【作者】 张娇娇；

【导师】 赵景茂；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2011， 硕士

【摘要】 随着油气工业的不断发展,含CO2、H2S等的强腐蚀性介质给油气田开发带来严峻的挑战。本文模拟油田现场工况环境,利用失重法、电化学方法以及表面分析手段等较系统的研究了L360管线钢及其焊接接头在饱和CO2/H2S溶液中的腐蚀行为及其不同因素的影响。本文分别考查了L360管线钢焊接接头上各个热经历区的金相显微组织状态及分布,进行了相应的硬度测试,并且对每个热经历区域进行了独立的微区电化学性能测试和研究。结果表明,L360管线钢焊接接头各微区显微组织具有不同的结构及特征。在模拟腐蚀溶液进行电化学测试,焊接接头各微区Ecorr,icorr不同,构成了一个多电极体系,其中热影响区易遭受到优先的腐蚀溶解。加入缓蚀剂可以有效抑制焊缝腐蚀。另外,从实际环境出发考查了温度、腐蚀时间、溶液pH、以及气液相等因素对L360管线钢在模拟油田深层水溶液中的CO2/H2S腐蚀的影响,使用EDS、SEM和XRD对腐蚀产物进行了观察和分析。结果表明,温度对腐蚀速率的影响很大,随着温度的升高,腐蚀速率先增大后减小,50℃时达到最大值,生成的腐蚀产物主要为FeS1-x；降低溶液pH值、增加溶液中的Cl-浓度均使L360钢的腐蚀加剧。从腐蚀产物表面来看,气相腐蚀产物表面疏松,并有点蚀坑出现,液相腐蚀产物致密无点蚀坑出现。更多还原

【Abstract】 With the development of oil and gas industry, strong corrosive medium containing CO2 and H2S has brought serious challenges. In this work, the behavior and main influence factors on L360 pipeline steel and L360 weld joints in CO2-H2S saturated solution were systematically studied using weight loss method, electrochemical measurement techniques and surface analytical technology in simulated water from Oilfield environment containing CO2-H2S.In this dissertation, state and distribution of metallographic microstructure, hardness and micro-area eleatrochemical performance of L360 weld joint were investigated in their thermal history zones. The results showed that the structure and characteristics of micro structures of L360 weld joint were different. Corrosion potential and corrosion current density at different zones were dissimilar in the simulation corrosion solution. A complex multiple electrode system occurred between these zones. The heat-affected zone suffered preferred corrosion dissolution. The H2S corrosion was the dominant factor. Corrosion inhibitor could retard the corrosion of weld joint effectively.Factors influencing corrosion rate of oil tube steels, such as effects of temperature, corrosion time, pH value and gas-liquid on corrosion rate in CO2-H2S saturated solution environment were studied by using weight-lossmethod, EDS, SEM and XRD. The results indicated that the temperature remarkably affected the characterization of corrosion rate, and the corrosion rate of L360 steel rose along with the increasing of temperature up to 50℃,then reduced dramatically due to the formation of a protective layer on the surface of steel. Corrosion product was proved to be FeS1-x in higher temperature. Corrosion was aggravated by reducing pH value and increasing the Cl- concentrations. The gas phase corrosion products were loose and a little corrosion pitting appeared on the surface.There was no corrosion pitting on the liquid corrosion product surface.更多还原