Thermal properties of rocks from deep boreholes in Poland in terms of obtaining geothermal energy from enhanced geothermal systems

Abstract

In the case of unconventional geothermal systems, the thermal conditions are decisive, i.e. heat flux and temperature at a certain depth, and the physical properties of rocks, their susceptibility to fracturing, etc., which should be determined on a local scale. The work carried out was aimed at determining the basic thermal parameters of rocks, i.e.: effusivity, thermal conductivity and diffusivity, basing on tests of samples taken from boreholes, representing selected geothermal structures in Poland. Both high-temperature structures (100-135 °C) recognized up to a depth of about 3,800 m within the Fore-Sudetic Monocline and up to about 3,000 m in the Szczecin Synclinorium and the Leba Elevation, as well as medium-temperature structures (60-90 °C), occurring at depth 2,000- 2,500 m (Warszawa Synclinorium, Lublin Synclinorium), were analyzed. Some samples representing low temperature structures (with temperatures below 60 °C), such as Lublin synclinorium and Podlasie-Lublin elevation from depths from about 1,000 to 1,500 m, were also analyzed. The tests of thermal parameters of rocks coupled with simulations showed, that the formations with the highest mean diffusivity and thermal conductivity values are characterized by the largest thermal penetration depth and smallest temperature drop. The research allowed to conclude that among the examined rocks, the Cambrian sandstones of the Leba Elevation and the Zechstein dolomites of the Fore-Sudetic monocline are characterized by the most appropriate parameters from the point of view of obtaining geothermal energy from the enhanced geothermal systems in Poland. Cited as: Labus, K., Labus, M., Leśniak, G. Thermal properties of rocks from deep boreholes in Poland in terms of obtaining geothermal energy from enhanced geothermal systems. Advances in Geo-Energy Research, 2023, 8(2): 76-88. https://doi.org/10.46690/ager.2023.05.02