Inversion of arbitrary segmented loop source TEM data over a layered earth

Hai, Li; Xue, Gang; Zhao, Pei; Zhou, Nannan; Zhong, Hua-sen

doi:10.1016/j.jappgeo.2016.03.017

Cited by 21 publications

(7 citation statements)

References 20 publications

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“…The authors of [9] use magnetic dipoles to simulate the geometry of the transmitter in an ATEM survey, yet their application is limited to the closed transmitter coil. The authors of [10] employ xand y-oriented electric dipoles to simulate the ground large loop TEM. However, studies on geometry effects for SATEM survey configurations have not been reported.…”

Section: Discussionmentioning

confidence: 99%

“…In [9], the authors proposed to record the orientation of the ATEM bird and decompose the tilted loop as a linear combination of three orthogonal magnetic dipoles. The authors of [10] modeled the actual geometry of a large ground loop using a series of electrical dipoles. Generally, it is required to record the actual size, position, and orientation of the transmitter and receiver, and model them by decomposing them into a number of elementary dipoles.…”

Section: Introductionmentioning

confidence: 99%

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Modeling and Inversion of Airborne and Semi-Airborne Transient Electromagnetic Data with Inexact Transmitter and Receiver Geometries

Chen

Yang

2022

Remote Sensing

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Airborne and semi-airborne transient electromagnetic (TEM) surveys have high efficiency but may suffer from systematic errors due to the inexact shape, position, and orientation of the transmitter and receiver, which can deviate from the nominal design because of complex terrain, platform instability, or external forces. Without considering actual survey geometry, modeling and inversion can bias the interpretation of results. We develop a universal approach to layered earth capable of modeling arbitrarily complex transmitter and receiver geometry used in airborne and semi-airborne surveys. Our algorithm decomposes an airborne loop or grounded wire source to a set of x-, y-, or z-oriented electric dipoles. An arbitrarily oriented receiver coil is simulated by projecting three-component data to the actual direction of receiving. In airborne TEM, the transmitter loop and receiver coil are often bound together on a rigid frame and tilt during the flight. Our simulations and synthetic inversion show that such a tilt may reduce responses relative to the data obtained with the nominal geometry; an inversion without considering the tilt can underestimate near-surface conductivity. In semi-airborne TEM, the transmitter wire on the surface can be crooked, and the airborne receiver coil can also tilt. Our modeling shows that the simulated data can change significantly if the actual transmitter and receiver geometry does not exactly follow the nominal survey design; if not appropriately accounted for, such an error may distort the recovered conductivity model. Finally, the benefit of our algorithm is demonstrated by an airborne TEM field data inversion of groundwater problems with the tilt angle of the transmitter–receiver frame accurately modeled. Our work provides a tool for improving the resolution of airborne and semi-airborne TEM in near-surface conductivity characterization.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modeling and Inversion of Airborne and Semi-Airborne Transient Electromagnetic Data with Inexact Transmitter and Receiver Geometries

Chen

Yang

2022

Remote Sensing

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“…Calculated according to the sampling time, the secondary signal received at a certain time node is caused by the inconsistency of various exploration depths. After comprehensive analysis of the collected secondary signal and resistivity, the geological information of each depth can be obtained, that is, separability in space [40][41][42][43].…”

Section: Transient Electromagnetic Methodmentioning

confidence: 99%

Geothermal Resource Exploration in Magmatic Rock Areas Using a Comprehensive Geophysical Method

et al. 2022

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Geothermal resources have significant development and usage potential. It is critical to conduct geological investigation of geothermal resources prior to mining, so as to deepen our knowledge and comprehension of geothermal resources. Ground water is heated by magmatic rocks and geothermal resources can be created in magmatic rock areas. However, their communication is weak, and the depth of burial is typically great. It is difficult for traditional geophysical methods, such as induced polarization method, to achieve useful exploration depths, and they have low accuracy. In this article, a comprehensive geophysical method, based on the controlled source audio-frequency magnetotelluric method (CSAMT) and transient electromagnetic method (TEM), is applied to geothermal exploration in a magmatic rock area. This method compensates for the shortcomings of a single method and achieves a good exploration effect, thereby providing a reliable geological foundation for further development and utilization of geothermal resources.

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“…Next, according to the sampling time, the secondary field signal received by a specific time node is transmitted from different exploration depths, and the secondary field signal is collected. After processing, the geological information at different depths can be obtained, which is known as separability in space [25][26][27][28][29]. The characteristics of TEM are based on these two separabilities.…”

Section: Characteristics Of the Transient Electromagnetic Methodsmentioning

confidence: 99%

Transient electromagnetic characteristics of coal seams intruded by magmatic rocks

et al. 2022

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The intrusion of magmatic rocks into coal seams affects the coal quality and leads to unforeseen hazards in safety of the coal mines’ production. This paper summarizes the mechanism of magmatic rocks intruding into coal seams, depicts the electromagnetic characteristics of the coal seams intruded by magmatic rocks, briefly describes the characteristics of transient electromagnetic method (TEM), and introduces the method of detection by TEM and the data processing steps. Then, the effectiveness of TEM in detecting the ranges of the coal seams intruded by magmatic rocks is theoretically analysed. It is observed that after the intrusion of magmatic rocks in the coal seams, the electromagnetic characteristics (secondary field potential and resistivity) will be dramatically affected, namely high secondary field potential and low resistivity. For experimental verification purposes, this study selects the test project of the Tongxin Minefield in the Datong Coalfield in Shanxi, China as an example, and the accuracy for the detection of the ranges of the coal seams intruded by magmatic rock using TEM is successfully verified.

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Inversion of arbitrary segmented loop source TEM data over a layered earth

Cited by 21 publications

References 20 publications

Modeling and Inversion of Airborne and Semi-Airborne Transient Electromagnetic Data with Inexact Transmitter and Receiver Geometries

Modeling and Inversion of Airborne and Semi-Airborne Transient Electromagnetic Data with Inexact Transmitter and Receiver Geometries

Geothermal Resource Exploration in Magmatic Rock Areas Using a Comprehensive Geophysical Method

Transient electromagnetic characteristics of coal seams intruded by magmatic rocks

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