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GeoSmaGriR Geomechanical integrity of heat stores in mines

Numerical simulations to predict the geomechanical behavior of the subsurface in heat storage in mines.

Central aspect of the foundation project 'GeoSmaGriR' is the storage of seasonal excess heat from district heating networks in mining buildings of disused coal mines. The seasonal supply of heat in and extraction of heat from underground storage results in a cyclic thermal load on the reservoir rocks and fluids.
For this, a geoscientific characterisation and thermo-hydromechanical modelling of the mine thermal store is required to allow reliable predictions about the long-term reservoir integrity in the context of seasonal heat storage. The objective of the SME project is to predict the geomechanical behavior of the subsurface during heat storage on the basis of existing geological investigations, voltage field measurements and large-scale thermo-hydraulic subsoil models.

The generic underground models for the Ruhr Carboniferous are transferred into numerical simulations based on the finite and advanced finite element method in order to take account of geological complexity. On the one hand, the expected temperature and pore pressure field around the injection point is simulated in large-scale models while on the other hand, changes in the stresses due to the thermal expansion of the rocks and the changed pore pressure are derived. From this, in turn, it is possible to locate elevations on the earth's surface and potentially geomechanical-critical areas in the 'Old Man' (decommissioned mine tunnel, which was not refilled properly) and the top layer and to derive the potential for the reactivation of existing fault zones or the formation of new ones. The first numerical models have been successfully tested. The interpretation of the results of fully coupled models is expected for the beginning of the second half of 2019.

Information on funding and further project participants

Funding code: 13FHOKO1IA

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