20.500.12556/RUL-141245 Exploring the 2013-2018 degassing mechanism from the Pesje and Preloge excavation fields in the Velenje coal basin, Slovenia insights from molecular composition and stable isotopes Gas samples were collected from 25 m long horizontal boreholes drilled into the excavation field at 10° inclination to the longwall face in two mining areas, Pesje and Preloge, in the Velenje Coal Mine, Slovenia, from 2013 to 2018. The degassing mechanism of coalbed gas and its stable isotopic composition (δ$^{13}$C$_{CO2}$, δ$^{13}$C$_{CH4}$, and δ$^2$H$_{CH4}$) were investigated in boreholes in advance of eight working faces. The major coalbed gas constituents were CO$_2$ and methane. Gas concentrations and isotope values revealed that the methane is biogenic in origin with δ$^{13}$C$_{CH4}$ values of −69.4 to −29.5 ‰, δ$^2$H$_{CH4}$ values of −301 to −222 ‰, and a fractionation factor (α$_{CO2^-CH4}$) of 0.998–1.073, suggesting that methane derives from microbial acetate fermentation and CO$_2$ reduction. The carbon dioxide methane index values ranged from 50.0–98.3 vol.% and δ$^{13}$C$_{CO2}$ values from −11.8 to −0.5 ‰, indicating that CO$_2$ is biogenic and endogenic in origin. The degassing mechanism results in isotope fractionation of methane and CO$_2$ for carbon isotopes up to 39.9 ‰ and up to 8.5 ‰, respectively, depending on the position of the excavation fields in space, e.g. under pre-mined coal area, fresh overburden. carbon-13 carbon dioxide coalbed gas excavation fields gas composition isotope geochemistry methane spatial distribution Velenje Basin Slovenia true false true Angleški jezik Ni določen Članek v reviji 2022-09-26 14:41:05 2022-09-26 14:41:06 2022-09-28 03:25:04 0000-00-00 00:00:00 2021 0 0 Str. 585-609 no. 6 Vol. 57 2021 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 502/504 1477-2639 10.1080/10256016.2021.1981309 79892995 Exploring_the_2013_2018_degassing_mechanism_from_the_Pesje_and_Preloge_excavation_fields_in_the_Velenje_Coal_basin_Slovenia_insights_from_molecular.pdf Exploring_the_2013_2018_degassing_mechanism_from_the_Pesje_and_Preloge_excavation_fields_in_the_Velenje_Coal_basin_Slovenia_insights_from_molecular.pdf 1 A42FAF72937C2D1B7C3547B88E514108 feec95ccc857ceba3cb010f34845e77aa190778de3013690366c8f4b9665adcf f6e300a1-3d98-11ed-9c94-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=162208 https://www.tandfonline.com/doi/full/10.1080/10256016.2021.1981309 0 d76cf9bb-3d98-11ed-9c94-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=162207 Naravoslovnotehniška fakulteta 0 0 0