Geomechanische Auswirkungen saisonaler Wärmespeicherung in stillgelegten Bergwerken

Abstract

AbstractFor the transition to sustainable heat sources, storage infrastructure is required to provide heat evenly throughout the year. Solar heat is typically produced in the summer and can be stored in underground heat reservoirs for the winter. Flooded coal mines, e.g., are potential heat reservoirs. To assess whether the geomechanical integrity of a colliery and the surrounding rock mass are affected by seasonally stored heat, a numerical case study was performed at ”Zeche Dannenbaum“ in the Ruhr valley, Germany. During summer, hot water was injected into level 8 of the colliery while cold water was produced from level 4. This process was reversed in winter. Detailed subsurface models of the colliery, rock mass and tectonic faults were used to numerically simulate the cyclical changes in pore pressure and temperature and the resulting stress changes. The displacement of the land surface, and geomechanically critical regions in the rock mass were derived. Moreover, the reactivation potential of the fault zones and the risk of induced seismicity were evaluated. The high injection temperatures induce strong thermoelastic effects, which could potentially lead to fault reactivation and induced seismicity. Surface displacements, however, are negligeable.