When identifying the conditions required for the sustainable and long-term exploitation of geothermal resources it is very important to assess the dynamics of processes linked to the formation, migration and deposition of particles in geothermal systems. Such particles often cause clogging and damage to the boreholes and source reservoirs. Solid particles: products of corrosion processes, secondary precipitation from geothermal water or particles from the rock formations holding the source reservoir, may settle in the surface installations and lead to clogging of the injection wells. The paper proposes a mathematical model for changes in the absorbance index and the water injection pressure required over time. This was determined from the operating conditions for a model system consisting of a doublet of geothermal wells (extraction and injection well) and using the water occurring in Liassic sandstone structures in the Polish Lowland. Calculations were based on real data and conditions found in the Skierniewice GT-2 source reservoir intake. The main product of secondary mineral precipitation is calcium carbonate in the form of aragonite and calcite. It has been demonstrated that clogging of the active zone causes a particularly high surge in injection pressure during the fi rst 24 hours of pumping. In subsequent hours, pressure increases are close to linear and gradually grow to a level of ~2.2 MPa after 120 hours. The absorbance index decreases at a particularly fast rate during the fi rst six hours (Figure 4). Over the period of time analysed, its value decreases from over 42 to approximately 18 m3/h/MPa after 120 hours from initiation of the injection. These estimated results have been confi rmed in practice by real-life investigation of an injection well. The absorbance index recorded during the hydrodynamic tests decreased to approximately 20 m3/h/MPa after 120 hours.
The paper presents a review of the geological and hydrogeological data of the Lower Cretaceous aquifer in the Polish Lowlands and discusses the possibilities for the utilisation of geothermal water resources in existing and new district heating systems. Based on experience related to the use of thermal waters in existing geothermal systems, and using data from the literature, assessments have been made of the energy and environmental effects of the application of low-enthalpy geothermal resources from the Lower Cretaceous aquifer as a source of heat for urban district heating systems. The authors concluded that the implementation of such solutions could result in the production of approximately 4 PJ of geothermal energy annually. To date, these resources have only been developed in three locations—Mszczonów, Uniejów and Poddębice—with the total amount of energy generated annually reaching 100 TJ/year. Similar district heating networks in 120 nearby localities have been also identified. Here, specified geological and hydrogeological conditions enable the extraction of heat from the investigated Lower Cretaceous aquifer, with the aim of using this for heating purposes. To achieve this goal, multiple measures are required, including the following: raising public awareness through appropriate education programmes aimed at the youngest school children; systemic, efficient energy management measures at the central, regional and local levels, and providing financial support and ensuring regulations and laws aimed at improving the development of geothermal resources.
a b s t r a c tThe article presents the results of modelling geothermal conditions in the Lower Triassic sedimentary formations of the Polish Lowland area (central Poland) and an electricity production model for a prospective EGS (Enhanced Geothermal System) installation situated in that area. On the basis of comprehensive analyses, this area has been selected as optimal for EGS plants operating in sedimentary complexes in the Polish Lowland. Numerical modelling was conducted using TOUGH2 code and served to evaluate the energy performance of the prospective EGS plant operating in the area. Modelling results indicate that the energy performance of the EGS plant is strongly dependent on the volume and permeability of the artificially fractured zone and its net power is dependent on the power consumed by the circulating pumps that stimulate the flow. For the top layer of the Buntsandstein formation at a depth of ca. 5500 m and temperature of ca. 170 C, the modelled net power of an EGS plant operating in the area ranged from 2 to 3 MW for a circulation of 200 m 3 /h, and at 100 m 3 /h it ranged from 1.3 to 1.6 MW depending on the permeability and volume of the fractured zone used for the circulation in question.
IntroductionBorehole reconstruction involves a number of technical and research measures which ultimately result in well and reservoir conditions that enable their commercial use. In terms of geothermal needs and goals, borehole reconstruction can be carried out in three areas, i.e.:• the reconstruction of a damaged or decommissioned well; • the restoration of an existing well; • the repair of entire or part of an existing well.Further, borehole reconstruction can be complete or partial. AbstractThe beginnings of geothermal implementation research in Poland date back to 1989-1993 when the Mineral and Energy Economy Research Institute of the Polish Academy of Sciences (MEERI PAS) launched the first geothermal installation in the Podhale region, using the reconstructed Bańska IG-1 well. The knowledge acquired during these 30 years has highlighted the importance of geothermal energy-among other things, borehole reconstruction operations and the need for their further refinement. The technologies developed have been used in virtually all geothermal heating systems operating in Poland. Examples of successful reconstruction work include the Bańska IG-1 and Biały Dunajec PAN-1 wells operated by the PEC Geotermia Podhalańska S.A. geothermal company. The Mszczonów IG-1 well, which is operated by the Geotermia Mazowiecka S.A. heating company, has also undergone considerable work almost 24 years after its complete closure. Reconstruction processes can also be important in adapting existing wells for geothermal purposes. After World War II, more than 8000 boreholes deeper than 1000 m were drilled in Poland. They were primarily made for the purpose of geological surveys and hydrocarbon exploration. Some of these boreholes can be adapted for operation in geothermal systems. The paper presents selected methods of reconstructing abandoned, disused (not abandoned and not decommissioned) or damaged boreholes in order to use them in the geothermal water extraction process. Four examples of borehole reconstruction, designed and carried out with the participation of MEERI PAS in Kraków, are discussed in more detail.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.