Numerical Investigation of Influence of In-Situ Stress Ratio, Injection Rate and Fluid Viscosity on Hydraulic Fracture Propagation Using a Distinct Element Approach
Numerical Investigation of Influence of In-Situ Stress Ratio, Injection Rate and Fluid Viscosity on Hydraulic Fracture Propagation Using a Distinct Element Approach
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DOI：
10.3390/en9030140
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发表时间：
2016-02
期刊：
影响因子：
3.2
通讯作者：
Bo Zhang-;Xiao Li;Zhaobin Zhang;Yanfang Wu;Yusong Wu;Yu Wang
中科院分区：
文献类型：
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作者：
Bo Zhang-;Xiao Li;Zhaobin Zhang;Yanfang Wu;Yusong Wu;Yu Wang
数值模拟对于理解水力压裂机理是非常有用的。本文采用离散元法对水力劈裂过程进行了数值模拟，研究了一些关键参数对水力劈裂特性的影响。用离散元法得到的破裂压力与解析解是一致的。这表明离散元法用于水力压裂模拟是可行的。我们独立地研究了地应力比、注入速度和流体粘度对水力压裂的影响。我们进一步强调了这三个因素之间的关系和它们对水力压裂的贡献。随着应力比的增大，裂缝开度几乎呈线性增大;随着注入速度和流体粘度的增大，裂缝开度和破裂压力明显增大。注入速率和流体粘度的乘积值较低（即，Qμ）将导致裂缝孔径变窄、破裂压力降低、水力裂缝复杂或分散。高Qμ值将导致宽裂缝孔径、高破裂压力和简单水力裂缝（例如，直的或翼形）。在低粘度流体条件下，水力裂缝几何形状对应力比不敏感，形成复杂的裂缝网络。
Numerical simulation is very useful for understanding the hydraulic fracturing mechanism. In this paper, we simulate the hydraulic fracturing using the distinct element approach, to investigate the effect of some critical parameters on hydraulic fracturing characteristics. The breakdown pressure obtained by the distinct element approach is consistent with the analytical solution. This indicates that the distinct element approach is feasible on modeling the hydraulic fracturing. We independently examine the influence of in-situ stress ratio, injection rate and fluid viscosity on hydraulic fracturing. We further emphasize the relationship between these three factors and their contributions to the hydraulic fracturing. With the increase of stress ratio, the fracture aperture increases almost linearly; with the increase of injection rate and fluid viscosity, the fracture aperture and breakdown pressure increase obviously. A low value of product of injection rate and fluid viscosity (i.e., Qμ) will lead to narrow fracture aperture, low breakdown pressure, and complex or dispersional hydraulic fractures. A high value of Qμ would lead wide fracture aperture, high breakdown pressure, and simple hydraulic fractures (e.g., straight or wing shape). With low viscosity fluid, the hydraulic fracture geometry is not sensitive to stress ratio, and thus becomes a complex fracture network.