Conceptual and numerical models of a tectonically-controlled geothermal system: a case study of the Euganean Geothermal System, Northern Italy

Abstract

The Euganean Geothermal Field (EGF) is the most important thermal field in northern Italy. It is located in the alluvial plain of the Veneto Region where approximately 17*10 6 m 3 of thermal water with temperatures of 60-86 °C are exploited annually. A regional-scale conceptual model of the Euganean Geothermal System is proposed in this paper using the available hydrogeologic, geochemical and structural data for both the EGF and central Veneto. The thermal water is of meteoric origin and infiltrates approximately 80 km to the north of the EGF in the Veneto Prealps. The water flows to the south in a Mesozoic limestone and dolomite reservoir reaching a depth of approximately 3,000 m and a temperature of approximately 100 °C due to the normal geothermal gradient. The regional Schio-Vicenza fault system and its highly permeable damage zone act as a preferential path for fluid migration in the subsurface. In the EGF area, a geologic structure formed by the interaction of different segments of the fault system increases the local fracturing and the permeability favoring the upwelling of the thermal waters. Numerical simulations are performed to validate the proposed conceptual model using a finite difference code that simulates thermal energy transport in hydrothermal systems. A specific configuration of thermal conductivity and permeability for the formations involved in the thermal system is obtained after calibration of these parameters. This set of parameters is verified in a long-term simulation (55,100 years) obtaining a 60-70 °C plume in the EGF area. The modeled temperatures approach the measured temperatures of 60-86 °C, demonstrating that this conceptual model can be realistically simulated.

Microbiota of the Therapeutic Euganean Thermal Muds with a Focus on the Main Cyanobacteria Species

“…The area is characterized by an underground hydrothermal basin with thermal waters flowing to the surfaces through natural springs and artificial wells [ 5 , 6 ]. The water, having an average temperature of 75 °C, is classified as ‘hyperthermal’ [ 5 ] and owes its heat to geothermal factors.…”

“…The area is characterized by an underground hydrothermal basin with thermal waters flowing to the surfaces through natural springs and artificial wells [ 5 , 6 ]. The water, having an average temperature of 75 °C, is classified as ‘hyperthermal’ [ 5 ] and owes its heat to geothermal factors. The rainwater, rising from depth to the surface in the highly permeable area of the Euganean hills, acquires a slight radioactivity and salinity due to rock erosion [ 5 , 6 ].…”

Low Enthalpy Geothermal Systems in Structural Controlled Areas: A Sustainability Analysis of Geothermal Resource for Heating Plant (The Mondragone Case in Southern Appennines, Italy)

“…Among them, the code TOUGH2®(Transport Of Unsaturated Groundwater and Heat) has been firstly applied to Wairakei (New Zealand) geothermal field [38][39][40] and subsequently to several other geothermal fields (i.e., [41,42]). Additionally, the Los Alamos National Laboratory Finite Element Heat and Mass Transfer (FEHM®) code has a good record of numerical modeling studies, mainly related to enhanced geothermal systems (EGS) [43][44][45][46], together with the U.S. Geological Survey code HYDROTHERM® [47][48][49]. The commercial software COMSOL®, in particular, is a widely used simulator that has been adapted (as for example with the link to MATLAB®) [50] to applications including geothermal studies and, in several cases, the evaluation of fault influence [23,51,52].…”

Terrestrial gamma dose rate mapping (Euganean Hills, Italy): comparison between field measurements and HPGe gamma spectrometric data

“…Though of limited extension, this area belongs to an important Tertiary Volcanic Province that produced submarine mafic lavas, volcanic breccias, tuffs and hyaloclastites, and lavas (intermediate to acidic) and sub-volcanic laccoliths, now emerging as hills from the Venetian alluvial plain (24,25). The area is densely populated and rich in economic activities, including tourism-based specifically on thermalism and spas connected to a tectonically controlled geothermal system (26), the latter being traditionally and historically recognized among the situations most likely connected with excess radon exposure (27, annex E, vol. II; 1, annex B).…”