The relationship of lithological and thermobarogeochemical factors in fluid-active zones: A casestudy of the Krasnodonetsky district of Eastern Donbass

Abstract

The distance of natural gas reservoirs from the country’s industrial centers, the irregularity of spreading of the reserves, the increased costs of gas production and supply, all contribute to the involvement of local and nonconventional resources in various-type production. Coal methane extraction in Eastern Donbass is a goal in this regard. The research included the field study of fluid-active methane-rich zones in coal seams in Eastern Donbass, as well as the lithological and thermobarogeochemical analyses of coal samples. The gas saturation of rocks was correlated with the material composition of deposits. The results of the work can be formulated as follows. Terrigenous rock sediments of age С27 feature the increased content of hydrocarbon gases. Most of methane is localized in the roof of commercialthickness coal seams overlaid with thin clayey shales, siltstones and sandstones of the scoured surface. The scoured-surface sandstone in the coal seam roof has good reservoir properties. The increased fluid permeability of rocks is due to cleavage, which is most intense in heterogeneous strata in the axial parts of small folds. The fluid-saturated zones in coal seams in terrigenous rocks of С27 age at a depth of 240–260 and 320–360 m contain signs of hydrothermal veined mineralization represented by pyrite, dickite, quartz and calcite. These fluidization zones feature high content of gases in coal seams (up to 40–42 m3/t) and enclosing rocks (up to 10–12 m3/t), which points at high prospects for the extraction of hydrocarbon gases from these zones.The study was carried out under the state contract with the Southern Scientific Center, Russian Academy of Sciences, State Registration No. 122020100352-6.