Abstract:

In the environment of CO₂ enhanced recovery (CCS?EOR), the corrosion cracking behavior and mechanism of X70 pipeline steel under different CO₂ 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 CO₂ pressure was analyzed by scanning electron microscope. The results show that the corrosion rate of X70 pipeline steel increases with the increase of CO₂ 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.

Key words: CCS?EOR, X70 pipeline steel, CO₂ pressure, Stress corrosion cracking behavior, Corrosion morphology

摘要：

在CO₂增采（CCS?EOR）环境下，研究了X70管线钢在不同CO₂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CO₂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CO₂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，CO₂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。

关键词: CO₂增采, X70管线钢, CO₂压力, 应力腐蚀开裂行为, 腐蚀形貌