## 1 Introduction
Additionally, in order to determine heat conductivity values at the regional and local scales, the thermal conductivity of 200 rock samples collected from four different regions of southern Italy (Calabria, Campania, Apulia and Sicily) was investigated by [11], measuring its value in both dry and wet conditions. [PERSON], in reference [12] it was utilised the framework of the MIUR\(-\)2008 project \"Geothermal resources of the Mesozoic basement of the Po Basin: groundwater flow and heat transport\" to accurately estimate the thermophysical properties of a wide variety of sedimentary and intracellularity volcanic rocks from the Po Basin through laboratory measurements of density and porosity. Since it is stored in subsurface geological formations and associated with hydrocarbons, geothermal energy must be extracted before it can be used. Decommissioned or disused oil and gas wells, especially those in mature oilfields, are good candidates for geothermal heat exploitation and may provide access to subsurface energy resources. Considering the large number of existing oil wells dismissed every year in Italian fields, various studies have proposed new engineering tools to evaluate the possible use of such thermal resources. In reference [13], it was developed an effective method for doing so through the use of a closed-loop system with associated Wellbore Heat Exchanger (WBHE) technology. Unlike in conventional open-loop geothermal systems, heat carrier fluids in closed-loop systems circulate inside WBHEs, with no ground fluids extracted from surrounding rocks. Despite the recent success of theoretical oilfield geothermal closed-loop system experiments, certain challenges remain for understanding the possibility of large-scale access to geothermal resources in oilfields using closed-loop technologies. Additionally, due to the continuous spatial variability of geological formations associated with deep oil and gas wells in oilfields, the thermophysical parameters of geological strata surrounding the well, as well as the depth and thickness of the strata, must be considered to achieve accurate and realistic estimates of heat exchanger performance. Given the above considerations, this study aims to contribute to the discussion, encouraging a reflection on the potential benefits and limitations of using low- to medium temperature geothermal energy resources associated with dismissed Italian hydrocarbon wells as a renewable source of energy. Using the information on Italian hydrocarbon wells and on-field temperatures available from both the National Mining Office of the Italian Ministry for Economic Development (MISE) and the Italian National Geothermal Database, the simplified heat exchange model (coaxial WBHE) described in [13] was applied to three hydrocarbon wells. The main purpose was to properly analyse heat exchange mechanisms in three different Italian oil and gas fields, emphasising that the quantity of the potentially extracted thermal energy can change based on geological and depositional context. Wells from the Villafortuna-Trecate field, the Val d'Agri field and the Gela field were selected. The assumption that the thermophysical parameters (thermal conductivity, volumetric heat capacity and rock density) are constant values, as described in [13], has been overcome by applying the elaborated model to the detailed stratigraphic data of each case study. The final use of the potentially extracted heat would be in possible direct applications by means of a cascade plant system, which provides specific thermal energy amounts to production cycles in manufacturing, agricultural and recreational districts near the oilfields. Considering specifically the examples of disused hydrocarbon wells analysed, located in the Italian territory, it is possible to state that they are located far from inhabited areas or buildings: it is therefore not generally possible to hypothesize the use of the extracted thermal energy for heating purposes.