含CO2油田介质环境中O2对X80钢腐蚀行为的影响

Effect of O2 on Corrosion Behaviour of X80 Steel in Environment of Oil Field Medium Containing CO2

通过电化学测试和浸泡试验研究了含CO2油田介质环境中O2对X80钢腐蚀行为的影响,并探讨了相关的腐蚀机理。结果表明:O2主要对X80钢的阴极极化过程产生影响;当O2分压较小时(0~12kPa),X80钢的自腐蚀电位和自腐蚀电流密度基本保持不变;随着O2分压的增大(17~22kPa),X80钢的腐蚀速率增大,自腐蚀电位正移,其双电层电容增大,而极化电阻、扩散电阻和电荷转移电阻均减小,这是由于O2破坏了X80钢表面CO2腐蚀产物膜,诱发局部腐蚀造成的。

Effect of O2 on the corrosion behaviour of X80 steel in the environment of oil field medium containing CO2 and the relative corrosion mechanism were investigated through electrochemical test and immersion test.The results show that O2 mainly affected the cathodic polarization process of X80 steel.Under low partial pressure of O2(012 kPa),the free corrosion potential and free corrosion current density of X80 steel basically remained the same.But with the increase of partial pressure of O2(17 22 kPa),the corrosion rate of X80 steel increased;the free corrosion potential shifted positively;the electric double layer capacitance increased;and the polarization resistance,diffusion resistance and charge transfer resistance reduced.This resulted from the localized corrosion because the O2 destroyed CO2 corrosion product film on X80 steel surface.