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亓宪寅, 王威. 基于结构异性比的含瓦斯煤渗透各向异性研究[J]. 岩土工程学报, 2017, 39(6): 1030-1037. DOI: 10.11779/CJGE201706008
引用本文: 亓宪寅, 王威. 基于结构异性比的含瓦斯煤渗透各向异性研究[J]. 岩土工程学报, 2017, 39(6): 1030-1037. DOI: 10.11779/CJGE201706008
QI Xian-yin, WANG Wei. Anisotropic permeability model for coal containing methane based on anisotropic structure ratio[J]. Chinese Journal of Geotechnical Engineering, 2017, 39(6): 1030-1037. DOI: 10.11779/CJGE201706008
Citation: QI Xian-yin, WANG Wei. Anisotropic permeability model for coal containing methane based on anisotropic structure ratio[J]. Chinese Journal of Geotechnical Engineering, 2017, 39(6): 1030-1037. DOI: 10.11779/CJGE201706008

基于结构异性比的含瓦斯煤渗透各向异性研究

Anisotropic permeability model for coal containing methane based on anisotropic structure ratio

  • 摘要: 渗透率是煤层气生产中的重要参数,而原煤的结构异性导致其渗透率具有明显的方向性。假设煤体结构各向异性,建立基于结构异性比的煤体各向异性渗透模型,再进一步推导出瓦斯煤各向异性气-固耦合控制方程,并植入Comsol计算平台,系统研究了煤体各向异性对气体扩散和渗透的影响。理论和数值研究结果表明:煤体结构异性比和平行层理方向渗透率与垂直层理方向渗透率的比值之间存在指数关系,结构异性比越大,则渗透率比值越大;恒定围压条件下,结构异性比随压力的增大而增大,平行层理方向的渗透率与垂直层理方向的渗透率比值也在增大;恒定围体积条件下,结构异性比随压力的增大而减小,平行层理方向的渗透率与垂直层理方向的渗透率比值也在减小;本文模型计算数据与渗透各向异性试验数据吻合度高,验证了本文模型的合理性,可适用恒定围岩应力、恒定储层体积等多种条件的渗透各向异性研究。

     

    Abstract: The coal permeability is the key parameter for the gas seepage characteristics and the migration law, and the structural anisotropy of the coal seam makes the permeability have obvious orientation dependence. By assumeing that the coal structure is anisotropic, an anisotropic permeability model is deduced using anisotropic structure ratio for the key parameters, and the Comsol computing platform is implanted. The effects of coal anisotropy on gas diffusion and penetration are investigated. The theoretical and numerical results show that based on the comparative analysis of anisotropic permeability experiments, the proposed model is verified to be reasonable and used for different conditions. There is an exponential relationship between the anisotropic structure ratio and the permeability ratio of the parallel direction of bedding plane to the vertical direction, in other words, the larger the anisotropic structure ratio, the greater the permeability ratio of the parallel direction of bedding plane to the vertical direction. Under the constant confining pressure, with the increasing pressure, the anisotropic structure ratio and the permeability ratio of the parallel direction of bedding plane to the vertical direction increase. Under the constant confining volume, with the increasing pressure, the anisotropic structure ratio and the permeability ratio of the parallel direction of bedding plane to the vertical direction decrease.

     

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