气井测试钻杆内涂层冲刷腐蚀影响因素研究

Study on Influencing Factors of Scouring Corrosion of Inner Coating of Gas Well Test Drill Pipe

为研究气井测试用钻杆的两种型号内涂层在不同因素下的冲刷腐蚀规律,通过高压高流速多相流环路设备及高温高压反应釜实验,设置不同的温度、CO_(2)含量、环境pH值、含砂情况、流速的影响因素,并通过涂层厚度、附着力、硬度及电化学阻抗的方式表征涂层的耐冲刷腐蚀性能并分析规律。实验结果表明,在高温高CO_(2)低pH高流速下钻杆内涂层受冲刷腐蚀影响较小,但在含砂或水携砂环境下,涂层低频区阻抗严重降低且涂层表面出现破损失效。指出测试钻杆内涂层不宜在含砂环境中使用,在无砂环境中钻杆内涂层具有优秀的耐冲刷腐蚀性能。

In this paper,a preliminary study is conducted on the scouring corrosion law of two types of internal coatings of drilling pipes for gas well testing under different factors.Through the experiments of high-pressure and high-flow rate multiphase flow loop equipment and high�temperature and high-pressure reactor,different influencing factors including temperature,CO_(2)content,environmental pH,sand content and flow rate are analyzed,and the scouring corrosion resistance of the coatings is characterized by coating thickness,adhesion,hardness and electrochemical resistance.The experimental results show that the inner coating of the drill pipe is less affected by the scouring corrosion under the conditions of high temperature,high CO_(2),low pH and high flow rate,however,the impedance of the coating in the low-frequency region is seriously reduced and the surface of the coating appears to be damaged under the conditions of sand or water-carrying sand.It is revealed that the inner coating of the tested drill pipe should not be used in a sandy environment and it has excellent scour corrosion resistance in a sand-free environment.