Gas trap stability in the Zechstein Limestone from the Rudna Copper Mine (SW Poland)

A gas and crashed rock burst in 2009 in the Rudna Copper Mine was the motivation to re-investigate the dolomite succession of the first Permian cyclothem (Werra), which covers the ceiling section of the excavations. Gas traps were recognized by previous research; however, the stability of gas traps during mining operations has not been studied yet. Mitigation of future gas bursts requires a complex analysis of these gas traps, involving petrological, petrophysical and mechanical analysis of the reservoir dolomite facies. The results indicate the significant influence of dolomite texture, porosity and extent of late diagenetic dolomite cement on the reservoir and geomechanical properties, and the induced failure pattern of the dolomite facies. The mechanism of dolomite failure allowed for interpreting the degree of dolomite degassing during and after mining operations.