凝析气田多相流环境下常用油套管钢的CO_2腐蚀规律

CO_2 Corrosion of Tubing and Casing Steel in Condensate Field in Multiphase Flow Environment

针对凝析气藏CO_2腐蚀工况,利用高温高压反应釜,进行了常用油套管钢N80、P110和3Cr在模拟凝析气田多相流环境中的动态腐蚀试验,研究了温度、CO_2分压及含水率等因素对N80、P110和3Cr腐蚀速率的影响规律。用扫描电镜对腐蚀试样进行了表面形貌观察,对腐蚀产物进行了X射线衍射分析。研究结果表明,在CO_2分压1.4MPa,含水率30%的情况下,N80和P110的腐蚀速率随温度增加而减小,3Cr的腐蚀速率随温度增加先增后减;在60℃条件下,N80、P110和3Cr的腐蚀速率均随含水率和CO_2分压的增加而增大;在模拟凝析气田多相流环境下,3Cr相对于N80和P110具有较好的耐蚀性。

Corrosion behaviors of common tubing and casing steel were studied by tests in simulated environments of condensate field multiphase flow in high pressure autoclave.Effects of temperature,CO_2 partial pressure and water content on corrosion behaviors of N80,P110 and 3Cr were analyzed by methods of corrosion weight loss,SEM and EDX.The results showed that with increasing of temperature when the CO_2 partial pressure was 1.4 MPa and water content was 30%,the corrosion rate of N80 and P110 increased and the corrosion rate of 3Cr increased firstly and then declined.The corrosion rate of N80,P110 and 3Cr increased with increasing of water content and CO_2 partial pressure at 60℃.In the simulated environment of condensate field multiphase flow,3Cr had better CO_2 corrosion resistance than N80 and P110.