小口径管道内壁覆盖层技术在单井集输管道腐蚀治理中的应用

Application of Inwall Coating Technique for Anti-corrosion of the Minor-caliber Gathering Pipeline of Single Well

大涝坝凝析气田单井集输管线为低碳钢材质,由于其服役环境介质的强腐蚀特性,造成愈演愈烈的腐蚀问题。经分析,在CO2-Cl--H2O环境下,H2S、CO2、O2是腐蚀剂,H2O是载体,Cl-是催化剂,集输管线表现为蚀坑、台面侵蚀和选择性侵蚀三种基本形式。管道内壁覆盖层技术着眼于材料-环境界面,靠"堵"的方法,隔离材料和环境而起到保护材料的作用,防止内壁发生腐蚀,其关键是选择防腐涂料和涂层内补口。经对比分析,选择无溶剂99.5%固体含量双组分环氧树脂管道防腐涂料,确定采用管道内喷涂机(带内窥镜)+UB保护套作为内涂层补口工艺。每个口涂料总用量为44.45g,每道口用时为0.311min,补口机行走速度为0.8m/min。管道内壁覆盖层技术从根本上解决了小口径内涂层补口和焊接区域涂层防腐性能薄弱问题,为解决小口径集输管道内腐蚀防护提供了技术支撑。

The corrosion of the gathering pipeline of single well has become more and more serious because of its mild steel material in the strongly corrosive surrounding in Dalaoba gas consensate field.In the environment of CO2-Cl——H2O,H2S,CO2 and O2 are the corrodent,H2O is carrier and Cl-is catalytic agent.The corrosion of the gather pipelines has three basis ways： etch pit,floor corrosion and selective corrosion.Inwall coating technique can work through separating the material with environment.Corrosion preventive coating and joint coating is the key of the technique.After compare and analysis,double-componet epoxy resin with 99.5% of solide content is selected as corrosion preventive coating,and pipeline flush coater and UB protective casing make up of the inwall joint coating technology.For every joint,the total volume of the coating is 4.45g in 0.311min,and the velocity of joint coating mechine is 0.8m/min.The inwall coating technique solves the problems of weak anti-corrosive property at the joint of the minor-caliber coating and weld zone,which provides technical support for anti-corrosion prevention in the minor-caliber gathering pipeline.