摘要
为探究岩石在定向水力压裂下诱导裂纹的扩展演化规律,建立了岩石预制裂纹定向水力压裂相场模型,提出采用降维的界面相场模型表征预制裂纹以优化建模过程,通过与砂岩压裂试验对比验证了模型的有效性。重点研究了预制裂纹倾角、压裂液黏度、流体注射速率、水平应力差以及天然裂隙对水力诱导裂隙扩展路径和岩石破裂压力的影响。结果表明:改变预制裂纹倾角会导致水力诱导裂隙扩展路径发生不同程度的偏转;压裂液黏度或注射速率越大,岩石破裂压力越大,但均不影响水力诱导裂隙扩展偏转角的改变;随着水平应力差增大,岩石破裂压力与水力诱导裂隙偏转角分别呈现线性递减和非线性递增趋势;水力诱导裂隙与天然裂隙交汇的接近角不同导致其主要发生贯穿式扩展或延伸式扩展;总体上,水力诱导裂隙倾向于指向或偏向最大水平主应力方向扩展。
To investigate the propagation and evolution laws of induced cracks in rocks under directional hydraulic fracturing,a phase-field model is developed.A dimension-reduced interface phase field model is adopted to characterize prefabricated cracks in order to optimize the modeling process.The model’s effectiveness is verified by comparison with hydraulic fracturing tests of sandstone.The model is used to study the effects of pre-crack inclination,fracturing fluid viscosity,fluid injection rate,horizontal stress difference,and natural fracture on the hydraulically induced fracture expansion path and rock fracture pressure.The results show that changing the inclination angle of the pre-crack will lead to different degrees of deflection of the hydraulic-induced crack propagation path.The larger the fracturing fluid viscosity or injection rate is,the larger the breakdown pressure is,but the change of hydraulic-induced fracture propagation deflection angle is not affected.With increase of horizontal stress difference,breakdown pressure and hydraulic-induced fracture deflection angle show linear decreasing and nonlinear increasing trends,respectively.The different approach angles at the intersection of hydraulically induced fractures and natural fractures lead to the penetration or extensional expansion mode.In general,hydraulically induced fractures tend to expand in the direction of the maximum horizontal principal stress.
作者
梁鑫
侯鹏
薛熠
刘嘉
高峰
LIANG Xin;HOU Peng;XUE Yi;LIU Jia;GAO Feng(State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi'an University of Technology,Xi'an 710048,China;School of Civil Engineering and Architecture,Xi'an University of Technology,Xi'an 710048,China;School of Civil Engineering,Wuhan University,Wuhan 430072,China;School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China)
出处
《岩土工程学报》
北大核心
2025年第9期1865-1873,共9页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(52204112,12202353)
陕西省教育厅科研计划项目(22JK0480)。
关键词
定向水力压裂
相场模拟
裂纹扩展偏转角
破裂压力
裂隙交互
directional hydraulic fracturing
phase-field simulation
crack propagation deflection angle
fracturing pressure
fracture interaction
