The Development of Near-source Electromagnetic Methods in China

2018 ◽  
Vol 23 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Guo-qiang Xue
Keyword(s):  
High Efficiency ◽  
Academic Research ◽  
Electromagnetic Method ◽  
Detection Accuracy ◽  
Wide Field ◽  
Transient Electromagnetic Method ◽  
Transient Electromagnetic ◽  
Detection Technology ◽  
Deep Depth ◽  
Central Loop

Near-source electromagnetic technology has been developed and applied in the exploration of petroleum, metallic ore, coal, and engineering geology due to its high efficiency, high detection accuracy, and deep depth of investigation. In this paper, research and applications of the frequency-domain electromagnetic sounding method (FDEM), wide-field electromagnetic method (WFEM), modified central-loop transient electromagnetic method (TEM), and short-offset grounded-wire TEM (SOTEM) with obvious near-source characteristics, were reviewed and analyzed. From the 1960s to 1990s, the FDEM method and equipment were extensively developed in China. These methods have played important roles in the exploration of coal resources. Based on controlled source audio-frequency magnetotelluric (CSAMT) and FDEM methods, a new method has been developed by deriving a new expression to calculate apparent resistivity. This method, which is referred to as WFEM, has been studied, applied, and received great attention in China. To increase work efficiency and reduce the influence of local transverse anisotropy on the detection processes, a modified central-loop TEM detection technology based on the central loop transient electromagnetic method was developed in China. The advantages of SOTEM in near-source surveys with high resolution and increased depth detection stimulated academic research interest to further develop grounded-wire TEM techniques. [Figure: see text]

scholarly journals Development of a full-waveform voltage and current recording device for multichannel transient electromagnetic transmitters

2017 ◽  
Vol 6 (2) ◽  
pp. 495-503 ◽  
Author(s):  
Xinyue Zhang ◽  
Qisheng Zhang ◽  
Meng Wang ◽  
Qiang Kong ◽  
Shengquan Zhang ◽  
...  
Keyword(s):  
High Efficiency ◽  
New Technologies ◽  
Computer Software ◽  
Electromagnetic Method ◽  
Recording Device ◽  
Transient Electromagnetic Method ◽  
Software Interface ◽  
Full Waveform ◽  
Transient Electromagnetic ◽  
Upper Computer

Abstract. Due to the pressing demand for metallic ore exploration technology in China, several new technologies are being employed in the relevant exploration instruments. In addition to possessing the high resolution of the traditional transient electromagnetic method, high-efficiency measurements, and a short measurement time, the multichannel transient electromagnetic method (MTEM) technology can also sensitively determine the characteristics of a low-resistivity geologic body, without being affected by the terrain. Besides, the MTEM technology also solves the critical, existing interference problem in electrical exploration technology. This study develops a full-waveform voltage and current recording device for MTEM transmitters. After continuous acquisition and storage of the large, pseudo-random current signals emitted by the MTEM transmitter, these signals are then convoluted with the signals collected by the receiver to obtain the earth's impulse response. In this paper, the overall design of the full-waveform recording apparatus, including the hardware and upper-computer software designs, the software interface display, and the results of field test, is discussed in detail.

Numerical calculation of All-Time Apparent Resistivity for Central Loop Transient Electromagnetic Method

2003 ◽  
Vol 46 (5) ◽  
pp. 998-1010 ◽  
Author(s):  
Denghai BAI ◽  
Maxwell A Meju ◽  
Jian LU ◽  
Lifeng WANG ◽  
Zhaohai HE
Keyword(s):  
Numerical Calculation ◽  
Apparent Resistivity ◽  
Electromagnetic Method ◽  
Transient Electromagnetic Method ◽  
Transient Electromagnetic ◽  
Central Loop

scholarly journals Theoretical and Experimental Investigation of Vehicle-Mounted Transient Electromagnetic Method Detection for Internal Defects of Operational Tunnels

2021 ◽  
Vol 11 (15) ◽  
pp. 6906
Author(s):  
Wangping Qian ◽  
Honghui Li ◽  
Jun Yu ◽  
Zhenyuan Gu
Keyword(s):  
Rapid Detection ◽  
High Speed ◽  
Surface Defects ◽  
Detection Method ◽  
Electromagnetic Method ◽  
Transient Electromagnetic Method ◽  
Internal Defects ◽  
Transient Electromagnetic ◽  
Detection Technology ◽  
Lining Structure

With the durable operation of high-speed railway tunnels in China, many tunnel defects successively appeared in the tunnel lining structure and gradually threatened the safe operation of the tunnels. In the limited maintenance time of high-speed railways, it is urgent to find out and maintain tunnel defects, especially internal defects. We propose an applied detection technology called the vehicle-mounted transient electromagnetic method (TEM). The detection technology aims to rapidly detect and locate the internal defects of the lining structure throughout the entire tunnel. Firstly, we investigate tunnel defects in detail and introduce the rapid detection method. Secondly, we analyze the principle and process of vehicle-mounted TEM. Thirdly, the rationality and applicability of vehicle-mounted TEM are verified by three different methods, including theoretical analysis, numerical simulation, and laboratory experiment. Finally, we compare the inversion results of experimental data under the two conditions. The results illustrate that tunnel surface defects are the external manifestations and characteristics of tunnel defects, while the forms of surface defects are directly related to internal defects. This detection method is suitable for the significant resistivity difference between tunnel defects and surrounding rocks, and its rationality is effectively validated. Furthermore, the apparent resistivity results reveal that there is a low resistivity region in front of the transmitter coil, and that the relative position can be preliminarily judged. The research results can provide a potential and significant application technology for the rapid detection of tunnel defects.

Configuration Detection of Substation Grounding Grid Using Transient Electromagnetic Method

2017 ◽  
Vol 64 (8) ◽  
pp. 6475-6483 ◽  
Author(s):  
Cigong Yu ◽  
Zhihong Fu ◽  
Gaolin Wu ◽  
Liuyuan Zhou ◽  
Xuegui Zhu ◽  
...  
Keyword(s):  
Electromagnetic Method ◽  
Transient Electromagnetic Method ◽  
Transient Electromagnetic ◽  
Grounding Grid

scholarly journals Application of Comprehensive Geophysical Prospecting Method in Water Accumulation Exploration of Multilayer Goaf in Integrated Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Lei Zhang ◽  
Lin Xu ◽  
Yong Xiao ◽  
NingBo Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Comprehensive Analysis ◽  
High Density ◽  
Electromagnetic Method ◽  
Mine Safety ◽  
Practical Significance ◽  
Time Base ◽  
Transient Electromagnetic Method ◽  
Transient Electromagnetic

A coal mine in Datong is an integrated mine. At present, there is goaf in the upper and lower part of the mining coal seam. There is a lot of ponding in the goaf, which has great potential safety hazards for production. In order to find out the scope and location of ponding in goaf, the comprehensive geophysical exploration method combining transient electromagnetic method and high-density resistivity method is used to carry out the research. Firstly, the time-base, turn-off time, receiving delay, current, superposition times, and other parameters of the instrument are tested on the surface of known goaf to obtain the best instrument parameters, and the parameters are used to verify the feasibility of the research scheme; then, the transient electromagnetic method is used for large-area exploration on the surface of the mine, the suspected goaf ponding area is found through comprehensive analysis, and the high-density resistivity exploration is arranged in the suspected goaf ponding area. According to the obtained results, the scope and location of the goaf ponding area are accurately located through comprehensive analysis. The results show that there are two goaf ponding areas in the exploration area, which are located above the 8# coal seam currently mined; the range and location of goaf ponding area can be accurately obtained by using the comprehensive geophysical method of high-density electrical method and transient electromagnetic method. This method can provide reference for mine water prevention and control in Datong area and has great practical significance to ensure coal mine safety production.

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