A combined method for evaluation and prediction on permeability in coal seams during enhanced methane recovery by pressure-relieved method

Xue Dongjie●Zhou Hongwei●Chen Chaofan●Jiang DY

Abstract

Pressure-relieved coal mining method has been successfully carried out in many mines in China, especially in high gassy mines. The motivation for the paper is to help engineers fill the knowledge gap on how to evaluate how the permeability changes and effect on improving low permeability prior to its construction. A new method is proposed in a combined theoretical and experimental way in laboratory. On the tests, the volumetric strain-dependent permeability is obtained based on triaxial compression tests. Then, we have designed a physical modeling experiment to know the mining field deformation especially in the subsidence data, which is easily measured and reliable ignoring the continuum concept hypothesis. Another, based onsemi-infinite integral model, the theoretical formulas of subsidence are solved consistent with the testing result from the physical modeling. The volumetric strain derived from the semi-infinite integral model is proposed to establish the relationship between permeability and volumetric deformation of mining field. Finally, the pressure-relieved effect on changing permeability is studied and discussed. The results show that the combinedmethod is a good way to determine the distribution on permeability changing with advancing distances, also a good tool for improving the traditional predraining borehole layout and opportunity to extract gas methane.

引用格式：

Xue D J, Zhou H W, Chen C F, et al. A combined method for evaluation and prediction on permeability in coal seams during enhanced methane recovery by pressure-relieved method[J]. Environmental Earth Sciences, 2015: 1-12.

SCI：WOS-000353801300015   EI：20151800801398

DOI：10.1007/s12665-015-4378-7

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