双井同步压裂裂缝扩展规律离散元模拟

doi:10.13809/j.cnki.cn32-1825/te.2023.05.013

摘要/Abstract

摘要：

针对不同条件下的双井同步水力压裂裂缝扩展及演化规律尚不明确，裂缝之间的相互作用会引起裂缝重新定向，影响水力压裂效果等问题。通过离散元法，研究不同因素影响下裂缝扩展规律及破坏模式。结果表明：当井间连线与最大主应力夹角θ为0°时，在水平应力差的影响下井壁周围应力分为2个阶段：裂缝相交前稳定阶段以及裂缝相交后急剧上升阶段。随着水平主应力差减小，破坏模式由单一裂缝转变为多裂缝破坏。当θ不为0°时，由于地层的地应力场发生改变，进而引起裂缝偏转，形成连通两井的倾斜裂缝。在压裂过程中裂缝的扩展对周围区域施加较大的应力，而局部应力状态大小和方向的改变都因主裂缝的扩展而改变，使裂缝偏离最大主应力方向扩展。

关键词: 非常规油气, 水力压裂, 同步压裂, 离散元, 破坏模式

Abstract:

The understanding of fracture propagation and evolution during dual well synchronous hydraulic fracturing, particularly under various conditions, remains limited. Meanwhile, the interaction between fractures will cause fracture reorientation and affect the hydraulic fracturing effect. In order to solve these problems, the fracture propagation law and failure mode under the influence of different factors are studied by the discrete element method. The results show that when the angle between the interwell connecting line and the maximum principal stress （θ） is 0°, and under the influence of the horizontal stress difference, the stress around the borehole wall can be divided into two stages: the stable stage before the fracture intersection and the steep rise stage after the fracture intersection. With the decrease of the horizontal principal stress difference, the failure mode changes from single fracture to multi fracture failure. When θ≠0°, the in-situ stress field of the formation changes, which causes the fracture deflection and forms an inclined fracture connecting the two wells. During the fracturing process, the expansion of the fracture exerts great stress on the surrounding area, and the magnitude and direction of local stress state change due to the expansion of the main fracture. So that the crack spreads away from the direction of the maximum principal stress.

Key words: unconventional oil and gas, hydraulic fracturing, synchronous fracturing, discrete element, destruction mode

中图分类号:

TE357

张家伟, 刘向君, 熊健, 梁利喜, 任建飞, 刘佰衢. 双井同步压裂裂缝扩展规律离散元模拟[J]. 油气藏评价与开发, 2023, 13(5): 657-667.

ZHANG Jiawei, LIU Xiangjun, XIONG Jian, LIANG Lixi, REN Jianfei, LIU Baiqu. Discrete element simulation study on fracture propagation law of dual well synchronous fracturing[J]. Petroleum Reservoir Evaluation and Development, 2023, 13(5): 657-667.

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