Abstract: There are always fixed piers along the pipeline or crossings in the pipeline during the operation of long-distance pipelines. For pipelines with cathodic protection, these places are more likely to produce shielding effect on negative current and increase the corrosion risk of pipelines. Based on the analysis of corrosion cases in oil field, it is found that corrosion often occurs in the pipeline inside the casing. The reasons for the shielding of cathodic protection current by the casing or the corrosion of the pipeline are discussed emphatically, and the corrective measures are given in view of the above corrosion situation.

摘要： 长输管线在运行过程中往往存在穿跨越处或沿线分布的固定支墩，对施加阴极保护的管线来说这些地方对阴保电流更易产生屏蔽效应增加管线的腐蚀风险。本文通过对油田现场的腐蚀案例进行分析，发现腐蚀情况往往发生在套管内的管线处，并着重讨论了套管对阴极保护电流产生屏蔽或管线发生腐蚀的原因，针对以上的腐蚀情况给出整改措施。

关键词: 阴极保护, 腐蚀 , 固定支墩, 套管, cathodic protection, corrosion, fixed pier, casing