Stimulating long and persistent fractures from multiple perforations in horizontal wells plays a vital role in enhancing the recovery of hydrocarbons from unconventional reservoirs. However, interaction among fractures may lead to dramatic nonuniformity, but the mechanism that drives the competition still eludes explanation. We proposed an improved two‐dimensional discrete element model to simulate fluid competition and stress interaction among perforations in the same fracturing stage. The fluid partitioning is implemented by dynamically dividing the injected fluid into different perforations to maintain pressure consistency and fluid conservation. The model is validated by comparing the induced stress, fracture aperture, and the evolution of the fracture height and the injection pressure with theoretical models. The influences of the perforation friction, fluid viscosity and injection rate are examined systematically. Simulation results reveal that fluid competition tends to stimulate one dominant fracture with other perforations suppressed. The effect of increasing the perforation friction for promoting the fluid partitioning is not remarkable while using more viscous fracturing fluid helps to initiate more fractures at the perforations. With a higher injection rate all fractures can propagate to the borders but the asymmetrical fracture pattern cannot be avoided. Four typical fracture patterns are distinguished by changing operational parameters.

中文翻译：

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同时刺激的多个水力裂缝之间的竞争：考虑流体分配的 DEM 模拟的见解


水平井多次射孔改造长而持久的裂缝对于提高非常规油藏油气采收率起着至关重要的作用。然而，裂缝之间的相互作用可能会导致显着的不均匀性，但驱动竞争的机制仍然无法解释。我们提出了一种改进的二维离散元模型来模拟同一压裂阶段射孔间的流体竞争和应力相互作用。流体分配是通过将注入的流体动态地分配到不同的射孔中来实现的，以保持压力一致性和流体守恒。通过将诱发应力、裂缝孔径、裂缝高度和注入压力的演化与理论模型进行比较，对该模型进行了验证。系统地考察了射孔摩阻、流体粘度和注入速度的影响。模拟结果表明，流体竞争往往会刺激一种主要裂缝，而抑制其他射孔。增加射孔摩擦力促进流体分配的效果并不显着，而使用较粘稠的压裂液有助于在射孔处引发更多裂缝。当注入速率较高时，所有裂缝都可以扩展至边界，但无法避免不对称裂缝模式。通过改变操作参数来区分四种典型的断裂模式。