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The axial and radial permeability testing of coal under cyclic loading and unloading

  • Cun ZhangEmail author
  • Lei Zhang
  • Wei Wang
Original Paper
  • 85 Downloads

Abstract

Porous reservoir rocks are often anisotropic in permeability. It is necessary, therefore, to study the effect of anisotropy on the permeability of porous coal seams that are subjected to stress during repeated mining of grouped coal seams. In the present investigation, specialized permeability evaluation equipment, known as gas injection to flush methane testing apparatus (GIFMTA), was used to study the directional permeability characteristics of the coal under various stress states according to the repeated mining of group coal seams. The stress states include three cyclic loading and unloading (0.5 MPa–16 MPa–0.5 MPa in a single cycle), and different axial stresses (0.5 MPa to 10 MPa) with the same confining stress, and different confining stresses (2 MPa to 10 MPa) with the same axial stress. The test results showed that the axial and radial permeability of the coal samples decreased with the increase in effective stress. The radial permeability of coal samples (parallel to the bedding structure) and their stress sensitivity were significantly larger than the axial permeability of the samples at the same effective stress level. It was observed that axial permeability was more sensitive to the confining stress than radial permeability, while the sensitivity of radial permeability to axial stress was much larger than that of axial permeability. The axial and radial permeability and their decrease during first loading were much greater than the case during later loading processes. With an increase in cycle time, the losses in axial and radial permeability, and their stress sensitivities, were observed to decrease gradually. Based on the laboratory test data and on a “matchstick model,” the axial and radial permeability models of the coal samples during a three-cycle loading/unloading procedure were obtained in this paper. Additionally, an anisotropic model was established to investigate the mechanisms that led to the test results using a digital evaluation model (DEM).

Keywords

Permeability Coal seams Stress sensitivity Anisotropy Cyclic loading and unloading 

Notes

Funding information

Financial support for this work was supported by the Beijing Natural Science Foundation (8184082), the National Natural Science Foundation of China (Nos. 51874281, 51874312, and 51861145403), the Young Elite Scientists Sponsorship Program by CAST (2017QNRC001), the Open Fund of State Key Laboratory of Coal Resources and Safe Mining (No. SKLCRSM19KFA17), the Independent Research Project of State Key Laboratory of Water Resources Protection and Utilization in Coal Mining (NO. GJNY-18-77) and the Yue Qi Distinguished Scholar Project, China University of Mining and Technology, Beijing.

References

  1. Baghbanan A, Jing L (2007) Hydraulic properties of fractured rock masses with correlated fracture length and aperture. Int J Rock Mech Min Sci 44(5):704–719CrossRefGoogle Scholar
  2. Busch A, Gensterblum Y (2011) CBM and CO2-ECBM related sorption processes in coal: a review. Int J Coal Geol 87(2):49–71CrossRefGoogle Scholar
  3. Chen D, Pan Z, Ye Z (2015) Dependence of gas shale fracture permeability on effective stress and reservoir pressure: model match and insights. Fuel 139:383–392CrossRefGoogle Scholar
  4. Chen D, Pan Z, Ye Z, Hou B, Wang D, Yuan L (2016) A unified permeability and effective stress relationship for porous and fractured reservoir rocks. J Nat Gas Sci Eng 29:401–412CrossRefGoogle Scholar
  5. Chen SY, Qin Y, Shen J, Wang G, Hou XW (2014) Temperature-stress sensitivity of high-rank coal permeability. J China Coal Soc 39(9):1845–1851 in ChineseGoogle Scholar
  6. Clarkson CR, Bustin RM (2000) Binary gas adsorption/desorption isotherms: effect of moisture and coal composition upon carbon dioxide selectivity over methane. Int J Coal Geol 42(4):241–271CrossRefGoogle Scholar
  7. Clarkson CR, Bustin RM, Levy JH (1997) Application of the mono/multilayer and adsorption potential theories to coal methane adsorption isotherms at elevated temperature and pressure. Carbon 35(12):1689–1705CrossRefGoogle Scholar
  8. Cui X, Bustin RM (2005) Volumetric strain associated with methane desorption and its impact on coalbed gas production from deep coal seams. AAPG Bull 89(9):1181–1202CrossRefGoogle Scholar
  9. Faiz M, Saghafi A, Sherwood N, Wang I (2007) The influence of petrological properties and burial history on coal seam methane reservoir characterisation, Sydney Basin, Australia. Int J Coal Geol 70(1):193–208CrossRefGoogle Scholar
  10. Gensterblum Y, Ghanizadeh A, Krooss BM (2014) Gas permeability measurements on Australian subbituminous coals: fluid dynamic and poroelastic aspects. J Nat Gas Sci Eng 19:202–214CrossRefGoogle Scholar
  11. Gu F, Chalaturnyk R (2010) Permeability and porosity models considering anisotropy and discontinuity of coalbeds and application in coupled simulation. J Pet Sci Eng 74(3):113–131CrossRefGoogle Scholar
  12. Itasca Consulting Group Inc (2011) UDEC: Universal Distinct Element Code, version 5.0. ICG, Minneapolis, Minn.Google Scholar
  13. Klinkenberg LJ (1941) The permeability of porous media to liquids and gases. Socar Proceedings 2(2):200–213Google Scholar
  14. Li B, Wei J, Wang K, Li P, Wang K (2014) A method of determining the permeability coefficient of coal seam based on the permeability of loaded coal. Int J Min Sci Technol 24(5):637–641CrossRefGoogle Scholar
  15. Li M, Yin G, Xu J, Cao J, Song Z (2016) Permeability evolution of shale under anisotropic true triaxial stress conditions. Int J Coal Geol 165:142–148CrossRefGoogle Scholar
  16. Liu Q, Cheng Y, Ren T, Jing H, Tu Q, Dong J (2016) Experimental observations of matrix swelling area propagation on permeability evolution using natural and reconstituted samples. J Nat Gas Sci Eng 34:680–688CrossRefGoogle Scholar
  17. Lv Y (2012) Test studies of gas flow in rock and coal surrounding a mined coal seam. Int J Min Sci Technol 22(4):499–502CrossRefGoogle Scholar
  18. McKee CR, Bumb AC, Koenig RA (1988) Stress-dependent permeability and porosity of coal and other geologic formations. SPE Form Eval 3(1):81–91CrossRefGoogle Scholar
  19. Min KB, Rutqvist J, Tsang CF, Jing L (2004) Stress-dependent permeability of fractured rock masses: a numerical study. Int J Rock Mech Min Sci 41(7):1191–1210CrossRefGoogle Scholar
  20. Palmer I (2009) Permeability changes in coal: analytical modeling. Int J Coal Geol 77(1):119–126CrossRefGoogle Scholar
  21. Pan R, Cheng Y, Yuan L, Yu M, Dong J (2014) Effect of bedding structural diversity of coal on permeability evolution and gas disasters control with coal mining. Nat Hazards 73(2):531–546CrossRefGoogle Scholar
  22. 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):252–261CrossRefGoogle Scholar
  23. Pan Z, Ma Y, Connell LD, Down DI, Camilleri M (2015) Measuring anisotropic permeability using a cubic shale sample in a triaxial cell. J Nat Gas Sci Eng 26:336–344CrossRefGoogle Scholar
  24. Ramandi HL, Mostaghimi P, Armstrong RT, Saadatfar M, Pinczewski WV (2015) Porosity and permeability characterization of coal: a micro-computed tomography study. Int J Coal Geol 154:57–68Google Scholar
  25. Ramandi HL, Mostaghimi P, Armstrong R, Saadatfar M, Pinczewski WV (2016) Porosity and permeability characterization of coal: a micro-computed tomography study. Int J Coal Geol 154-155:57–68Google Scholar
  26. Ren F, Ma G, Fu G, Zhang K (2015) Investigation of the permeability anisotropy of 2D fractured rock masses. Eng Geol 196:171–182CrossRefGoogle Scholar
  27. Saghafi A (2010) Potential for ECBM and CO2 storage in mixed gas Australian coals. Int J Coal Geol 82(3):240–251CrossRefGoogle Scholar
  28. Seidle JP, Jeansonne MW, Erickson DJ (1992) Application of matchstick geometry to stress dependent permeability in coals. In: SPE Rocky Mountain Regional MeetingGoogle Scholar
  29. Shi JQ, Durucan S (2013) Exponential growth in San Juan Basin Fruitland coalbed permeability with reservoir drawdown? model match and new insights. SPE Reserv Eval Eng 13(6):914–925CrossRefGoogle Scholar
  30. Wang D, Wei J, Yin G (2012) Investigation on change rule of permeability of coal containing gas under complex stress paths. Chin J Rock Mech Eng 31(2):303–310Google Scholar
  31. Yang TH, Xu T, Liu HY, Tang CA, Shi BM, Yu QX (2011) Stress–damage–flow coupling model and its application to pressure relief coal bed methane in deep coal seam. Int J Coal Geol 86(4):357–366CrossRefGoogle Scholar
  32. Yao C, Jiang QH, Shao JF (2015) A numerical analysis of permeability evolution in rocks with multiple fractures. Transp Porous Media 108(2):289–311CrossRefGoogle Scholar
  33. Yin G, Li M, Wang JG, Xu J, Li W (2015) Mechanical behavior and permeability evolution of gas infiltrated coals during protective layer mining. Int J Rock Mech Min Sci 80:292–301CrossRefGoogle Scholar
  34. Zhang C, Tu S, Bai Q, Yang G, Zhang L (2015a) Evaluating pressure-relief mining performances based on surface gas venthole extraction data in longwall coal mines. J Nat Gas Sci Eng 24:431–440CrossRefGoogle Scholar
  35. Zhang C, Zhang L, Zhao Y, Wang W (2018) Experimental study of stress-permeability behavior of single persistent fractured coal samples in the fractured zone. J Geophys Eng 15(5):2159–2170CrossRefGoogle Scholar
  36. Zhang C, Tu S, Zhang L, Chen M (2016b) A study on effect of seepage direction on permeability stress test. Arab J Sci Eng 41(11):4583–4596CrossRefGoogle Scholar
  37. Zhang L, Aziz N, Ren T, Nemcik J, Tu S (2015b) Nitrogen injection to flush coal seam gas out of coal: an experimental study. Arch Min Sci 60(4):1013–1028Google Scholar
  38. Zhang L, Ren T, Aziz N (2014) Influences of temperature and moisture on coal sorption characteristics of a bituminous coal from the Sydney Basin, Australia. Int J Oil Gas Coal Technol 8(1):62–78CrossRefGoogle Scholar
  39. Zhang L, Zhang C, Tu S, Tu H, Wang C (2016a) A study of directional permeability and gas injection to flush coal seam gas testing apparatus and method. Transp Porous Media 111(3):573–589CrossRefGoogle Scholar
  40. Zou J, Chen W, Yang D, Yu H, Yuan J (2016) The impact of effective stress and gas slippage on coal permeability under cyclic loading. J Nat Gas Sci Eng 31:236–248CrossRefGoogle Scholar

Copyright information

© Saudi Society for Geosciences 2019

Authors and Affiliations

  1. 1.State Key Laboratory of Coal Resources and Safe MiningChina University of Mining and TechnologyBeijingChina
  2. 2.School of Resource and Safety EngineeringChina University of Mining and TechnologyBeijingChina
  3. 3.State Key Laboratory of Groundwater Protection and Utilization by Coal MiningNational Energy Group Co., Ltd.BeijingChina
  4. 4.Key Laboratory of Deep Coal Resource Ministry of Education of China, School of MinesChina University of Mining and TechnologyXuzhouChina

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