水力压裂解析模型裂缝扩展参数敏感性分析

水力压裂形成复杂裂缝网络是致密储层油气开采的重要技术，掌握水压裂缝扩展机理是控制压裂行为和优化压裂效果的关键．水压裂缝动态扩展行为涉及储层岩体、注入压裂液、压裂实施工艺等方面，其中水力压裂扩展时间、压裂液流体动力粘度系数、压裂液流体注入流速、储层岩石剪切模量成为决定裂缝扩展长度和裂缝开度的重要因素．本研究采用KGD、PKN两类等高解析模型对主控因素的参数敏感性进行分析，直观、快速、可靠地获得水压裂缝扩展长度、张开度动态演化行为的量化数值．研究发现，压裂持续开展过程中水压裂缝扩展长度呈线性增长、开度逐渐趋于稳定，高流体动力粘度导致裂缝难扩展、形成较大裂缝开度，通过增加压裂液流体注入流速可同时增加裂缝扩展长度和开度，较高的岩石剪切模量将降低水压裂缝的开度．通过对比两类解析模型在不同参数下的水压裂缝扩展结果，分析压裂参数与裂缝扩展的相关性和敏感系数，讨论水力压裂解析模型的裂缝扩展参数敏感性．

Sensitivity Analysis for Controlling Parameters of Fracture Propagation in Hydrofracturing Based on Analytical Models

Hydrofracturing for producing the complex hydraulic fracture network is an important technology for oil and gas exploitation in tight reservoirs. Understanding the mechanisms of propagation of hydraulic fractures is crucial to control the fracturing behaviours and optimize the fracturing effects. The dynamic propagation behaviours of the hydraulic fractures are related to the properties of reservoir rock, the injection of fracturing fluid, and the fracturing implementation technique. The most significant factors that control the length and aperture of the hydraulic fractures are the hydrofracturing propagation duration time, the dynamic viscosity coefficient of the fracturing fluid, the injection flow rate of the fracturing fluid, and the shear modulus of the reservoir rock. This study introduces the KGD and PKN analytical models with uniform fracture height to analyze the sensitivity of the aforementioned parameters in hydrofracturing. The quantitative dynamic evolutionary behaviours of the hydraulic fractures in terms of the length and aperture are directly, quickly and reliably derived. It is found that the length of hydraulic fracture increases linearly and the aperture of hydraulic fracture tends to be stable during the fracturing process. The high dynamic viscosity coefficient of fracturing fluid may hinder the fracture propagation and induce large aperture. As the injection flow rate of the fracturing fluid increases, both the length and aperture of hydraulic fracture increase simultaneously. The high shear modulus of rock will reduce the aperture of the hydraulic fracture. Comparing the results of dynamic propagation of hydraulic fractures under different parameters in two analytical models, the correlation and sensitivity of the fracturing parameters with the fracture length and aperture are analyzed, and the sensitivity of the controlling parameters of fracture propagation in hydrofracturing are subsequently discussed.