Interpretation of Down-hole Transient EM Data Using Current Filaments

Duncan, Andrew

doi:10.1071/eg987036

Cited by 9 publications

(6 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As the receiving probe is close to the targets, more reliable information on the deep ore bodies can be obtained than on the surface [4,5]. The receiving probe has the opportunity to detect the deep targets at close range and can gain useful geological information in the deep exploration [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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

Zhi

Deng

et al. 2022

Minerals

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 99%

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

Zhi

Deng

et al. 2022

Minerals

View full text Add to dashboard Cite

show abstract

“…Focusing on thin‐sheet modelling, the simplest and most common approach is to consider a thin sheet in free space (Duncan ; Macnae et al . ).…”

Section: Introductionmentioning

confidence: 99%

“…Focusing on thin-sheet modelling, the simplest and most common approach is to consider a thin sheet in free space (Duncan 1987;Macnae et al 1998). In mineral exploration, this is often a reasonable approximation, since the host rock is usually several orders of magnitude more resistive than the mineral deposit.…”

mentioning

confidence: 99%

A parallel computing thin‐sheet inversion algorithm for airborne time‐domain data utilising a variable overburden

Boesen

Auken

Christiansen

et al. 2018

Geophysical Prospecting

View full text Add to dashboard Cite

Accurate modelling of the conductivity structure of mineralisations can often be difficult. In order to remedy this, a parametric approach is often used. We have developed a parametric thin‐sheet code, with a variable overburden. The code is capable of performing inversions of time‐domain airborne electromagnetic data, and it has been tested successfully on both synthetic data and field data. The code implements an integral solution containing one or more conductive sheets, buried in a half‐space with a laterally varying conductive overburden. This implementation increases the area of applicability compared to, for example, codes operating in free space, but it comes with a significant increase in computational cost. To minimise the cost, the code is parallelised using OpenMP and heavily optimised, which means that inversions of field data can be performed in hours on multiprocessor desktop computers. The code models the full system transfer function of the electromagnetic system, including variable flight height. The code is demonstrated with a synthetic example imitating a mineralisation buried underneath a conductive meadow. As a field example, the Valen mineral deposit, which is a graphite mineral deposit located in a variable overburden, is successfully inverted. Our results match well with previous models of the deposit; however, our predicted sheet remains inconclusive. These examples collectively demonstrate the effectiveness of our thin‐sheet code.

show abstract

“…The method has its genesis in the concept of the current filament used as an approximation to the EM response of a thin plate (Barnett, 1984;Duncan, 1987). The reasons for developing this model are twofold; firstly the current filament method is computationally exceeding fast when compared with analytic methods for spheroids, or 3D numerical modeling methods, and secondly the method allows for inversion for empirical magnetic flux-gathering and polarization parameters which are a function of target shape and may have a useful role in developing discrimination criteria for intact munitions versus scrap metal.…”

Section: Introductionmentioning

confidence: 99%

Fast approximate EM induction modeling of metallic and UXO targets using a permeable prism

Asten

Duncan²

2007

Journal of Applied Geophysics

View full text Add to dashboard Cite

Interpretation of Down-hole Transient EM Data Using Current Filaments

Cited by 9 publications

References 1 publication

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

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

A parallel computing thin‐sheet inversion algorithm for airborne time‐domain data utilising a variable overburden

Fast approximate EM induction modeling of metallic and UXO targets using a permeable prism

Contact Info

Product

Resources

About