Status and future perspectives of airborne magnetic gradiometry

Stolz, R.; Schiffler, Markus; Zakosarenko, V.; Larnier, H.; Rudd, Jonathan; Chubak, Glenn; Polome, L.; Pitts, Brad; Schneider, Michael; Schulz, M.; Meyer, Matthias; Campbell, Kit

doi:10.1190/segam2021-w6-05.1

Cited by 4 publications

(3 citation statements)

References 40 publications

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“…As we will show, all components of the magnetic field can be computed as the spatial derivatives of Equation (2). For example, the magnetic field, H(r), is the first derivative of the magnetic potential: H(r) = ∇U(r).…”

Section: Modeling Of Ftmg Data For the Models Without Remanent Magnet...mentioning

confidence: 99%

“…As for the case without the remanent magnetization considered above, this implies that of the nine tensor components, only five are independent. 2 and after some algebra, we find discrete forms for each component of the magnetic tensor:…”

Section: Modeling Of Ftmg Data For the Models With Remanent Magnetiza...mentioning

confidence: 99%

“…Despite this, direct measurements of magnetic tensors have advantages, as they contain directional sensitivity, which is important for determining rock magnetization vector and studying remanent magnetization. Recently, full tensor magnetic gradiometers based on superconducting quantum interference devices (SQUIDs) have been developed and are now commercially used for geophysical surveying (e.g., [1][2][3][4]). The quantum magnetic tensor (QMAGT) system, developed by Dias Airborne of Saskatoon, Saskatchewan, Canada in collaboration with Supracon AG of Jena, Thuringia, Germany, is a helicopter-borne magnetic survey system that measures the FTMG data using the SQUID, operating within a liquid helium bath (https://www.diasgeo.com/technology-innovation/full-tensor-magneticgradiometry-ftmg/, accessed on 21 June 2023).…”

Section: Introductionmentioning

confidence: 99%

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3D Focusing Inversion of Full Tensor Magnetic Gradiometry Data with Gramian Regularization

2023

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Full tensor magnetic gradiometry (FTMG) is becoming a practical method for exploration due to recent advancements in superconducting quantum interference device (SQUID) technology. This paper introduces an efficient method of 3D modeling and inversion of FTMG data. The forward modeling uses single-point Gaussian integration with pulse basis functions to compute the volume integrals representing the second spatial derivatives of the magnetic potential. The inversion is aimed at recovering both the magnetic susceptibility and magnetization vectors. We have introduced a 3D regularized focusing inversion technique that utilizes Gramian regularization and a moving sensitivity domain approach. We have also developed a new method of magnetization vector decomposition into induced and remanent parts. The case study includes applying the developed inversion method and computer code to interpret a helicopter-borne FTMG survey carried out over the Thompson Nickel Belt. We have analyzed and separately inverted the observed FTMG and total magnetic intensity (TMI) data using the developed 3D inversion methods to obtain the subsurface susceptibility and magnetization vector models. Furthermore, we present a comparison of the inversions utilizing the FTMG data and the TMI data.

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Section: Modeling Of Ftmg Data For the Models Without Remanent Magnet...mentioning

confidence: 99%

Section: Modeling Of Ftmg Data For the Models With Remanent Magnetiza...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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3D Focusing Inversion of Full Tensor Magnetic Gradiometry Data with Gramian Regularization

2023

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SQUIDs for magnetic and electromagnetic methods in mineral exploration

et al. 2022

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Research on quantum sensors for the detection of magnetic fields (quantum magnetometers) is one of the fast-moving areas of Quantum Technologies. Since there exist expectations about their use in geophysics, this work will provide a brief overview on the various developing quantum technologies and their individual state of the art for implementing quantum magnetometers. As one example, the developments on superconducting quantum interference devices, so-called SQUIDs as a specific implementation of a quantum magnetometer, are presented. In the course of this, SQUID instrument implementations and associated demonstrations and case studies will be presented. An airborne vector magnetometer with ultra-low noise ($$<10 \mathrm{fT}/\sqrt{\mathrm{Hz}}$$ < 10 fT / Hz ) and high dynamic range of $$>32 \mathrm{bit}$$ > 32 bit will be introduced which has the prospect to be applied for the magnetic method in parallel with electromagnetic methods such as passive audio-frequency magnetics or semi-airborne methods using active transmitters such as elongated grounded dipole sources. The according signals are separated in the frequency domain. A second implementation is an airborne full tensor gradiometer instrument will be discussed which has shown already a number of successful case studies and which turned into commercial operation in the past years. Besides the airborne instrument, a very successful implementation of quantum magnetometers is the SQUID-based receiver for the ground-based transient electromagnetic method. Today it is a mature technology which has been in commercial use for more than a decade and has led to a number of discoveries of conductive ore bodies. One case study will be presented which demonstrates the performance of this instrument. Finally, future prospects of using quantum magnetometers, including SQUIDs and new optically pumped magnetometers, in geophysical exploration will be discussed. Particular applications for both sensor types will be introduced.

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