• 全部
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
花岗岩干热岩体裂隙的大位移动态剪切-渗流特征
  • Title

    Characteristics of large⁃displacement based dynamic shearing⁃flow through the fractures in the granitic hot dry rock mass

  • 作者

    赵鹏冯子军南翰墨李杰

  • Author

    ZHAO Peng;FENG Zijun;NAN Hanmo;LI Jie

  • 单位

    太原理工大学矿业工程学院太原理工大学原位改性采矿教育部重点实验室

  • Organization
    College of Mining Engineering,Taiyuan University of Technology
    Key Laboratory of In-situ Property Improving Mining of Min⁃istry of Education,Taiyuan University of Technology
  • 摘要

    水力剪切是干热岩地热、页岩气等深部能源开采的又一重要技术手段,水力剪切在提高储层渗透性的同时还会诱发地震。水力剪切增透和注入诱发地震的本质均是节理裂隙/ 断层的剪切-渗流。为深入研究不同诱因下,节理裂隙/ 断层岩体的剪切-渗流特性演化特征,利用自主研发的高围压大位移实时剪切渗流装置,研究了花岗岩干热岩体裂隙在剪切蠕变、剪应力增加、水压力增加和位移速率增加4 种诱因引起的滑动过程中的渗流特征,并利用现有的速率-状态方程分析了诱发地震过程中裂隙/ 断层的摩擦特性。结果表明:① 在三轴静水压力下,花岗岩裂隙内的注水压力与注水流量之间呈线性关系,裂隙的等效张开度与渗透率随法向应力的增加呈负指数衰减特征。② 剪切蠕变、注水压力、剪切应力速率和剪切位移速率4 种诱因所引起的裂隙/ 断层的黏滑均导致裂隙/ 断层的渗透性显著增加,且滑移变形和滑移速率越大,渗透率增幅越大。4 种诱因中,剪切蠕变引起的渗透率增幅最小,剪切应力速率引起的渗透率增幅最大。③ 在剪切-渗流过程中,速率-状态摩擦定律仍然可以用于分析裂隙/ 断层的稳定性特征,随着黏滑次数的增多,剪切应力降、b 值(即摩擦因数随时间或变形的降幅)及滑移速率等摩擦参数在规则黏滑中以对数形式增长,断层滑移的不稳定程度增加;而在混沌黏滑中,上述参数符合朗格缪尔方程,并趋向于0,断层滑移的不稳定程度降低。

  • Abstract
    Hydro⁃shearing is an important technical method for deep energy extraction,such as hot dry rock geothermalenergy and shale gas extraction. In addition to improving reservoir permeability,the hydro⁃shearing will also induceearthquakes. The essence of both hydro⁃shearing induced permeability enhancement and injection⁃induced seismicityare shearing⁃seepage through the geological joints or faults. In order to study the evolution of shearing⁃flow propertiesof joints or faults due to different derived conditions, we employed a high confining pressure and real⁃time large⁃displacement shearing⁃flow setup designed by ourselves to study the fluid flow characteristics of man⁃made frac⁃ture in the granitic hot dry rock mass during shearing⁃slip which were derived by shearing creep,increasing shearingstress,increasing water⁃injected pressure and increasing displacement rate,and further analyzed the friction character⁃istics of fracture or fault in the process of induced seismicity using the rate⁃state equation. The results indicate that:① Under the triaxially hydrostatic stresses,there existed linear relationship between water⁃injected pressure and injec⁃tion rate in the granitic fracture,and the equivalent opening and permeability of the fracture showed negative exponen⁃tial decay with the increment of normal stress. ② The stick⁃slip of fracture or fault caused by shearing creep,water⁃in⁃jected pressure,shearing stress rate and shearing displacement rate could induce a significant increment in the permea⁃bility. The greater the slip deformation and slip rate,the greater the permeability enhancement. Among the four deriva⁃tions,the permeability increment caused by shearing creep was the smallest as shearing stress rate induced enhance⁃ment was the largest. ③ During the shearing flow process,the rate⁃state friction law could still be used to analyze thestability of fracture or fault. With the increment of stick⁃slip times,the friction parameters such as shearing stress drop,b value (That is the drop of frictional coefficient with time and/ or displacement) and slip rate increased in the form oflogarithmic function in the regular stick⁃slip which represented the increment of instability of fault slip. In the chaoticstick⁃slip,the above parameters conformed to the Langmuir equation and tended to zero which indicated that the insta⁃bility of fault slip decreased.
  • 关键词

    水力剪切注入诱发地震剪切-渗流干热岩地热储层改造

  • KeyWords

    hydro⁃shearing;injection⁃induced seismicity;shearing⁃flow;hot dry rock geothermal energy;reservoir mod⁃ ification

  • 相关文章
  • 相关专题
  • 图表
    •  
    •  
    • 恒定剪应力56 MPa下花岗岩裂隙剪切蠕变-渗流曲线(σc=30 MPa,σp=5 MPa,τ=56 MPa)

    图(16) / 表(0)

相关问题
立即提问

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

©版权所有2015 煤炭科学研究总院有限公司 地址:北京市朝阳区和平里青年沟东路煤炭大厦 邮编:100013
京ICP备05086979号-16  技术支持:云智互联