geological Exploration Engineering Technology Research Center, Jinan 250013, China
According to the observation mode, Controlled Source Audio-frequency Magnetotelluric Method (CSAMT) can be divided into scalar CSAMT and tensor CSAMT. Due to the difference between the construction method and the resistivity calculation method, the minimum transmission and reception distance in the division of far-field of the scalar CSAMT cannot be accurately applied to the tensor CSAMT. According to the relative errors of tensor apparent resistivity and Magnetotelluric (MT) apparent resistivity, the relative errors of the homogeneous geodetic model and the two-layer model were calculated respectively, and the minimum transmission and reception distances under different error limits was accurately given. The results show that, for the two-layer model, when the thickness of the first layer is less than 3 times the skin depth, the result of homogeneous half space cannot be directly applied, which causes a large error for the G-type model. Multilayer results can be approximately evaluated from the two-layer model with equivalent resistivity . The research results in this paper have certain theoretical guiding significance for the tensor CSAMT field construction.
Tang J T, He J S . Methods and applications of controlled source audio-frequency magnetotellurics[M]. Changsha: Central South University Press, 2005: 1-8.
Huang G Y, Zhang G H . Comparative experiments of tensor and scalar measurement with CSAMT method in known iron ore minerals[J]. Geophysical and Geochemical Exploration, 2014,38(6):1207-1211.
[8]
Hu Y C, Li T L, Fan C S , et al. Three-dimensional tensor CSAMT modeling based on the vector finite-element method[J]. Applied Geophysics, 2015,12(1):35-46,121.
[9]
Li X B, Pedersen L B, 邓前辉 . 可控源张量大地电磁法[J]. 地震地质译丛, 1993,15(3):35-42.
[9]
Li X B, Pedersen L B, Deng Q H . Controllable source tensor magnetotelluric method[J]. Seismological Translation Series, 1993,15(3):35-42.
Meng Q K, Lin P R, Li Y , et al. Preliminary study and demonstration of tensor CSAMT data processing technology[J]. Journal of Jilin University:Earth Science Edition, 2015,45(6):1846-1854.
[11]
周亚东 . CSAMT多偶极子源特征与张量测量研究[D]. 成都:成都理工大学, 2015.
[11]
Zhou Y D . Characterization and tensor measurement of CSAMT multipole sources[D]. Chengdu:Chengdu University of Technology, 2015.
Cai J T, Chen X B, Zhao G Z . Refined techniques for data processing and two-dimensional inversion in magnetotelluric I:Tensor decomposition and dimensionality analysis[J]. Chinese Journal of Geophysics, 2010,53(10):2516-2526.
Luan X D, Di Q Y, Lei D . Near-field correction of CSAMT data based on Newton iteration method and GA method[J]. Chinese Journal of Geophysics, 2018,61(10):266-277.
Tang J T, Zhou C, Xiao X . Selection of minimum transmit-receive distance of CSAMT in complicated media[J]. The Chinese Journal of Nonferrous Metals, 2013,23(6):1681-1693.
Li H, Li T L, Wu L , et al. Transformation of all-time apparent resistivity of CSAMT and analysisits effect[J]. Progress in Geophysics, 2015,30(2):889-893.
Zhang K, Xu C J, Huang S H , et al. A brief analysis of CSAMT near-field geoelectric information and utilization[J]. Coal Geology of China, 2018,30(8):62-69.
Zhou A, Zhang Y J, Su J H . Application of CSAMT near-field correction and whole area apparent resistivity calculation in prospecting[J]. World Nonferrous Metals, 2018(11):273-274,276.
Liu J F, Deng J Z, Chen H . Calculation of minimum separation between receiver and transmitter of CSAMT based on 1D model structured by AMT date[J]. Progress in Geophysics, 2016,31(6):2593-2597.
Shang T X, Guan Y X, Zhu S F , et al. The application of CSAMT with small and medium-sized transmit-receive distance to the shallow geological exploration[J]. Geophysical and Geochemical Exploration, 2015,39(2):425-431.
Zhan S Q, Qian M P, Feng J J . The CSAMT Near-field correction method for electric field apparent resistivity forward iterative fitting[J]. Geophysical and Geochemical Exploration, 2011,35(5):663-665.
Yan L J . Research and application of CSAMT Near-field correction method[A]// Geomagnetics Committee of Chinese Geophysical Society.Papers of the 8th China International Symposium on Geomagnetism[C]. 2007.
Fu C M . 2.5-D finite element simulation and near-field correction of CSAMT method[A]// China Geophysical Society.Papers of the 22nd Annual Meeting of the Chinese Geophysical Society[C]. 2006.
Liu Z X, Xue G Q, Zhang L B . Comparison and analysis on effective observation area of tensor CSAMT by numerical simulation method[J]. Chinese Journal of Geophysics, 2017,60(8):3278-3287.
