As part of the Grado geothermal Project - Phase 2, an integrated gravity and seismic prospecting was recently conducted in downtown Grado Island (North Eastern Italy) and in the surrounding lagoon. The aim of this study was to characterize the carbonatic geothermal reservoir and to locate the second well of the geothermal doublet, planned to feed the district-heating system for public buildings on the island. The joint interpretation of the new seismic and gravity data, integrated with the previous Grado-1 site-survey and well data, allowed us to define the major structural features characterizing the carbonatic geothermal reservoir. This preliminary characterization was integrated into a 3-D thermo-fluid dynamic numerical modelling to evaluate the coupling of the production/re-injection wells with the geothermal reservoir and to assess the geothermal potential and the sustainability of the production.
