复杂应力条件下岩心水力压裂实验装置设计及验证  

Design and verification of core hydraulic fracturing experimental device under complex stress conditions

作　　者：李沁[1] 代朝辉 卢渊[1] 伊向艺[1] 陈文玲[1] 刘旭 吴元琴[1] LI Qin;DAI Zhaohui;LU Yuan;YI Xiangyi;CHEN Wening;LIU Xu;WU Yuanqin(College of Energy(College of Modern Shale Gas Industry),Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学能源学院(页岩气现代产业学院),四川成都610059

出　　处：《实验技术与管理》2024年第11期131-136,共6页Experimental Technology and Management

基　　金：成都理工大学2023年中青年骨干教师发展资助计划(10912-SJGG2023-04200);国家自然科学基金联合基金项目(U20A20265)。

摘　　要：非常规油气储层物性特征差、应力条件复杂,水力压裂是提高非常规油气勘探开发效率的关键技术之一。该文研制了轴向应力独立加载的全直径岩心水压致裂超声波检测装置,实验装置包含多套独立加压系统,可以模拟实际地层的复杂应力条件,并根据声发射实时检测岩石破坏特征。基于实验装置开展了30°、45°、60°天然裂缝的岩心在复杂应力条件下的水力压裂实验,实验结果表明:45°天然裂缝的岩心相较于其他角度稳定性最差,压力达到14.1 MPa时产生破裂,声发射特征明显;天然诱导应力干扰下,水力裂缝逼近时扩展路径发生偏移,随着天然裂缝角度增大,偏移更加明显。该实验装置可以为复杂应力的储层增产改造提供理论依据。[Objective]Unconventional oil and gas reservoirs are characterized by poor physical properties and complex stress conditions.Hydraulic fracturing is essential for improving the efficiency of exploring and developing these resources.Traditional indoor hydraulic fracturing experiments typically simulate crack propagation under a single stress state,failing to capture the crack morphology under the complex stresses of actual formations and natural fracture disturbances.[Methods]In this paper,a full-diameter core hydraulic fracturing ultrasonic testing device with independent axial stress loading has been developed.This experimental device includes multiple sets of independent pressure systems and acoustic emission data acquisition systems,allowing it to simulate various complex stress conditions found in real formations.It detects rock failure characteristics through acoustic emissions and records the response during fracture initiation and propagation in real time.Experiments focused on natural fracture stability and hydraulic fracturing under complex stress conditions were carried out on cores with natural frequencies at angles of 30°,45°,and 60°using the instrument.Custom-designed rock samples were used to explore fracture propagation laws under varying conditions,offering a new method for simulating reservoir hydraulic fracturing effects under complex stress.[Results]The experimental results indicate the following:①The amplitude of acoustic emission signals is positively correlated with crack formation characteristics.A sudden increase in acoustic emission signals demonstrates the pressure point where cracks begin to destabilize;②Cores with 45°natural fractures exhibit the least stability.Fracture occurs at a pressure of 14.1 MPa,with prominent acoustic emission characteristics.By contrast,30°and 60°natural fractures mainly result in shear and partial tensile fractures after instability;③Induced stress interference causes the fracture path to shift as hydraulic fractures approach.With increasing natu

关 键 词：复杂应力 天然裂缝 水力压裂 声发射特征 

分 类 号：TE13[石油与天然气工程—油气勘探]