油气田长输管道腐蚀分析及防腐措施

Corrosion Analysis and Anti-corrosion Measures of Oilfield Long-distance Pipeline

针对油气田集输管道腐蚀严重的情况,对现场管道用钢在现场采出介质的环境中进行了试验,并通过失重法和极化曲线法对影响管线钢腐蚀的因素进行研究,同时筛选出适合油田使用的缓蚀剂。实验结果表明:腐蚀速率随温度的升高呈先增大后减小的趋势,其中腐蚀速率在60℃处出现峰值;当Cl^(-)质量浓度处于82000~102000 mg·L^(-1)的范围时,腐蚀速率变化不大,当Cl^(-)增加到124000 mg·L^(-1)时,腐蚀速率迅速增加,整体起到了加重腐蚀的作用;当pH小于6.5时,整体腐蚀速率随pH的降低而增加。现场失重试验结果表明,油水混输管道挂件的腐蚀为点蚀且腐蚀情况较为严重。采用动态失重法对常见的缓蚀剂进行优选评价,NG570缓蚀剂是缓蚀率最高的,高达84.21%,且缓蚀效果随加量的增加而保持稳定。通过对M油田管道进行腐蚀影响因素及原因分析,提出针对性的管道防护方法,可为油田生产中的腐蚀防护工作提供可靠的依据。

In view of the serious corrosion of oil and gas gathering pipelines,field pipeline steel was tested in the environment of field extraction media,and the weight loss method and polarization curve method were also used to study the factors affecting the corrosion of pipeline steel,while the corrosion inhibitors suitable for the oilfield were screened out.The experimental results showed that the corrosion rate increased first and then decreased with the increasing of temperature,with the corrosion rate was highest at 60℃.The corrosion rate did not change much when Cl^(-)was in the range of 82000~102000 mg·L^(-1).When Cl^(-)increased to 124000 mg·L^(-1),the corrosion rate increased rapidly,and the overall played a role in aggravating corrosion;when the pH was less than 6.5,the overall corrosion rate increased with the decrease of pH.Field weightlessness test results showed that the corrosion of oil-water mixed pipeline pendant was pitting corrosion and corrosion was more serious.The dynamic weight loss method was used to evaluate the common corrosion inhibitors,NG570 corrosion inhibitor had the highest corrosion inhibition rate,up to 84.21%,and corrosion inhibition effect remained stable with the increase of the amount.Based on the analysis of corrosion influencing factors and causes of M oilfield pipelines,targeted pipeline protection methods were put forward,it could provide a reliable basis for the corrosion protection work in oilfield production.