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@PHDTHESIS{Fielitz:877986,
      author       = {Fielitz, Daniel},
      title        = {2{D} cross-hole {MMR} – {S}urvey design and sensitivity
                      analysis for cross-hole applications of the magnetometric
                      resistivity method},
      volume       = {95},
      school       = {Universität Köln},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2020-02560},
      isbn         = {978-3-89336-689-7},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {XVI, 123 S.},
      year         = {2010},
      note         = {Dissertation, Universität Köln, 2010},
      abstract     = {The magnetometric resistivity (MMR) method measures
                      low-level (typically < 1nT) magnetic fields associated with
                      a low-frequency (1 - 20 Hz) electric current impressed into
                      the ground to determine the subsurface resistivity
                      structure. As a step towards the implementation of MMR for
                      cross-hole imaging, in this Ph.D. thesis several aspects of
                      survey design for near-surface applications are discussed.
                      In numerical, laboratory and field studies the potential of
                      MMR for advanced structural characterization and process
                      monitoring at the field scale is assessed. The 2D cross-hole
                      setup considers borehole measurements of the magnetic field
                      as response to borehole current injection; in this case the
                      magnetic field has only one non-zero component
                      (perpendicular to the imaging plane – B$_{y}$). Optimal
                      survey parameters are inferred from numerical studies
                      regarding signal strength, source-generated noise level and
                      resolving power. Modeling of MMR responses over 2D
                      conductivity structures was performed using a newly
                      developed 2.5D FE program MMRMod. It could be proven that
                      current injection via vertical dipoles provides superior
                      signal-to-noise ratio compared to other transmitter
                      configurations. Analyzing resolving power in terms of
                      sensitivity distribution reveals that dipole configurations
                      reflect confined subsurface volumes, advantageous for
                      tomographic surveys and that transmitter-receiver
                      combinations exceeding an offset equal to the borehole
                      separation do not contribute significantly to the overall
                      crosshole resolution. With the assistance of laboratory
                      testing two concepts for solving two major difficulties
                      inherent in cross-hole MMR field surveying are derived: the
                      correction for the arbitrary borehole sensor orientation and
                      the correction for parasitic correlated noise fields induced
                      by the measurement system itself. The (latter) measurement
                      method with phase switching is thereby first-time
                      successfully applied to the processing of MMR data. In
                      addition, the proposed data processing procedure includes
                      modern lock-in-technique and has proven to be an appropriate
                      tool for an effective information extraction from the
                      measured magnetic fields. Finally, cross-hole MMR data were
                      collected during a water infiltration experiment at the
                      Gorgonzola test site. Acquisition and processing are
                      accomplished according to the developed tomographic
                      measurement approach involving multiple-offset
                      transmitter-receiver arrangements and repeated measurements
                      with time (time-lapse mode). Data, obtained during initially
                      conducted background measurement, are qualitatively
                      validated based on two different conductivity models, one of
                      which is obtained from the inversion of independently
                      collected ERT data. Importantly, the comparison of field
                      data with predicted model curves suggests better
                      resolvability of contrasts by MMR than by ERT. Moreover, the
                      analysis of time-lapse measurements reveals a clear
                      spatiotemporal dependence of the anomalous MMRresponse (MMR
                      response with respect to background value) based upon the
                      water saturation.},
      cin          = {PRE-2000 ; Retrocat / IBG-3},
      cid          = {I:(DE-Juel1)PRE2000-20140101 / I:(DE-Juel1)IBG-3-20101118},
      pnm          = {899 - ohne Topic (POF3-899)},
      pid          = {G:(DE-HGF)POF3-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/877986},
}