喹啉与硫脲在含饱和CO_2气井采出水中的协同效应

Synergetic effects of quinoline and thiourea in the produced water from saturated CO_2-containing gas wells

加注缓蚀剂抑制CO_2腐蚀是天然气开发过程中的常见工艺,利用缓蚀协同效应可以有效降低缓蚀剂的用量,减少对环境的污染,提高经济效益。为此,采用静态失重法、电化学极化曲线、阻抗谱(EIS)、扫描电子显微镜(SEM)及电子能谱等实验分析方法,研究了在含饱和CO_2模拟气井采出水腐蚀体系中,喹啉季铵盐(QN)与硫脲(TU)对N80碳钢的缓蚀协同效应。结果表明:①喹啉季铵盐和硫脲均能有效抑制N80碳钢的腐蚀;②喹啉季铵盐是一种以抑制阴极型为主的缓蚀剂;③硫脲对N80碳钢的阴极和阳极均具有较强的抑制作用,是一种混合型缓蚀剂;④当喹啉季铵盐与硫脲复配使用时,在较低的使用浓度下,喹啉季铵盐缓蚀剂与硫脲具有较好的缓蚀协同效应,当3 mg/L喹啉季铵盐缓蚀剂与7 mg/L硫脲复配使用时,缓蚀效果最佳,缓蚀率可达到93.59%;⑤喹啉季铵盐与硫脲相互作用在N80碳钢表面能形成稳定的吸附膜,较大程度地抑制N80碳钢的腐蚀过程。进而还对喹啉季铵盐与硫脲之间的协同作用机理进行了探讨。

Adding inhibiter for restraining CO_2 corrosion is a common process used in the natural gas development,synergetic effects can be used in effectively reducing the volume of corrosion inhibitors,thus minimizing environmental pollution and enhancing economic benefits.The static weight-loss method,electrochemical polarization curves,electrochemical impedance spectroscopy（EIS）,scanning electron microscope（SEM）,electron spectroscopy and other experimental analysis methods were deployed to determine the synergetic effects of quinoline quaternary ammonium salt（QN） and thiourea（TU） on corrosion to N80 carbon steel in the corrosion system of produced water from saturated CO_2-containing gas wells.The results show that,both quinoline quaternary ammonium salt and thiourea can significantly reduce corrosion to N80 carbon steel.Quinoline quaternary ammonium salt can be classified as a corrosion inhibitor characterized by the inhibition of cathode.As a mixed type corrosion inhibitor,thiourea may present strong inhibition to both the cathode and anode of N80 carbon steel.Satisfactory synergetic effects on corrosion inhibition can be observed during joint application of quinoline quaternary ammonium salt and thiourea at lower concentration.Combination of 3 mg/L quinoline quaternary ammonium salt corrosion inhibitor with 7 mg/L thiourea may present the optimal corrosion inhibition performances of up to 93.59%.Interaction between quinoline quaternary ammonium salt and thiourea may form stable absorption coating on the surface of N80 carbon steel to minimize the corrosion to N80 carbon steel.In-depth discussions with regard to the mechanism of the synergetic effects of quinoline quaternary ammonium salt and thiourea were conducted.