Hydraulic and Thermal Modelling of an Underground Mining Reservoir

Flooded mines are a groundwater reservoir that can be used geothermally. Modelling such a reservoir can be complicated because it is necessary to simultaneously solve the equations of flow and heat transport within the mine voids and the surrounding medium, whose hydraulic parameters may have been affected by mining. We present a numerical model developed for the reservoir formed by the Barredo and Figaredo shafts in the Central Coal Basin of Asturias (Spain), using FEFLOW software. Both 2- and 3-D versions of the model were used to simulate the flooding of the mine. They were calibrated by comparing the results with actual water levels measured during flooding. The hydrogeological and thermal characteristics of the reservoir were adjusted to predict the long-term temperature of the water under different scenarios of water extraction and injection.