Abstract
To comprehensively understand the mining-induced coal permeability change, a series of laboratory unloading experiments are conducted based on a simplifying assumption of the actual mining-induced stress evolution processes of three typical longwall mining layouts in China, i.e., non-pillar mining (NM), top-coal caving mining (TCM) and protective coal-seam mining (PCM). A theoretical expression of the mining-induced permeability change ratio (MPCR) is derived and validated by laboratory experiments and in situ observations. The mining-induced coal permeability variation under the three typical mining layouts is quantitatively analyzed using the MPCR based on the test results. The experimental results show that the mining-induced stress evolution processes of different mining layouts do have an influence on the mechanical behavior and evolution of MPCR of coal. The coal mass in the PCM simulation has the lowest stress concentration but the highest peak MPCR (approximately 4000 %), whereas the opposite trends are observed for the coal mass under NM. The results of the coal mass under TCM fall between those for PCM and NM. The evolution of the MPCR of coal under different layouts can be divided into three sections, i.e., stable increasing section, accelerated increasing section and reducing section, but the evolution processes are slightly different for the different mining layouts. A coal bed gas intensive extraction region is recommended based on the MPCR distribution of coal seams obtained by simplifying assumptions and the laboratory testing results. The presented results are also compared with existing conventional triaxial compression test results to fully comprehend the effect of actual mining-induced stress evolution on coal property tests.
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Abbreviations
- CBM:
-
Coal bed methane
- CTC:
-
Conventional triaxial compression
- MPCR:
-
Mining-induced permeability change ratio
- NM:
-
Non-pillar mining
- PCM:
-
Protective coal-seam mining
- TCM:
-
Top-coal caving mining
References
Adhikary DP, Guo H (2014) Measurement of longwall mining induced strata permeability. Geotech Geol Eng 32(3):617–626
Adhikary DP, Guo H (2015) Modelling of longwall mining-induced strata permeability change. Rock Mech Rock Eng 48(1):345–359
Alehossein H, Poulsen BA (2010) Stress analysis of longwall top coal caving. Int J Rock Mech Min Sci 47(1):30–41
Beamish B, Crosdale PJ (1998) Instantaneous outbursts in underground coal mines: an overview and association with coal type. Int J Coal Geol 35(1):27–55
Cai Y et al (2014) Permeability evolution in fractured coal—combining triaxial confinement with X-ray computed tomography, acoustic emission and ultrasonic techniques. Int J Coal Geol 122:91–104
Cao Y, Mitchell GD, Davis A, Wang D (2000) Deformation metamorphism of bituminous and anthracite coals from China. Int J Coal Geol 43:227–242
Cappa F, Rutqvist J (2011) Modeling of coupled deformation and permeability evolution during fault reactivation induced by deep underground injection of CO2. Int J Greenhouse Gas Control 5(2):336–346
Chen Z, Pan Z, Liu J, Connell LD, Elsworth D (2011) Effect of the effective stress coefficient and sorption-induced strain on the evolution of coal permeability: experimental observations. Int J Greenhouse Gas Control 5(5):1284–1293
Chen Z, Liu J, Pan Z, Connell LD, Elsworth D (2012) Influence of the effective stress coefficient and sorption-induced strain on the evolution of coal permeability: model development and analysis. Int J Greenhouse Gas Control 8:101–110
Chen H-D, Cheng Y, Zhou H-X, Li W (2013) Damage and permeability development in coal during unloading. Rock Mech Rock Eng 46(6):1377–1390
Chen H, Cheng Y, Ren T, Zhou H, Liu Q (2014) Permeability distribution characteristics of protected coal seams during unloading of the coal body. Int J Rock Mech Min Sci 71:105–116
Cui X, Bustin RM (2005) Volumetric strain associated with methane desorption and its impact on coalbed gas production from deep coal seams. Aapg Bulletin 89(9):1181–1202
Dabbous M, Reznik A, Taber J, Fulton P (1974) The permeability of coal to gas and water. Soc Petrol Eng J 14(06):563–572
Deng J, Yue Z, Tham L, Zhu H (2003) Pillar design by combining finite element methods, neural networks and reliability: a case study of the Feng Huangshan copper mine, China. Int J Rock Mech Min Sci 40(4):585–599
Diederichs M, Kaiser P, Eberhardt E (2004) Damage initiation and propagation in hard rock during tunnelling and the influence of near-face stress rotation. Int J Rock Mech Min Sci 41(5):785–812
Durucan S, Edwards J (1986) The effects of stress and fracturing on permeability of coal. Mining Sci Technol 3(3):205–216
Flores RM (1998) Coalbed methane: from hazard to resource. Int J Coal Geol 35(1):3–26
Gale JE (1982) The effects of fracture type (induced versus natural) on the stress-fracture closure-fracture permeability relationships. In: The 23rd US Symposium on Rock Mechanics (USRMS). American Rock Mechanics Association, Berkeley
Gilman A, Beckie R (2000) Flow of coal-bed methane to a gallery. Transp Porous Media 41(1):1–16
Gray I (1987) Reservoir engineering in coal seams: part 1-The physical process of gas storage and movement in coal seams. SPE Reser Eng 2(1):28–34
Guo H, Yuan L, Shen B, Qu Q, Xue J (2012) Mining-induced strata stress changes, fractures and gas flow dynamics in multi-seam longwall mining. Int J Rock Mech Min Sci 54(3):129–139
Harpalani S, Chen G (1997) Influence of gas production induced volumetric strain on permeability of coal. Geotech Geol Eng 15(4):303–325
Klinkenberg L (1941) The permeability of porous media to liquids and gases. Drilling and production practice. American Petroleum Institute, New York, pp 200–213
Kong S, Cheng Y, Ren T, Liu H (2014) A sequential approach to control gas for the extraction of multi-gassy coal seams from traditional gas well drainage to mining-induced stress relief. Appl Energy 131(9):67–78
Li Z, Dou L, Cai W, Wang G, Ding Y, Kong Y (2015) Roadway stagger layout for effective control of gob-side rock bursts in the longwall mining of a thick coal seam. Rock Mech Rock Eng. doi:10.1007/s00603-015-0746-6
Liu J, Chen Z, Elsworth D, Miao X, Mao X (2010) Linking gas-sorption induced changes in coal permeability to directional strains through a modulus reduction ratio. Int J Coal Geol 83(1):21–30
Liu Y, Zhou F, Liu L, Liu C, Hu S (2011) An experimental and numerical investigation on the deformation of overlying coal seams above double-seam extraction for controlling coal mine methane emissions. Int J Coal Geol 87(2):139–149
Liu Q, Cheng Y, Zhou H, Guo P, An F, Chen H (2014) A mathematical model of coupled gas flow and coal deformation with gas diffusion and klinkenberg effects. Rock Mech Rock Eng 48(3):1163–1180
Mazumder S, Wolf KH (2008) Differential swelling and permeability change of coal in response to CO2 injection for ECBM. Int J Coal Geol 74(2):123–138
Meng Z, Li G (2013) Experimental research on the permeability of high-rank coal under a varying stress and its influencing factors. Eng Geol 162(14):108–117
Moore TA (2012) Coalbed methane: a review. Int J Coal Geol 101(6):36–81
Ouyang Z, Li C, Xu W, Li H (2009) Measurements of in situ stress and mining-induced stress in Beiminghe Iron Mine of China. J Cent South Univ Technol 16(1):85–90
Palmer I (2009) Permeability changes in coal: analytical modeling. Int J Coal Geol 77(1):119–126
Pan Z, Connell LD, Camilleri M (2010) Laboratory characterisation of coal reservoir permeability for primary and enhanced coalbed methane recovery. Int J Coal Geol 82(3):252–261
Perera M, Ranjith P, Choi S, Bouazza A, Kodikara J, Airey D (2011) A review of coal properties pertinent to carbon dioxide sequestration in coal seams: with special reference to Victorian brown coals. Environ Earth Sci 64(1):223–235
Perera M, Ranjith P, Choi S, Airey D (2012) Investigation of temperature effect on permeability of naturally fractured black coal for carbon dioxide movement: an experimental and numerical study. Fuel 94:596–605
Raven K, Gale J (1985) Water flow in a natural rock fracture as a function of stress and sample size. Int J Rock Mech Min Sci Geomech Abst 22(4):251–261
Rezaei M, Hossaini MF, Majdi A (2015) Determination of longwall mining-induced stress using the strain energy method. Rock Mech Rock Eng 2015:1–13. doi:10.1007/s00603-014-0704-8
Ried G, Towler B, Harris H (1992) Simulation and economics of coalbed methane production in the Powder River Basin. In: SPE Rocky Mountain Regional Meeting. Society of Petroleum Engineers, Casper, Wyoming, USA. Paper 24360. doi:10.2118/24360-MS
Robertson EP, Christiansen RL (2007) Modeling laboratory permeability in coal using sorption-induced strain data. SPE Reservoir Eval Eng 10(3):260–269
Shi J, Durucan S (2004) Drawdown induced changes in permeability of coalbeds: a new interpretation of the reservoir response to primary recovery. Transp Porous Media 56(1):1–16
Singh AK, Singh R, Maiti J, Kumar R, Mandal P (2011) Assessment of mining induced stress development over coal pillars during depillaring. Int J Rock Mech Min Sci 48(5):805–818
Siriwardane H, Haljasmaa I, McLendon R, Irdi G, Soong Y, Bromhal G (2009) Influence of carbon dioxide on coal permeability determined by pressure transient methods. Int J Coal Geol 77(1):109–118
Somerton WH, Söylemezoḡlu I, Dudley R (1975) Effect of stress on permeability of coal. Int J Rock Mech Min Sci Geomech Abst 12(5):129–145
Sparks D, McLendon T, Saulsberry J, Lambert S The effects of stress on coalbed reservoir performance, Black Warrior Basin, USA. In: Society of Petroleum Engineers. Annual Technical Conference, Dallas, TX, USA 1995. pp 339–351 doi:10.2118/30734-MS
Suchowerska A, Merifield R, Carter J (2013) Vertical stress changes in multi-seam mining under supercritical longwall panels. Int J Rock Mech Min Sci 61:306–320
Wang L, Cheng Y-P, Li F-R, Wang H-F, H-b Liu (2008) Fracture evolution and pressure relief gas drainage from distant protected coal seams under an extremely thick key stratum. J China Univ Min Technol 18(2):182–186
Wang G, Wei X, Wang K, Massarotto P, Rudolph V (2010) Sorption-induced swelling/shrinkage and permeability of coal under stressed adsorption/desorption conditions. Int J Coal Geol 83(1):46–54
Wang S, Elsworth D, Liu J (2011) Permeability evolution in fractured coal: the roles of fracture geometry and water-content. Int J Coal Geol 87(1):13–25
Wang C, Zhang N, Han Y, **ong Z, Qian D (2013a) Experiment research on overburden mining-induced fracture evolution and its fractal characteristics in ascending mining. Arab J Geosci 8(1):13–21
Wang H, Jiang Y, Zhao Y, Zhu J, Liu S (2013b) Numerical investigation of the dynamic mechanical state of a coal pillar during longwall mining panel extraction. Rock Mech Rock Eng 46(5):1211–1221
Wang S, Elsworth D, Liu J (2013c) Permeability evolution during progressive deformation of intact coal and implications for instability in underground coal seams. Int J Rock Mech Min Sci 58:34–45
Whittaker B (1974) An appraisal of strata control practice. Min Eng 134:9–24
**e G, Chang J, Yang K (2009) Investigations into stress shell characteristics of surrounding rock in fully mechanized top-coal caving face. Int J Rock Mech Min Sci 46(1):172–181
**e H, Zhou H, Liu J, Xue D (2011) Mining-induced mechanical behavior in coal seams under different mining layouts. J China Coal Soc 36(7):1067–1074 (in Chinese)
**e H, Zhao X, Liu J, Zhang R, Xue D (2012) Influence of different mining layouts on the mechanical properties of coal. Int J Min Sci Technol 22(6):749–755
**e H, Gao F, Zhou H-W, Cheng H-M, Zhou F-B (2013) On theoretical and modeling approach to mining-enhanced permeability for simultaneous exploitation of coal and gas. J China Coal Soc 38(7):1101–1108 (in Chinese)
**e H, **e J, Gao M, Zhang R, Zhou H, Gao F, Zhang Z (2015) Theoretical and experimental validation of mining-enhanced permeability for simultaneous exploitation of coal and gas. Environ Earth Sci 73(10):5951–5962
Yang W, Lin B, Qu Y, Li Z, Zhai C, Jia L, W-q Zhao (2011) Stress evolution with time and space during mining of a coal seam. Int J Rock Mech Min Sci 48(7):1145–1152
Yang W, B-q Lin, Yan Q, Zhai C (2014) Stress redistribution of longwall mining stope and gas control of multi-layer coal seams. Int J Rock Mech Min Sci 72:8–15
Yasitli N, Unver B (2005) 3D numerical modeling of longwall mining with top-coal caving. Int J Rock Mech Min Sci 42(2):219–235
Zhang H, Liu J, Elsworth D (2008) How sorption-induced matrix deformation affects gas flow in coal seams: a new FE model. Int J Rock Mech Min Sci 45(8):1226–1236
Zhang M, Shimada H, Sasaoka T, Matsui K, Dou L (2014a) Evolution and effect of the stress concentration and rock failure in the deep multi-seam coal mining. Environ Earth Sci 72(3):629–643
Zhang Z, Zhang R, Liu J, Liu X, Li J (2014b) Permeability evolution of unloaded coal samples at different loading rates. Thermal Sci 18(5):1497–1504
Zhang R, Ai T, Zhou HW, Ju Y, Zhang ZT (2015a) Fractal and volume characteristics of 3D mining-induced fractures under typical mining layouts. Environ Earth Sci 73(10):6069–6080
Zhang Z, Zhang R, **e H, Gao M (2015b) The relationships among stress, effective porosity and permeability of coal considering the distribution of natural fractures: theoretical and experimental analyses. Environ Earth Sci 73(10):5997–6007
Zhou C, Yao Y, Guo L, Yin X, Fan X, Shang Y (2007) Numerical simulation of independent advance of ore breaking in the non-pillar sublevel caving method. J China Univ Min Technol 17(2):295–300
Zhu W, Liu J, Sheng J, Elsworth D (2007) Analysis of coupled gas flow and deformation process with desorption and Klinkenberg effects in coal seams. Int J Rock Mech Min Sci 44(7):971–980
Zhu WC, Wei CH, Liu J, Xu T, Elsworth D (2013) Impact of gas adsorption induced coal matrix damage on the evolution of coal permeability. Rock Mech Rock Eng 46(6):1353–1366
Acknowledgments
This research was funded by the State Key Basic Research Program of China (No. 2011CB201201) and the National Natural Science Foundation of China (No. 51204113, 51134018 and 51104101).