Geothermal energy of the Mesozoic Basin in the Carpathian Foredeep, Kraków Region, Poland

Although the most favourable conditions for the use of geothermal energy are found in the Tatra region, in addition, the Foreland of the Carpathians in Poland is rich in low-temperature geothermal waters, both in Cenomanian sandstones and Middle Jurassic sandstones. The geothermal activity is manifested by thermal waters in boreholes situated between the towns of Wloszczowa, Myslenice and Tarnów. Here the Mesozoic waters occur 200 to 2000 m below the surface and their temperatures vary between 20 and 70 °C. The continuous artesian outflow of geothermal waters was observed in many wells during long-term tests. The maximum artesian outflow of fresh water was observed in the zone north of Cracow, i.e. 100 m3/h with a temperature of about 20 °C. The results of the analyses which were carried out on the Mesozoic formation confirmed considerable zonation and the existence of local constraints on the reservoir parameters which result from the characteristics of the deposited environment. A distinct relationship was also noted between the total thickness and other reservoir parameters. Moreover, a strong correlation was observed between the degree of water mineralization and the distance from the infiltration zone or depth at which the waters occurred. In the western zones, located close to the recharge areas, waters are fresh or nearly fresh and their temperatures are influenced by surface waters. Favourable conditions for the financial investment in geothermal energy in the Mesozoic Basin of this region are associated with the low mineralization (allowing for exploitation with a single well) and shallowness of the aquifers (i.e. low drilling costs). The paper presents results of analyses of the temperature characteristics of the Mesozoic formation, yields from existing wells and the energy potential of geothermal waters from the point of view of future geothermal projects.