EI、Scopus 收录
中文核心期刊

基于高频光栅监测的水力压裂裂缝动态演化实验研究

DYNAMIC FRACTURE PROPAGATION EXPERIMENT IN HYDRAULIC FRACTURING BASED ON HIGH-FREQUENCY GRATING MONITORING

  • 摘要: 水力压裂裂缝扩展行为直接决定储层改造效果与增产潜力, 是压裂工程设计与优化中的核心科学问题, 对其动态演化过程的精准监测具有重要的理论与应用价值. 本研究提出了一种基于高频光纤布拉格光栅(FBG)的水力压裂裂缝动态演化监测实验方法, 解决了传统手段难以实时捕捉裂缝扩展动态特征的问题. 在真三轴压裂实验中, 通过嵌入高频FBG传感器阵列, 系统采集了不同采样频率(10 Hz、100 Hz、1000 Hz)下的应变与应变率响应信号. 实验结果表明, 1000 Hz高频监测能够清晰识别裂缝起裂前的近井筒压力积聚、损伤发育与累积过程, 揭示近井岩石损伤-破裂的力学机制. 进一步对比曲面裂缝与平直裂缝的扩展行为发现, 随着曲面裂缝迂曲度增加, 应变率响应呈现局部瞬态增强特征, 应变率尖峰更为频繁且幅值更大, 表明其在转向过程中局部应变响应剧烈程度显著增加. 本研究验证了高频FBG监测技术在识别裂缝扩展阶段、判别裂缝形态及预测演化趋势方面的高分辨率优势, 并揭示了水力压裂裂缝扩展过程中应变响应与裂缝形态的关联性, 为实验尺度下非平面裂缝扩展研究及压裂监测方法设计提供了实验依据.

     

    Abstract: The propagation behavior of hydraulic fractures directly determines the effectiveness of reservoir stimulation and the potential for production enhancement, which constitutes a core scientific problem in the design and optimization of fracturing engineering. Accurate characterization of this dynamic evolution process therefore holds profound theoretical value and substantial practical significance. This study proposes an experimental method for monitoring the dynamic evolution of hydraulic fracturing fractures based on high-frequency Fiber Bragg Grating (FBG) technology, which effectively addresses the critical technical challenge that traditional monitoring means face in capturing the dynamic characteristics of fracture propagation in real time. In true triaxial fracturing experiments, a high-frequency FBG sensor array was strategically embedded within the rock specimen, and both strain and strain rate response signals were systematically acquired at different sampling frequencies of 10 Hz, 100 Hz, and 1000 Hz. The experimental results demonstrate that high-frequency monitoring at 1000 Hz can clearly identify the pressure accumulation near the wellbore, the development and progressive accumulation of damage prior to fracture initiation, thereby revealing the fundamental mechanical mechanism that governs rock damage and rupture in the near-wellbore region. Furthermore, through comparative analysis of the propagation behaviors between curved and planar fractures, it is found that with increasing tortuosity of curved fractures, they exhibit significantly more pronounced localized transient strain response enhancement during propagation, which are characterized by strain rate spikes that become progressively more frequent and of substantially greater amplitude, clearly indicating a significant enhancement of the local strain response intensity during the fracture deflection process.. This study validates the high-resolution advantages of high-frequency FBG monitoring technology in identifying fracture propagation stages and discriminating fracture morphology, and further reveals the correlation between strain response and fracture morphology during hydraulic fracturing fracture propagation, thus providing experimental evidence for laboratory-scale investigation of non-planar fracture propagation and for the design of fracturing monitoring methods.

     

/

返回文章
返回