| Title | Hydrochemical Characteristics of Erma Reka Geothermal Reservoir (S. Bulgaria) |
|---|---|
| Authors | Aleksey BENDEREV, Radostina ATANASSOVA, Atanas ANDREEV, Vladimir HRISTOV, Klara BOJADGEIVA, Sava KOLEV |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | geothermal water, hydrogeochemistry, mineral depositions, Bulgaria |
| Abstract | Erma Reka geothermal reservoir is located in the southern part of the Rhodopes massif (South Bulgaria), close to Greek border, and is a unique combination with a polymetallic Pb-Zn mineralization. The deposit was discovered in 1955 and the exploitation of polymetallic ore continues until now.Water temperature is within the range of 30 to 90oC. The thermal water is accumulated in karst and cavernous marble body, located at a depth of 450 m below the surface and embedded in a gneiss complex. It is pumped to the surface and discharges in a small river, without using its thermal energy. Cavities and caverns, some of which are huge in size (from 400-1300 m) have been crossed during the drilling in the marble body. Thermal water from Erma Reka reservoir discharges through several springs located in the region of Termes (N. Greece). The obtained TDS values of the water samples vary between 0.6 to 1.3 g/l depending on the depth and special deposition of the reservoir. The TDS is correlating with the ratio change of concentrations of the main species HCO3-/SO42-, Ca2+/Na+, and with the H2SiO3 content, which reaches up to 250 mg/l at highest mineralization. Contents of other elements are analyzed in thermal water. Varied in composition and texture mineral depositions occur in wellhead where a significant temperature decrease is observed. The values of saturation index of various compounds regarding mineral phases have been determined. It has been established that various carbonate, phosphate and silicate mineral phases could be deposited in the cooling down process. Knowing the process of thermal water scaling is essential for the future use for a space heating in the town of Zlatograd, located at about 12 km to the southeast of Erma Reka geothermal reservoir. |