Upper Silesian Coal Basin Research Articles

Simulation of ground motion in a polish coal mine using spectral-element method

Mining seismic events have been associated with the mining of hard coal in the Upper Silesian Coal Basin in Poland for many years. These seismic events pose a threat to people working underground and cause damage to construction facilities on the surface. It is possible to predict seismic vibrations from mining seismic events using numerical calculations. One such method is the spectral element method (SEM). In this method, synthetic seismograms that enable the imaging of the full waveform are calculated. A complex mechanism of the source is assumed by applying the seismic moment tensor, which best reflects the balance of forces in the source. This paper presents the results of SEM modeling of ground motions of a seismic event which occurred on November 8, 2018, in the Budryk mine with a magnitude of 3.8 on the Richter scale. The modeling results show that even if the calculated synthetic seismograms do not fully correlate with real vibration registrations, it is possible to determine the peak values of seismic vibrations at any point in the model. This method can be a good complement to the analytical methods used to assess seismic hazard caused by mining seismic events.

Assessment of post-mining terrain suitability for economic use

Upper Silesian Coal Basin in Poland is subjected to underground mining for several hundreds of years. Due to intensive extraction, land surface has been widely transformed, causing a lot of mining damages. Of great importance is the issue of recovering the surface to its previous conditions after mining activity is finished. In specific conditions, a threat of mining damages may rest for several years after mine closure. In this paper, some chosen issues connected with assessment of post-mining terrain suitability for economic use have been discussed. Two important elements of such threat have been described: determining the possibility of discontinuous deformations creation and the evaluation of active subsidence process duration. In the introductory part of the paper some theoretical base has been given. Next, the example of probability assessment of sinkhole creation has been presented, together with determination of subsidence process cease time. For determination of subsidence process duration, own empirical formulas have been utilized. They can be used in cases, when there is a lack of survey results from the area of interest.

Research on the Processes of Injecting CO2 into Coal Seams with CH4 Recovery Using Horizontal Wells

The paper presents a research study on modeling and computer simulation of injecting CO2 into the coal seams of the Upper Silesian Coal Basin, Poland connected with enhanced coal bed methane (ECBM) recovery. In the initial stage of the research activities, a structural parameter model was developed specifically with reference to the coal-bearing formations of the Upper Carboniferous for which basic parameters of coal quality and the distribution of methane content were estimated. In addition, a lithological model of the overall reservoir structure was developed and the reservoir parameters of the storage site were analyzed. In the next stage of the research, the static model was supplemented with detailed reservoir parameters as well as the thermodynamic properties of fluids and complex gases. The paper discusses a series of simulations of an enhanced coalbed methane recovery process with a simultaneous injection of carbon dioxide. The analyses were performed using the ECLIPSE software designed for simulating coal seam processes. The results of the simulations demonstrated that the total volume of CO2 injected to a designated seam in a coal mine during the period of one year equaled 1,954,213 sm3. The total amount of water obtained from the production wells during the whole period of the simulations (6.5 years) was 9867 sm3. At the same time, 15,558,906 sm3 of gas was recovered, out of which 14,445,424 sm3 was methane. The remaining 7% of the extracted gas was carbon dioxide as a result of reverse production of the previously injected CO2. However, taking into consideration the phenomena of coal matrix shrinking and swelling, the total amount of injected CO2 decreased to approximately 625,000 sm3.

Correction to: Investigation of organic material self-heating in oxygen-depleted condition within a coal-waste dump in Upper Silesia Coal Basin, Poland.

The original publication of this paper contains a mistake.

Investigation of organic material self-heating in oxygen-depleted condition within a coal-waste dump in Upper Silesia Coal Basin, Poland.

Self-heating occurring was studied in the Bytom coal-waste dump using petrographic, mineralogical, and organic geochemical to assess the changes induced by heating on organic material and quantify-qualify the emitted gases. The distribution of geochemical markers such as n-alkanes, alkylbenzenes, alkylcyclohexanes, phenols, sulfurous compounds, and emitted gases in the waste dump is outlined. Heating of organic material there is indicated by high vitrinite random reflectance (Rr)% values that typically characterize samples with short-chain n-alkanes, alkylbenzenes, and alkylmethylbenzenes. Contents of minerals showing minor alterations are high with ~ 90% in burned-out samples. Inside the dump where temperatures can reach up to 700-1300°C and oxygen contents are significantly reduced, conditions favor coking. This situation is confirmed by the formation of enormous quantities of phenols and alkylbenzenes or by elevated amounts of H2 formed under low-oxygen conditions (pyrolysis). Aromatization, pyrolysis (thermal cracking), and oxidation are associated with the heating in the dump. Gases such as methane, ethane, propane, and ethylene formed during self-heating can serve as fuel for the fire inside the dump, in the process generating huge amounts of CO2.

An Assessment of the Formations and Structures Suitable for Safe CO2 Geological Storage in the Upper Silesia Coal Basin in Poland in the Context of the Regulation Relating to the CCS

The paper presents an analysis of the possible location of geological formations suitable for CO2 storage in the Upper Silesia Coal Basin, Poland. The range of the reservoir has been determined on the basis of an analysis of basic geological parameters, which determine the selection criteria for sites suitable for CO2 storage. A dynamic modelling of the CO2 distribution in the aquifer is presented. Based on the constructed model of migration, reactivity, and geochemical transport of CO2 in geological structures, it is possible to identify potential migration routes and escape sites of CO2 on the surface. The analysis of the technical and geological possibilities of CO2 storage was carried out according to the regulations of the complex Polish geological law, specifically in terms of sequestration possibilities in geological formations.

Mining exploitation forecasted effects caused by a hard coal extraction from a thick seam

Paper describes an example of underground mining exploitation which in a thick seam divided into a few layers has been conducted. It took place in the years 2013 – 2018 in the southern part of Poland, in the Upper Silesian Coal Basin and was carried out by the use of four, high longwalls with a roof rocks cave-in. In article a reprognosis of the mining exploitation impacts on a terrain surface has been done. For this purpose the EDN – OPN computer program was used. Extraction influences by the use of the Bialek’s formula for subsidence have been predicted. There the subsidence, inclinations and horizontal strains after the end of every exploitation stage have been calculated. Thanks to that it is possible to determine the expected range and size of exploitation impacts on a terrain surface and the objects located on it.

CH4 and CO2 IPDA Lidar Measurements During the Comet 2018 Airborne Field Campaign

Installed onboard the German research aircraft HALO, the integrated-path differential-absorption (IPDA) lidar CHARM-F measures weighted vertical columns of both greenhouse gases (GHG) below the aircraft and along its flight track, aiming at high accuracy and precision. Results will be shown from the deployment during the CoMet field campaign that was carried out in spring 2018, with its main focus on one of the major European hot spots in methane emissions: the Upper Silesian Coal Basin (USCB) in Poland. First analyses reveal a measurement precision of below 0.5% for 20-km averages and also low bias, which was assessed by comparison with in-situ instruments. The measurements flights were designed to capture individual CH4 and CO2 plumes from e.g. coal mine venting and coal-fired power plants, respectively, but also to measure large and regional scale GHG gradients and to provide comparisons with the Total Carbon Column Observing Network (TCCON). Many other different instruments, both airborne and ground-based, complemented the lidar measurements to provide a comprehensive dataset for model analyses. CHARM-F also acts as the airborne demonstrator for MERLIN, the “Methane Remote Lidar Mission”, conducted by the German and French space agencies, DLR and CNES, with launch foreseen in ~ 2024. In this context, the airborne lidar data are likewise important for mission support such as for e.g. algorithm development and improvement and, moreover, the CoMet mission was also an important step for MERLIN validation preparation.

Impact of secondary salinisation on the structure and diversity of oligochaete communities

Secondary salinisation has become one of the most important factors responsible for changes in the aquatic biota. Earlier research has focused on macroinvertebrates including oligochaetes in anthropogenically saline rivers and streams, but studies on oligochaetes in anthropogenically saline stagnant waters remain scarce. Therefore, this study was conducted to assess changes in the species composition as well as the abundance and biomass of oligochaete communities along a large salinity gradient in the anthropogenic inland water bodies located in the Upper Silesian Coal Basin (Southern Poland), which is one of the largest coal basins in Europe. Herein, a total of 27 oligochaete species including five alien species were assessed, namely,Potamothrix bavaricus,Potamothrix hammoniensis,Potamothrix moldaviensis,Psammoryctidesalbicola,andPsammoryctides barbatus. The results confirmed that the freshwater oligochaetes could tolerate elevated water salinity and showed highest densities and taxa richness in intermediate salinity. Moreover, the waters with the highest salinity had an extremely low number of oligochaete species. A salinity level above 2800 mg L−1led to significant loss of diversity of the oligochaetes, and consequently, these habitats were colonized by halotolerant species, especiallyParanais litoralis, whose abundance increased with increasing salinity gradient.

Burial and thermal history of the Upper Silesian Coal Basin (Poland) constrained by maturity modelling – implications for coalification and natural gas generation

Maturity modelling was carried out using basin and petroleum system modelling (BPSM) software in the lithologic sections of 17 wells of the Upper Silesian Coal Basin (Poland). The best fit between calculated and measured vitrinite reflectance (VR), porosity and density data was obtained by applying a thickness of eroded sedimentary overburden from 1700 m in the east to 4500 m in the west and relatively low to moderate heat flow values during the maximum late Carboniferous burial. These heat flow values were in the range 50–71 mW/m 2 , most likely owing to rapid deposition of molasse sediment that led to a downward deflection of the isotherms. The upper Carboniferous strata were heated to temperatures in the range c. 90–170 °C, which is in accordance with the moderate to high levels of thermal maturity of these rocks (c. 0.6–1.7%VR). The coal rank pattern was reached before the Variscan tectonic inversion at the transition between the Carboniferous and the Permian (c. 300 Ma). This coalification level was not overprinted by any later thermal processes. The coalification resulted in the generation of natural gases. The upper Carboniferous strata are characterized by early to late phases of hydrocarbon generation. The kerogen transformation ratio (c. 5–75%TR) values vary across the basin. Most coals generated significant amounts of hydrocarbons, which reached over 80 mg of methane per gram of total organic carbon. Although most hydrocarbons generated most likely were lost during the intense post-Variscan exhumation, the hydrocarbon potential of the basin is still substantial.

Influence of Humidity on the Energy of Specific Strain in the Process of Loading Sedimentary Rocks

Abstract This article presents the results of tests on the energy properties of sedimentary rocks in the Upper Silesian Coal Basin. The rocks were tested both in an air-dry state and in a water saturation state. Samples of sedimentary rocks were collected from boreholes drilled in the underground workings of coal mines located within the area of the city of Jastrzębie, in the areas of the Chwałowice Trough and Rybnik Trough (south-western part of the Upper Silesian Coal Basin) and in the Main Trough. Influence of saturation condition on the values of the tested energy parameters was observed. The values of elastic energy and dissipated energy obtained for the samples tested in water saturation were lower compared to the values obtained for samples tested in air-dry state. As observed, an increase in the values of the given types of specific energy corresponds to an increase in the uniaxial compression strength in air-dry state and in water saturation state. Results of the tests are original and they can be applied while analysing the possibility of the occurrence of some dynamic phenomena and hazards in mine workings in Carboniferous rock mass in the Upper Silesian Coal Basin, caused by mining operations.

Tests to Ensure the Minimum Methane Concentration for Gas Engines to Limit Atmospheric Emissions

During the extraction of hard coal in Polish conditions, methane is emitted, which is referred to as ‘mine gas’. As a result of the desorption of methane, a greenhouse gas is released from coal seams. In order to reduce atmospheric emissions, methane from coal seams is captured by a methane drainage system. On the other hand, methane, which has been separated into underground mining excavations, is discharged into the atmosphere with a stream of ventilation air. For many years, Polish hard coal mines have been capturing methane to ensure the safety of the crew and the continuity of mining operations. As a greenhouse gas, methane has a significant potential, as it is more effective at absorbing and re-emitting radiation than carbon dioxide. The increase in the amount of methane in the atmosphere is a significant factor influencing global warming, however, it is not as strong as the increase in carbon dioxide. Therefore, in Polish mines, the methane–air mixture captured in the methane drainage system is not emitted to the atmosphere, but burned as fuel in systems, including cogeneration systems, to generate electricity, heat and cold. However, in order for such use to be possible, the methane–air mixture must meet appropriate quality and quantity requirements. The article presents an analysis of changes in selected parameters of the captured methane–air mixture from one of the hard coal mines in the Upper Silesian Coal Basin in Poland. The paper analyses the changes in concentration and size of the captured methane stream through the methane capturing system. The gas captured by the methane drainage system, as an energy source, can be used in cogeneration, when the methane concentration is greater than 40%. Considering the variability of CH4 concentration in the captured mixture, it was also indicated which pure methane stream must be added to the gas mixture in order for this gas to be used as a fuel for gas engines. The balance of power of produced electric energy in gas engines is presented. Possible solutions ensuring constant concentration of the captured methane–air mixture are also presented.

Distribution of methane and carbon dioxide concentrations in the near-surface zone over regional fault zones and their genetic characterization in the Pszczyna-Oświęcim area (SE part of the Upper Silesian Coal Basin, Poland)

The objective of this paper was to characterize the variability of methane (CH4) and carbon dioxide (CO2) concentrations in the near-surface zone, measured along 4 selected sampling lines positioned perpendicularly to regional fault zones, in the SE part of the Upper Silesian Coal Basin (USCB), Poland. This way it was possible to check the migration activity of these gases to the surface through low-permeable Miocene strata. It was also possible to evaluate the applicability of surface geochemical survey methodology to the identification of potential accumulations of free natural gas in the topmost parts of the Carboniferous formations in the USCB. The results of 319 soil-gas samples were supported by stable isotope analyses and related to the geological setting and the distribution of methane potential at various depths. Moreover, the sampling included the area of the closed and remediated Andrzej VII mining shaft, where 5 soil-gas samples were taken. Additionally, gas flux was evaluated at 3 measurement points at which increased gas concentrations were detected. The maximum concentrations of CH4 and CO2 in soil gases were 15.4 and 9.39 vol%, respectively. Soil gases contain both thermogenic and microbial CH4 and CO2 that migrated from secondary and primary gas zones within the Pennsylvanian coal-bearing strata. In some sites, CO2 was also generated by the oxidation of soil organic matter and/or CH4 in a near-surface zone. Anomalous CH4 concentrations were generally found over elevated fragments of erosional structures of Carboniferous coal-bearing formations. This indicates the presence of free CH4 accumulations beneath the Miocene overburden. However, the surface anomalies did not always correlate with the zones of CH4 secondary accumulations. Anomalous concentrations of CH4 and CO2 correlated with the regional fault zones that cut through the Carboniferous formations. This indicates the potential presence of fault traps saturated with free CH4 in the upper parts of Carboniferous formations. Relatively low values were observed for both CH4 and CO2 emissions (maximum: 25 and 4320 mg m−2 d−1, respectively). This suggests relatively low dynamics of gas migration from the depth to the soil zone.

Burial and thermal history modelling of the Upper Carboniferous strata based on vitrinite refl ectance data from Bzie-Dębina-60 borehole (Upper Silesian Coal Basin, southern Poland)

Integrated modeling of the coal rank in the Upper Carboniferous sediments of the BzieDebina-60 borehole from SW of the Upper Silesian Coal Basin was performed based on a new vitrinite reflectance measurements from the Westphalian A. Microscopic investigations of Westphalian samples in the Bzie-Debina-60 well have shown that organic matter is dominated by vitrinite maceral group. The coal rank in the well shows an increase with depth. The mean vitrinite reflectance values in these samples range from 0.76 to 1.07 %. One-dimensional forward modelling of thermal maturity in the Bzie-Debina-60 borehole section has been performed in order to explain the burial and thermal history. The maximum temperature (c. 145 °C) causing the coalification occurred in the Latest Carboniferous (c. 300 Ma). These processes were likely related to signifi cant late Variscan burial heating in this area as indicated by previous authors.

Polish underground coal mines as point sources of methane emission to the atmosphere

The Upper Silesian Coal Basin in Poland is one of the major European hotspots of CH4 release. Until now, no data concerning short-term CH4 emissions from coal mines have been accessible worldwide. They are available only on a yearly timescale. No values are provided on a higher temporal scale, that’s why the measurements presented here are of great importance. This paper discusses short-term CH4 emissions from ventilation shafts of three mining fronts (Mf) divided into two periods. The concentrations of CH4 in shafts varied from 0.05 to 0.4 %. The highest levels occurred in Shaft IV (Mf I) and Shaft VI (Mf II): from 0.15 to 0.38 % (Period 1). These values correspond to emission levels ranging from 27 to 75 m3/min (Shaft IV) and from 18 to 40 m3/min (Shaft VI). In Period 2, the highest concentrations of CH4 occurred in Shaft VI (Mf II and III): from 0.2 to 0.4 %. The most significant CH4 emissions were recorded for Shaft VI (Mf II) and ranged from 29 to 54 m3/min. Presented data have been used to validate the measurements obtained in the CoMet campaign, which aimed at verifying the sensitivity of the test equipment operating from aircraft. During the test flights of HALO in 2015, the CoMet team achieved a remarkable consistency of measurements conducted with airborne equipment (26 ± 3m3/min) and the emission data (24.34 m3/min), for Shaft VI (Mf II). The analysed short-term data for individual shafts are more reliable and can improve CH4 flux estimates during the CoMet campaign in 2018.

Geology and thermal maturity of Namurian deposits in the Němčičky Sub-basin as the South-eastern continuation of the Upper Silesian Coal Basin (Czech Republic)

The southernmost documented occurrences of Namurian coal-bearing strata can be found in the Němčičky area, SE Moravia, that is considered to be the southern continuation of the Upper Silesian Coal Basin. Since the south-eastern Moravia belongs to the most prospective areas in terms of hydrocarbon exploration and production in the Czech Republic and Namurian deposits are considered to be one of the potential source rocks, there was a systematic evaluation of the southernmost occurrence of coal-bearing Carboniferous deposits in the Czech Republic during the hydrocarbon exploration within the area with regard to the regional geological setting and thermal maturity. 2D and high-quality 3D seismic surveys were used for a detailed thermal maturation analysis and a determination of the regional situation of heavily faulted/eroded Namurian strata. Cores and cuttings of coal and siltstones were used from 8 boreholes to investigate and measure the vitrinite reflectance; the lithology and petrography definition was also done based on thin sections. All new measurements were compared with archived data and older studies. In the Němčičky Sub-basin, the complete sedimentary succession occurs as part of typical cyclic development, starting with basal conglomerates and followed by sandstones alternating with claystones, siltstones and coal seams of marine and transitional origin. Samples from the Nikolčice-Kurdějov ridge are showing significantly lower vitrinitte reflectance values with respect to their depths than those from the Nesvačilka graben; this fact is supporting the distinctive lateral movement along the western Nesvačilka fault as presumed from the seismic interpretation. Dominant source from “immature” orogen is combined with the source from the “mature” continetal block i.e. opposite margin of the basin. The seismic interpretation shows that the thicknesses of Namurian deposits are not decreasing at all towards the recently deeper positions; accordingly, it is suggested that it is right within this erosionally untouched accommodational space of the Němčičky Sub-basin where we can find the interconnection to the USCB in the north.

Attempts to determine the geomechanical and Thomsen’s anisotropy parameters of coal from Upper Silesian Coal Basin area

Attempts to determine the geomechanical and Thomsen’s anisotropy parameters of coal from Upper Silesian Coal Basin area

Quantifying CH<sub>4</sub> emissions from hard coal mines using mobile sun-viewing Fourier transform spectrometry

Abstract. Methane (CH4) emissions from coal production amount to roughly one-third of European anthropogenic CH4 emissions in the atmosphere. Poland is the largest hard coal producer in the European Union with the Polish side of the Upper Silesian Coal Basin (USCB) as the main part of it. Emission estimates for CH4 from the USCB for individual coal mine ventilation shafts range between 0.03 and 20 kt a−1, amounting to a basin total of roughly 440 kt a−1 according to the European Pollutant Release and Transfer Register (E-PRTR, http://prtr.ec.europa.eu/, 2014). We mounted a ground-based, portable, sun-viewing FTS (Fourier transform spectrometer) on a truck for sampling coal mine ventilation plumes by driving cross-sectional stop-and-go patterns at 1 to 3 km from the exhaust shafts. Several of these transects allowed for estimation of CH4 emissions based on the observed enhancements of the column-averaged dry-air mole fractions of methane (XCH4) using a mass balance approach. Our resulting emission estimates range from 6±1 kt a−1 for a single shaft up to 109±33 kt a−1 for a subregion of the USCB, which is in broad agreement with the E-PRTR reports. Three wind lidars were deployed in the larger USCB region providing ancillary information about spatial and temporal variability of wind and turbulence in the atmospheric boundary layer. Sensitivity studies show that, despite drawing from the three wind lidars, the uncertainty of the local wind dominates the uncertainty of the emission estimates, by far exceeding errors related to the XCH4 measurements themselves. Wind-related relative errors on the emission estimates typically amount to 20 %.

FIRE DETECTION BASED ON A SERIES OF THERMAL IMAGES AND POINT MEASUREMENTS: THE CASE STUDY OF COAL-WASTE DUMPS

Abstract. The development of mining areas is always associated with a huge amount of unused gangue. It is treated as waste that should be disposed of. Most often it is done by creating waste dumps. Unfortunately, in the case of hard coal, such treatments can be dangerous, because the remaining coal can self-heat, what then leads to ignition and fire. These fires are uncontrolled and significantly affect the environment and the health of residents. Areas at risk of fire should be properly secured and its thermal conditions monitored. There are currently many methods available for measuring temperature. The latest and also the most popular are pyrometric and remote sensing methods. For the purposes of analysis, fieldwork on the selected coal-waste dump in the Upper Silesian Coal Basin was made using pyrometric (point measurements) and remote sensing methods (thermal images). A series of photos and measurements were compared over time and space to catch change trends. Differences in the received data were identified. Studies have shown that using only one method helps identify a fire, but does not provide enough information about its structure. Comprehensive monitoring is the best solution.

Geophysical Evaluation of Effectiveness of Blasting for Roof Caving During Longwall Mining of Coal Seam

Deep longwall mining of coal seams is made in the Upper Silesian Coal Basin (USCB) under complicated and mostly unfavourable geological and mining conditions. Usually, it is correlated with rockburst hazard mostly at a high level. One of the geological factors affecting the state of rockburst hazard is the presence of competent rocks in the roof of extracted coal seams, so rock falling behind the longwall face does not occur, and hanging-up of roof rocks remains. The long-lasting absence of caving may lead to an occurrence of high-energy tremor in the vicinity of the longwall face. Roof caving behind the longwall face may be forced by blasting. The column of explosives is then located in blastholes drilled in layers of roof rocks, e.g. sandstones behind the longwall face. In this article, a characterization of tremors initiated by blasts for roof caving during underground extraction of coal seam no. 507 in one of the collieries in the USCB has been made using three independent methods. By the basic seismic effect method, the effectiveness of blasting is evaluated according to the seismic energy of incited tremors and mass of explosives used. According to this method, selected blasts gave extremely good or excellent effect. An inversion of the seismic moment tensor enables determining the processes happening in the source of tremors. In the foci of provoked tremors the slip mechanism dominated or was clearly distinguished. The expected explosion had lesser significance or was not present. By the seismic source parameters analysis, among other things, an estimation of the stress drop in the focus or its size may be determined. The stress drop in the foci of provoked tremors was in the order of 105 Pa and the source radius, according to the Brune’s model, varied from 44.3 to 64.5 m. The results of the three mentioned methods were compared with each other and observations in situ. In all cases the roof falling was forced.