Abstract
Multiturn coils is an effective transmitter for transient electromagnetic method (TEM) used in narrow space and complex terrain at presently. However, its high mutual inductance coupling and long turn-off time affect the quality of later data processing and interpretation. Compared with multiturn coils, the new conical source has low mutual inductance and short turn-off time. Based on the superposition principle, we use Hankel transform and numerical filtering method for forward modelling of the conical source field in the layered-media and explore TEM characteristics excited by this source. We apply improved damped least square inversion to integrated transient electromagnetic (TEM) data. We first invert the induced voltage into similar resistivity and apparent depth, and then use the inverted results as input parameters in the initial model and transform the apparent resistivity data into the frequency domain. Then, damped least square inversion is performed in the frequency domain using the initial model. Subsequently, we use automated model building to search for the extremes and inflection points in the resistivity–depth data that are treated as critical layer parameters. The inversion of theoretical and observed data suggests that the method modifies the resistivity and depth and yields a model of the underground layers.
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Acknowledgements
The authors wish to thank Xue Guo-Qiang at the Institute of Geology and Geophysics of the Chinese Academy of Sciences for his help and the chief editor, Fan Wei-Cui, and the reviewers for their comments that improved the manuscript.
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This work was supported by the National Natural Science Foundation of China (Nos. 41564001, 41674133, 41572185, and 41604104) and the Distinguished Young Talent Foundation of Jiangxi Province (No. 20171BCB23068).
Yang Hai-Yan, Professor in East China University of Technology. He received his Ph.D. (2009) in Geophysical Prospecting and Information Technology and B.S. (2004) in Applied Mathematics from China University of Mining and Technology. He is interested in the theory and application of electromagnetic fields.
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Yang, HY., Li, FP., Chen, SE. et al. An inversion of transient electromagnetic data from a conical source. Appl. Geophys. 15, 545–555 (2018). https://doi.org/10.1007/s11770-018-0691-8
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DOI: https://doi.org/10.1007/s11770-018-0691-8