Development of improved methane drainage technologies by stimulating coal seams for major risks prevention and increased coal output (GasDrain)

The main objective of this project was to develop new borehole stimulation techniques and develop improved methane drainage technologies. The project commenced with laboratory experiments to characterise the baseline reservoir properties of coal and coal measures rock. These data were supplemented by the necessary in situ measurements at JSW Zofiowka and HUNOSA Sueros Collieries. In parallell, research on borehole stimulation technologies and developed tools for use in the field were carried out. Necessary equipment and tools were developed, and performed their preliminary testing for water jet and mechanical cutting and hydrofracturing of coal. Two different explosives were also developed and tested. Numerical simulations carried out for the Zofiowka Colliery, applying reservoir engineering techniques for assessment of the performance of propped and unpropped hydrofracturing. Similar models, applying a coupled flow-geomechanical model of the seams at Sueros Colliery and modelled the performance of a set of slotted boreholes. In the Zofiowka colliery, in two field testing a trial performed stimulation of the borehole using the slot cutting shown lack of patency in one of the boreholes set and poor permeability of the coal seam in another one. A massive seismic tremor and rockburst made the further works impossible to finish. In the Sueros Colliery boreholes were drilled and equipped with monitoring devices controlling methane content and its pressure inside. In another boreholes in second testing location, sudden drop in methane concentration was observed. It implied faulty instalment of the packer. Continuation of further tests was stopped due to mining authority's decision.