Geothermal investigations in Slovenia
The paper presents the methodology and the results of geothermal investigations, based on seventy-two boreholes in the territory of the Republic of Slovenia. The data of fundamental geothermal quantities: formation temperature, thermal conductivity, and radiogenic heat production of rocks as well as surface heat flow density are stored in a computerized data base. Their synthesis is given in the map of formation temperatures at 1000 m depth and in the map of surface heat flow density. In both maps the thermal difference between the Pannonian basin in the eastern and the Dinarides in the western part of Slovenia is clearly expressed. However, in the boundary area between these two tectonic units, for a distance of about 100 km in SW-NE direction, elevated horizontal gradients of formation temperature as well as heat flow density are evident. A small positive thermal anomaly in the Ljubljana depression is conspicuous. The low-temperature geothermal resources in Slovenia such as thermal springs and thermal water from boreholes, are estimated to have a flow rate of 1120 kg/s, corresponding to the ideal total heat production of 144 MWt. In the geothermally promising areas amounting to 3200 km2 the rate of accessible resource base (ARB) down to the depth of 3 km has been assessed to about 8.5 x 1020 J.