某油田联络管线腐蚀原因分析

Analysis on causes of corrosion of interconnecting pipeline in an oilfield

为减少某油田联络管线腐蚀穿孔次数,降低经济损失,有必要对腐蚀原因进行识别。通过对腐蚀穿孔现场的勘察及管线检测结果、运行数据、流体介质参数等资料的综合分析,发现管线内流体介质具有高腐蚀性、防腐层破损、环焊缝金属与本体金属成分不同、施工工艺不科学及复杂应力作用等重要因素,造成了管线本体腐蚀、环焊缝处腐蚀及锚固墩处腐蚀。对某油田联络管线进行了整改:更换起点站库出站5 km管线;拆除所有固定式锚固墩,在必要处安装可更换式锚固墩,做好锚固墩与管线连接部位的防腐措施;做好管线内、外检测,以及修复、补强工作;对强度不达标的环焊缝处进行碳纤维补强,并提升焊接水平。分析腐蚀原因并做好整改措施,可延长管线使用寿命,保障管线安全平稳运行。

The interconnecting pipeline in an oilfield has been running for 19 years with serious corrosion.In order to reduce the number of corrosion perforations and lower economic losses,it is necessary to identify the causes of corrosion.Through the comprehensive analysis on the corrosion perforation site investigation and pipeline inspection results,operation data,fluid parameters and other data,it is found that the key factors for the corrosion of the pipeline body,girth weld and anchor pier are as per the following:the high corrosiveness of the fluid medium in the pipeline,the damage to the outer corrosion protection layer,the disparities between the girth weld metal and the main body metal,the irrational construction technology,complex stress action and so on.The rectifications are made for the interconnecting pipeline in that oilfield in the following steps.The first step is to replace the 5km outbound pipeline of the starting depot.The second one includes removing all the existing fixed anchor piers and installing replaceable anchor piers where necessary,and implement appropriate corrosion protection measures between anchor piers and pipeline contact points.The third step is to make sure that the internal and external inspection and repair and reinforcement of the pipeline shall be properly carried out.The fourth step is to strengthen the girth welds with carbon fiber where the strength is found to be not up to standard and improve the welding quality.Analysis on causes of corrosion and rectification measures will ensure safe and stable pipeline operation and prolong theservice life of the pipeline.