J55导管钢的HCl-凝析水腐蚀行为研究

Corrosion Behavior of J55 Conduit Steel in HCl-Condensated Solution

涪陵页岩气井中HCl-凝析水给其长期生产带来了巨大的腐蚀风险,揭示井口J55导管钢的HCl-凝析水腐蚀行为,可为制定后期井口防腐蚀措施提供理论依据。通过模拟页岩气生产井井口环境进行腐蚀试验,利用静态失重法、表观检测法、极化曲线法、交流阻抗法系统地研究了J55导管钢在HCl-凝析水中的腐蚀行为。结果表明:随着凝析水中HCl浓度的增加,J55导管钢的腐蚀速率逐渐增大,HCl浓度为6%的腐蚀速率增幅最大;当腐蚀温度从50℃升至80℃时,腐蚀加剧,均匀腐蚀趋势增强;随着腐蚀时间的延长,腐蚀产物层增厚,腐蚀速率迅速下降,腐蚀反应主要发生在前12 h;腐蚀产物层不连续,表面附着弱,其主要组分为Fe2O3、Fe(OH)3和FeO(OH);J55钢腐蚀主要受酸性溶解过程控制,表面沉积中间产物,其阻抗谱具有高频容抗弧和低频感抗弧,感抗随HCl浓度的增大而减弱,腐蚀反应服从Bockris机理。

HCl-condensated solution can lead to large corrosion risks during a long-term production of Fuling shale gas wells.Therefore,it is necessary to disclose corrosion behavior of conduit steel in the HCl-condensated solution,which will supply theoretical basis for wellhead anti-corrosion measurements.The corrosion experiments were carried out at the simulated wellhead environments of Fuling shale gas fields,and a series of analyses such as weight loss,appearance analysis,polarization curves and impendence spectrum,were systematically conducted to study the corrosion behaviors of J55 steel in HCl-condensated solution.Results showed that with the increase of HCl concentration,the corrosion rate continuousely increased.When the HCl concentration was 6%,the corrosion rate beame the maxminum.Moreover,when the temperature increased from 50℃to 80℃,the corrosion was accelated,and the tendency of uniform corrosion became stronger.With prolonging corroion time,the film of corrosion products turned into thicker,and the corrosion rate reduced sginificantly,presenting that the corrosion reaction mainly occurred in the first 12 h.In addition,the corrosion product was discontinous and weakly adsorptive to the surface,and the main components were Fe2O3,Fe(OH)3 and FeO(OH).The corrsoion behaviors of J55 steel were mainly controlled by anodic dissolution,and the intermediates formed on electrode surface.Otherwise,the Nyquist diagram was composed of a capactive loop at high frequency and an inductive loop at the low frequency.The latter of which reduced with increasing HCl contration,and the corrosion behavior of J55 steel in the HCl-condensated solution was confirmed to Bockris Law.