环境因素对BT80S-5Cr抗CO_(2)/H_(2)S腐蚀套管均匀腐蚀速率的影响

Effect of Environmental Factors on Uniform Corrosion Rate of BT80S-5Cr Anti-CO_(2)/H_(2)S Corrosion Casing

通过模拟国内某油田腐蚀工况,采用高温高压釜模拟腐蚀试验,利用失重法研究试验周期、温度、CO_(2)及H2S分压环境因素对BT80S-5Cr油套管均匀腐蚀速率的影响。研究表明,随着试验周期的延长,试验钢均匀腐蚀速率逐渐降低,且降幅趋于平缓,试验周期360 h是BT80S-5Cr在该油气田模拟工况下衡量耐蚀性能的最佳试验周期;随着试验温度的提高,试验钢均匀腐蚀速率逐渐增加,试验温度100℃的试验钢的均匀腐蚀速率是试验温度40℃时的均匀腐蚀速率的1.67倍;随着CO_(2)分压的提高,试验钢均匀腐蚀速率逐渐增加,CO_(2)分压1.0 MPa的试验钢均匀腐蚀速率是不含CO_(2)时的均匀腐蚀速率的10倍;随着H2S分压的提高,试验钢均匀腐蚀速率逐渐降低,微量H_(2)S气体的引入对试验钢电化学腐蚀行为有一定的抑制作用。

For simulation the corrosive working conditions of a certain domestic oil field,the corrosion test is conducted with the high temperature/high pressure caldron and the weight loss method to investigate the effects of relevant environmental factors on the uniform corrosion rate of the BT80S-5Cr oil casing,including the test cycle,the temperature and the CO_(2)and H_(2)S partial pressures.The results show that along with the extension of the test period,the uniform corrosion rate of the test steel gradually decreases,and the decrease tends to be steady and slow;and the test period of 360 h is the best test period for the BT80S-5Cr steel to measure the corrosion resistance under the simulated working conditions of the said oil/gas field;with the increase of test temperature,the uniform corrosion rate of the test steel gradually increases;the uniform corrosion rate of the test steel as tested at 100℃is 1.67 times that of the test steel as tested at 40℃;With the increase of the CO_(2)partial pressure,the uniform corrosion rate of the test steel gradually increases,and the uniform corrosion rate of the test steel with a partial pressure of CO_(2)of 1.0 MPa is 10 times that of the test steel free of CO_(2);along with the increase of the H2S partial pressure,the uniform corrosion rate of the test steel gradually decreases,and the introduction of trace H2S gas has a certain inhibitory effect on the electrochemical corrosion behavior of the test steel.