Feasibility of signal enhancement with multiple grounded-wire sources for a frequency-domain electromagnetic survey
Feasibility of signal enhancement with multiple grounded-wire sources for a frequency-domain electromagnetic survey
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用于频域电磁测量的多个接地线源信号增强的可行性
DOI：
10.1111/1365-2478.12596
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发表时间：
2018-05-01
影响因子：
2.6
通讯作者：
Zeng, Xinsen
中科院分区：
文献类型：
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作者：
Zhou, Haigen;Yao, Yao;Zeng, Xinsen
使用接地线源的频域电磁方法是地球物理勘探中的强大工具。然而，在复杂的电磁环境下，尤其是新开发的地源机载频域电磁法，接收机位于空中时，信号可能会过弱，无法保证测量数据的质量。本文提出了一种多源信号增强方法来解决这一问题。为了评估信号增强效果，我们比较了单个源和等电矩多个源产生的信号。分析了同步误差和源元件之间的间隔距离引起的信号差异，并介绍了获得最大信号的方法。此外，我们还讨论了相邻源元件之间的相互作用以确保系统安全，包括使用双源模型输出电流的变化和两个源之间的安全距离。最后，设计并进行了综合现场实验来测试多源方法。单源和双源的数据处理结果相当，现场测试中双源的信噪比更高。试验场地下电阻率结构与以往的可控源音频大地电磁法一致。这些结果表明多源信号增强是可行的。本研究为调查环境复杂、严酷时多源在实地调查中的应用提供了指导。
Frequency-domain electromagnetic methods with a grounded-wire source are powerful tools in geophysical exploration. However, the signal may be too weak to guarantee the quality of survey data in complex electromagnetic environments, especially when the receiver is located in the air for the newly developed grounded-source airborne frequency-domain electromagnetic method. In this paper, a signal enhancement method with multiple sources is proposed to solve this problem. To evaluate the signal enhancement effect, we compared the signals generated by a single source and multiple sources with equal electric moment. The signal differences caused by synchronisation error and separation distance between source elements were analysed, and the methods to achieve maximum signal were introduced. Besides, we discussed the interaction between adjacent source elements to ensure the system safety, including the changes in output current and the safe distance between two sources using a dual-source model. Lastly, a comprehensive field experiment was designed and conducted to test the multiple-source method. The data processing results are comparable for single and dual sources, and the signal-to-noise ratio of dual source is higher in the field test. The subsurface resistivity structure at the test site is consistent with the previous controlled-source audio-frequency magnetotellurics method. These results show that signal enhancement with multiple sources is feasible. This study provides guidance to the application of multiple sources in field surveys when the survey environment is complex and rigorous.