Abstract
The paper presents the variability of hard coal output, methane content and methane emissions into coal workings and into the atmosphere from the two most methane-gassy coal mines in Poland, Budryk and Pniówek, which are both incorporated in the Jastrzębie Coal Company. The Budryk mine is one of the youngest mines in Poland, but it is the most methane-gassy as well. In 2016, the total CH4 emissions exceed 140 million of m3. This large increase in methane emissions to mine workings is primarily related to the increase in the depth of coal extraction (up to 1290 m) and, consequently, the rapid increase in the methane content in coal seams (up to 10-12 m3 / Mg coaldaf). On the other hand, in the Pniówek mine, methane emission was the highest at the beginning of the study period (1986-1991). During the following years emission decreased to the values of less than 140 million of m3, which were still one of the largest amounts of emitted methane in the entire Upper Silesian Coal Basin. The vertical distribution of methane content, different than in the Budryk mine, and the presence of a secondary high methane zone at the Carboniferous top, seem to be decisive for the long-term distribution of methane emissions in the Pniówek mine. The coexistence of natural factors, such as the geological structure and gas distribution, as well as mining-related factors, i.e. the depth of mining, the concentration of coal extraction determines the temporal variability of methane emissions in the studied mines.
IMPACT OF GEOLOGICAL AND MINING CONDITIONS ON TO COSTS OF DRILLING THE ACCESS WORKINGS IN HARD COAL MINES WITHIN THE UPPER SILESIAN COAL BASIN (POLAND)