Removal of cultural noise from high-resolution aeromagnetic data using a two stage equivalent source approach

Salem, Ahmed; Lei, Kaxia; Green, Christopher M.; Fairhead, J. D.; Stanley, Gerry

doi:10.1071/eg09047

Cited by 12 publications

(12 citation statements)

References 5 publications

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“…Hassan and Pierce (2005) developed a semi-automated technique for removing cultural noise from aeromagnetic profiles prior to gridding. Salem et al (2010) proposed an equivalent-source technique to remove cultural noise. They used the analytic signal calculated along a profile to identify shallow sources and then removed corresponding magnetic data from the profile.…”

Section: Data Processingmentioning

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: Data Processingmentioning

confidence: 99%

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

2011

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“…Noise level varies between techniques and sites but subtle cavity signals can easily be obscured in all techniques. Frequency and space filtering may be used to eliminate the effects of noise but filtering is limited in its ability to distinguish between noise and features (being based solely on wavelength or width) and can distort the shape of genuine signal pulses or even create artificial anomalies (Parasnis, 1996;Salem et al, 2010). To avoid losing subtle cavity signals in processing, the original, noisy data must often be used.…”

Section: Site Specific Noise Levelmentioning

confidence: 99%

Geophysical Modeling of Typical Cavity Shapes to Calculate Detection Probability and Inform Survey Design

James

Ferreira

2013

JEEG

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Feasibility analysis of near surface cavity detection is presented using modelling of the gravity, gravity gradient, magnetic, magnetic gradient, and ground penetrating radar techniques. The geophysical signal is modelled over typical cavity shapes in three dimensional subsurface environments with varying geologies and survey parameters. The cavity detection probability is calculated for each technique in the outlined environments and these values are used aid technique choice, assess the feasibility of cavity detection, assess the limits of detection for each technique, and optimise survey design before entering the field. Tests in a range of conditions show that technique choice is conditional to site characteristics and site parameters and highlight the need for modelling in the desk study stage of site investigation and survey design. Detection probability results show that standard survey direction practice in magnetometry is not always optimal and demonstrate the importance of site specific noise level consideration. Comparisons with case study measurements demonstrate that the process chose appropriate techniques and survey parameters but also highlights the limitations of the method.

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“…The manual approach is successful but is always more time consuming compared with automated techniques (Hassan et al 1998). Schemes for automatic deculturing of magnetic data are often based on the identification and removal of localized equivalent sources (Muszala et al 2001;Salem et al 2010). Nabighian et al (2005) provide a historical review of deculturing methods.…”

Section: Introductionmentioning

confidence: 99%

“…An example of cross-correlation between a local dipolar anomaly and cultural responses due to oilfield facilities is given by Wilson (1997). Schemes for automatic deculturing of magnetic data are often based on the identification and removal of localized equivalent sources (Muszala et al 2001;Salem et al 2010). Wavelet decomposition (filtering) methods are described by Leblanc and Morris (2001) and Hassan and Pierce (2005).…”

Section: Introductionmentioning

confidence: 99%

A contribution to aeromagnetic deculturing in populated areas

Beamish

2016

Geophysical Prospecting

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Modern regional airborne magnetic datasets, when acquired in populated areas, are inevitably degraded by cultural interference. In the United Kingdom context, the spatial densities of interfering structures and their complex spatial form severely limit our ability to successfully process and interpret the data. Deculturing procedures previously adopted have used semi‐automatic methods that incorporate additional geographical databases that guide manual assessment and refinement of the acquired database. Here we present an improved component of that procedure that guides the detection of localized responses associated with non‐geological perturbations. The procedure derives from a well‐established technique for the detection of kimberlite pipes and is a form of moving‐window correlation using grid‐based data. The procedure lends itself to automatic removal of perturbed data, although manual intervention to accept/reject outputs of the procedure is wise. The technique is evaluated using recently acquired regional United Kingdom survey data, which benefits from having an offshore component and areas of largely non‐magnetic granitic response. The methodology is effective at identifying (and hence removing) the isolated perturbations that form a persistent spatial noise background to the entire dataset. Probably in common with all such methods, the technique fails to isolate and remove amalgamated responses due to complex superimposed effects. The procedure forms an improved component of partial automation in the context of a wider deculturing procedure applied to United Kingdom aeromagnetic data.

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Removal of cultural noise from high-resolution aeromagnetic data using a two stage equivalent source approach

Cited by 12 publications

References 5 publications

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

Geophysical Modeling of Typical Cavity Shapes to Calculate Detection Probability and Inform Survey Design

A contribution to aeromagnetic deculturing in populated areas

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