| Abstract |
This report is a compilation of the results of geological and geothermal surveys and investigations conducted in the territory of Surdulica granitoid massif for assessing its potential and possibilities for obtaining thermal water with temperature above 100°C. A wider zone of Surdulica granitoid massif belongs to the Serbian-Macedonian massif. The oldest lithological member is the complex of Paleozoic shale, mostly composed of mica schist, leptynolite, gneiss and chlorite schist rocks. Systematic exploration of the Surdulica granitoid massif, for possible use of thermal waters and geothermal energy, started in the mid 1960’s. Two deep exploratory and production wells VG-2 and VG-3, were drilled for that purpose in Vranjska spa. The temperatures and quantities of thermal water, the hydrogeothermal system of Surdulica massif with Vranjska spa makes it the most perspective zone for obtaining and using, for multiple purposes, thermal water and geothermal energy. Two deep wells: VG-2 (1064 m) and VG-3 (1603 m) were drilled in Vranjska spa. Hydrogeochemical investigations covered groundwater analyses, determining that waters of Vranjska spa are: thermal, bicarbonate-sulphate-sodium, low alkaline, mineralized, with a low content of hydrogen sulfide, fluorosilic, with an elevated content of HBO2 component and iron (Fe2+). Temperature of thermal water in well VG-2 is 126°C, with self discharge of 26 l/s, and wellhead pressure of 9.5 bars. Temperature of thermal water in well VG-3 is 124°C, with self discharge of 21 l/s, and wellhead pressure of 8.5 bars. The silica geothermometer gives estimated values for temperatures of thermal water in Vranjska spa between 115 and 144°C. Possible production rate is about 80 l/s of thermal water with temperature of 120°C in area of Surdulica granitoid massif. |