Abrasive waterjet (AWJ) fracturing has become an accepted horizontal multistage stimulation technique due to its flexibility and high efficiency of extensive fracture placement. The downhole tool failure of AWJ fracturing becomes an issue in the massive hydraulic fracturing because of high velocity and proppant erosion. This paper proposed a 3D computational fluid dynamics (CFD)-based erosion model by considering high-velocity waterjet impact, proppant shear erosion, and specific inner structure of hydra-jet tool body. The discrete phase approach was used to track the proppant transport and its concentration distribution. Field observation provides strong evidence of erosion patterns and mechanisms obtained from CFD simulation. The results show that the erosion rate has a space dependence in the inner wall of the tool body. The severe erosion areas are primarily located at the entries of the nozzle. Evident erosion patterns are found including a ‘Rabbit’s ear’ erosion at the upper-layer nozzles and a half bottom loop erosion at the lower-layer nozzles. Erosion mechanisms attribute to high flow velocity at the entry of nozzles and the inertia force of proppant. Sensitivity analysis demonstrates that the pumping rate is a primary factor contributing to erosion intensity.

中文翻译：

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磨料水射流压裂导致刀具腐蚀的CFD分析和现场观察

磨料射流压裂（AWJ）压裂技术具有灵活性和高效率的广泛裂缝压裂技术，已成为一种公认的水平多级增产技术。由于高速和支撑剂侵蚀，AWJ压裂的井下工具故障成为大规模水力压裂的一个问题。通过考虑高速水射流冲击，支撑剂剪切侵蚀以及水力喷射工具主体的特定内部结构，提出了一种基于3D计算流体动力学（CFD）的侵蚀模型。离散相方法用于跟踪支撑剂的传输及其浓度分布。现场观察提供了从CFD模拟获得的侵蚀模式和机理的有力证据。结果表明，腐蚀速率在工具主体的内壁中具有空间依赖性。严重腐蚀区域主要位于喷嘴的入口处。发现明显的腐蚀模式，包括在上层喷嘴处的“兔子耳朵”腐蚀和在下层喷嘴处的半底部回路腐蚀。侵蚀机理归因于喷嘴入口处的高流速和支撑剂的惯性力。敏感性分析表明，抽水速率是造成侵蚀强度的主要因素。