Multi-EM

Electromagnetic (EM) techniques are nowadays routinely used in geodynamic research or to characterize hydrocarbon reservoirs in offshore petroleum exploration. Moreover, distinct electrical conductivity properties make EM techniques prime geophysical tools to characterize saline aquifers for geothermal reservoirs or CO2 storage. Still, the interpretation techniques need to be improved. With the Multi-EM project we attempt to enhance resolution properties by combining electromagnetic diffusion and DC-geoelectric methods in a multi-scale environment. This collaborative effort combines research groups from applied and numerical geophysics, information technology and numerical mathematics.

The electrical conductivity of the subsurface can be explored using a variety of techniques. In the framework of the Multi-EM project we focus on the natural source magnetotellurics (MT), controlled source electromagnetics (CSEM), DC resistivity method and transient electromagnetics (TEM). The resolution power of the individual method depends on the experimental design, the strength, geometry, and signature of the source field, and the characteristics of the subsurface current system.

Technology

Joint multi-scale multi-method EM inversion strategies aim at combining the strengths of different methods to obtain enhanced resolution power. The combination of various sensitivity patterns is expected to result in (i) better coverage of the model space (ii) more complete and better resolved reconstructions of the subsurface conductivity structure and (iii) reduction of model ambiguities.
Considering the enormous numerical complexity of multi-method three-dimensional inversion, the new algorithms are designed for parallel computing architectures integrating memory and run-time efficient state-of-the-art numerical simulation techniques.

Time Frame

  • 07/2010 - 12/2013

Principal Investigators

  • PD Dr. Oliver Ritter (GFZ)
  • Prof. Dr. K. Spitzer (TU Bergakademie Freiberg, Institute of Geophysics)

Personnel

  • Dr. Naser Meqbel (GFZ)
  • Dr. Alexander Grayver (GFZ)
  • Dr. Ute Weckmann (GFZ)
  • Dr. Rita Streich (GFZ, now at Shell Global Solutions International)

Cooperations

  • J. Thaler, Dr. J. Klump, M. Köhler (GFZ)
  • M. Afanasjew, M. Scheunert, J. Weißflog, Dr. R.-U. Börner (TU Bergakademie Freiberg, Institute of Geophysics)
  • F. Eckhofer, Prof. Dr. M. Eiermann, Prof. Dr. O. G. Ernst (TU Bergakademie Freiberg, Institute of Numerical Mathematics and Optimization)
  • Jun. Prof. Dr. M. Becken (University of Münster, Institute for Geophysics)

Publications/Results

  • Streich, R., Becken, M. and Ritter, O., 2011, 2.5D controlled-source EM modeling with general 3D source geometries, Geophysics 76(6), F387-F393
  • Streich, R. and Becken, M., 2011, Sensitivity of controlled-source electromagnetic fields in planarly layered media, Geophysical Journal International, 187, 705-728
  • Protokoll über das 24. Schmucker-Weidelt-Kolloquium für Elektromagnetische Tiefen-forschung, Neustadt an der Weinstraße, 19. - 23. September 2011, Herausgeber: Ralph-Uwe Börner und Katrin Schwalenberg, 2012, ISSN 2190-7021
  • Grayver, A., & Streich, R. (2012). 3D CSEM inversion: strategy and synthetic studies, pp. 75-81.
  • Tietze, K., & Ritter, O. (2012). Resolution of 3D elongated deep conductive bodies embedded in a 2D background conductivity structure by 3D and 2D magnetotelluric inversion, pp. 278-288.
  • Scheunert, M., Afanasjew, M., Börner, R.-U., Eiermann, M., Ernst, O. G., & Spitzer, K. (2012). Solving the Electromagnetic Inverse Problem Using Krylov Subspace Methods, pp. 233-238.
  • Weißflog, J., Eckhofer, F., Börner, R.-U., Eiermann, M., Ernst, O. G., & Spitzer, K. (2012). DC resistivity FE modelling and inversion in view of a parallelised Multi-EM inversion approach, pp. 289-294.
  • Grayver, A. V., Streich, R., and Ritter, O., 2013, Three-dimensional parallel distributed inversion of CSEM data using a direct forward solver, Geophysical Journal International, 193(3), pp. 1432-1446.

Acknowledgment

  •  The project is funded by the German Federal Ministry of Education and Research (Grant Nr. 03G0746A-MULTI-EM ) and is part of the Geotechnologien programm

Additional Information

Contact

Oliver Ritter
Group Leader
Prof. Dr. Oliver Ritter
Geophysical Imaging
Albert-Einstein-Straße 42-46
Building A 42, Room 114
14473 Potsdam
+49 331 288-1257
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