| Abstract |
The change in geothermal water exploitation (replacing of the free outflow by increased pumping) could cause changes in geothermal water properties not only in a respective geothermal well, but consequently, in the whole geothermal structure. As an example of such changes, geothermal well VZO- 13 Zlatna na Ostrove (Slovakia) located in the central depression of the Danube Basin was chosen. Qualitative properties of geothermal water exploited by free outflow of 7.5 l/s were compared with those, exploited by pumping with the rate of 18.33 l/s. The value of TDS has increased from 2.5 g/l to 13 g/l. The change was accompanied by changes of gas composition and content. The total gas content increased from 274 l/m3 to 1 117 l/m3, nitrogen content decreased from 20 l/m3 to 1.8 l/m3, CO2 content increased from 15 l/m3 to 57 l/m3 and the methane content increased from 239 l/m3 to 1 058 l/m3. The change in gas content resulted in the change of bubble point depth which decreased from 150 m (by the free outflow of 7.5 l/s) to the depth of 250 m below the surface (by the pumping rate of 18.33 l/s). Hydrodynamic calculations also documented that by the long-term abstraction of the 18 l/s, the free outflow will disappear and the piezometric head of geothermal water will decrease to the depth of 85 m below the surface. |