高温作用下五峰组–龙马溪组页岩动力学特征及损伤演化规律研究  

Dynamic characteristics and damage evolution law of Wufeng formation-Longmaxi formation shale under high temperature effects

作　　者：王宇 翟成[1,2] 余旭[1,2] 孙勇[1,2] 丛钰洲[1,2] WANG Yu;ZHAI Cheng;YU Xu;SUN Yong;CONG Yuzhou(School of Safety Engineering,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;National Engineering Research Center for Coal Gas Control,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)

机构地区：[1]中国矿业大学安全工程学院,江苏徐州221116 [2]中国矿业大学煤矿瓦斯治理国家工程研究中心,江苏徐州221116

出　　处：《岩石力学与工程学报》2023年第5期1110-1123,共14页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家重点研发计划(2020YFA0711800)。

摘　　要：甲烷原位燃爆压裂是一项变革性页岩气储层压裂改造技术,压裂过程井周储层受到高温–冲击波协同作用,研究高温作用下页岩动力学特征及损伤演化,对揭示页岩储层燃爆压裂的致裂增透规律具有重要意义。综合运用热重分析仪、马弗炉、分离式霍普金森压杆(SHPB)实验系统、扫描电镜(SEM)和能谱分析(EDS)技术,对经历不同高温热损伤的页岩试样进行动态冲击实验,得到了页岩动力学特征随温度的演化规律,构建考虑热损伤和压密阶段的页岩动态损伤本构模型,并通过实验数据进行验证,最后利用扫描电镜(SEM)分析高温作用下页岩动力学特性演化的微观损伤机制。结果表明,随温度升高,页岩表面逐渐出现连通裂隙,且高温热效应导致该页岩中水分散失,黏土矿物改性,白云石、方解石等主要碳酸盐矿物热分解,孔、裂隙结构发育连通,综合导致随温度升高页岩损伤劣化作用明显。试样动态冲击破碎形态随温度升高逐渐由单一裂缝转变为粉碎型破坏,碎块平均粒度、动态抗压强度和弹性模量先小幅增大,随后迅速降低;破碎分形维数、平均应变率和能量吸收比先降低后升高,700℃高温作用下页岩动力学特性显著劣化。这说明,燃爆压裂的高温–冲击波协同作用有利于构建页岩储层井周复杂裂缝网络。实验数据验证了考虑高温和压密阶段的动态损伤本构模型,该模型能够反映高温作用下岩石的动力学特性。研究结果对于揭示甲烷原位燃爆压裂机制具有重要意义。The explosive fracturing of shale with in-situ methane is a revolutionary technique,with a high temperature-shock wave synergy in the fracturing process.Therefore,it is important to study the dynamic characteristics and damage evolution of shale under high temperature to reveal the fracturing evolution of shale reservoir using explosive fracturing technology.In this paper,by comprehensive application of the rmogravimetric analyzer,muffle furnace,separated Hopkinson pressure bar(SHPB)experimental system,scanning electron microscope(SEM)and energy spectrum analysis(EDS),the evolution law of shale dynamic characteristics with temperature was obtained,a dynamic damage constitutive model of shale considering thermal damage and compression-density stage was constructed and verified by experimental data,and finally the microscopic damage mechanism of the evolution of shale dynamic characteristics under high temperature was analyzed by SEM.The results show that the shale surface gradually develops connected fractures,and the high temperature thermal effect leads to water dissipation and thermal decomposition of the clay minerals and main carbonate minerals such as dolomite and calcite in this shale,and the pore-fracture structure is developed and connected,which integrally leads to the significant deterioration of the dynamic properties.With the increase of treatment temperature,the fracture form of the specimen changes from single fracture to complex fracture network,the dynamic compressive strength and elastic modulus first increase slightly and then decrease suddenly,and the strain rate and energy absorption ratio first decrease and then increase.These suggests that the high-temperature-shock wave synergy of the explosive fracturing of shale with in-situ methane facilitates the construction of complex fracture networks around the well perimeter of shale reservoirs.The dynamic damage constitutive model of shale is verified by experimental data,which proves that the model can better reflect the dynamic properties of sha

关 键 词：岩石力学 五峰组–龙马溪组页岩 高温热效应 SHPB动态冲击实验 动态损伤本构模型 

分 类 号：TU45[建筑科学—岩土工程]