基于声发射分形参数分析的储层岩石裂纹演化特征研究

研究储层岩石压裂过程中所产生的信号特征,能够分析岩石压裂过程中的裂纹演化特征。对不同类型的储层岩石进行单轴受压破坏全过程的声发射实验,结合声发射信号振幅、上升时间及持续时间的累积频度和离散频度分形b值分析,研究了声发射信号在岩石破坏全过程中的变化规律。研究结果表明:①不同类型的岩石受其内部结构特征的影响,应力、应变状态有显著差异,声发射参数分形b值在不同的应力加载阶段分布特征有明显的差异;②振幅、上升时间以及持续时间的分形b值在储层岩石加载的不同阶段表现出明显的规律性。室内试验结果和现场微地震研究结果都表明,分形b值的研究对于致密储层水压致裂过程中的裂纹演化研究具有一定的指导意义。

 Acoustic emission signal characteristics can be used to analyze the characteristics of crack evolution during reservoir rock fracturing process.Using acoustic emission tests under uniaxial compression on different types of reservoir rocks,the change law of the acoustic emission signal with stress load variation in the whole process of rock failure was studied by analyzing the fractal b values of amplitude,rising time,and duration of the acoustic emission signal obtained using the cumulative frequency and discrete frequency methods.The test results show that,during uniaxial compression process,the stress and strain state of different types of rocks differ significantly,because they have different internal structures,and the distribution characteristics of the fractal b value in different stress loading stages differ obviously.Moreover,the fractal b values of amplitude,rising time,and duration show obvious regularity at different stress loading stages.Both the laboratory experiment and the field microseismic test results show that the analysis of fractal b value can be used to clarify crack evolution characteristics in tight reservoir hydraulic fracturing.

国家自然科学基金项目(41504097,41374123)、国家科技重大专项(2016ZX05006-002)与中央高校基本科研业务费(15CX08002A)联合资助。