低硫油田环境中20号和L245NS管线钢的耐蚀性

Corrosion Resistance of 20^(#)and L245NS Pipeline Steels in Low-Sulfur Oilfield Environment

通过动电位极化曲线和电化学阻抗谱,分析了20号和L245NS管线钢在模拟不含硫和H_(2)S/CO_(2)共存的低含硫油田环境中的腐蚀行为,采用扫描电镜和能谱仪分析了其表面腐蚀产物的微观形貌和成分。结果表明:20号和L245NS管线钢在低含硫油田环境中的腐蚀电位(E_(corr))变化较小,腐蚀电流密度(J_(corr))显著减小,相同条件下L245NS管线钢的J_(corr)比20号管线钢的略小;20号和L245NS管线钢在不含硫油田环境中的电化学阻抗谱均呈中高频区容抗弧和低频区感抗弧的时间常数特征,在低含硫油田环境中低频区感抗特征消失;L245NS管线钢在低含硫油田环境中的耐蚀性比20号管线钢的略好。

The corrosion behavior of 20^(#)and L245NS pipeline steels in simulated sulfur-free and low-sulfur oilfield environment with coexistence of H_(2)S/CO_(2)was analyzed by potentiodynamic polarization curves and electrochemical impedance spectroscopy.Scanning electron microscope and energy dispersive spectrometer were used to analyze the micro morphology and composition of corrosion products on the surface.The results showed that the corrosion potential(E_(corr))of 20^(#)and L245NS pipeline steels in low-sulfur oilfield environment had a small change,and the corrosion current density(J_(corr))was significantly reduced.Under the same conditions,the J_(corr)of the L245NS pipeline steel was slightly smaller than that of 20^(#)pipeline steel.The electrochemical impedance spectra of 20^(#)and L245NS pipeline steels in sulfur-free oil field environment showed the time constant characteristics of capacitive reactance arc in the medium and high frequency region and inductive reactance arc in the low frequency region.The inductive reactance characteristics in low frequency region in low-sulfur oilfield environment disappeared.The corrosion resistance of L245NS pipeline steel in low-sulfur oilfield environment was slightly better than that of 20^(#)pipeline steel.