A new hydrothermal conceptual and numerical model of the Euganean geothermal system - NE Italy

The Euganean Geothermal Field (EGF) is the most important thermal field in the northern Italy. The EGF extends on a plain band of about 36 Km2, east of the Euganei Hills and southwest of Padova (Veneto; Italy), and comprises the famous spa towns of Abano and Montegrotto Terme. At present about 250 wells are active and the total average flow rate of exploited thermal fluids is 17 Mm3/year. The temperature of thermal waters ranges from 65°C to 86°C and their T.D.S. is 6 g/L (primary Cl- and Na+). 3H and 14C measurements suggest a residence time greater than 60 years, probably a few thousand years. Oxygen isotopes analyses show that the thermal waters are of meteoric origin and infiltrate in an area up to 1500 m a.s.l. . Recently, Zampieri et al. (2009) demonstrated that the previous conceptual model of the Euganean Geothermal System (EGS) (Piccoli et al., 1976) cannot work. The aim of this research is to renew the hydrothermal model of the EGS using the new knowledge developed in the last 30 years of study and during the research. The new conceptual model is constrained with a numerical simulation. This is the first numerical model developed for the EGS. A sensitivity analysis is performed, with the aim to evaluate how different parameters could affect the temperature and the flow in the subsurface of the EGF.