Charakter gazów metanowych i prawidłowości ich rozmieszczenia w pokładach węgla Lwowsko-Wołyńskiego Zagłębia Węglowego

Abstract

CHARACTER OF METANE GASES AND PRINCIPLES OF THEIR DISTRIBUTION IN COAL MEASURES OF THE LVOV-VOLHYNIA COAL BASIN

Summary

After a short introduction into the general problems related to geology and geochemistry of natural gases, the authors focus their attention on gases that occur in the coal measures and in the coal-bearing series of the Namurian, within the Lvov-Volhynia Coal Basin. The authors have analysed an ample of gases taken from the Volhynian, trans-Bug, Sokal and Miezrjetshe coal deposits. The analyses of gas samples comprise quantitative determination of methane, carbon dioxide and nitrogen, as well as isotope composition of chemical elements which constitute methane, i.e. hydrogen and carbon. The authors demonstrate that the distribution of gases in the coal deposits is not accidental, and that the highest amounts of gases are found within zones. As a rule the gas content increases with the depth. In individual deposits examined before there are found regularities in the change of relationships between methane, carbon dioxide and nitrogen. Isotope examinations of hydrogen have led to a discovery of a relatively high amount of deuterium. Its highest amount has been noted to occur in gases of the Miezrjetshe coal deposit (7,5 γ on the average). This deposit is very interesting also as concerns its carbon content, as proved during the isotope examinations of this chemical element. The ratio C¹²/C¹³ ranges here from 94,5 to 97,16. In the coal basin under consideration the Volhynian coal deposit is characterized by the lowest gas content. The trans-Bug river coal deposit discloses also a low gas content in its coal-bearing series. The highest gas content has been observed in the Miezrjetshe coal deposit, where the total gas amount, and the parcentage of methane, increase with the depth, and westwards, i. e. towards, the natural gas deposit Wielkie Mosty, in which reservoir rocks are represented by the Devonian formations. The authors conclude that part of the gas found to occur in the coal measures and in the coal-bearing series, as a whole, could have penetrated into the Miezrjetshe deposit after the migration from the natural gas deposit Wielkie Mosty.