CO_(2)驱油井环境下N80钢与3Cr13钢的电偶腐蚀行为

Galvanic Corrosion Behavior of N80 Steel and 3Cr13 Steel in CO_(2) Flooding Oil Wells

N80钢与3Cr13钢常作为油管和水力锚等的材料使用,在CO_(2)驱油井环境中不可避免偶接使用易产生电偶腐蚀。为此,通过开展CO_(2)环境下N80钢和3Cr13钢的腐蚀速率试验和电偶腐蚀试验,明确了CO_(2)含量、温度、压力和矿化度等因素作用下2种钢的电偶腐蚀规律。结果表明:CO_(2)驱油井中2种钢产生电偶腐蚀,3Cr13钢为阴极,且不受电偶腐蚀影响,N80钢为阳极,电偶腐蚀速率增大;且N80钢的电偶腐蚀速率随CO_(2)含量、温度、压力和矿化度的增大而增大;电偶腐蚀敏感因子随CO_(2)含量和压力增大而减小,当CO_(2)含量达到20.0%时电偶腐蚀敏感因子为负值,随温度升高先减小后增大,随矿化度增加而增大,电偶腐蚀速率最大可高于常规腐蚀69%。

N80 steel and 3Cr13 steel used as tubing and hydraulic anchors are inevitably coupled in the CO_(2) flood oil well,which is prone to galvanic corrosion.Hence,the corrosion rate test and galvanic corrosion test of N80 steel and 3Cr13 steel under CO_(2) environment were carried out,for clarifying the galvanic corrosion laws of the two steels under the action of various factors including CO_(2) content,temperature,pressure and salinity.Results showed that the galvanic corrosion occurred at the two steels in CO_(2) flooding oil wells.3Cr13 steel was the cathode,which was not affected by galvanic corrosion.In contrast,N80 steel was the anode,and its galvanic corrosion rate increased,which exhibited the same trend as the conventional corrosion,namely increasing with the increase of CO_(2) content,temperature,pressure and salinity.In addition,the galvanic corrosion sensitivity factor decreased with the increase of CO_(2) content and pressure.When the CO_(2) content reached 20%,the gal-vanic corrosion sensitivity factor was negative,which decreased first and then increased with the increase of temperature,and increased with the increase of salinity.Besides,the maximum galvanic corrosion rate was 69%higher than conventional corrosion rate.