Fluctuations in methane and carbon dioxide concentrations in the near-surface zone and their genetic characterization in abandoned and active coal mines in the SW part of the Upper Silesian Coal Basin, Poland

Sechman, Henryk; Kotarba, Maciej J.; Kędzior, Sławomir; Kochman, Alicja; Twaróg, Anna

doi:10.1016/j.coal.2020.103529

Cited by 12 publications

(15 citation statements)

References 52 publications

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“…USCB coalbed gases contain high volumes of methane and lower amounts of carbon dioxide and higher hydrocarbons, and their emissions associated with coal mining cause a serious environmental problem. After the shutting down high-methane coal mines in the USCB, the growth of average methane concentrations in the near-surface zone has been observed, and the highest anomalies of methane and carbon dioxide recorded in soil gases are assumed to be related to the secondary accumulation zone of coalbed gases [35,36]. Carbon dioxide in coal-bearing strata associated with hydrocarbon gases occurs in insignificant concentrations, and its origin is related to thermogenic processes of coalification and microbial processes [30,33].…”

Section: Origin Of Emitted Gasesmentioning

confidence: 99%

Molecular and Stable Isotope Composition of Pollutants Emitted during Thermal Processes within the Rymer Coal Waste Dump (Upper Silesia, Poland)

et al. 2021

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Twenty-seven gases and sixteen rock wastes from the thermal active Rymer coal waste dump were collected. The composition and origin of gaseous, liquid, and solid pollutants emitted during the self-heating process and the development of these processes with time were established. Gases were subjected to determination of molecular and stable isotope (δ13C and δ2H) composition. Rock-Eval pyrolysis and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) were applied for evaluation of the quantity and molecular composition of pyrolysates released during the heating of rocks in temperatures from 100 to 650 °C. The main products of Py-GC-MS are released between 350 and 650 °C, namely alkanes, aromatic hydrocarbons, and aromatic alcohols. These components were also recorded in Py-GC-MS products of samples collected from the dump surface. Besides the high-molecular-weight organic compounds, in emitted gases CO2, CO, gaseous hydrocarbons, and S-compounds were recorded. The stable isotope data indicated that methane was generated mainly during the low-temperature thermogenic process, but a share of the microbial-originated gas was visible. The source of the CO2 was the oxidation of organic matter. The gaseous S-compounds were products of high-temperature decomposition of sulphides and organic S-compounds. The hydrocarbon and CO contents of the emitted gases proved to be good indicators for tracking of the self-heating processes.

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Section: Origin Of Emitted Gasesmentioning

confidence: 99%

Molecular and Stable Isotope Composition of Pollutants Emitted during Thermal Processes within the Rymer Coal Waste Dump (Upper Silesia, Poland)

et al. 2021

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“…After coal mining, the remaining area is the mined-out area, which has poor ventilation and a lot of residual coal. e residual coal is oxidized continuously under the influence of air leakage, which is likely to cause gas accumulation [1][2][3]. As a result, it is easy to cause coal spontaneous combustion and other coal thermodynamic disasters.…”

Section: Introductionmentioning

confidence: 99%

“…(1) According to the trend characteristics of CO gas data, the difference rate entropy feature is extracted to get the processed feature sequence, in which the entropy feature value of abnormal mode is higher and that of normal mode is lower, to highlight the difference between abnormal mode and normal mode. (2) e anomaly pattern of entropy feature sequence is detected by using a generative countermeasure network, and a new calculation method for the anomaly score is proposed in the detection stage, which considers both the weighted outlier score of the generated samples and the outlier score of the discrimination results, and judges whether the data segment of the one-dimensional time series is determined by calculating the anomaly score of the sample. e rest of this article is arranged as follows.…”

Section: Introductionmentioning

confidence: 99%

Anomaly Detection for Time Series with Difference Rate Sample Entropy and Generative Adversarial Networks

et al. 2021

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The spontaneous combustion of residual coals in the mined-out area tends to cause an explosion, which is one kind of severe thermodynamic compound disaster of coal mines and leads to serious losses to people's lives and production safety. The prediction and early warning of coal mine thermodynamic disasters are mainly determined by the changes of the index gas concentration pattern in coal mine mined-out areas collected continuously. The time series anomaly pattern detection method is mainly used to reach the state change of gas concentration pattern. The change of gas concentration follows a certain rule as time changes. A great change in the gas concentration indicates the possibility of coal spontaneous combustion and other disasters. To emphasize the features of collected maker gas and overcome the low anomaly detection accuracy caused by the inadequate learning of the normal mode, this paper adopted a method of anomaly detection for time series with difference rate sample entropy and generative adversarial networks. Because the difference rate entropy feature of abnormal data was much larger than that of normal mode, this paper improved the calculation method of the abnormal score by giving different weights to the detection points to enhance the detection rate. To verify the effectiveness of the proposed method, this paper employed simulation models of the mined-out area and adopted coal samples from Dafosi Coal Mine to carry out experiments. Preliminary testing was performed using monitoring data from a coal mine. The experiment compared the entropy results of different time series with the detection results of generative adversarial networks and automatic encoders and showed that the method proposed in this paper had relatively high detection accuracy.

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“…Previous work reported multiple advanced identification indicators for different CBM genesis types. The carbon and hydrocarbon isotopic compositions of methane (δ 13 C(CH 4 ) and δD(CH 4 )) are the common signs used to identify the gas genetic types of CBM. − Besides, there are others with combined identification, such as the CO 2 carbon isotopic composition of δ 13 C(CO 2 ), ,, C 1 /(C 2 + C 3 ) (ratios of methane to ethane and propane), , CDMI (carbon dioxide–methane index) of [CO 2 /(CO 2 + CH 4 )] × 100, ethane carbon isotopic composition of δ 13 C(C 2 H 6 ), the carbon isotope fractionation coefficient of CO 2 and methane (αCO 2 –CH 4 ), and the hydrogen isotope fractionation coefficient of methane and water (αCH 4 –H 2 O). , For example, the CBM origin of the Upper Silesian Coal Basin was investigated using the identified index of C 1 /(C 2 + C 3 ), δ 13 C(CH 4 ), δD(CH 4 ), δ 13 C(CO 2 ), δ 13 C(C 2 H 6 ), and α(CO 2 –CH 4 ). , The gas in origin is biogenic, thermogenic, and mixed methane distributed in the southeastern part of the Upper Carboniferous strata from shallow to deep . Thermogenic CBM occurs in the Mississippian and Pennsylvanian coal-bearing strata in the southwestern part of the Upper Silesian Coal Basin.…”

Section: Introductionmentioning

confidence: 99%

“…Thermogenic CBM occurs in the Mississippian and Pennsylvanian coal-bearing strata in the southwestern part of the Upper Silesian Coal Basin. Biogenic CBM accumulates in the top zone of the Pennsylvanian coal-bearing strata . The gas origin and its significance on CBM accumulation of the No.…”

Section: Introductionmentioning

confidence: 99%

Gas Origin and Constraint of δ¹³C(CH₄) Distribution in the Dafosi Mine Field in the Southern Margin of the Ordos Basin, China

Bao

Wang

et al. 2020

Energy Fuels

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Coalbed gas or coalbed methane (CBM) is a vital hydrocarbon gas which is mainly absorbed in the surface of the coal matrix and has multiple benefits as in being effective in development and utilization. To determine the gas origin, the distribution of the stable carbon isotopic composition for methane, and its constraint in the Middle Jurassic strata in the Dafosi mine area in the southern margin of the Ordos Basin, nine CBM samples were collected from pumping wells at the surface, arranged along three profiles located in different tectonic areas. The gas components and stable isotope compositions were measured, and the results show that the average methane and carbon dioxide concentrations in the coal seams measured are 77.44 and 1.04 mol %, respectively. CBM has apparent dry gas characteristics, with more than 6835 distributed C1/(C2 + C3) ratio values. The average values of the carbon and hydrogen isotopic compositions of CBM are −79.2‰ and −241.9‰, respectively. The gas origin in the Dafosi mine field is mainly composed of biogenic gas from CO2 reduction and mixed thermogenic gas. The former content accumulated in the present coal seams ranges from 68.93% to 100.00%, as calculated by the binary mixing model. A web-based learning tool also indicates mostly CO2 reduction-biogenic gas. Fold types play an essential role in controlling the distribution of different genetic CBM with different stable carbon isotope ratios. Biogenic gas with low carbon isotopic composition lies in the southern parts of the Qijia anticline blocked by the footwall of the fault. The mixed CBM comprised of biogenic and thermogenic gases with high carbon isotopic composition is distributed in the areas of Anhua and Shijiadian synclines sealed with lithology and hydrocarbon concentration, respectively.

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Fluctuations in methane and carbon dioxide concentrations in the near-surface zone and their genetic characterization in abandoned and active coal mines in the SW part of the Upper Silesian Coal Basin, Poland

Cited by 12 publications

References 52 publications

Molecular and Stable Isotope Composition of Pollutants Emitted during Thermal Processes within the Rymer Coal Waste Dump (Upper Silesia, Poland)

Molecular and Stable Isotope Composition of Pollutants Emitted during Thermal Processes within the Rymer Coal Waste Dump (Upper Silesia, Poland)

Anomaly Detection for Time Series with Difference Rate Sample Entropy and Generative Adversarial Networks

Gas Origin and Constraint of δ¹³C(CH₄) Distribution in the Dafosi Mine Field in the Southern Margin of the Ordos Basin, China

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Fluctuations in methane and carbon dioxide concentrations in the near-surface zone and their genetic characterization in abandoned and active coal mines in the SW part of the Upper Silesian Coal Basin, Poland

Cited by 12 publications

References 52 publications

Molecular and Stable Isotope Composition of Pollutants Emitted during Thermal Processes within the Rymer Coal Waste Dump (Upper Silesia, Poland)

Molecular and Stable Isotope Composition of Pollutants Emitted during Thermal Processes within the Rymer Coal Waste Dump (Upper Silesia, Poland)

Anomaly Detection for Time Series with Difference Rate Sample Entropy and Generative Adversarial Networks

Gas Origin and Constraint of δ13C(CH4) Distribution in the Dafosi Mine Field in the Southern Margin of the Ordos Basin, China

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Gas Origin and Constraint of δ¹³C(CH₄) Distribution in the Dafosi Mine Field in the Southern Margin of the Ordos Basin, China