The paper presents results of geothermal projects carried out in the last 23 years by the interdisciplinary research team at the AGH University of Science and Technology, in cooperation with numerous scientific institutions, published in the form of geothermal atlases in different parts of Poland. For many years, the Department of Fossil Fuels at the Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, has conducted the fundamental research and implementation work, aiming at the selection of optimum areas for utilization of geothermal waters and energy. Over the years, a methodology of estimation of geothermal resources with use of advanced techniques and numerical modeling has been developed. Recapitulation of the studies of the occurrence and utilization of geothermal waters and energy within geological units of the Polish Lowlands, Carpathians and Carpathian Foredeep has been reflected in seven Atlases. The Atlases represent a result of interdisciplinary, constructive cooperation of specialists from various, often remote fields of knowledge, fundamental and technological in nature, including: geologists, geophysicists, hydrogeologists, geochemists, drilling engineers, heat engineers, and many other specialists. The Atlases enable the selection of the most promising areas for utilization of geothermal waters and energy in Poland. The best geothermal conditions are predicted in the Polish Lowlands and Podhale region although in many areas of the Carpathians and the Carpathian Foredeep favorable geothermal conditions also occur.

The geothermal waters constitute a specific type of water resources, very important from the point of view of their thermal energy potential. This potential, when utilized, supplies an ecological and renewable energy, which, after effective development, brings many environmental, social, and industrial benefits. The key element of any geothermal investment is the proper location of geothermal installation, which would guarantee the relevant hydrogeothermal parameters of the water intake. Hence, many studies and analyses are carried out in order to characterize the reservoir parameters, including the integrated geophysical methods. For decades, the geophysical surveys have been the trusty recognition methods of geological structure and petrophysical parameters of rock formations. Thus, they are widely applied by petroleum industry in exploration of conventional and unconventional (shale gas/oil, tight gas) hydrocarbon deposits. Advances in geophysical methods extended their applicability to many other scientific and industrial branches as, e.g., the seismic survey used in studies of geothermal aquifers. The following paper presents the opportunities provided by seismic methods applied to studies of geothermal resources in the central Poland where the geothermal waters are reservoired in both the Lower Cretaceous and the Lower Jurassic sedimentary successions. The presented results are obtained from a network of seismic profiles. An important advantage of the seismic survey is that they may support the selection of an optimal location of geothermal investment and determination of the geometry of geothermal aquifer. Furthermore, the application of geophysical methods can significantly contribute to the reduction of estimation error of groundwater reservoir temperature.

Numerical models of geothermal doublet allows us to reduce the high risk associated with the selection of the most effective location of a production well. Furthermore, modeling is a suitable tool to verify possible changes in operational geothermal parameters, which guarantees liveliness of the system. An appropriate selection of software as well as the methodology used to generate numerical models significantly affects the quality of the obtained results. In this paper, the authors discuss the influence of such parameters as grid density and distance between wells on the efficiency of geothermal heating plant. The last stage of the analysis was connected with estimation of geothermal power potential for a hypothetical geothermal doublet. Numerical simulations were carried out using the TOUGH2 code, which applies the finite-difference method. The research was conducted in the Szczecin Trough area (NW Poland), based on archival data from Choszczno IG-1 well. The results demonstrated that in the studied case of the Choszczno region, the changes in the distance of boreholes can have a visible influence on obtained results; however the grid density of the numerical model did not achieve a significant impact on it. The results show the significant importance of numerical modeling aimed at increasing the efficiency of a potential geothermal heating plant.

In Poland, geothermal energy and waters are utilized in several geothermal plants as well as in balneological and recreation centers. The research projects run in last years aimed to recognize the geothermal potential in various regions of Poland. These projects were especially focused on selection of sites prospective for development of geothermal resources. For this purpose, various integrated exploration methods were applied to reduce the geological risk, which affects any design of geothermal installation. Among the convenient exploration tools are geophysical methods widely applied to the recognition of geological structure of the Earth and to petroleum exploration. Taking into account the Malanów area located in the Mogilno-Łódź Trough (central part of the Polish Lowlands), the authors present the opportunities provided by the usage of archival geophysical data for characterization of geothermal aquifer. The results demonstrate that geophysical methods can effectively support the selection of areas favorable for future geothermal investments. Simultaneously, such methods can be useful in determination of hydrogeothermal parameters of particular aquifer. In the study area, local depressions of the top surface of geothermal aquifer are known, which can be identified with the seismic data. Moreover, seismic inversion can be applied to porosity estimations of Lower Cretaceous aquifer. The most favorable reservoir properties occur in the NE part of the study area where the top surface of Lower Cretaceous formation is located at < 1500 m depth and in its marginal parts where this surface drops down to even 1900 m depth. Seismic data also indicate that the Lower Cretaceous aquifer remains tectonically undisturbed.

For many years, geothermal energy has been successfully used for both energy as well as balneological, healing, and recreational purposes. It should be emphasized that, along with the great interest in geothermal investments, the development of other economic sectors (i.e., tourism, cosmetology, food production, and many other sectors related directly or indirectly to geothermal waters) are also noted in this paper. That kind of development is seen both in regions where centers using geothermal energy are created, as well as in their immediate vicinity. An important aspect of the use of geothermal energy is also its positive impact on the environment by reducing the emission of pollutants that could end up in the environment as a result of using conventional energy sources, namely coal or natural gas. Given the high level of air pollution in Poland, according to data from the European Environment Agency, 12 Polish cities are among the 20 most polluted cities in Europe (data for 2021–2022), and this aspect seems to be key for achieving sustainability while maintaining economic balance. In this article, a new approach to the development of geothermal water utilization in the context of identifying and meeting the social needs of local communities in the Mogilno–Łódź Trough region is described.

The numerical modeling enables us to reduce the risk related to the selection of best localization of wells. Moreover, at the stage of production, modeling is a suitable tool for optimization of well operational parameters, which guarantees the long life of doublets. The thorough selection of software together with relevant methodology applied to generation of numerical models significantly improve the quality of obtained results. In the following paper, we discuss the impact of density of calculation grid on the results of geothermal doublet simulation with the TOUGH2 code, which applies the finite-difference method. The study area is located between the Szczecin Trough and the Fore-sudetic Monocline, where the Choszczno IG-1 well has been completed. Our research was divided into the two stages. At the first stage, we examined the changes of density of polygon calculation grids used in computations of operational parameters of geothermal doublets. At the second stage, we analyzed the influence of distance between the production and the injection wells on variability in time of operational parameters. The results demonstrated that in both studied cases, the largest differences occurred in pressures measured in production and injection wells whereas the differences in temperatures were less pronounced.