The AeroTEM airborne electromagnetic system

Balch, S.J.; Boyko, W.P.; Paterson, Norman R.

doi:10.1190/1.1587679

Cited by 45 publications

(23 citation statements)

References 1 publication

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“…The pioneering work on commercial systems was done by Aeroquest, THEM Geophysics, and Geotech (Allard, 2007). The corresponding systems were the AeroTEM system (Balch et al, 2003), the THEM system (Allard, 2007), and a system that eventually was called the VTEM system (Witherly et al, 2004b). In a short amount of time, some of these systems, or their descendants, developed very quickly, with reduced noise levels and higher dipole moments (Witherly and Irvine, 2006).…”

Section: Development Of New Systemsmentioning

confidence: 99%

Metalliferous mining geophysics — State of the art after a decade in the new millennium

2011

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Mining exploration was very active during the first decade of the twenty-first century because there were numerous advances in the science and technology that geophysicists were using for mineral exploration. Development came from different sources: instrumentation improvements, new numerical algorithms, and cross-fertilization with the seismic industry. In gravity, gradiometry kept its promise and is on the cusp of becoming a key technology for mining exploration. In potential-field methods in general, numerous techniques have been developed for automatic interpretation, and 3D inversion schemes came into frequent use. These inversions will have even greater use when geologic constraints can be applied easily. In airborne electromagnetic (EM) methods, the development of time-domain helicopter EM systems changed the industry. In parallel, improvements in EM modeling and interpretation occurred; in particular, the strengths and weaknesses of the various algorithms became better understood. Simpler imaging schemes came into standard use, whereas layered inversion seldom is used in the mining industry today. Improvements in ground EM methods were associated with the development of SQUID technology and distributed-acquisition systems; the latter also impacted ground induced-polarization (IP) methods. Developments in borehole geophysics for mining and exploration were numerous. Borehole logging to measure physical properties received significant interest. Perhaps one reason for that interest was the desire to develop links between geophysical and geologic results, which also is a topic of great importance to mining geologists and geophysicists.

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Section: Development Of New Systemsmentioning

confidence: 99%

Metalliferous mining geophysics — State of the art after a decade in the new millennium

2011

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“…There are three main methods to eliminate the primary field problem: measurement during the off-time, maintaining a (very) rigid transmitter-receiver orientation so that primary field is a fixed value and can be subtracted from the measured response, and the use of a bucking coil to electromagnetically shield the receiver from the primary field. All of these methods have associated issues: limited band width reduces the ability of off-time measurements to discriminate high conductivity; rigid airborne systems require very small transmitter loops, reducing the dipole moment and thus the effective depth of exploration; bucking coil systems have proven to be too variable in effect to much improve detection of highconductance targets (Balch et al, 2003).…”

Section: Primary Field Removalmentioning

confidence: 99%

Detection of a perfect conductor with an airborne electromagnetic system: The Gemini Field Test

Smiarowski

Macnae

2013

GEOPHYSICS

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The cores of high-grade nickel and copper sulphides appear as "perfect conductors" to most electromagnetic (EM) and airborne electromagnetic (AEM) systems, because they have bulk electrical conductivities of the order of 100;000 S∕m. The EM response of these highly conductive cores is essentially undetectable with off-time measurements or when using nonrigid towed-bird systems. Compact AEM systems with accurate primary field bucking and on-time or in-phase measurements are sensitive to perfect conductors, but are incapable of detecting deep targets. Using a GPS system to define geometry, calculations suggest that it should be easy for an AEM system to detect "perfect conductors" provided the receiver was several hundred meters distant from the transmitter. A twin (Gemini) aircraft test was undertaken to test this concept in 2005. The field test successfully demonstrated detection of very conductive targets. Errors associated with geometric changes were better than 0.5% of the primary field at 400 m separation, allowing detection and characterization of the 30 Hz, in-phase response of small and extended conductors. The test shows that a 200 × 100 m very-strongly conductive thin-sheet target would be detectable to depths of 200 m below surface using off-the-shelf technology. Larger conductors would be detectable at greater depths.

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“…Helicopter systems such as SkyTEM (Sørensen and Auken, 2004), VTEM (Witherly et al, 2004), AeroTEM (Balch et al, 2003) and HoistEM (Boyd, 2004) carry the instrument as a sling load beneath the helicopter. These systems have relatively fixed transmitter/receiver geometries with loops that remain close to horizontal during operation.…”

Section: Introductionmentioning

confidence: 99%

On the value of including x-component data in 1D modeling of electromagnetic data from helicopterborne time domain systems in horizontally layered environments

Kirkegaard

Foged

Auken

et al. 2012

Journal of Applied Geophysics

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The AeroTEM airborne electromagnetic system

Cited by 45 publications

References 1 publication

Metalliferous mining geophysics — State of the art after a decade in the new millennium

Metalliferous mining geophysics — State of the art after a decade in the new millennium

Detection of a perfect conductor with an airborne electromagnetic system: The Gemini Field Test

On the value of including x-component data in 1D modeling of electromagnetic data from helicopterborne time domain systems in horizontally layered environments

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