Geophysical techniques contribute significantly to the structural, geological and petrophysical characterization of all reservoir types investigated within GeoEn, i.e., geothermal resources, CO₂ storage sites and gas shales. This makes geophysical exploration a cross-cutting theme within GeoEn. The distribution of pore fluids and inter-connectivity of pores are important parameters for understanding reservoir systems. In sedimentary rocks, bulk electrical conductivity primarily depends on the conductivity of the pore fluids. Therefore, images of electrical conductivity obtained from surface-based (or borehole-to-surface) electromagnetic measurements help determine pore fluid distribution and further rock properties.
Within this research group, we are developing active controlled-source magnetotellurics (CSMT) as an innovative geophysical exploration tool to be used jointly with “classical” passive MT. We aim to image the electrical conductivity distribution of various reservoir types under investigation in GeoEn, varying in depth ranges from a few 100 m to several kilometres.

Tasks:

• CSMT surveying: Developing and applying innovative electromagnetic geophysical techniques (controlled-source magnetotellurics), including the development of active current transmitters, algorithms for data processing and reconstruction of electrical conductivity from measured electric and magnetic field data
• Imaging and monitoring of fossil and renewable energy resources in reservoirs down to depths of several kilometers
• Time-lapse geophysical measurements to monitor deep aquifers in terms of fluid motion, the size and stability of geothermal and CO₂ reservoirs and development of shale gas reservoirs

Contact:
Dr. Rita Streich (team leader, University of Potsdam / German Research Centre for Geosciences GFZ)
PD Dr. Oliver Ritter (German Research Centre for Geosciences)

Interfaces:

CO₂ storage, shale gas, geothermal energy

Concept of using CSMT for reservoir characterization: Active current transmitters are installed at the surface and possibly also in boreholes. Arrays of classical MT receiver stations record both active and passive signals.
Figure: M. Becken, formerly German Research Centre for Geosciences GFZ

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