CO_(2)增采环境下X70管线钢的应力腐蚀开裂行为研究

Study of Stress Corrosion Cracking Behavior of X70 Pipeline Steel in CO_(2)Enhanced Mining Environment

在CO_(2)增采(CCS‐EOR)环境下,研究了X70管线钢在不同CO_(2)压力下的腐蚀开裂行为及其机理。使用高压反应釜及模拟采出水溶液,对现场环境进行了模拟;通过电化学实验,研究了X70管线钢在CCS‐EOR环境下的腐蚀速率与腐蚀机理;通过慢应变速率拉伸实验,研究了模拟环境下X70管线钢的腐蚀开裂行为;通过扫描电镜,分析了不同CO_(2)压力下X70管线钢的腐蚀开裂机理。结果表明,X70管线钢的腐蚀速率随着CO_(2)压力的增加而增加;X70管线钢表面产生的腐蚀产物膜不能保护金属基体,而且加剧局部腐蚀;在腐蚀产物膜的影响下,CO_(2)压力的增高使X70管线钢应力腐蚀敏感性增加,X70管线钢腐蚀开裂同时受金属表面裂纹的影响。

In the environment of CO_(2)enhanced recovery(CCS‐EOR),the corrosion cracking behavior and mechanism of X70 pipeline steel under different CO_(2)pressures were studied.The on‐site environment was simulated by using a high‐pressure reactor and a simulated produced aqueous solution;the corrosion rate and corrosion mechanism of X70 pipeline steel in the CCS‐EOR environment were investigated by electrochemical experiments;the corrosion cracking behavior of X70 pipeline steel under simulated environment was investigated by slow strain rate tensile experiments;finally,the corrosion cracking behavior of X70 pipeline steel under different CO_(2)pressure was analyzed by scanning electron microscope.The results show that the corrosion rate of X70 pipeline steel increases with the increase of CO_(2)pressure;the corrosion product film produced on the surface of X70 pipeline steel can not protect the metal matrix,and intensify the local corrosion;under the influence of the corrosion product film,the increase of CO2 pressure makes X70 pipeline steel stress corrosion susceptibility increases;and the corrosion cracking of X70 pipeline steel is also affected by the metal surface cracks.