Nu mer i cal 3D para met ric mod els of tem per a ture and ther mal gra di ent dis tri bu tion within the Pol ish Carpathians and the Carpathian Foredeep are con structed for the in ter val be tween ground level and the 160°C iso therm. The model con struc tion was pre ceded by de tailed anal y sis of over 500 ther mal logs from the area in ves ti gated and its clos est vi cin ity. This anal y sis showed that the ver ti cal changes in tem per a ture and ther mal gra di ent have a non-lin ear char ac ter with no reg u lar pat tern in the dis tri bu tion of the pa ram e ters mod elled, so a 3D mod el ing ap proach was cho sen as the most ap pro pri ate method for their quan ti ta tive de scrip tion. Fur ther more, stan dard iza tion of the ther mal logs was rec og nized as man da tory so the in flu ence of drill ing pro cess would be elim i nated. Among a broad ar ray of meth ods and their pre con di tions dis cussed, the Kukkonen-Szewczyk method was se lected for the data col lected in the study area. Mod el ing re sults show a close re la tionship be tween ther mal gra di ent, li thol ogy and petrophysical rock prop er ties as well as a cor re la tion be tween the dis tri bu tion of pos i tive ther mal anom a lies and yield of hy dro car bon ac cu mu la tions within the Carpathian Foredeep. The ac cu racy of the model has been as sessed as ~10%. The model was then used for dis cus sion of hy dro car bon gen er a tion and pre dic tion of for ma tion tem per a ture.

New seismic data and the completion of the K-1 petroleum exploratory well, located close to the axial zone of the Mogilno-Łódź Trough (Polish Lowlands) delivered new insight into local structural, tectonic, facial and thermal variability of this geological unit. In this paper, the two variants of 3D models (SMV1 and SMV2) of Permian-Mesozoic strata are presented for the salt pillow related Kłecko Anticline, while resources assessment was confined to the Rotliegend Enhanced Geothermal System (EGS) type reservoir, that is divided into Playa, Eolian and Fluvial facies-based complexes. Using very conservative assumptions on the methods of the EGS reservoir development, authors assessed that heat in place and technical potential for eolian sandstones are about 386 PJ and ca. 2814 kW, respectively, and for Fluvial 367 PJ and ca. 2850 kW in relation to the volume of 1 km3 at depths of about 5000 m b.s.l. The authors recommend for the further development of the Eolian complex because of its low shale content, influencing the high susceptibility to fracking. The presented research is the first Polish local resources assessment for an EGS reservoir in sedimentary Rotliegend, within thermal anomaly below the salt pillow, which is one of over 100 salt structures mapped in Poland.

The study evaluates the geothermal energy potential of two depleted oil and gas reservoirs representing two different lithostratigraphic formations—the carbonate formation of the Visean age from the basement of the Carpathian Flysch and the Rotliegend sandstone formation from the Eastern part of the Foresudetic Monocline, Poland. Advanced modeling techniques were employed to analyze the studied formations’ heat, storage, and transport properties. The obtained results were then used to calculate the heat in place (HIP) and evaluate the recoverable heat (Hrec) for both water and CO2 as working fluids, considering a geothermal system lifetime of 50 years. The petrophysical parameters and Hrec were subsequently utilized in the generalized c-means (GFCM) clustering analysis, which helped to identify the plays with the greatest geothermal potential within the studied formations. The central block emerged as the most promising area for the studied carbonate formation. It exhibited significant potential for heat production, with Hrec values of approximately ~4036 and 932 MW when H2O and CO2 were used as working fluids, respectively. The central block has three wells that can be easily adapted for geothermal production. The area, however, may require permeability enhancement techniques to increase reservoir permeability. Two prospective zones were determined for the analyzed Rotliegend sandstone formation: one in the NW region and the other in the SE region. In the NW region, the estimated Hrec was 233,855 MW and 44,018 MW, while in the SE region, it was 257,457 MW and 48,231 MW, using H2O and CO2 as working fluids, respectively. Both areas have high porosity and permeability, providing good storage and transport properties for the working fluid, and abundant wells that can be configured for multiple injection-production systems. When comparing the efficiency of geothermal systems, the water-driven system in the Visean carbonate formation turned out to be over four times more efficient than the CO2-driven one. Furthermore, in the case of the Rotliegend sandstone formation, it was possible to access over five times more heat using water-driven system.