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

Anna Poszytek,Barbara Rybak-Ostrowska,Paweł Łukaszewski,Marcin Włodarczyk

doi:10.1007/s00531-019-01813-8

Anna Poszytek, Barbara Rybak-Ostrowska + Show 2 more

Open Access

https://doi.org/10.1007/s00531-019-01813-8

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Abstract

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.

Highlights

Gas traps in the Rudna Copper Mine have a very low oil industrial potential because of small thicknesses and high contents of nitrogen
The dolomicrite is characterized by porosity of 2–4% and lack of permeability; it was termed the sealing dolomicrite
The dolomite facies from the gas reservoir horizon are characterized by different textures, porosity, reservoir and geomechanical properties, and failure patterns (Table 6)

Summary

Introduction

Gas traps in the Rudna Copper Mine have a very low oil industrial potential because of small thicknesses and high contents of nitrogen. (Fig. 1a, c) in dolo-grainstones with a higher porosity (> 2%) compared to other dolomites occurring below and above them (Fig. 2). The dolo-grainstones occur a few meters above the excavations within rocks of the Werra cyclothem (Poszytek et al 2018). They are characterized by variable porosity from 2 to 15% (Poszytek et al 2018). Petrophysical analysis of the gas trap stability has not been performed. Based on experimental research (Wong and Baud 2012), a hypothesis

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