The Podhale Low-Enthalpy system (S-Poland): Geothermal Characteristics

Abstract

The Podhale geothermal system belongs to the most interesting and prospective in Poland and Europe with respect to reservoir conditions and utilization. Since the 1980s it has been the subject of an intense activity aimed at wide direct use. The system was formed within the particular sector of the Carpathian arc, along the former subduction zone active during the Alpine orogenesis. It has long geological evolution (Triassic-rec.) while the present geothermal conditions were created during the Neogene and Quaternary. It makes a good example of low enthalpy system with complex geological evolution greatly influencing its present state. Many features of the classical geothermal systems are also recognized within the Podhale.

In the paper, there are given geological, tectonical, reservoir, thermal features, main evolution stages and their relationships which control the system. Its main advantages important in view of exploitation are indicated.

Geothermal aquifers occur mostly within the Mesozoic and Middle Eocene carbonates. Secondary fractured permeability is of main importance in water circulation and high production from the wells. The TDS is low, not creating serious exploitation problems. The reservoir temperatures reach up to 80-100oC (depths of 2-3 km), i.e. markeably higher than resulted from the local geothermal gradient. The aquifers and heat convection reflect as a distinct thermal blanket effect within the overlying caprock. Geothermal conditions have been recorded in hydrothermal minerals. The system also possesses some surface manifestations.

Careful study of the Podhale system is a key for proper exploitation, and planned wide activity. It makes an excellent subject of may further researches.