动载荷冲击后页岩蠕变试验及分数阶蠕变本构模型研究  

Study on shale creep experiment and fractional creep constitutive model after dynamic load impact

作　　者：刘春[1] 田纪辉 孙海涛 魏明尧[1] 李文龙 戴康 LIU Chun;TIAN Jihui;SUN Haitao;WEI Mingyao;LI Wenlong;DAI Kang(Institute of Internet of Things,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;School of Safety Engineering,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)

机构地区：[1]中国矿业大学矿山互联网应用技术国家地方联合工程实验室,江苏徐州221116 [2]中国矿业大学安全工程学院,江苏徐州221116

出　　处：《中国矿业大学学报》2024年第4期726-736,共11页Journal of China University of Mining & Technology

基　　金：国家重点研发计划资助项目(2020YFA0711802)。

摘　　要：页岩存储层甲烷燃爆压裂技术利于提高页岩气的产量,但燃爆冲击会对井筒造成损伤,在地应力作用下井筒周围页岩蠕变会导致井身变形,引发井壁失稳.为了分析冲击强度对页岩蠕变特性的影响,开展了不同冲击强度条件下页岩试样单次和多次冲击试验,然后对不同冲击损伤程度的页岩试验进行分级加载蠕变试验.试验结果表明:蠕变总形变量随冲击强度的增加而增加,冲击强度由1.6 J增加到25.6 J,冲击试样的应变量较原样分别增加了7.3%,16.1%,31.5%.同时,冲击强度的增加会降低蠕变破坏应力水平,增强加速蠕变效果,增加减速阶段蠕变速率与持续时间.最后,提出了一种新的页岩非线性分数阶损伤蠕变模型.该模型由胡克体、黏性元件、分数阶元件、分数阶改进Kelvin模型及非线性分数阶黏塑性模型组成,与经典Burgers模型相对比,新模型能很好地拟合蠕变过程的各个阶段的应变数据,特别是在蠕变加速阶段拟合度更高.研究结果能够为分析燃爆冲击后页岩井筒蠕变特性提供理论支持.The combustion and detonation fracturing technology of methane in shale reservoir is conducive to improving the production of shale gas,but the combustion and detonation impact will cause damage to the wellbore,and the shale creep around the wellbore under the action of in-situ stress will lead to wellbore deformation and shaft wall instability.In order to analyze the impact of impact strength on the creep characteristics of shale,single and multiple impact tests of shale samples under different impact strength conditions were carried out in this paper,and then the shale tests with different impact damage degrees were subjected to graded loading creep tests.Finally,a new nonlinear fractional-order damage creep model for shale was pro-posed.The model is composed of Hooker,viscous element,fractional-order element,fraction-al-order improved Kelvin model and nonlinear fractional-order viscoplastic model in series.The experimental results show that the total shape variable of creep increases with the increase of impact strength.The impact strength increases from 1.6 J to 25.6 J,and the strain variable of impact sample increases by 7.3%,16.1%and 31.5%,respectively.At the same time,the in-crease of impact strength will reduce the creep failure stress level,enhance the accelerated creep effect,and increase the creep rate and duration in the deceleration stage.The nonlinear fractional-order damage creep model can reproduce all stages of the creep process well.Com-pared with the classic Burgers model,the new model fits the experimental data better.The re-search results can provide theoretical support for analyzing the creep characteristics of shale wellbore after blasting.

关 键 词：蠕变 分数阶 损伤 非线性模型 

分 类 号：TD262[矿业工程—矿井建设] X936[环境科学与工程—安全科学]