Paper contribution

Impact of elastic and strength anisotropy on seal integrity in energy storage

Daniel Bücken; Tobias Backers; Ki-Bok Min

Proceedings
EUROCK 2026
Pages
959-964
Submitted
28 January 2026
Accepted
15 June 2026
Published
12 August 2026

Summary

Abstract

Subsurface thermo-mechanical energy storage approaches such as supercharged hybrid gas-based energy storage (SH-GES) lead to significant poro- and thermoelastic stress changes, possibly affecting the integrity of the sealing formations. In clastic reservoir systems, these formations typically consist of shales or similar lithologies, often characterised by bedding parallel transversely isotropic material behaviour. In this study, the effect of both elastic and strength anisotropy of the sealing formation is assessed by means of coupled multiphase thermo-hydro-mechanical simulations. An anisotropy ratio of E/E’ = 1.66 was used for the transversely isotropic sealing formation. The results are compared to the behaviour of an isotropic reference case. Two reservoir permeabilities were considered. Strength anisotropy is implemented using the single plane of weakness approach, with implicit weakness planes characterised by a lower friction coefficient (µweak = 0.37) and lower cohesion (c0,weak = 9.6 MPa) than the intact rock. The effect of weakness plane orientation is assessed by a systematic variation of dip angle and azimuth. The results show that the elastic anisotropy made only minor differences in seal integrity between isotropic and transversely isotropic cases, regardless of reservoir permeability. Instead, seal integrity is predominantly controlled by weakness plane orientation and reservoir permeability. The analysis of Coulomb Failure Stress (CFS) shows that during energy storage operations, i.e., cyclic injection of CO2 and production, seal stability changes significantly even when the seal was stable initially. This is attributed to dynamic stress rotations induced by thermo-poro-elastic effects. These findings highlight the necessity of time-dependent numerical analyses to accurately assess seal integrity in thermo-mechanical gas-based energy storage systems and other geo-energy applications.

Contributors

Authors

  1. Daniel Bücken Ruhr University Bochum, Germany; geomecon GmbH, Germany ORCID 0009-0007-8575-8740
  2. Tobias Backers Ruhr University Bochum, Germany
  3. Ki-Bok Min Seoul National University, Republic of Korea

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References

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