摘要
为了进一步探讨砂岩在水力冲击致裂技术下的裂缝扩展规律,采用自行研发的真三轴定向水力冲击致裂试验系统,以沿钻孔轴向垂直层面预制裂缝紫砂岩为研究对象,重点分析水平应力差与压裂液黏度对预制裂缝的起裂与扩展的影响。试验结果表明:随着水平应力差的增大,砂岩裂缝的起裂压力和应变率显著增加;压裂液黏度的提升也对起裂压力和应变率的增加起到促进作用,较高黏度的压裂液能够更有效地传递压力,缩短裂缝起裂时间并促使裂缝沿预定方向稳定扩展。此外,基于弹性断裂力学,建立了砂岩预制裂缝的起裂压力计算公式并验证了其有效性。
To further discuss fracture propagation regularity in sandstone under hydraulic impact fracturing technology,a self-developed true triaxial directional hydraulic fracturing impact testing system was employed.Using pre-fractured purple sandstone specimens with vertical bedding planes along the borehole axis as the research object,this study specifically analyzed the effects of confining stress differentials and fracturing fluid viscosity on the initiation and propagation of prefabricated fractures.Experimental results indicate that increasing horizontal stress differentials significantly elevates both fracture initiation pressure and strain rate.Enhanced fracturing fluid viscosity similarly promotes these parameters.Furthermore,higher-viscosity fracturing fluids demonstrate superior pressure transmission efficiency,shortening fracture initiation time while facilitating stable propagation along predetermined directions.Additionally,an initiation pressure calculation model for sandstone prefabricated fractures was established based on elastic fracture mechanics theory,with experimental validation confirming its validity.
作者
李鸿宾
范文兵
刘正和
LI Hongbin;FAN Wenbing;LIU Zhenghe(Key Laboratory of In-situ Property-improving Mining of Ministry of Education,Taiyuan University of Technology,Taiyuan 030024,China)
出处
《广西大学学报(自然科学版)》
北大核心
2025年第2期253-263,共11页
Journal of Guangxi University(Natural Science Edition)
基金
国家自然科学基金项目(52174123)。
关键词
水力冲击
定向致裂
预制裂缝
围岩应力差
压裂液黏度
起裂压力
hydraulic impact
directional fracturing
prefabricated fracture
confining stress differential
fracturing fluid viscosity
fracture initiation pressure
作者简介
通信作者:刘正和(1976-),男,宁夏盐池人,教授,博士生导师,博士,E-mail:liuzhenghe@tyut.edu.cn。
