Transcarpathian geothermal resources
In Ukraine, areas with an increased geothermal gradient are naturally associated with the zones of young Alpine folding – the Crimea and the Carpathians. Zakarpattia is the region with the highest subsurface temperature in Ukraine.
In the Zakarpattia trough, the geothermal gradient ranges from 3.57 to 8.0°C/100 m. At depths of 2 km, the temperature reaches +120°C. Wells bring water to the surface with temperatures ranging from +23 to 61°C.
The analysis of the natural conditions of Zakarpattia (temperatures, depths, chemical composition of water) suggests that the use of geothermal resources for heating and water supply is promising, especially considering modern technologies for extracting energy from low-potential heat carriers. However, the most promising is still the development of the hydro-mineral potential of Zakarpattia for resort services.
This direction is promising both in terms of the fact that Ukraine has lost some of its resort resources in the south for an indefinite period of time and in the context of our country’s course towards European integration. After all, a number of deposits with proven healing properties are located on the border with EU countries, which are still unknown to European consumers. However, they have a number of significant advantages, namely: proximity, mild climate, beautiful nature, moderate prices, a sufficiently high level of medical personnel, and hospitable local population.
In Zakarpattia, there are 30 deposits and manifestations of thermal waters and brines with different chemical compositions. Among them, there are subthermal (warm) ones with temperatures of 20–25°C, thermal (hot) ones with temperatures of 35–42°C, and high-temperature ones (very hot) with temperatures >42°C.
The aquifers are associated with neogene andesites, tuffs, tufts, sandstones, and argillites, with depths ranging mostly from 500 to 1000 m. The well yields range from 0 to 23 dm³/s, with temperatures at the wellhead ranging from 23 to 61°C. The mineralization ranges from 3–25 to 150 g/dm3 and higher. The waters have a varied chemical composition, including sodium chloride, sodium-calcium chloride, and less frequently, calcium bicarbonate chloride and calcium bicarbonate, with various specific components such as carbon dioxide, silica, boron, iodine-bromine boron, and high iron content.
The diversity of the chemical composition of thermal waters determines their wide range of use in balneotherapy practice.
Currently, the resources of thermal waters in Zakarpattia are used extremely insufficiently, although in recent years several modern thermal pools have been built, including in Kosino and Berehove. Examples of the development of thermal waters are the balneotherapy complexes Zhaivoronok (Berehove), Teply Vody (Velyatyn), and Thermal Star (Nyzhnie Solotvyno).
Balneotherapy procedures are used in the treatment of diseases of the musculoskeletal system, central and peripheral nervous system, cardiovascular system, skin diseases, respiratory organs, and so on. However, even in these balneotherapy facilities, thermal water resources are used no more than 50%. At the same time, the water from several deposits remains unused, and known water manifestations are not explored.
Thus, there are significant resources in Transcarpathia for increasing the extraction of thermal mineral water. However, there are also certain risks associated with the complex geological structure of the region, the instability of aquifers, significant depths of occurrence, often low flow rate. Therefore, hydrothermal resources in Transcarpathia require detailed study.