In order to explore the feasibility of the Computational Fluid Dynamics (CFD) method for plunger gas lift and the flow pattern in a long wellbore, a lab simulation test was conducted to verify the reliability of the CFD simulation results. Verification data were provided for CFD simulation through carrying out a plunger gas lift lab test for vertical wells, identifying the plunger movement patterns and delivery rates under different flow pressures, and determining the minimum plunger startup pressure or differential pressure and leakage, and an identical CFD physical model was created on the basis of the lab test model, CFD dynamic grid programming and CFD simulation were conducted under test conditions, and a comparison of the simulation and test results was made to identify the calculation accuracy and the rationality of the CFD model and method; finally, boundary conditions such as temperature and pressure were set according to the actual long wellbore (200 m) conditions, the CFD simulation was performed, and the impacts of the downhole conditions on the gas lift performance were analyzed, so as to develop CFD calculation methods to predict the bottom-hole flow pressure, plunger speed, and delivery rate. The results show: the average plunger speed range is 7.74–22.5 m/s when the flow pressure varies from 199.77 to 632.93 kPa, and the leakage rate increases in a nearly linear way with the speed; compared with the lab test results, the simulation results from the created dynamic grid model and multi-phase turbulent flow model have the leakage error of 7.2% and the plunger speed average error is smaller than 11.1%; under long-wellbore conditions, the plunger lift speed shows the change pattern of increasing and then decreasing, the wellbore pressure has a wave-like drop, and in addition to this pressure drop characteristic, the fact that the plunger startup pressure differential increases with the wellhead pressure should be considered (when the bottom-hole pressure is 15 MPa, the wellhead pressure must not exceed 10 MPa).

中文翻译：

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基于柱塞气举试验的数值计算流体力学（CFD）模拟研究

为探讨柱塞气举和长井筒内流型的计算流体动力学（CFD）方法的可行性，进行了室内模拟试验，验证了CFD模拟结果的可靠性。通过对直井进行柱塞气举实验室试验，识别不同流动压力下的柱塞运动模式和排量，确定柱塞最小启动压力或压差及泄漏量，以及相同的CFD，为CFD模拟提供了验证数据在实验室试验模型的基础上建立物理模型，在试验条件下进行CFD动态网格规划和CFD仿真，并将仿真结果与试验结果进行对比，以确定CFD模型的计算精度和合理性。方法; 最后根据实际长井筒（200 m）条件设置温度、压力等边界条件，进行CFD模拟，分析井下条件对气举性能的影响，开展CFD计算预测井底流动压力、柱塞速度和输送量的方法。结果表明：当流动压力为199.77～632.93 kPa时，平均柱塞速度范围为7.74～22.5 m/s，泄漏率随速度呈近线性增加；与实验室测试结果相比，建立的动态网格模型和多相湍流模型的模拟结果泄漏误差为7.2%，柱塞速度平均误差小于11.1%；在长井条件下，