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Underground hydrogen storage facilities require cushion gas to operate, which is an expensive one-time investment. Only some of this gas is recoverable after the end of UHS operation. A significant percentage of the hydrogen will remain in underground storage as non-recoverable cushion gas. Efforts must be made to reduce it. This article presents the results of modeling the cushion gas withdrawal after the end of cyclical storage operation. It was found that the amount of non-recoverable cushion gas is fundamentally influenced by the duration of the initial hydrogen filling period, the hydrogen flow rate, and the timing of the upconing occurrence. Upconing is one of the main technical barriers to hydrogen storage in deep saline aquifers. The ratio of non-recoverable cushion gas to cushion gas (NRCG/CG) decreases with an increasing amount of cushion gas. The highest ratio, 0.63, was obtained in the shortest 2-year initial filling period. The lowest ratio, 0.35, was obtained when utilizing the longest initial filling period of 4 years and employing the largest amount of cushion gas. The presented cases of cushion gas recovery can help investors decide which storage option is the most advantageous based on the criteria that are important to them. [ABSTRACT FROM AUTHOR]

nowadays, hydrogen is considered a potential successor to the current fossil-fuel-based energy. within a few years, it will be an essential energy carrier, and an economy based on hydrogen will require appropriate hydrogen storage systems. Due to their large capacity, underground geological structures (deep aquifers, depleted hydrocarbon fields, salt caverns) are being considered for hydrogen storage. their use for this purpose requires an understanding of geological and reservoir conditions, including an analysis of the preparation and operation of underground hydrogen storage. the results of hydrogen injection and withdrawal modeling in relation to the deep Lower Jurassic, saline aquifer of the Konary geological structure (trap) are presented in this paper. A geological model of the considered structure was built, allowable pressures were estimated, the time period of the initial hydrogen filling of the underground storage was determined and thirty cycles of underground storage operations (gas injection and withdrawal) were simulated. the simulations made it possible to determine the essential parameters affecting underground hydrogen storage operation: maximum flow rate of injected hydrogen, total capacity, working gas and cushion gas capacity. the best option for hydrogen storage is a two-year period of initial filling, using the least amount of cushion gas. Extracted water will pose a problem in relation to its disposal. the obtained results are essential for the analysis of underground hydrogen storage operations and affect the economic aspects of uHS in deep aquifers. [ABSTRACT FROM AUTHOR]

This paper presents the results of an analysis of selected seismic profiles (reflection and refraction data) from the Radom-Lublin area aimed at obtaining a better understanding of geological structure and the identification of hydrocarbon deposits. To accurately reproduce the seismic reflection covering the sub-Permian formations, seismic cross sections were interpreted based on effective reflection coefficients (ERC). In interpreting the results, reference was made to the results of studies of the area using other geophysical methods. The results of these studies made it possible to obtain new information on the geology and structure of the Paleozoic complex of the Radom-Lublin area and its relationships with the basement tectonics. The structural arrangement of Carboniferous and Devonian formations as well as older Silurian, Ordovician, and Cambrian series were recognized. Selected significant tectonic and lithological discontinuities and the nature and directions of their course were characterized. Special attention was given to regional tectonic zones: the Skrzynno Fault, the Ursynów-Kazimierz fault zone and the Kock zone. The use of ERC methodology made it possible to define the boundaries of lithostratigraphic units in Carboniferous, Devonian, and older formations. The obtained results can be used to assess hydrocarbon accumulation in the area under consideration. [ABSTRACT FROM AUTHOR]

The subject of this study is the analysis of influence of capillary threshold pressure and injection well location on the dynamic CO 2 and H 2 storage capacity for the Lower Jurassic reservoir of the Sierpc structure from central Poland. The results of injection modeling allowed us to compare the amount of CO 2 and H 2 that the considered structure can store safely over a given time interval. The modeling was performed using a single well for 30 different locations, considering that the minimum capillary pressure of the cap rock and the fracturing pressure should not be exceeded for each gas separately. Other values of capillary threshold pressure for CO 2 and H 2 significantly affect the amount of a given gas that can be injected into the reservoir. The structure under consideration can store approximately 1 Mt CO 2 in 31 years, while in the case of H 2 it is slightly above 4000 tons. The determined CO 2 storage capacity is limited; the structure seems to be more prospective for underground H 2 storage. The CO 2 and H 2 dynamic storage capacity maps are an important element of the analysis of the use of gas storage structures. A much higher fingering effect was observed for H 2 than for CO 2 , which may affect the withdrawal of hydrogen. It is recommended to determine the optimum storage depth, particularly for hydrogen. The presented results, important for the assessment of the capacity of geological structures, also relate to the safety of use of CO 2 and H 2 underground storage space. • Capillary threshold pressure as an important factor for UHS and CCS is introduced. • The dynamic storage capacity of CO 2 and H 2 at different well locations is estimated and compared. • Dynamic capacity maps of the CO 2 and H 2 as important element of storage assessment are presented. • Variable impact of the fingernig effect on the underground storage of CO 2 and H 2 is shown. [ABSTRACT FROM AUTHOR]

The rational management of underground space, especially when used for various purposes, requires a comprehensive approach to the subject. The possibility of using the same geological structures (aquifers, hydrocarbon reservoirs, and salt caverns) for the storage of CH4, H2 and CO2 may result in conflicts of interest, especially in Poland. These conflicts are related to the use of the rock mass, spatial planning, nature protection, and social acceptance. The experience in the field of natural gas storage can be transferred to other gases. The geological and reservoir conditions are crucial when selecting geological structures for gas storage, as storage safety and the absence of undesirable geochemical and microbiological interactions with reservoir fluids and the rock matrix are essential. Economic aspects, which are associated with the storage efficiency, should also be taken into account. The lack of regulations setting priorities of rock mass development may result in the use of the same geological structures for the storage of various gases. The introduction of appropriate provisions to the legal regulations concerning spatial development will facilitate the process of granting licenses for underground gas storage. The provisions on area based nature protection should take other methods of developing the rock mass than the exploitation of deposits into account. Failure to do so may hinder the establishment of underground storage facilities in protected areas. Knowledge of the technology and ensuring the safety of underground gas storage should translate into growing social acceptance for CO2 and H2storage. [ABSTRACT FROM AUTHOR]

Based on the reinterpretation of gravimetric, magnetic, seismic and magnetotelluric studies, new features of the sub-Permian basement in the area between the Dolsk Fault and the Middle Odra Fault, SW Poland, are identified. Among numerous faults and lineaments indicated in the article, those limiting both the Wolsztyn-Pogorzela High and a positive anomaly in the Lower Silesian Basin, as well as the faults in the vicinity of the Odra River are particularly prominent. N-S oriented structural elements are also visible in the gravity image. One of them separates the Pogorzela High from the Wolsztyn High. In light of the obtained results, according to refraction seismic surveys, the Polish equivalent to the Mid-German Crystalline Rise is located farther north from commonly accepted position within the Middle Odra Metamorphic Complex. The study results, supported by data from the neighboring area of Germany, may be important for further prospecting for sediment-hosted Cu and other metal deposits. The reprocessing of archival geophysical data using method of effective reflection coefficients (ERC) enabled the creation of more accurate structural model of ore series within the area of the Nowa Sól deposit in SW Poland. In terms of mineral resource prospects, this creates the possibility of applying new results from the study area to the similar zones in the corresponding part of Germany, which is the area between the phyllite zone and the Harz Mountains hosting very diverse and rich mineralization. [ABSTRACT FROM AUTHOR]

The objective of the study was determination of experiment-induced alterations and changes in the properties of reservoir rocks and sealing rocks sampled from potential reservoir for CO2. In the experiment, rocks submerged in brine in specially constructed reactors were subjected to CO2 pressure of 6 MPa for 20 months at room temperature. Samples of Lower Jurassic reservoir rocks and sealing rocks (sandstones, claystones, and mudstones) from the Zaosie Anticline (central Poland) were analysed for their petrophysical properties (specific surface area, porosity, pore size and distribution) before and after the experiment. Comparison of the ionic composition the brines before and after the experiment demonstrated an increase in total dissolved solids as well as the concentration of sulphates and calcium ions. This indicates partial dissolution of the rock matrix and the cements. As a result of the reaction, the properties of reservoir rocks did not changed significantly and should not affect the process of CO2 storage. In the case of the sealing rocks, however, the porosity, the framework density, as well as the average capillary and threshold diameter increased. Also, the pore distribution in the pore space changed in favour of larger pores. The reasons for these changes could not be explained by petrographic characteristics and should be thoroughly investigated. [ABSTRACT FROM AUTHOR]