Magnetic tensor gradiometry and marine CSEM*
David AnnettsCSIRO Earth Science and Resource Engineering 25 Dick Perry Avenue Kensington WA 6151. Email: David.Annetts@csiro.au
The APPEA Journal 50(2) 711-711 https://doi.org/10.1071/AJ09075
Published: 2010
Abstract
In recent times, surveys employing tensor gradiometers have been used in mineral exploration. Some reasons for this are potential advantages such as improved resolution, data interpolation, noise suppression and relative insensitivity to survey orientation. The last two potentialities are particularly germane to marine CSEM surveys, which are typically sparsely sampled and require processing of measured fields to ensure that the correct vector component is analysed.
In a series of numerical modelling studies of typical frequency-domain CSEM surveys in both shallow and deep water columns, this paper shows that tensor gradient measurements have advantages over conventional CSEM measurements in terms of target definition, especially when survey lines do not fall over target centres.
Keywords: marine, controlled source, electromagnetic, magnetic gradiometry, tensor, exploration, hydrocarbon
David has been fortunate to be able to intersperse periods of study with periods of gainful employment by industry (Geoterrex, Lamontagne Geophysics and Midspar Systems) and academia, earning a BSc (Hons) and an MSc from The University of Sydney and a PhD from Macquarie University. He has studied electromagnetic prospecting in various forms since 1988, modelling surface, down-hole and airborne surveys in environments ranging from massive sulphide deposits through the regolith to mapping variations in ice thickness and bathymetry. In his present role with CSIRO, he models electromagnetic applications for the petroleum industry. His scientific interests include forward and inverse electromagnetic modelling and applications of computer algebra. |
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