摘要
利用自行研制的"TCHFSM-I"型大尺寸真三轴压裂渗流模拟装置,研究不同应力条件下煤岩组合体跨界面水力裂缝起裂、扩展规律,分析压裂过程中注液压力与声发射动态响应特征。结果表明:当轴向载荷与最小水平主应力差值≥6 MPa时,水力裂缝能够跨界面扩展进入煤体,形成贯穿型裂缝;反之,水力裂缝沿界面扩展。各试件水力裂缝跨界面扩展行为不同,其注液压力演化规律和声发射动态响应特征也存在差异。当水力裂缝扩展进入煤体时,注液压力呈现明显二次上升,声发射事件累计数占比显著提升,增幅达51.4%,且多位于煤体中;当水力裂缝沿界面扩展时,声发射累计数增幅量仅为6%,且注液压力无二次上升。此外,建立考虑交汇角度、界面摩擦、应力状态等因素作用的水力裂缝跨界面扩展模型,该模型能够很好地描述与预测水力裂缝跨界面扩展行为。研究结果可为煤层气高效开采提供技术指导。
The self-developed'TCHFSM-I'large-scale true triaxial hydraulic fracturing seepage simulation device was used to study the crack initiation and propagation in coal-rock blocks under different stress conditions,and the hydraulic pressure and acoustic emission event evolutions were also analyzed.The results show that,when the difference of the axial stress and the minimum horizontal principal stress was equal or greater than 6 MPa,the hydraulic cracks can extend into coal across the interface,otherwise extend along the interface.The hydraulic pressure and acoustic emission response characteristics can well reflect the behaviors of hydraulic fractures across the interface.When the hydraulic cracks extend into the coal,the hydraulic pressure shows a significant secondary rise,and the cumulative number of the acoustic emission events increases significantly at a rate of 51.4%,most of which occur in coal.When the hydraulic cracks expand along the interface,the cumulative number of the acoustic emission events increases just by 6%and there is no secondary rise in fluid injection pressure.A crack expansion model crossing the interface,considering the angle between the crack and the interface,the interfacial friction and the stress state,was established,which can well describe and predict the crack expansion behavior crossing interfaces in hydraulic fractures.The research results in this paper can provide a technical guidance for efficient exploitation of coalbed methane.
作者
姜玉龙
梁卫国
李治刚
廉浩杰
武鹏飞
耿毅德
姚宏波
JIANG Yulong;LIANG Weiguo;LI Zhigang;LIAN Haojie;WU Pengfei;GENG Yide;YAO Hongbo(College of Mining Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;Key Laboratory of In-situ Property-improving Mining of Ministry of Education,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;College of Safety and Emergency Management Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2019年第5期875-887,共13页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(51874206
51704204)
山西省科技重大专项资助项目(MQ2016–01)~~
关键词
岩石力学
煤岩组合体
水力压裂
声发射响应
裂缝跨界面扩展模型
rock mechanics
coal-rock blocks
hydraulic fracturing
acoustic emission response
crack expansion model crossing interface
