准脆性地层中水平井多段水压致裂的扩展有限元法模拟

发布时间：2018-02-12 22:15

  本文关键词： 水力压裂 扩展有限元法(XFEM) 应力阴影效应 多段压裂　出处：《地震工程学报》2017年02期 　论文类型：期刊论文

【摘要】：在实际的水力压裂过程中,裂缝总是沿着垂直于最小地应力的方向扩展,地应力的分布形式和多个压裂段之间的互相影响(应力阴影效应)对于形成复杂的裂缝网络具有重要的影响。本文基于扩展有限单元法(XFEM)模拟页岩等多孔介质在水压作用下裂缝的任意扩展,由于在传统有限元法的基础上引入了扩充自由度和可以描述间断的位移阶跃函数,所以裂缝可以独立于网格扩展,而不需要重新剖分网格。通过引入一维流动假设,求解润滑方程,并考虑流体在裂缝内的流动。同时也考虑裂缝向基质中流动的滤失效应。研究实际施工中不同段间距下裂缝的扩展模式和段间距对裂缝形态的影响,结果表明,压裂段间距过小时中间的裂缝会被屏蔽;此外,裂缝会由于应力阴影效应而发生转向。
[Abstract]:In the actual hydraulic fracturing process, the fracture always extends along the direction perpendicular to the minimum in-situ stress. The distribution of in-situ stress and the interaction between multiple fracturing sections (stress shadow effect) have important influence on the formation of complex fracture networks. In this paper, the expanded finite element method (XFEMM) is used to simulate the formation of shale and other porous media. The arbitrary propagation of cracks under the action of water pressure, Due to the introduction of extended degrees of freedom and displacement-step functions based on the traditional finite element method, cracks can be expanded independently of the mesh without the need to redivide the meshes. The lubrication equation is solved, and the flow of fluid in the fracture is considered. At the same time, the filtration failure due to the flow of the crack to the matrix is also considered. The effect of crack propagation mode and segment spacing on the fracture morphology under different segments spacing in actual construction is studied. Fractures in the middle of the fracturing interval are shielded, and the fractures turn due to the stress shadow effect.
【作者单位】： 兰州大学土木工程与力学学院;宁夏大学物理与电子电气工程学院;中国地震局黄土地震工程重点实验室;
【基金】：国家自然科学基金项目(51478444,51408567) 宁夏“十三五”重点建设学科项目
【分类号】：TE357.1
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本文编号：1506681