Abstract A gradual pipe contraction may cause severe localized corrosion resulted from the flow acceleration, thus threating the operating safety of pipelines in the oil and gas field. Until now, the quantitative study on the correlation between local corrosion rate and local hydrodynamics at the gradual pipe contraction is still missing. In this work, the flow accelerated corrosion and its mitigation at different locations of a gradual pipe contraction of N80 steel are in situ investigated using computational fluid dynamics simulation and array electrode technique combined with electrochemical impedance spectroscopy. The results show that the distribution of corrosion rate at the gradual pipe contraction is in good accordance with the distribution of hydrodynamics parameters including flow velocity and wall shear stress, i.e., the higher flow velocity or higher wall shear stress is, the higher local corrosion rate is. The presence of an imidazoline derivative inhibitor can greatly mitigate the corrosion at the gradual pipe contraction through hindering the mass transfer process and charge transfer process of corrosion. Furthermore, in the presence of inhibitor the differences in corrosion rate among different locations at the gradual pipe contraction are also effectively reduced, or even disappeared at low flow velocity. Therefore, the addition of the inhibitor is an effective way to mitigate or even eliminate the flow accelerated corrosion at the gradual pipe contraction in the oil and gas field.

中文翻译：

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N80钢逐渐收缩不同部位流动加速腐蚀及其缓解的原位研究

摘要 管道逐渐收缩可能会因流速加速而引起严重的局部腐蚀，从而威胁油气田管道的运行安全。到目前为止，关于管道逐渐收缩时局部腐蚀速率与局部流体动力学之间相关性的定量研究仍然缺乏。在这项工作中，使用计算流体动力学模拟和阵列电极技术结合电化学阻抗谱，原位研究了 N80 钢管道逐渐收缩的不同位置的流动加速腐蚀及其缓解。结果表明，管道逐渐收缩时腐蚀速率的分布与流速和壁面剪应力等流体动力学参数的分布非常吻合，即：流速越高或壁面剪应力越大，局部腐蚀速率越大。咪唑啉衍生物抑制剂的存在通过阻碍腐蚀的传质过程和电荷转移过程，可以大大减轻管道逐渐收缩时的腐蚀。此外，在缓蚀剂的存在下，管道逐渐收缩时不同位置的腐蚀速率差异也有效减小，甚至在低流速下消失。因此，缓蚀剂的加入是缓解甚至消除油气田管道逐渐收缩处流动加速腐蚀的有效途径。咪唑啉衍生物抑制剂的存在通过阻碍腐蚀的传质过程和电荷转移过程，可以大大减轻管道逐渐收缩时的腐蚀。此外，在缓蚀剂的存在下，管道逐渐收缩时不同位置的腐蚀速率差异也有效减小，甚至在低流速下消失。因此，缓蚀剂的加入是缓解甚至消除油气田管道逐渐收缩处流动加速腐蚀的有效途径。咪唑啉衍生物抑制剂的存在通过阻碍腐蚀的传质过程和电荷转移过程，可以大大减轻管道逐渐收缩时的腐蚀。此外，在缓蚀剂的存在下，管道逐渐收缩时不同位置的腐蚀速率差异也有效减小，甚至在低流速下消失。因此，缓蚀剂的加入是缓解甚至消除油气田管道逐渐收缩处流动加速腐蚀的有效途径。甚至在低流速下消失。因此，缓蚀剂的加入是缓解甚至消除油气田管道逐渐收缩处流动加速腐蚀的有效途径。甚至在低流速下消失。因此，缓蚀剂的加入是缓解甚至消除油气田管道逐渐收缩处流动加速腐蚀的有效途径。