Study of the gas composition ahead of the working face in a lignite seam from the Velenje basin

摘要

The lignite seam in the Velenje basin has been exploited since 1875. During excavation of lignite in the Velenje coalmine, seam problems with gas outbursts occur. Flow-ever, geochemical studies of the coalbed gases in the Velenje basin have been initiated only recently. Mass spectrometric methods were used to determine the gas composition. Coalbed gases in the Velenje basin are highly variable in both their concentrations and stable isotope composition. Major gas components are CO_2 and methane. Their concentrations and isotopic studies revealed several genetic types of coalbed gases, including thermogenic methane, endogenic and thermogenic CO_2, CO_2 originating from carbonates, microbial methane and CO_2. Most of the gases in the Velenje basin are the result of mixing of gases of different origin, caused by physicochemical processes.