摘要
油田火驱尾气中存在CO2、H2S和O2 3种腐蚀性气体,且O2分压会在一定范围内变化。目前,鲜有关于O2分压对注气管常用钢316L钢腐蚀行为影响的报道。以316L钢为试材,利用高温高压模拟试验、失重法和扫描电镜等分析技术,研究在O2-H2S-CO2条件下O2分压对316L钢腐蚀行为的影响规律并分析其机理。结果表明:O2-H2S-CO2条件下,316L钢的腐蚀速率和产物膜厚度随O2分压的升高呈先减小再增大的变化规律;钝化膜均由极细的颗粒构成,有Cr和Ni的化合物沉积,有利于提高316L钢的抗腐蚀能力;一定范围内,O2分压升高会促进316L钢发生钝化,提高钝化膜的稳定性;但随O2分压的继续升高,会促进O2与H2S生成S8,更多的S8局部沉积,与H2O反应引起局部酸化,导致钝化膜出现破损点,并形成腐蚀电偶,发生严重的点蚀。
Three corrosive gases such as CO2,H2S and O2 exist in the fire-exhaust gas of oilfield,and the partial pressure of O2 always changes within a certain range.There were few reports on influence law of O2 partial pressure on the corrosion behaviors of 316 L stainless steel under O2-H2S-CO2 condition.In this paper,the 316 L steel commonly used in gas injection pipelines was used as experimental material.The effects of O2 partial pressure on the corrosion behavior of 316 L steel under O2-H2S-CO2 conditions and its mechanism were studied by using high-temperature and high-pressure simulation experiments,weight loss method and scanning electron microscope(SEM)analysis techniques.Results showed that under the condition of O2-H2S-CO2,with the increase of O2 partial pressure,the corrosion rate and product film thickness of 316 L steel decreased firstly and then increased.The passivation film was composed of superfine particles.The deposition of compounds with Cr and Ni was beneficial to the improvement of the corrosion resistance of 316 L steel.Within a certain range,the increase of O2 partial pressure would promote the passivation of 316 L steel and improve the stability of the passivation film.As the partial pressure of O2 continued to rise,it would promote the formation and local deposition of S8 by the reaction between O2 and H2S.Local acidification would occur due to the reaction of S8 and H2O,which induced the breakage of passivation film and formation of corrosion galvanic couples and caused severe pitting corrosion.
作者
宋晓琴
王喜悦
王彦然
SONG Xiao-qin;WANG Xi-yue;WANG Yan-ran(Petroleum Engineering School,Southwest Petroleum University,Chengdu 610500,China;PetroChina Southwest Oil&Gas Field Company,Chengdu 610500,China)
出处
《材料保护》
CAS
CSCD
北大核心
2019年第8期61-68,共8页
Materials Protection
