Three-Dimensional Transient Electromagnetic Modeling Based on Fictitious Wave Domain Methods

Ji, Yanju; Hu, Yanpu; Imamura, Naoto

doi:10.1007/s00024-017-1528-8

Cited by 7 publications

(3 citation statements)

References 43 publications

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“…( 17), and it was normalized by the square of the single-turn receiving coil. The solution of the forward modeling solver agrees well with that in the study by Ji et al (2017) (Figure 5B). These examples serve as strong evidence for the accuracy and reliability of our forward modeling code.…”

Section: Model Verificationsupporting

confidence: 80%

“…Second, we take the RFLTEM as an example, and a loop source with dimensions of 10 m × 10 m can be decomposed into many EDs. A 3D conductive body (50 m × 50 m × 50 m) of 20 Ωm is embedded in a twolayer Earth model in Ji et al (2017) (Figure 5A). In the numerical simulation, the origin of the coordinate system is at the surface with the z-axis downward through the center of the abnormal body.…”

Section: Model Verificationmentioning

confidence: 99%

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A general forward solver for 3D CSEMs with multitype sources and operating environments

Wang

et al. 2023

Front. Earth Sci.

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To determine the electromagnetic (EM) fields of different three-dimensional (3D) controlled-source electromagnetic methods (CSEMs) using the same parameters of the forward solution, by explicitly considering the commonalities, we present a general 3D forward modeling solver for CSEMs with multitype sources and operating environments. The commonality of the solver is reflected in two aspects. First, the solver is based on a frequency-domain (FD) vector Helmholtz equation for determining the scattered electric field. The different types of sources are imposed on the right-hand term of the equation, expressed as background Green’s function. Second, sources of any CSEM can be composed of electric dipole (ED) or magnetic dipole (MD) superposition. Thus, the focus of the 3D forward modeling of CSEMs is reduced to determining the EM fields of ED or MD sources for the background medium. The quasi-minimal residual (QMR) method is used to solve the large sparse complex linear system. Once the FD EM fields have been calculated, the time-domain (TD) response can be obtained using the cosine/sine transformation. The numerical results show that the relative error is less than 5% between the 3D numerical and analytical solutions, which verifies the accuracy of the solver. We further study the difference between the real (bent) and theoretical (straight) wires. We suggest that the shape of the source must be considered for TD and FD CSEMs with a wire source during data processing and inversion. The last example investigated the characteristics of FD EM fields from a finite-length wire and TD EM fields from a rectangular fixed loop on the same conductive tilted disk model buried in resistive sediments. According to the numerical results, we recommend FD CSEMs with a wire source for detecting deep anomalies.

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Section: Model Verificationsupporting

confidence: 80%

Section: Model Verificationmentioning

confidence: 99%

A general forward solver for 3D CSEMs with multitype sources and operating environments

Wang

et al. 2023

Front. Earth Sci.

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“…Mittet (2018) used the least squares fitting method to calculate the IP response of sea water in the fictitious wave field [24]. Ji (2017) improved the emission source, applied the wave field transformation method to the ground transient electromagnetic simulation, and realized a three-dimensional transient electromagnetic numerical simulation including the air layer [25]. However, it did not consider the IP effect of the earth.…”

Section: Introductionmentioning

confidence: 99%

3D Numerical Modeling of Induced-Polarization Grounded Electrical-Source Airborne Transient Electromagnetic Response Based on the Fictitious Wave Field Methods

Meng

Huang

et al. 2020

Applied Sciences

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The grounded electrical-source airborne transient electromagnetic (GREATEM) system is widely used in mineral exploration. Meanwhile, the induced polarization (IP) effect, which indicates the polarizability of the earth, is often found. In this paper, the Maxwell equations in the frequency domain are transformed into fictitious wave domain, where Maxwell equations are solved by the time domain finite difference method. Then, an integral transformation method is used to convert the calculation results back to the time domain. A three-dimensional (3D) numerical simulation in a polarizable medium is presented. The accuracy of this method is proven by comparing it with the analytical solution and the existing method, and the calculation efficiency is increased five-fold. The simulation results show that the GREATEM system has a higher response amplitude in the conductive region, while IP effects cannot be identified in the conductive area. The GREATEM system has a higher response amplitude in the low-resistance region, but IP effects cannot be identified in the low-resistance area, and the detection of IP effects is more suitable for the high-resistance area. Therefore, it is necessary to improve the detection ability of the GREATEM system in the low-resistance area.

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Grounded electrical source ground–airborne transient electromagnetic modelling with fictitious wave field methods

Meng

Qiu

2020

J Earth Syst Sci

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Three-Dimensional Transient Electromagnetic Modeling Based on Fictitious Wave Domain Methods

Cited by 7 publications

References 43 publications

A general forward solver for 3D CSEMs with multitype sources and operating environments

A general forward solver for 3D CSEMs with multitype sources and operating environments

3D Numerical Modeling of Induced-Polarization Grounded Electrical-Source Airborne Transient Electromagnetic Response Based on the Fictitious Wave Field Methods

Grounded electrical source ground–airborne transient electromagnetic modelling with fictitious wave field methods

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