注氮气三次采油井下腐蚀发生现状及机理探索

Occurrence status and mechanism of down-hole string corrosion by nitrogen injection

马剡 杨阳 郭靖 杨荣荣

Ma Yan Yang Yang Guo Jing Yang Rongrong

中国石化 西北油田分公司 采油一厂, 新疆 轮台 841600

No. 1 Oil Production Plant, SINOPEC Northwest Company, Luntai, Xinjiang 841600, China

注氮气三次采油是现阶段碳酸盐岩油藏提高采收率的有效手段，但随着注氮气三采技术的推广，越来越多的注气井管柱存在腐蚀穿孔的现象。该文在注氮气工艺、介质及生产分析的基础上，重点研究造成井下管柱腐蚀的因素及机理，表明了井下管柱腐蚀主要是受到高浓度氧及高矿化度、弱酸性的水的影响，两者混合后形成氧的电化学腐蚀与冲刷腐蚀，因此造成管柱内部整体腐蚀及管柱外壁点蚀、坑蚀的现象；并结合现场实际情况提出了具体的应对措施。

Nitrogen injection is a chief technique to efficiently improve oil recovery rate in carbonate reservoirs now. With the promotion of nitrogen injection technology, more and more corrosion failures were found in wellbores. Based on the studies of nitrogen injection technique, media and production, we analyzed the corrosion mechanism and influencing factors of down-hole strings. Results showed that the mixture of high-concentration oxygen and high salinity, week-acidic water created electrochemical corrosion and erosion corrosion, which caused whole corrosion inside pipe and pitting corrosion outside pipe wall. Corresponding countermeasures were proposed in this paper combining with field applications.

https://doi.org/10.11781/sysydz2016S1126