Numerical studies of improved methane drainage technologies by stimulating coal seams in multi-seam mining layouts

This paper presents procedures and results of the numerical modelling of different stimulation methods as applied to the specific conditions of a multi-seam mining layout at the Zofiówka Coal Mine operated by Jastrzębska Spółka Węglowa (JSW), Poland. Studies reported in this paper include constructions of three types of numerical models: (1) a geological model of the Zofiówka coal mine area based on large set of available data (structure maps, cross-sections, well logs, lithological profiles, laboratory measurements); (2) both large and small scale geomechanical models including the multi-seam mining layout and details of local geomechanical conditions resulting from the application of different stimulation technologies; (3) dynamic flow models including transport properties modified by the geomechanical state of the analysed seam and its surroundings. Resulting drainage process simulations were performed for three different technologies (hydraulic fracturing, high pressure jet slotting, and the use of explosives). Detailed analyses of the technologies pointed out the hydrofracturing and jet slotting as the stimulating methods that can potentially enhance methane drainage from the analysed seam. Quantitative results of the simulations estimate the dependence of the drainage process characteristics upon the basic technological parameters of the stimulation methods.