水力压裂工况对活动弯头冲蚀行为的影响

目的探究压裂施工参数对活动弯头冲蚀的影响,厘清不同工况条件下活动弯头冲蚀行为及冲蚀速率的演化趋势。 方法使用CFD软件建立通径为69.85 mm的双弯弧活动弯头模型,结合压裂实际工况,分别针对不同安装角度、支撑剂质量流量、压裂液流速及黏度条件下活动弯头冲蚀行为进行仿真计算。 结果不同工况条件下弯头最大冲蚀速率均出现在第二弯弧外拱侧出口处。在其他参数相同的条件下,活动弯头最大冲蚀速率在安装角度75°时出现极小值;支撑剂质量流量在4.2～25.2 kg/s 范围内,最大冲蚀速率呈线性增大,当支撑剂质量流量达到 33.6 kg/s 后,由于“屏蔽效应”导致冲蚀速率增速较略有降低;冲蚀速率随着压裂液流速增大呈近似指数型增长趋势;压裂液黏度在 10～40 mPa·s 范围内时,活动弯头最大冲蚀速率较为平稳,随着黏度逐渐增大,最大冲蚀速率也随之增大,并在 120 mPa·s 后趋于平稳。 结论研究结果与现场实际基本符合,可为压裂现场活动弯头布局及施工参数优化提供有效参考。 

Influence of hydraulic fracturing working conditions on the erosion behavior of movable elbows

ObjectiveThe aim is to explore the impact of fracturing construction parameters on the erosion of movable elbow, and movable elbow erosion behavior and change trend of maximum erosion rate under different working conditions. Methods The CFD software is used to establish a model of double-curved movable elbow with a diameter of 69.85 mm, and the erosion behavior of the movable elbow under different installation angles, proppant mass flow rates, fracturing fluid flow rates and viscosity conditions is simulated and calculated in combination with the actual fracturing conditions. ResultsUnder different working conditions, the maximum erosion rate of the elbow occurs at the outlet of the outer arch side of the second curved arc. Under the same condition of other parameters, the maximum erosion rate of the movable elbow appears a minimum when the installation angle is 75°. When the mass flow rate of proppant is in the range of 4.2-25.2 kg/s, the maximum erosion rate increases linearly. When the mass flow rate of proppant reaches 33.6 kg/s, the erosion rate decrease slightly due to the "shielding effect". Erosion rate shows an approximate exponential growth trend with the increase of fracturing fluid flow rate; When the viscosity of the fracturing fluid is within the range of 10-40 mPa·s, the maximum erosion rate of the movable elbow is relatively stable, and the maximum erosion rate also increases with the increase of the viscosity, and tends to be stable after the viscosity reaches 120 mPa·s. ConclusionsThe research results are basically consistent with the field practice, which can provide effective reference for the layout of moveable elbow and the optimization of construction parameters in the fracturing field.