Abstract
Controlled-source audio magnetotellurics, which is a common technology in geophysical surveys, typically uses the multichannel mode of data acquisition. Often, a capacitive coupling effect occurs among the multiple receiving wires and receiving electrodes and the earth. This effect causes the distortion of the observed apparent resistivity and phase curves. The capacitive coupling of the observation mode is simulated using an equivalent circuit model, and the characteristics of the influence of the length of the receiving wire and grounding resistance of the electrode on capacitive coupling are investigated via the forward simulation of several typical models. The capacitive decoupling of a device for controlled-source audio geomagnetic observation is studied and applied to process the measured data from the Hongtoushan mining area in Liaoning Province, China. This approach effectively weakens the capacitance coupling effect and improves observation quality, and the inversion results match well with known geological information. This study examines the capacitive decoupling technique and offers a scientific foundation for the standardization of the controlled-source audio geomagnetic data gathering technology.
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Acknowledgments
This work was supported by the National Major Project of China (2017ZX05008-007), the National Natural Science Foundation of China (42374170), and the National Key Research Development Program of China (2016YFC0601102 and 2016YFC0601104).
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Lei Da received his B.Sc. in survey geophysics from the China University of Geosciences (Wuhan) in 1989 and his Ph.D. in earth exploration and information technology from the China University of Geosciences (CUG) in 2005. He works as a researcher at the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS). He is presently primarily involved in research on the forward and inverse approaches of the electromagnetic method, as well as the development of electromagnetic method equipment.
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Lei, D., Zhen, Qh., Wang, R. et al. Capacitively coupled effect and capacitive decoupling of multichannel controlled-source audio magnetotellurics observations. Appl. Geophys. 20, 146–156 (2023). https://doi.org/10.1007/s11770-023-1037-8
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DOI: https://doi.org/10.1007/s11770-023-1037-8