无烟煤各向异性吸附膨胀动态响应实验研究

    Experimental study on dynamic response of anisotropic adsorption swelling of anthracite

    • 摘要: 为研究注入CO2后煤岩吸附膨胀的各向异性特征,以沁水盆地无烟煤为研究对象,开展了煤岩CO2吸附量及各向异性膨胀实验研究,并讨论了煤岩CO2吸附量与应变量之间的关系。结果表明:煤岩注入CO2后体积发生变形,体积应变随时间呈现阶段性变化;CO2绝对吸附量和膨胀应变与CO2注入压力之间均可用Langmuir模型来表征;煤岩吸附膨胀变形呈现明显的各向异性特征,煤岩垂直层理方向应变最大,其次是平行面割理方向,而平行端割理方向应变最小;煤岩绝对吸附量和煤岩膨胀应变符合S型曲线变化关系,可用Slogistic函数拟合;煤岩吸附CO2基质膨胀首先以内部膨胀为主,割理或裂隙遭受压缩之后开始向外部膨胀,最终当煤岩内部应力状态达到平衡后,煤岩膨胀变形趋于稳定。

       

      Abstract: In order to study the anisotropic adsorption swelling characteristics of coal-rock after CO2 injection, taking anthracite in Qinshui Basin as the research object, the experiments regarding CO2 adsorption capacity and anisotropic swelling of coal-rock were carried out, and the relationship between CO2 adsorption capacity and swelling strain was discussed. Results show that the volume of coal-rock is deformed after CO2 injection, the volume strain changes periodically with time; the Langmuir model can be used to describe the relationship between the CO2 absolute adsorption capacity and the adsorption swelling strain of coal-rock with the CO2 injection pressure; the adsorption swelling deformation of coal-rock presents obvious anisotropic characteristics. The strain in vertical bedding direction is the largest, followed by the shear direction of parallel plane, and the strain in the shear direction of parallel end is the smallest; the relationship between absolute adsorption capacity and swelling strain of coal-rock is in accordance with S-curve, which can be fitted by the Slogistic function; the matrix swelling of CO2 adsorbed by coal-rock is mainly internal swelling at first, and it begins to expand to the outside after cleats or fractures are compressed. Finally, when the internal stress state of coal rock reaches equilibrium, the expansion deformation of coal rock tends to be stable.

       

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