Numerical analysis of multicomponent responses of surface-hole transient electromagnetic method

Meng, Qingxin; Hu, Xiangyun; Pan, Heping; Zhou, Feng

doi:10.1007/s11770-017-0600-6

Cited by 4 publications

(3 citation statements)

References 12 publications

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“…Numerous researchers have focused on processing and interpreting groundborehole TEM. For instance, Meng and Pan (2012) examined the forward modeling characteristics of ground-borehole TEM under the influence of the earth medium. Zhang et al (2014) studied the acquisition technology of transient electromagnetic data in the borehole and the technology from qualitative analysis to semiquantitative interpretation and proposed the rapid positioning technology of abnormal vector intersection.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of water-bearing coal goaf using ground-borehole TEM—a case study of Tongxin Coal Mine, Shanxi Provice, China

Yang,

Peng,

Shan

et al. 2024

Front. Earth Sci.

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Transient electromagnetic method (TEM) is widely used in coalfield hydrogeological exploration and goaf investigation. However, given the limitations of the method, the vertical resolution of ground TEM is somewhat low for effectively detecting water-bearing coal goaf. Compared with ground TEM, ground-borehole TEM is characterized by a relatively better ability for detecting low-resistivity target bodies. In this study, a low-resistivity thin plate model was established, and the ground-borehole TEM electromagnetic responses of different points (within and without of the plate) were numerically simulated. We considered an exploration project in Datong City (Shanxi Province, China) as a study case, to conduct the field investigation, examine the characteristics of ground-borehole TEM electromagnetic responses under different situations, and validate the numerical model as well, including (a) water-bearing coal goaf and (b) solid coal. The result showed that, (a) the longer the sampling time is, the weaker the electromagnetic response of ground-borehole TEM will be; (2) ground-borehole TEM stands out with a high vertical resolution for water-bearing coal goaf; (c) the extreme points of the Z component and the polarity changing points of the X and Y components can indicate the interface where the physical properties alternated.

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Section: Introductionmentioning

confidence: 99%

Numerical simulation of water-bearing coal goaf using ground-borehole TEM—a case study of Tongxin Coal Mine, Shanxi Provice, China

Yang,

Peng,

Shan

et al. 2024

Front. Earth Sci.

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“…The vector intersection method can only primarily indicate the approximate orientation of the target body center [9]. The 1D inversion and apparent resistivity interpretation methods are suitable for understanding the electrical distribution of background strata, which is not conducive to displaying local targets [10][11][12][13][14]. The equivalent current filaments method can roughly delineate the scope and central position of the target body [15][16][17], but at present, there needs to be equivalence in the inversion of borehole data to some extent, which is not accurate enough to reflect the information of the target bodies [18,19].…”

Section: Introductionmentioning

confidence: 99%

Joint Inversion with Borehole and Semi-Airborne TEM Data Based on Equivalent Filament Approximation

Zhi

Deng

et al. 2022

Minerals

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The borehole transient electromagnetic (TEM) method can be useful in deep mineral exploration to detect blind ore bodies beside or below the borehole, and is especially adapted to finding small-scale, deep, rich ore bodies. In this method a transmitting loop is deployed on the top surface of the Earth, while a receiving coil is moved down the borehole. As the borehole TEM method is limited by the borehole’s location and depth, so its exploration scope is limited. The surface to airborne TEM method is a semi-airborne TEM configuration that transmits on the surface and receives TEM response in air. The two systems are combined into one system in this study, sharing the transmission loop deployed on the surface. With this combined system, the TEM response in the borehole and in the air can be observed at the same time. This paper employs a joint interpretation method based on the equivalent filament, which is introduced to obtain more reliable geometric information for the target with both borehole and aerial TEM data. The eddy currents induced in a thin confined conductor can be represented by equivalent current filaments, and the distribution of filaments can reflect the position and geometry of the conductor. Therefore, geometric parameters of targets can be obtained by filament inversion, and the joint inversion can be more accurate with both borehole and aerial response. Numerical modeling results show that the joint inversion based on the equivalent filament results can reliably obtain the geometric parameters of the thin conductive plate embedded in half space.

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“…Wu et al [4] defined the global apparent resistivity of grounded source G-W TEM; in literature [5] they verified the effectiveness of G-W TEM for determining electrical interface under the condition of electrical emission source; their study in [6] further showed that the three-component transient response curve of G-W TEM has a good response to electrical interfaces and anomality. Xu et al [7] studied the vertical contact zone and its G-W TEM response characteristics when containing low resistance bodies; they also performed forward modelling of uniform half-space and vertical fault planes [8], and carried out three-dimensional forward modelling of G-W TEM, summarizing the main factors affecting G-W TEM anomalies [9]; Meng and Pan [10] calculated the G-W TEM anomaly response of low-resistance plate-shaped conductors in the case of homogeneous half-space and low-resistance coating, and studied the response characteristics and laws; Meng et al [11] believe that the response obtained by G-W TEM observation is the result of the interaction between the surrounding rock background field and the target anomaly field, and proposed that the earth medium will affect the observation results; Meng et al [12] calculated and analysed the multi-component response of the G-W TEM, obtaining the results that the response characteristics depend on the "diffusion, attenuation, distortion" process of the transient field in the formation under different conditions and the electromagnetic field state of the observed position. Miao et al [13] carried out the design and application research of mine ground-tunnel TEM detection system; Fan [14] used the borehole-transient electromagnetic method to carry out the test of goaf in advance detection; Li et al [15] studied the TEM response curves of different aquifers and inclined water-filled faults using ground-downhole TEM; Yi [16] conducted research on the G-W TEM response characteristics in lower half space of the rectangular loop source.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation and Anomalies Qualification Based on Ground-well Transient Electromagnetics Method

Zhang¹,

Liu²,

Wu³

et al. 2019

EJEE

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The ground-well transient electromagnetics (G-W TEM) method is an important way to enhance the resolution and depth of detection, for its signals, emitted on the ground and received in the well or tunnel, are close to anomalies. This paper attempts to detect deep, small anomalies accurately through the G-W TEM. Drawing on the 2D finite-difference timedomain (FDTD) method and the ground TEM method, several field potential models were created for plate-shape conductors and square conductors at different depths and locations. The model construction was conducted with a large fixed loop as the emitter, assuming that the medium obeys uniform distribution. The signals were observed under the ground-borehole or ground-tunnel modes, and subjected to forward modelling, with the aim to disclose the response characteristics of small anomalies to the vertical magnetic field intensity (Hz) curve and multi-track electromagnetic absorption (EA) curves. On this basis, the author put forward an interpretation method that accurately locate small anomalies based on the extreme point of the Hz curve and the intersections of the EA curves. The research results show that the FDTD method can solve the established field potential models of linear conductors in an effective and accurate manner, and output the curve response characteristics of small anomalies; under the ground-borehole mode, the longitudinal position of each anomaly can be identified, and different anomalies can be distinguished based on the extreme point of the Hz curve, and the amplitude of the TEM response curve decreases with the elapse of time; under the groundtunnel mode, the lateral position of each anomaly can be identified, and different anomalies can be distinguished based on the intersections of EA curves, and the EA value is negatively correlated with the distance to the anomaly. To sum up, the proposed method pinpoints small anomalies based on the extreme point of the Hz curve and the intersections of the EA curves, and improves the resolution in both vertical and horizontal directions.

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Numerical analysis of multicomponent responses of surface-hole transient electromagnetic method

Cited by 4 publications

References 12 publications

Numerical simulation of water-bearing coal goaf using ground-borehole TEM—a case study of Tongxin Coal Mine, Shanxi Provice, China

Numerical simulation of water-bearing coal goaf using ground-borehole TEM—a case study of Tongxin Coal Mine, Shanxi Provice, China

Joint Inversion with Borehole and Semi-Airborne TEM Data Based on Equivalent Filament Approximation

Numerical Simulation and Anomalies Qualification Based on Ground-well Transient Electromagnetics Method

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