| 短偏移距电磁探测技术概述 |
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| 引用本文： | 何继善,薛国强.短偏移距电磁探测技术概述[J].地球物理学报,2018,61(1):1-8. |
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| 作者姓名： | 何继善 薛国强 |
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| 作者单位： | 1. 中南大学地球科学与信息物理学院, 长沙 410083;2. 中国科学院矿产资源研究重点实验室, 中国科学院地质与地球物理研究所, 北京 100029;3. 中国科学院大学, 北京 100049 |
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| 基金项目： | 国家重点研发计划（2017YFC0601204，2016YFC0600101）和国家自然科学基金（41474095，41704076）联合资助. |
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| 摘 要： | 由于人工源电磁探测效果与收发距离有一定关系，本文首先分析了收发距离为零的中心回线源瞬变电磁法（Transient Electromagnetic Method，TEM）视电阻率定义和算法特点，回溯了从圆形回线到矩形的修正式中心回线装置的发展过程；概述了从中心回线发展到接地导线源短偏移瞬变电磁（Short-Offset TEM，SOTEM）理论上的可行性；列举了将LOTEM（Long-Offset TEM）从数倍于探测深度的观测区推进到近源区后的探测实例.对于频率域人工源电磁法，介绍了起源于MT（Magneto-Telluric）的CSAMT（Controlled Source Audio-frequency Magneto-Telluric）与电磁频率测深法不同发展道路.电磁频率测深将观测区从远区推进到了中区；广域电磁法通过全区视电阻率新定义不仅提高了解释精度，而且将传统CSAMT远场观测模式推进到中区探测模式；最后指出，如能采用新的点微元假设计算方法，可有望分离自有场和辐射场，实现频域电磁近源探测.
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| 关 键 词： | 近源电磁探测 中心回线TEM 短偏移SOTEM 电磁频率测深 广域电磁法 |
| 收稿时间： | 2017-01-05 |
Review of the key techniques on short-offset electromagnetic detection |
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| HE JiShan,XUE GuoQiang.Review of the key techniques on short-offset electromagnetic detection[J].Chinese Journal of Geophysics,2018,61(1):1-8. |
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| Authors: | HE JiShan XUE GuoQiang |
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| Institution: | 1. School of Geosciences and Info-Physics of Central South University, Changsha 410083, China;2. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;3. University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | Because the detecting effect of artificial-source electromagnetic methods is related to transceiver distance, taking the analysis expression and apparent resistivity algorithm as starting point, this paper reviews the development process from central-loop to modified central-loop TEM (Transient Electromagnetic Method), and summaries the principle of near-source prospecting from central-loop to grounded-wire source TEM. And the case history of SOTEM (Short-Offset TEM), which expands observation area of LOTEM (Long-Offset TEM) from several times of detection depth to near-source zone, is enumerated. For frequency-domain artificial-source electromagnetic methods, we present CSAMT (Controlled Source Audio-frequency Magnetotelluric) developed from MT (Magnetotelluric) and show the different way of frequency-domain electromagnetic sounding. Frequency sounding method enlarges the observation area from far-to middle-zone while the wide-field electromagnetic method improves interpretation accuracy and realize middle-zone data collection through whole zone apparent resistivity. If self-field and radiation field could be separated from each other based on the point-charge infinitesimal, frequency-domain near-source prospecting would be possible in the future. |
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| Keywords: | Near-source electromagnetic prospecting Central-loop TEM Short-Offset TEM Frequency-domain sounding Wide field electromagnetic method |
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