GNGTS 2021 - Atti del 39° Convegno Nazionale

101 GNGTS 2021 S essione 1.2 THERMAL REGIME MAPPING OF THE HYBLEAN DOMAIN (SOUTH- EASTERN SICILY) AIMED AT LOW- ENTHALPY GEOTHERMAL ANALYSIS G. Floridia 1* , M. Viccaro 1,2 1 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università degli studi di Catania, Italia 2 Istituto Nazionale di Geofisica e Vulcanologia – Sezione di Catania, Osservatorio Etneo, Catania (Italy). Introduction The constant increase of energy demand requires a redefinition of the energy use according to unconventional forms of exploitation. In such a context, low-temperature geothermal energy underwent a major development, as it affects many important socio-economic sectors in which either small or big enterprises are involved [1]. For this reason, the correct evaluation of the geothermal properties allows the optimization of the exploitation of shallow geothermal resources within suitable areas. In this study, geothermal properties of the south-eastern domain of Sicily (Hyblean sector) have been analysed to obtain a steady-state thermal conductive model of the subsurface. The study focuses on a 50 x 50 km extended area that represents an emerged undeformed structural domain, the so-called Hyblean foreland. The area consists of a segment covered by a thick Meso- Cenozoic carbonate succession (> 5 km) with repeated volcanic intercalations and flexed towards the N portion [2]–[4]. Methods From a multi-scale detailed geological framework (exploration wells from [5]) and a wide geo- physical background (national exploration surveys from [5], [6][7], [8], gravimetric and magnetic dataset [9][10]), a low-resolution geological model has been obtained. The geological model pro- vided the basis for the subsequent geothermal analysis. The thermal modelling started from the analysis of the available temperature dataset of several exploration wells existing in the investigated area. In this regard, several correction methods have been applied to define the correct temperature related to the investigation depth [11]. Among the main geothermal parameters, thermal conductivity has been analysed according to the petrophysical (density [12][1][13]) and stratigraphic properties (average thermal conducti- vity weighted on the thickness of the investigated lithologies) as well as the geophysical attribu- tes (seismic wave velocities – sonic logs [5]). According to the Fourier’s law, the vertical geothermal gradient and the heat flow have been extrapolated based on corrected temperature associated to lithological variation. The definition of geothermal parameters has allowed the identification of the thermal regime up to 1000 meters depth and to solve the linear variations in heat transfer reconstructing the temperature distribution at depth. Results and discussion The main research topic concerns the development of geothermal maps at a different depth, to obtain preliminary information for the subsequent analysis on the low-enthalpy geothermal potential. For this reason, the temperature, thermal conductivity, and heat flow distribution at 200-, 500-, and 1000-meters of depth has been considered. The preliminary results are summa- rized as follow: