Hydraulic Fracture Crossing Natural Fracture at Nonorthogonal Angles: A Criterion and Its Validation
Hydraulic Fracture Crossing Natural Fracture at Nonorthogonal Angles: A Criterion and Its Validation
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DOI：
10.2118/139984-pa
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发表时间：
2012-02-01
影响因子：
1.2
通讯作者：
Suarez-Rivera, R.
中科院分区：
文献类型：
--
作者：
Gu, H.;Weng, X.;Suarez-Rivera, R.
在页岩气田开发中，水力压裂已成为完井作业中不可缺少的重要组成部分。页岩地层通常含有天然裂缝，在压裂过程中可能会形成复杂的水力裂缝网络。复杂的裂缝网络受水力裂缝与现有天然裂缝相互作用的强烈影响。已经开发了一个准则来确定裂缝是否以非正交角度穿过摩擦界面（预先存在的裂缝）。该准则是Renshaw和Pollard（1995）最初提出的正交交叉准则的扩展。利用扩展准则定量地说明了交点与交点角的关系。当角度小于90度时，断口更容易沿界面旋转和扩展，而不是穿过界面。用不同角度的实验室实验对判据的验证进行了描述和讨论。当应用于实验室实验时，在广泛的角度范围内观察到准则与实验之间的良好一致性。该准则可用于确定在特定的现场条件下水力裂缝是否与天然裂缝相交，并已被纳入模拟天然裂缝地层中水力裂缝扩展的水力裂缝模型中。
Hydraulic-fracturing treatments have become an indispensable part of well completion in shale gasfield development. Shale formations often contain natural fractures, and complex hydraulic-fracture networks may form during a treatment. The complex fracture network is strongly influenced by the interaction between the hydraulic fracture and the pre-existing natural fractures. A criterion has been developed to determine whether a fracture crosses a frictional interface (pre-existing fracture) at nonorthogonal angles. This criterion is an extension of the one for orthogonal crossing originally developed by Renshaw and Pollard (1995). The dependence of crossing on the intersection angle is shown quantitatively using the extended criterion. The fracture is more likely to turn and propagate along the interface than to cross it when the angle is less than 90 degrees. The validation of the criterion using laboratory experiments for various angles is described and discussed. When applied to laboratory experiments, good agreement between the criterion and experiments is observed for a wide range of angles. The criterion can be used to determine whether hydraulic fractures cross natural fractures under particular field conditions, and it has been incorporated in a hydraulic-fracture model that simulates hydraulic-fracture propagation in a naturally fractured formation.