温度对CO_(2)饱和页岩气压裂液环境中N80和TP125V钢腐蚀行为影响研究

Effect of Temperature on Corrosion Behavior of Pipeline Steels N80 and TP125V in Artificial CO_(2)-saturated Fracturing Fluid of Shale Gas

采用失重法、扫描电镜、X射线衍射仪、三维超景深显微镜结合电化学测量,着重研究了N80和TP125V钢在页岩气环境中60~120℃范围内的腐蚀速率的变化规律。结果表明,N80和TP125V钢腐蚀速率随温度的增加先增加后减小,100℃时达到最高值,分别为(0.169±0.014)和(0.198±0.007) mm/a;局部腐蚀速率也达到最大值,分别为1.13和2.47 mm/a,点蚀坑密度分别是2.0×10^(3)和2.6×10^(3)pits/cm^(2)。在60和120℃时,N80钢的腐蚀速率要高于TP125V钢的;而在90、100和110℃时,TP125V钢的腐蚀速率要高于N80钢的。表面分析结果表明,温度同时也会显著影响腐蚀产物膜的结构和组成。

Temperature is one of the key factors influencing the corrosion of oil pipeline steel in the shale gas environment. This work studied the effect of temperature on the corrosion behavior of pipeline steels N80 and TP125V in an artificial CO_(2)-saturated fracturing fluid of shale gas by means of mass loss measurement, electrochemical measurement, scanning electron microscopy, X-ray diffractometer and 3D microscope. Results indicate that among others, the corrosion rates of steels N80 and TP125V reached the highest at 100 ℃ with values of(0.169±0.014) and(0.198±0.007) mm/a, respectively. Correspondingly, the highest localized corrosion rates were 1.13 and 2.47 mm/a, while the densities of corrosion pits were 2.0×10^(3) and 2.6×10^(3) pits/cm^(2), respectively. In conclusion, the corrosion rates of steels N80 and TP125V increased firstly with the increasing temperature, further reached the maximum at 100 ℃, and then decreased gradually. The corrosion rates of N80 steel were higher than those of TP125V steel at 60 and 120 ℃ respectively, but the corrosion rates of the two steels are reversed at 90, 100, and 100 ℃. The temperature could also influence the structure and components of the formed corrosion products according to the surface analysis results.