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Methane observed in soil atmosphere above active and abandoned bituminous coal mines has a thermogenic (coalbed) and/or microbial (produced by anaerobic bacteria or resulted from in situ coal biodegradation) origin or it may be a mixture of gases generated from various sources. Identification of the origin of methane may support or refute the thesis on the uncontrolled migration of mine gases in rock formations followed by their emission to the atmosphere at coal extraction sites. Surface geochemical surveys were carried out in the vicinity of the decommissioned mine shafts at the Murcki-Staszic Coal Mine, located in the Upper Silesian Coal Basin (southern Poland). Over a 3-month period, measurements were carried out cyclically at 2 locations. Totally, 43 fixed geochemical probes were installed in the area of the Murcki II “Stanislaw” Shaft, in which measurements were carried out in six sessions. Next 29 probes were installed in the area of the Staszic III Shaft, where measurements were taken twice. Each measurement included concentrations of 5 components (methane, non-methane volatile organic compounds, total hydrocarbons, carbon dioxide and oxygen), which provided a total number of 1405 individual analytical determinations. For measurements, portable EcoProbe 5 instrument was used. The stable carbon isotope composition of methane and carbon dioxide was analyzed in selected 10 samples. The isotopic composition of hydrogen in methane was also measured in one sample. The comparative material consisted of eight samples of soil gases and two samples of mine gases, which were used as reference ‘soil’ gases. The isotopic analyses were conducted using a mass spectrometry method. Based on the results of our analyses, it is stated that both the Murcki II “Stanislaw” and the Staszic III shafts were properly decommissioned. The successful sealing of mine shafts prevented mine gases from migration through the shaft into the atmosphere. However, at a single geochemical probe located more than 100 m from the former shaft center, methane concentration in soil gases reached over 1 vol%. This confirms the general observation that mine gas migrates from coal seams and/or gobs through crushed rocks into the atmosphere. The stable carbon isotope analysis of methane and carbon dioxide as well as stable hydrogen isotope analysis of methane suggest that methane in the soil atmosphere is of thermogenic origin with minor contribution of microbial component.

History of hard coal mining in Upper Silesia, started in the mid‐seventeenth century, which is confirmed in documents from 1657. On its site operated the open‐pit mine in Murcki, where the first coal mine shaft was built and underground coal mining started in 1755. Nowadays, after consolidation with KWK Staszic in 2010, and since then hard coal mine has operated as Murcki‐Staszic, in the Katowice Coal Holding SA structure [1]. First coal mine in Lesser Poland District was established in 1767 in Szczakowa – nowadays in Jaworzno district [2]. Despite of long time experience in the Polish mining industry, methane associated with coal seams (CMM‐coal‐mine methane) was considered as a serious problem in coal exploration [3]. During the hard coal mine operation, methane together with wasted air was removed directly to the atmosphere through ventilation system, causing an increase in greenhouse gases (GHG) [4]. European Union adopted policy to reduce greenhouse gas emissions. Implementation of this policy causes an additional costs for mining company (related to methane emission). Ventilation methane content and methane drainage is shown in Figure 1. Based on experience of USA, China and Australia, also in Poland, started to looking for the possibility to extract methane from coal beds. Due to US investors interest to perform assessment of methane extraction possibility from Polish coal basins, the first pilot projects has been performed in the early 90s of twentieth century. Performed research were mostly based on a review of collected geological information and laboratory tests on samples taken from geological exploration drilling in the Upper Silesian Coal Basin.