3D hydrogeological reconstruction of the fault-controlled Euganean Geothermal System (NE Italy)

Abstract

Assessing the renewability of geothermal and hydrogeological resources is a particular requirement for their future preservation. The sustainable exploitation of a geothermal resource for its long-term utilization is related to both the water demand and the hydrogeological characteristics of the geothermal field, while its renewability is influenced by the geological and hydrogeological processes that enhance the groundwater flow. Numerical modeling can be successfully used to assess both the impacts of processes occurring in the geothermal system and the renewability of associated resources. However, the reliability of a numerical simulation is influenced by the accuracy of the dataset used to reproduce the geological system. A 3D hydrogeological reconstruction model, rather than a simplified conceptualization of the geological setting, can increase the consistency of the modeling results. In the case of the Euganean Geothermal System (NE Italy), a detailed reconstruction was performed to quantitatively reproduce the hydrogeological elements that allow the development of the geothermal system and to estimate the amount of thermal waters stored in the reservoir. The structural setting of the central Veneto region, in particular the high-angle NNW-trending faults of the Schio-Vicenza Fault System, plays a fundamental role in the existence of the Euganean Geothermal System, permitting hydraulic connection between the recharge area and the exploitation field. In addition, regional- and local-scale faults and fractures favor fluid convection, which represents the main process that warms thermal fluids. Reproducing such a complex geological setting in a 3D model allows improving knowledge about the features that characterize the geothermal system and attaining a solid framework for the construction of a 3D regional numerical model that will be used to assess the renewability of the system.