Preprints
https://doi.org/10.5194/essd-2022-196
https://doi.org/10.5194/essd-2022-196
 
21 Jun 2022
21 Jun 2022
Status: this preprint is currently under review for the journal ESSD.

In situ stress database of the greater Ruhr region (Germany) derived from hydrofracturing tests and borehole logs

Michal Kruszewski1,2, Gerd Klee3, Thomas Niederhuber4, and Oliver Heidbach5,6 Michal Kruszewski et al.
  • 1Fraunhofer IEG, Fraunhofer Research Institution for Energy Infrastructures and Geothermal Systems IEG, Am Hochschulcampus 1 IEG, 44801 Bochum, Germany
  • 2Institute of Geology, Mineralogy, and Geophysics, Ruhr-University Bochum, Universitätsstraße 150, 44801 Bochum, Germany
  • 3Solexperts GmbH (former MeSy GmbH), Meesmannstraße 49, 44807 Bochum, Germany
  • 4Karlsruhe Institute of Technology, Institute of Applied Geosciences Division of Technical Petrophysics Campus Süd, Adenauerring 20b, Geb. 50.40, 76131 Karlsruhe
  • 5GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
  • 6Technical University Berlin, Institute for Applied Geosciences, Ernst-Reuter Platz 1, 10587 Berlin, Germany

Abstract. Between 1986 and 1995 429 hydrofracturing tests have been carried out in six, now abandoned, coal mines and two coal bed methane boreholes at depths between 600 and 1950 m within the greater Ruhr region in western Germany. From these tests, stress magnitudes and orientations of the stress tensor are derived. The majority of hydrofracturing tests were carried out from mine galleries away from mine workings in a relatively undisturbed rock mass. These data along with detailed information have been disclosed recently. In combination with already published material, we provide the first comprehensive stress database of the greater Ruhr region. Our study summarizes results of the extensive in situ stress test campaign and assigns quality to each data record using the established quality ranking schemes of the World Stress Map project. The stress magnitudes suggest predominantly strike-slip stress regime, where the magnitude of the minimum horizontal stress, Shmin, is half of the magnitude of the maximum horizontal stress, SHmax, implying that the horizontal differential stress is high. We observe no particular change in the stress gradient at depth throughout the Carboniferous layers and no significant difference between tests carried out in coal mines and deep boreholes. The mean SHmax orientation varies between 133 ± 13° in the easternmost located Friedrich-Heinrich coal mine and 168 ± 23° in the westernmost located Westfalen coal mine. The mean SHmax orientation, based on 87 data records from this as well as already published studies, of 161 ± 43° is in good agreement with the regional stress orientation observed in Northwestern Europe. The presented public database provides in situ stress magnitude and stress orientation data records that are essential for the calibration of geomechanical numerical models on regional and/or reservoir scales for, among others, assessing stability issues of borehole trajectories, caverns, and georeservoirs in general. For an application example of this database, we estimate slip and dilation tendencies of major geological discontinuities, discovered during the 700-year-long coal mining activities in the region. The result shows that the discontinuities striking in the N-S and NW-SE directions have a higher slip tendency compared to the ones striking ENE-WSW and NNW-SSE, whereas a high dilation tendency is observed for discontinuities striking NNW-SSE and a low dilation tendency for the ones striking ENE-WSW.

Michal Kruszewski et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on essd-2022-196 - Slip Tendencies', Daniel Bücken, 09 Aug 2022
    • AC1: 'Reply to the comment by Daniel Bücken', Michal Kruszewski, 24 Aug 2022
  • RC1: 'Comment on essd-2022-196', Jochem Kück, 09 Aug 2022
    • AC2: 'Reply to the review by Jochem Kück', Michal Kruszewski, 24 Aug 2022
  • RC2: 'Comment on essd-2022-196', P. Montone, 03 Sep 2022
  • CC2: 'Comment on essd-2022-196', Joschka Röth, 15 Sep 2022

Michal Kruszewski et al.

Data sets

In-Situ Stress Orientation Data from the Greater Ruhr Region (Germany) Derived from Hydrofracturing Tests and Borehole Logs Kruszewski, Michal; Klee, Gerd; Niederhuber, Thomas; Heidbach, Oliver http://dx.doi.org/10.24406/fordatis/200

In-Situ Stress Magnitude Data from the Greater Ruhr Region (Germany) Derived from Hydrofracturing Tests and Borehole Logs Kruszewski, Michal; Klee, Gerd; Niederhuber, Thomas; Heidbach, Oliver http://dx.doi.org/10.24406/fordatis/201

Michal Kruszewski et al.

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Short summary
The authors assemble in-situ stress magnitude and orientation data base based on 429 hydrofracturing tests have been carried out in six coal mines and two coal bed methane boreholes between 1986 and 1995 within the greater Ruhr region (Germany). Our study summarises the results of the extensive in situ stress test campaign and assigns quality to each data record using the established quality ranking schemes of the World Stress Map project.