苏东区块X-59A井油管失效原因分析

Failure Cause Analysis and Suggestion on Tubing of X-59A Well in Sudong Block

通过对苏东区块X-59A井油管腐蚀失效影响因素的分析,确定服役约7年的开发井不同井段油管腐蚀损伤及穿孔失效原因。用金相显微镜、扫描电镜(SEM)以及能谱仪等进行试验分析,对现场提取的三种环境下失效的油管进行宏观形貌、微观形貌及腐蚀特征综合分析。结果表明,穿孔失效油管位于服役温度约为80℃的井深处,该区域油管的内壁和外壁均发生了较严重的腐蚀。油管失效模式主要为内腐蚀起源向外发展至穿孔失效,接箍内壁空腔残留腐蚀介质是导致油管外螺纹端面腐蚀损伤的主要原因。

Through the analysis of the influential factors of tubing corrosion failure of X-59A well in Sudong block,this paper intends to clarify the tubing corrosion damage and perforation failure causes of different sections in development wells that have been in service for about 7 years.By means of metallographic microscope,scanning electron microscope(SEM)and energy dispersive spectrometer,the macroscopic morphology,microscopic morphology and corrosion characteristics of the failed tubing in three environments were comprehensively analyzed.The results show that the perforatedly failed tubing is located in the depth of the well where the service temperature is about 80℃,and the pit corrosion of the inner and outer wall of the pipe string is serious.The failure mode of tubing is mainly the propergation of internal corrosion resulting in perforation failure.The residual corrosive medium in the inner cavity of the coupling is the main reason for the corrosion damage of the tubing pin end face.