Optimum tubing size (OTS) selection was traditionally done by using nodal analysis to perform sensitivity analysis on the different tubing sizes. This approach was found to be both cumbersome and time-consuming. This study developed a user-friendly and time-efficient OTS prediction computer model that could allow Petroleum Production Engineers to select the best tubing size for any vertical oil well. The tubing size selection was based on the present operating flow rate, economic considerations and future operating flow rate as defined by the OTS selection criteria of this study. The robustness of the model was tested using tubing sizes ranging from 0.824 to 6.0 inch in a vertical well producing from both saturated and undersaturated oil reservoirs. The 2.750-inch tubing was found the OTS for both scenarios. In the validation, the results obtained from the novel OTS prediction model and Guo et al. (Petroleum production engineering: a computer-assisted approach, Gulf Professional Publishing, Cambridge) spreadsheet program using the Poetmann–Carpenter method were in excellent agreement for operating flow rate but not for operating pressure. Furthermore, the novel OTS prediction model was in excellent agreement with the same spreadsheet program based on modified Hagedorn–Brown correlation for both operating flow rate and pressure. The results showed that the model developed in this study is reliable and can be used in the field for vertical oil wells. The new model could as well inform the Production Engineer when the well would need artificial lift for economic production of the well. It was recommended that Newton–Raphson and modified Hagedorn–Brown methods be used in future study.

中文翻译：

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油井产油期垂直多相流最优油管尺寸预测模型

传统上，最佳管道尺寸（OTS）选择是通过使用节点分析对不同管道尺寸进行灵敏度分析来完成的。发现这种方法既麻烦又费时。这项研究开发了一种用户友好且省时的OTS预测计算机模型，该模型可以使石油生产工程师为任何垂直油井选择最佳的油管尺寸。管道尺寸的选择基于本研究的OTS选择标准所定义的当前运行流速，经济考虑因素和未来运行流速。在饱和和欠饱和油藏中生产的垂直井中，使用尺寸为0.824至6.0英寸的油管来测试模型的鲁棒性。在这两种情况下，都发现了2.750英寸油管OTS。在验证中，从新型OTS预测模型和Guo等人获得的结果。（石油生产工程：计算机辅助方法，海湾专业出版公司，剑桥）使用Poetmann-Carpenter方法的电子表格程序在工作流量方面，但在工作压力方面，具有极好的一致性。此外，新颖的OTS预测模型与基于修正的Hagedorn-Brown相关性的相同电子表格程序在工作流量和压力方面都非常吻合。结果表明，该模型开发的模型是可靠的，可用于垂直油井现场。新模型还可以通知生产工程师何时井需要人工举升以实现井的经济生产。