辅助蒸汽驱油环境中CO_2分压对N80钢腐蚀行为的影响

Effect of CO_2 Partial Pressure on Corrosion Behavior of N80 Steel in Auxiliary Steam Drive Oil Environment

采用高温高压釜模拟CO_2辅助蒸汽驱油注气井的工况条件,在温度160℃和CO_2分压1～4MPa条件下,对N80钢进行了挂片腐蚀试验,研究了CO_2分压对其腐蚀行为的影响。结果表明:随着CO_2分压的升高,腐蚀速率先升高后降低,并在CO_2分压为2MPa时达到最大,其值为0.073 7mm·a-1;N80钢腐蚀产物的主要成分是FeCO3和少量Fe2O3,随着CO_2分压的升高,FeCO3晶体尺寸减小,当CO_2分压为3～4 MPa时FeCO3晶体发生融合;在试验条件下,N80钢的腐蚀速率在0.034 7～0.073 7mm·a-1范围,均小于油田腐蚀速率控制指标(0.076mm·a-1),满足CO_2辅助蒸汽驱油注气井油套管的性能要求。

The high temperature and high pressure autoclave was used to simulate the working conditions of CO2 auxiliary steam drive oil gas injection well.The coupon corrosion test was conducted on N80 steel at 160℃and CO2 partial pressures of 1-4MPa,and the effect of CO2 partial pressure on corrosion behavior of N80 steel was studied.The results show that with CO2 partial pressure increasing,the corrosion rate increased first and then decreased;when the CO2 partial pressure was 2MPa,the corrosion rate reached the maximum value of 0.073 7mm·a^-1.The main composition of corrosion products of N80 steel was FeCO3 and a small amount of Fe2O3.With the increase of CO2 partial pressure,the size of FeCO3 crystals decreased,and FeCO3 crystals mixed together when CO2 partial pressure was 3-4 MPa.Under the test condition,the corrosion rate of N80 steel was 0.034 7-0.073 7mm·a^-1 which was lower than the corrosion rate control line of oil field(0.076 mm·a^-1)and met the property requirement of CO2 auxiliary steam drive oil well casing.