利用交流阻抗技术对比研究了N80油套管钢和09Cr2AlMoRE钢(称新型合金)在饱和CO2的地层水中的腐蚀电化学行为,同时利用SEM观察了两种材料在1 MPa,120 ℃腐蚀7 d(天)所成膜的形貌。结果表明,N80钢的阳极电化学阻抗谱出现了高频的容抗弧、中低频的感抗弧和低频的容抗弧;而新型合金的阳极电化学阻抗谱只出现了高、低频容抗弧,感抗弧已很少了。对于阴极电化学阻抗谱,N80钢的阻抗谱只由一容抗弧组成,而新型合金则由高频容抗弧、中频Warburg阻抗和低频容抗弧共同组成。对两种材料阴、阳极过程中极化电阻的计算表明,新型合金阴、阳极过程中的极化电阻大于N80钢相应过程的极化电阻,表明新型合金能有效地抑制了CO2腐蚀。

The electrochemical behaviors of N80 steel and 09Cr2AlMoRE steel in stratum water with saturated CO2 were comparably investigated using electrochemical impedance spectra (EIS),and the microstructures of corrosion scales formed on two samples at 1 MPa,120 ℃ for 7 days were also observed by SEM. The results showed that the anodic impedance of N80 steel was consisted of capacitance at high frequency,inductance at middle frequency and capacitance at low frequency. While for the anodic impedance of novel alloy,the spectra was only consisted of capacitance at high and low frequencies,and the inductance shrinked. For the cathodic impedance spectras of two samples,the spectra of N80 steel was only consisted of one capacitance,and the spectra of novel alloy were consisted of capacitance at high frequency,Warburg impedance at middle frequency and capacitance at low frequency. Calculating the polarization impedances of anodic and cathodic processes for two samples,it revealed that the polarization impedances of anodic and cathodic processes for novel alloy were all higher than that for N80 steel,this means that the novel alloy can effectively inhibited the occurrence of CO2 corrosion formed on it.