长庆气田污水回注井井筒腐蚀现状及对策  

Anti-Corrosion Measures for Sewage Re-injection Wells in Changqing Gas Field

作　　者：田建峰[1] 常永峰[1] 王兴龙[1] 吕江[2] 

机构地区：[1]中国石油长庆油田分公司气田开发处,陕西西安710021 [2]中国石油长庆油田分公司第一采气厂,陕西西安710021

出　　处：《中外能源》2010年第3期102-104,共3页Sino-Global Energy

摘　　要：长庆气田污水回注井主要用来将天然气生产过程中产生的污水回流至地下遮挡层,回注水主要来自气井产水以及天然气净化处理过程中产生的污水,其矿化度较高,含有大量硫化物、Ca、Mg等物质,水质复杂,腐蚀性较强。先后对5口污水回注井井下管柱起出分析和腐蚀检测,发现4口井井下管柱腐蚀严重。套管腐蚀会导致回注污水窜层,甚至威胁到饮用淡水层。对回注污水水质分析显示,回注污水水型为CaCl2型,pH值较低,在5.65～6.52之间,呈酸性,污水中含有大量的H2S、CO2等酸性气体,4口严重腐蚀井单井平均H2S含量为820mg/m3,CO2含量为5%,这些酸性气体在污水中溶解,导致套管腐蚀。提出优化回注井井身结构,下入双层套管;使用非金属套管,加强套管涂层防腐技术研究;下封隔器,封隔油套环空,打入缓蚀剂以保护套管;对井下管柱定期检测、维护等防护措施。In Changqing Gas Field,sewage re-injection wells are mainly used to flow the sewage produced during the production of natural gas back into underground barriers and the water used for re-injection mainly comes from gas wells and sewage produced during natural gas purification.The water has high salinity and contains large amounts of sulfides,Ca,Mg and other substances.The water is also highly corrosive.Pipe strings of five sewage re-injection wells were pulled out for analysis and corrosion testing and serious corro- sion was detected for four wells.Casing corrosion could lead to cross-flow of re-injected sewage and even threatens fresh drinking water layers.Analysis of the quality of re-injected water showed that the re-injected sewage was CaCl2 sewage with relatively low pH value：between 5.65 and 6.52.The sewage was acidic as large amounts of acidic gases such as H2S and CO2 were contained in the sewage.The average single-well H2S content of the four seriously corroded wells was 820mg/m3 and the average CO2 content was 5%.These acidic gases were dissolved in sewage,leading to the corrosion of casings.Countermeasures proposed included optimizing the well-body structure of re-injection wells by introducing double-layer casings;using non-metallic casings and strengthening the research of casing coating anti-corrosion technologies;installing packers to pack the annulus between the casing and the tubing and using corrosion inhibitors to protect the casing;taking other maintenance measures such as periodically inspecting downhole pipe strings.

关 键 词：气田 污水回注井 套管 腐蚀防护 

分 类 号：X703[环境科学与工程—环境工程]