Joint Magnetic Resonance and Electrical Resistivity Tomography as hydrogeophysical characterization tool

• Applicant: Professor Dr. Mike Müller-Petke
• Subject Area: Geophysics
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280065108

• Final Report Year: 2019

Final Report Abstract

The main objective of the comet-project to develop a framework to combine surface-NMR and electrical resistivity tomography has been achieved. We have developed an open-source software COMET freely available via GitLab (https:// gitlab.com/Skibbe/comet) that allow to account for arbitrary resistivity distribution during the surface-NMR kernel calculation. This kernel calculation is sufficiently fast to allow for recalculation of the kernel function during the inversion which is necessary for the structural coupled cooperative inversion. COMET includes SCCI of surface-NMR and ERT both for 1D and 2D. We evaluated the main controlling parameter of this coupled cooperative inversion to select the optimal parameter and analyses the model space of the inversion. In a 1D field case we demonstrated the use of the SCCI to distinguish between saltwater, freshwater and clay which is of importance in the field of saltwater intrusion into coastal area. In a 2D synthetic case we show that SCCI improves the resolution of the obtained subsurface image. Finally, a 2D field case proved practical applicability of the developed schemes and demonstrated the hydrogeophysical information content provided by 2D SCCI of surface-NMR and ERT. Besides the main objective and achievements, further outcome of the project was (i) a close cooperation and mutual benefit to the BMBF funded project ”DESMEX“ leading to a joint publication and (ii) thanks the comprehensive new implementation of magnetic field calculation within the project, conceptually new surface-NMR measurements using grounded dipoles instead of surface loop could be evaluated for the first time leading to an internal cooperation and high-level publication.

Publications

• (2017): The potential of mobile nuclear magnetic resonance sensors for moisture detection in tunnels and mines. - 9. CMM Tagung und 4. Herbstschule Material - Prozesse - Systeme; Karlsruhe
  Costabel, S., Skibbe, N., Dlugosch, R. & Müller-Petke, M.
  
• (2018): COMET - A Python toolbox for 1D/2D/3D modelling and inversion of magnetic resonance and resistivity data . - Proceedings of the 7th International Workshop of Magnetic Resonance, MRS2018, 2018, Jilin University, China
  Skibbe, N., Rochlitz, R., Gunther, T., Müller-Petke, M.
  
• (2018): custEM: Customizable finite-element simulation of complex controlled-source electromagnetic data, Geophysics, 84 (2), F17-F33
  Rochlitz, R., Skibbe, N., Günther, T.
  
• (2018): Structurally coupled cooperative inversion of magnetic resonance with resistivity soundings. Geophysics, 83 (6), JM51-JM63
  Skibbe, N., Günther, T., Müller-Petke, M.
  
• (2019): First measurements of surface nuclear u magnetic resonance signals in a grounded bipole. Geophysical Research Letters
  Davis, A., Skibbe, N., Müller-Petke, M.