In Situ Stress State of the Ruhr Region (Germany) and Its Implications for Permeability Anisotropy

Montegrossi, Giordano
Backers, Tobias
Saenger, Erik H.

DOI: https://doi.org/10.1007/s00603-021-02636-3
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/10966
Montegrossi, Giordano; Institute of Geoscience and Earth Resources, National Research Council of Italy, Florence, Italy
Backers, Tobias; Institute of Geology, Mineralogy, and Geophysics, Ruhr-University Bochum, Bochum, Germany
Saenger, Erik H.; Department of Civil and Environmental Engineering, Bochum University of Applied Sciences, Bochum, Germany
Abstract
In this study, we carried out reactivation potential analysis of discontinuities revealed from four exploration boreholes penetrating heavily faulted and folded Upper Carboniferous rock strata of the Ruhr region. We performed this study based on the notion that slip is controlled by the ratio of shear to effective normal stresses acting on a pre-existing plane of weakness in the prevailing stress field configuration. The results of this analysis were supported by indicators of localized fluid flow, both on micro- and macro-scales, which confirm relationship between secondary permeability and in situ stress state in the Ruhr region. Findings from this study, in conjunction with results of destructive laboratory testing, indicate that the steep NW–SE- and NNE–SSW-striking planar discontinuities are likely to be either close to the critical state or critically stressed in the in situ stress configuration in the Ruhr region. These planar structures, as evidenced by indicators of localized permeability, are the main fluid pathways in the studied region. The NE–SW-striking discontinuities, on the other hand, are most likely to be closed and hydraulically inactive in the prevailing stress state. Based on results gained from this study, implications for utilization of deep geothermal energy in the region were discussed.
Subjects
Reservoir geomechanicsGeothermal geomechanics
Crustal stresses
Geothermal energy
Deep geothermal systems
Ruhr region