Preprints
https://doi.org/10.5194/egusphere-2024-2692
https://doi.org/10.5194/egusphere-2024-2692
18 Sep 2024
 | 18 Sep 2024
Status: this preprint is open for discussion.

Lithologically constrained velocity–density relationships and vertical stress gradients in the North Alpine Foreland Basin, SE Germany

Peter Obermeier, Florian Duschl, and Michael C. Drews

Abstract. We systematically analysed density and velocity data from 41 boreholes to establish velocity-density relationships for the main lithological units in the North Alpine Foreland Basin in SE Germany. We applied these relationships to velocity data and spliced the resulting density values with actual density data and a shallow density model to retrieve complete density profiles along 55 deep wellbores, which at least penetrated the Cenozoic section in the study area. We integrated density profiles to vertical stress to investigate the spatial distribution of vertical stress gradients. Thereby, we observed an eastward decrease of vertical stress gradients, which correlates well with the geological configuration of the North Alpine Foreland Basin in SE Germany. Thereby, vertical stress gradient profiles can be reasonably estimated as a function of true vertical depth below ground level TVD in the western, central, and eastern parts of the study area using a power law relationship:

West: 21 MPa/km + (TVD/325)1/1.80, R² = 0.98

Central: 21 MPa/km + (TVD/410)1/1.93, R² = 0.99

East: 21 MPa/km + (TVD/531)1/1.95, R² = 1.00 

In addition, we also investigated the distribution of vertical stress gradients at the top of Upper Jurassic carbonates, an important aquifer for deep geothermal energy production. Our study, therefore, provides a valuable resource for future geophysical, geomechanical, and geological studies in the North Alpine Foreland Basin, both in a fundamental and applied research context.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Peter Obermeier, Florian Duschl, and Michael C. Drews

Status: open (until 07 Nov 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2024-2692', Giacomo Medici, 30 Sep 2024 reply
Peter Obermeier, Florian Duschl, and Michael C. Drews
Peter Obermeier, Florian Duschl, and Michael C. Drews

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Short summary
We investigate geophysical properties and the distribution of vertical stress, which is defined by the weight of the rock column above a certain location in the subsurface, in the upper 5 km of the North Alpine Foreland Basin in Germany. Our results help to understand the present-day geological configuration and to improve safety for subsurface use, such as deep geothermal energy production in the study area.