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Advances in Electromagnetic, Gravity and Magnetic Methods for Exploration
  • E-ISSN: 1365-2478

Abstract

ABSTRACT

Airborne transient electromagnetic (TEM) is a cost‐effective method to image the distribution of electrical conductivity in the ground. We consider layered earth inversion to interpret large data sets of hundreds of kilometres. Different strategies can be used to solve this inverse problem. This consists in managing the  information to avoid the mathematical instability and provide the most plausible model of conductivity in depth.

In order to obtain fast and realistic inversion program, we tested three kinds of regularization: two are based on standard Tikhonov procedure which consist in minimizing not only the data misfit function but a balanced optimization function with additional terms constraining the lateral and the vertical smoothness of the conductivity; another kind of regularization is based on reducing the condition number of the kernel by changing the layout of layers before minimizing the data misfit function. Finally, in order to get a more realistic distribution of conductivity, notably by removing negative conductivity values, we suggest an additional recursive filter based upon the inversion of the logarithm of the conductivity.

All these methods are tested on synthetic and real data sets. Synthetic data have been calculated by 2.5D modelling; they are used to demonstrate that these methods provide equivalent quality in terms of data misfit and accuracy of the resulting image; the limit essentially comes on special targets with sharp 2D geometries. The real data case is from Helicopter‐borne TEM data acquired in the basin of Franceville (Gabon) where borehole conductivity loggings are used to show the good accuracy of the inverted models in most areas, and some biased depths in areas where strong lateral changes may occur.

© 2011 European Association of Geoscientists & Engineers
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2011-08-01
2024-04-20

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References

  1. AsterR.C., BorchersB. and ThurberC.H.2005. Parameter Estimation and Inverse Problem . Academic Press.
    [Google Scholar]
  2. AukenE., VioletteS., d’OzouvilleN., DesfontainesB., SorensenK.I., ViezzoliA. and de MarsilyG.2009. An integrated study of hydrogeology of volcanic islands using helicopter borne transient electromagnetic: Application in the Galapagos Archipelago. C.R. Geosciences341, 899–907.
    [Google Scholar]
  3. AukenE., ChristiansenA.V., JacobsenB.H., FogedN. and SǿrensenK.I.2005. Piecewise 1D laterally constrained inversion of resistivity data. Geophysical Prospecting53, 497–506.
    [Google Scholar]
  4. ChenJ. and RaicheA.1998. Inverting AEM data using a damped eigeparameter method. Exploration Geophysics29, 128–132.
    [Google Scholar]
  5. ChristensenN.B.2002. A generic 1‐D imaging method for transient electromagnetic data. Geophysics67, 438–447.
    [Google Scholar]
  6. ChristiansenA.V., AukenE., FogedN. and SǿrensenK.I.2007. Mutually and laterally constrained inversion of CVES and TEM data: a case study. Near Surface Geophysics, 5, 115–123.
    [Google Scholar]
  7. ConstableS.C., ParkerR.L. and ConstableC.G.1987. Occam's inversion: a practical algorithm for generating smooth models from electromagnetic sounding data. Geophysics52, 289–300.
    [Google Scholar]
  8. CoxL.H., WilsonG.A. and ZhdanovM.S.2010. 3D inversion of airborne electromagnetic data using a moving footprint. Exploration Geophysics41, 250–259.
    [Google Scholar]
  9. HansenP.C.1992. Analysis of discrete ill‐posed problems by means of the L‐curve. SIAM Review34, 561–580.
    [Google Scholar]
  10. HansenP.C.2010. Discrete Inverse Problem: Insight And Algorithms . SIAM.
    [Google Scholar]
  11. HuangH. and PalackyG.J.1991. Damped least‐square inversion of time‐domain airborne EM data based on singular value decomposition. Geophysical Prospecting39, 827–844.
    [Google Scholar]
  12. HuangH. and RuddJ.2008. Conductivity‐depth imaging of helicopter‐borne TEM data based on pseudo‐layer half space model. Geophysics73, F115–F120.
    [Google Scholar]
  13. LanczosC.1961. Linear Differential Operators . Dover Publication.
    [Google Scholar]
  14. Ley‐CooperA.Y., MacnaeJ. and ViezzoliA.2010. Breaks in lithology: Interpretation problems when handling 2D structures with a 1D approximation. Geophysics75, 179–188.
    [Google Scholar]
  15. MenkeW.1989. Geophysical Data Analysis: Discrete Inverse Theory . Academic Press.
    [Google Scholar]
  16. Monteiro SantosF.A.2004. 1‐D laterally constrained inversion of EM34 profiling data. Journal of Applied Geophysics56, 123–134.
    [Google Scholar]
  17. OldenburgD.W. and LiY.1994. Subspace linear inverse method. Inverse Problem10, 915–935.
    [Google Scholar]
  18. PalackyG.J.1987. Resistivity characteristics of geologic targets. In: Electromagnetic Methods (ed. N.M.Nabighian ), pp. 53–129. SEG.
    [Google Scholar]
  19. PortniaguineO. and ZhdanovM.S.1999. Focusing geophysical inversion images. Geophysics64, 874–887.
    [Google Scholar]
  20. RaicheA.2008. The P223 software suite for planning and interpreting EM surveys. Preview (February)132, 25–30.
    [Google Scholar]
  21. SiemonB., AukenE. and ChristiansenA.V.2009. Laterally constrained inversion of helicopter borne frequency‐domain electromagnetic data. Journal of Applied Geophysics67, 259–268.
    [Google Scholar]
  22. ValléeM.A. and SmithR.S.2009. Inversion of airborne time‐domain electromagnetic data to a 1D structure using lateral constraints. Near Surface Geophysics7, 63–71.
    [Google Scholar]
  23. ViezzoliA., ChritiansenA.V., AukenE. and SorensenK.2008. Quasi‐3D modeling of airborne TEM data by spatially constrained inversion. Geophysics73, 105–113.
    [Google Scholar]
  24. WardS.H. and HohmannG.W.1987. Electromagnetic theory for geophysical application. In: Electromagnetic Methods (ed. N.M.Nabighian ), pp. 131–311. SEG.
    [Google Scholar]
  25. WilsonG.A., RaichA.P. and SugengF.2006. 2.5D inversion of airborne electromagnetic data. Exploration Geophysics37, 363–371.
    [Google Scholar]
  26. WitherlyK., IrvineR. and MorrisonE.2004. The Geothech VTEM time domain helicopter EM system. 17th ASEG meeting, Sydney, Australia, Expanded Abstracts.
  27. WolfgramP., SattelD. and ChristensenN.B.2003. Approximate 2D inversion of AEM data. Exploration Geophysics34, 29–33.
    [Google Scholar]
  28. ZhdanovM.S.2009. New advances in regularized inversion of gravity and electromagnetic data. Geophysical Prospecting57, 463–478.
    [Google Scholar]
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Regularization strategy for the layered inversion of airborne transient electromagnetic data: application to in‐loop data acquired over the basin of Franceville (Gabon)
Geophysical Prospecting 59, 1132 (2011); https://doi.org/10.1111/j.1365-2478.2011.00990.x
/content/journals/10.1111/j.1365-2478.2011.00990.x
/content/journals/10.1111/j.1365-2478.2011.00990.x
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  • Article Type: Research Article
Keyword(s): Airborne electromagnetic; Imaging; Inversion; Regularization; Transient electromagnetic

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