An inversion of transient electromagnetic data from a conical source
Yang Hai-Yan1, Li Feng-Ping2, Chen Shen-En3, Yue Jian-Hua2, Guo Fu-Sheng1, Chen Xiao1, and Zhang Hua1
1. State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013, China.
2. School of Resource and Earth Science, State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology, Xuzhou 221006, China.
3. Department of Civil and Environmental Engineering, University of North Carolina at Charlotte, Charlotte 28223, USA.
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.
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).
Cite this article:
. An inversion of transient electromagnetic data from a conical source[J]. APPLIED GEOPHYSICS, 2018, 15(3-4): 545-555.
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2018, Vol. 15 
