川南某页岩气区块油管腐蚀分析与防护技术优选

Corrosion Analysis and Protection Technology Optimization of Tubing in a Shale Gas Block in Southern Sichuan

因所处井筒环境复杂,油管腐蚀已成为国内页岩气生产过程中面临的一个新难题,直接影响气井正常生产、动态监测和排水采气措施的实施。为解决川南某页岩气区块井下油管腐蚀,明确区块油管腐蚀原因,采取针对性措施改善管材腐蚀情况。文章基于流体工况、油管腐蚀形貌,区块流体特征分析了影响页岩气井管材腐蚀的主要因素。针对上述腐蚀原因,在管材失效分析基础上进行室内腐蚀评价实验,比选了几种常见管材腐蚀防护措施,在考虑经济性和现场适用性基础上,优选并推荐酚醛环氧内涂层技术进行油管防腐。现场实施后通过起出试用内涂油管并开展油套管损伤检测测井,结果显示:酚醛环氧内涂层油管未见腐蚀,管材腐蚀现象得到有效控制。

Limited by the complex wellbore environments,tubing corrosion has become a tough problem in shale gas production,which directly affects the productive system of gas wells,dynamic monitoring and the implementation of drainage and gas production measures.To solve the downhole tubing corrosion in southern Sichuan shale gas block,the causes of tubing corrosion in the block are clarified,and targeted measures are taken to retard the pipe corrosion.Based on the fluid condition,tubing corrosion morphology and fluid characteristics in this block,the main factors affecting the tubing corrosion of shale gas wells are analyzed in this paper.For the above corrosion reasons,corrosion evaluation experiments are carried out on the basis of tubing failure analysis,several common tubing corrosion protection measures are compared and selected.Considering economy and field applicability,phenolic epoxy inner coating technology is optimized and recommended for tubing corrosion protection.After the field implementation,the trial inner coated tubings were pulled out and the tubing damage detection logging was carried out.The results showed that the phenolic epoxy inner coated tubing had no corrosion,and the corrosion of the tubing had been effectively controlled.