Detection and correction of SPM effects in airborne EM surveys

被引：12

作者：

Kratzer, Terence ^{[1
]}

Macnae, James ^{[1
]}

Mutton, Paul ^{[2
]}

机构：

[1] RMIT Univ, Melbourne, Vic 3001, Australia

[2] Southern Geosci Consultants, Belmont, WA 6984, Australia

来源：

EXPLORATION GEOPHYSICS | 2013年 / 44卷 / 01期

关键词：

airborne EM; magnetic viscosity; SPM; superparamagnetism;

D O I：

10.1071/EG12048

中图分类号：

P3 [地球物理学]; P59 [地球化学];

学科分类号：

0708 ; 070902 ;

摘要：

Recent noise reductions in airborne electromagnetic (AEM) systems have allowed detection of conductors at great depths, but systems now have also become sensitive to superparamagnetic (SPM) effects. We distinguish SPM effects in airborne electromagnetic survey data from the response of good conductors. In electromagnetic data processing, off-time data can be accurately represented as amplitudes of a set of basis functions that are comprised of decays that decrease exponentially as a function of time. The SPM impulse response can be approximated by a decay that is proportional to time to the inverse power, a time dependence associated with magnetic viscosity. We identify the presence of SPM effects, as distinct from the decay of good conductors, by using inverse power-law decays as additional basis functions in constrained least-squares fitting. Application of the method to airborne time-domain electromagnetic (TEM) surveys shows that the method allows correction of SPM and hence aids significantly in conductive target identification.

引用

页码：6 / 15

页数：10

共 15 条

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