Anna Sowiżdżał

Modelling geothermal conditions in part of the Szczecin Trough – the Chociwel area

Abstract The Chociwel region is part of the Szczecin Trough and constitutes the northeastern segment of the extended Szczecin-Gorzów Synclinorium. Lower Jurassic reservoirs of high permeability of up to 1145 mD can discharge geothermal waters with a rate exceeding 250 m3/h and temperatures reach over 90°C in the lowermost part of the reservoirs. These conditions provide an opportunity to generate electricity from heat accumulated in geothermal waters using binary ORC (Organic Rankine Cycle) systems. A numerical model of the natural state and exploitation conditions was created for the Chociwel area with the use of TOUGH2 geothermal simulator (i.e., integral finite-difference method). An analysis of geological and hydrogeothermal data indicates that the best conditions are found to the southeast of the town of Chociwel, where the bottom part of the reservoir reaches 3 km below ground. This would require drilling two new wells, namely one production and one injection. Simulated production with a flow rate of 275 m3/h, a temperature of 89°C at the wellhead, 30°C injection temperature and wells being 1.2 km separated from each other leads to a small temperature drop and moderate requirements for pumping power over a 50 years’ time span. The ORC binary system can produce at maximum 592.5 kW gross power with the R227ea found as the most suitable working fluid. Geothermal brine leaving the ORC system with a temperature c. 53°C can be used for other purposes, namely mushroom growing, balneology, swimming pools, soil warming, de-icing, fish farming and for heat pumps.

3D Static Models as a Tool to Indicate Prospective Geological Structures for EGS in Sedimentary Rocks of Central Poland

The paper illustrates the results of 3D static modeling in sedimentary cover of the Polish lowlands and their suitability for characterizing Enhanced Geothermal System. The resultant basic structural framework of the EGS systems model covers an area of ca. 36000 km2. It is composed of 13 structural horizons, starting from the base of the Carboniferous strata up to the top of the Cretaceous succession, and contains 12 stratigraphic zones being equivalents of stratigraphic epochs. The results of structural and parametric modeling were finally presented as maps of average parameters and effective thicknesses, superimposed on maps of temperatures related to the tops of the mapped zones. Superposition of depth, thermal and reservoir criteria allow to indicate spatial extent of hypothetically favorable conditions for EGS/HDR development. The results of static modeling indicate that relatively favourable conditions for EGS systems development can be expected locally of Upper Rotliegend and Carboniferous reservoir. The most important problem referring to practically the whole area of interest is lack of good quality data.

Analyses of permeability and porosity of sedimentary rocks in terms of unconventional geothermal resource explorations in Poland

Abstract Petrophysical investigations are fundamental to natural resource exploration. In order to recognise the geothermal potential of sedimentary rocks in central Poland, 259 samples were collected from prospective deep-lying geothermal reservoirs. Parameters measured include bulk density, skeletal density, effective porosity, permeability, average pore diameter and specific surface. Results indicate that at great depths (mostly > 3,000 m below surface) sedimentary rocks show low values of porosity (mainly less than 5%) and permeability (only sporadically in excess of 1 md). These values call for a petrothermal use of reservoirs, for which an Enhanced Geothermal System (EGS) was developed. Reservoirs suited for the EGS are Carboniferous and Lower Triassic sandstones in the central part of Poland (Mogilno-Łódź Trough region and a small part of the Kujawy Swell and Fore-Sudetic regions). In addition, Carboniferous limestones in this area are potentially prospective.

The Energy Efficiency in a Commune. The Formal and Legal Requirements with Examples of a Good Practice

The energy efficiency together with the utilization of renewable energy resources are considered to be crucial parts of a transition to the low-carbon economy. Their development can involve various administrative levels, nevertheless, the tremendous potential is assigned to a commune. Thus, the paper presents the most important formal and legal regulations that have an influence on the improvement of the energy efficiency, considering mainly obligations arising directly from the Energy Law and the Energy Efficiency Act. Moreover, the importance of the effective energy management in a commune is strongly emphasized, as the key for the low-carbon and resource-efficient economy. In the instance of the development of the energy efficient economy, many benefits are pointed out, and in case of the collaboration between neighboring communes, they are often multiplied at that. The particular examples of projects that have been realized in Polish communes of Niepolomice (the installation of renewable energy systems for public and private buildings) and Charasznica (the modernization of the street lighting), together with the indication of costs and profits relevant to the investment in the energy efficiency, as well as the environmental and socio-economic aspects, are also presented.

Geophysical Methods in the Recognition of Geothermal Resources in Poland—Selected Examples

Seismic and magnetotelluric methods are most frequently used under Polish conditions predominant by low temperature geothermal associated with sedimentary complexes and crystalline rocks. The application of those methods to recognizing of geological structure and differentiation of petrophysical parameters is presented in the work. The examples of hydrogeothermal investigation in sedimentary complexes of Polish Lowlands and crystalline rocks of Sudetes area are used. The results demonstrate that seismic structural interpretation and seismic inversion can effectively support the selection of areas optimal for future geothermal investments inside sedimentary complexes. Simultaneously, such methods can be important for determination of hydrogeothermal parameters of particular aquifer. Results of seismic inversion can be applied to porosity estimations. Within the crystalline rocks non—seismic methods are usually used, mainly different variants of magnetotelluric method. This method allows to recognize resistivity distribution in geological medium. Geothermal reservoirs inside crystalline rocks are usually connected with fractured tectonic zones conducting warm and mineralized water. Such zones appear as low resistivity at the background of predominant, radically high resistivity rocks.

Geothermal Energy in Poland. Selected Aspects of Geothermal Resources Development

Geothermal energy is an ecological, renewable energy source. However, its effective utilization depends on many different factors, related to (i) hydrogeothermal conditions of the region, (ii) proper design of the investment and (iii) formal and legal framework. The characteristic features of geothermal investments are high investment expenditures resulted mostly from high drilling costs of geothermal wells. Hence, the critical element facilitating the utilization of geothermal energy is the financial support in the form of government grants or loans. Recently, geothermal resources in Poland are relatively underdeveloped as only 6 geothermal plants are in operation together with spa-and-wellness, and therapeutical centers. Geothermal potential confirmed by extended scientific studies is much higher, particularly in the Polish Lowlands where both the Lower Cretaceous and the Lower Jurassic aquifers reveal favourable hydrogeothermal conditions suitable for effective development of geothermal resources. The following paper presents the currently recognized geological conditions, which control the size of geothermal resources and macroeconomic determinants (financial support, energy prices), which control the operation of geothermal installations in Poland.

Selected technical aspects of well construction for geothermal energy utilization in Poland

Abstract Geothermal resources have been used in Poland since the 90s of the last century. Since then, several geothermal heating plants, recreation and balneological centers have been operated. Accessing geothermal resources is possible due to deep boreholes that are either brand-new wells or old but revitalized petroleum and/or exploratory wells. In this case, the construction of production and injection wells is of significant importance. The utilization of deep geothermal energy resources is strongly dependent on the binding domestic law regulations – primarily in case of acquiring the concession enabling an execution of geological and drilling works, and subsequently a proper exploitation. The paper presents the current state of development of the geothermal energy sector in Poland, indicating examples of exploitation systems based on deep boreholes. Furthermore, the constructions of existing wells are discussed extensively. The existing examples of old but reconstructed wells in Poland, are characterized. The importance of national law and its influence on the development of a geothermal investment is highlighted, as well.

The influence of variability of calculation grids on the results of numerical modeling of geothermal doublets - an example from the Choszczno area, north-western Poland

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.