N80油管钢的CO_2高温高压腐蚀电化学行为与机理研究

Electrochemical corrosion behavior and mechanism of N80 steel in the aqueous solution of carbon dioxide under high-temperature high-pressure

在高温高压釜中模拟油气井腐蚀环境 ,采用电化学交流阻抗和动电位扫描极化曲线测试技术 ,研究了N80钢在温度为 10 0℃ ,CO2 分压为 1.18MPa条件下的腐蚀电化学行为和阳极与阴极反应机理 ,实时监测了腐蚀产物膜对腐蚀行为和腐蚀反应机理的影响 .研究结果表明 :N80钢的阳极反应过程服从Bockris机理 ;N80钢的阴极反应以H2 CO3的还原为主 ;反应中间产物吸附与腐蚀产物膜覆盖的竞争导致交流阻抗谱随腐蚀时间而变化 ,影响着钢的腐蚀行为 。

The corrosion environment in oil/gas wells is simulated in high-temperature high-pressure autoclave, and the electrochemical corrosion behavior of N80 steel and the reaction mechanism between positive pole and negative pole under 100 ℃ and the fractional pressure of carbon dioxide of 1.18 MPa are studied by means of the measurement of electrochemical impendence spectrum and dynamic polarization curve. The effects of corrosion product film on the corrosion behavior and the corrosion reaction mechanism are monitored. The results show that: (1) the anode reactions obey Bockris mechanism; (2) the predominant cathode reaction is the reduction of carbonic acid; (3) the competition between the deposition of corrosion product and the adsorption of reaction intermediate product influences the corrosion behavior of N80 steel and leads to the variation of the electrochemical impendence spectrums with corrosion time. The corrosion product film prevents N80 steel from being further corroded.