Multi-turn small-loop transient electromagnetic data processing using constraints from borehole and electrical resistivity tomography data

The traditional large-loop transient electromagnetic method (TEM) is strongly affected by the large terrain undulations and limited working space in mountainous areas. A multi-turn small-loop TEM is thus more convenient and flexible in these environments because of the small size of the working loop...

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Bibliographic Details
Published in:Arabian journal of geosciences 2022-11, Vol.15 (22), Article 1675
Main Authors: Zhou, Yang, Jianwei, Pan, Hao, Liu, Zhongmei, Wang, Jiang, Zhou, Haixin, Luo, Jiaxu, Liu
Format: Article
Language:English
Subjects:
Boreholes
Configurations
Conversion
Data analysis
Data processing
Depth
Earth and Environmental Science
Earth science
Earth Sciences
Electrical resistivity
Inductance
Inversion
Karst
Mountainous areas
Original Paper
Three dimensional models
Tomography
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Summary:The traditional large-loop transient electromagnetic method (TEM) is strongly affected by the large terrain undulations and limited working space in mountainous areas. A multi-turn small-loop TEM is thus more convenient and flexible in these environments because of the small size of the working loop. However, notable mutual inductance occurs between the transmitting and receiving loops in the multi-turn small-loop configuration, which leads to low inversion resistivity values and an inaccurate time–depth conversion, which therefore results in inconsistencies between the inversion result and actual situation. In this paper, a method based on joint geophysical prospecting is used to constrain the multi-turn small-loop TEM data processing procedure and overcome the shortcomings of this configuration. A karst detection experiment was conducted in Zhijin County, Guizhou Province, China. Borehole data with intuitive and accurate strata information were used to determine the depth coefficient and adjust the karst burial depth. Electrical resistivity tomography (ERT), which could provide more accurate resistivity values than TEM when it has sufficient geological information to constrain the inversion process, was thus used to reduce the TEM errors and obtain a more accurate time–depth conversion and resistivity. A three-dimensional model of the karst channel was established according to the corrected resistivity and burial depth parameters, and the model reliability was verified by a separate borehole.
ISSN:1866-7511
1866-7538
DOI:10.1007/s12517-022-10952-3