• 论文
主办单位:煤炭科学研究总院有限公司、中国煤炭学会学术期刊工作委员会
循环加卸载过程中的水化页岩渗透特性
  • Title

    Permeability of hydrated shale rocks under cyclic loading and unloading conditions

  • 作者

    刘先珊潘玉华李满康治勇周虎乔士豪

  • Author

    LIU Xianshan,PAN Yuhua,LI Man,KANG Zhiyong,ZHOU Hu,QIAO Shihao

  • 单位

    重庆大学 山地城镇建设与新技术教育部重点实验室重庆大学 土木工程学院

  • Organization
    Key Laboratory of New Technology for Construction of Cities in Mountain Area,Ministry of Education,Chongqing University;School of Civil Engineering,Chongqing University
  • 摘要

    页岩气开发过程中储层页岩的水化效应突出其力学特性及渗透特性的演化规律不明确, 准确把握其过程中的水化页岩水力学特性尤为关键。 以不同水化天数的储层页岩为研究对象分 析水化作用后的页岩力学特性深入研究循环加卸载过程中的水化页岩渗透性。 试验结果表明:单 一加载时水化时间越多的页岩峰值强度越低渗透率越大并结合损伤理论建立页岩渗透率与结 构损伤的关联性。 分析初始加卸载过程中的页岩渗透特性显示加载渗透率随围压增大而减小卸 载渗透率随围压减小而增大且同围压下的加载渗透率大于卸载渗透率阐明损伤的不可逆变形导 致页岩加卸载渗透率的显著差异。 通过试验数据的拟合显示:初始加载的页岩渗透率与围压成负 指数关系随循环加载次数增多而变为幂函数关系说明循环围压加载导致渗透特性变化大而形成 不同的渗透率演化模型卸载渗透率变化则较平缓与围压均呈幂函数关系。 进一步分析 次循环 加卸载中的页岩渗透率损伤率及恢复率均随循环加载次数的增加而降低。 最后通过页岩渗透率 对围压敏感因子的变化规律阐明初始加卸载的渗透率对围压的敏感性最大随着循环次数的增 加其敏感因子逐渐减小且低围压的加载渗透率对围压变化较敏感随围压的增大而减小而卸载 后的应力敏感因子仍保持较小验证了页岩渗透率演化的损伤性及恢复性揭示循环加卸载过程中 的水化页岩渗透性演化机理


  • Abstract

    The hydration of reservoir shale is obvious during shale gas extraction,resulting in some vague permeability evolution and mechanical characteristics. Thus the understanding on the hydraulic characteristics of shale during the shale gas extraction process is very important. Taking the reservoir shales under different hydrated days as a case study,the mechanical properties and permeability evolution under cyclic loading and unloading conditions have been investigated. According to the experiments results of the hydrated shale under loading condition,the peak strength is lower and the corresponding permeability is higher for multi-day hydration. Then,the damage theory is applied to ana⁃ lyze the shale permeability evolution resulted in by rock damage. Also,from the permeability variation under initial loading and unloading conditions, the permeability while loading decreases with the increase of confining pressure, however, it increases while unloading with the decrease of confining pressure, and the former is greater than the latter under same confining pressure,indicating that the irreversible deformation causes marked differ⁃ ence of the permeability in the process. In addition, the fitting curves based on the experimental data firstly show the negative exponential relationship between the permeability and confining pressure under initial cyclic condi⁃ tions and the power function for more cyclic processes, changing the permeability evolution into different fitting model,however,the permeability variation while unloading is in accordance with a power function. Furthermore,the loss ratio and recovery ratio under five cyclic loading and unloading conditions have been analyzed showing a permea⁃ bility decreasing with more cyclic processes. Finally,the permeability-stress sensitive coefficient has been investiga⁃ ted demonstrating the coefficient is more sensitive to the initial confining pressure and decreases with more cyclic processes. Especially it is more sensitive to lower confining pressure while loading and maintains lower while unloading,calibrating the shale permeability loss and recovery,which reveals the permeability evolution of the hydrated shale under cyclic loading and unloading conditions.


  • 关键词

    储层页岩水化作用循环加卸载渗透性应力敏感因子

  • KeyWords

    reservoir shale rocks;hydrated effect;cyclic loading and unloading;permeability evolution;stress sensi⁃ tive coefficient

  • 引用格式
    刘先珊,潘玉华,李满,等. 循环加卸载过程中的水化页岩渗透特性[J].煤炭学报,2022,47(S1):103-114.
  • Citation
    LIU Xianshan,PAN Yuhua,LI Man,et al. Permeability of hydrated shale rocks under cyclic loading and unloa⁃ ding conditions[J]. Journal of China Coal Society,2022,47(S1):103-114.
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主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会

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