超临界CO_2/油/水系统中油气管材钢的腐蚀机制  

CORROSION MECHANISM OF OCTG CARBON STEEL IN SUPERCRITICAL CO_2/OIL/WATER SYSTEM

作　　者：孙冲[1] 孙建波[1] 王勇[1] 王世杰[2] 刘建新[2] 

机构地区：[1]中国石油大学(华东)机电工程学院,青岛266580 [2]中石化胜利油田分公司采油工艺研究院,东营257000

出　　处：《金属学报》2014年第7期811-820,共10页Acta Metallurgica Sinica

基　　金：十二五国家科技支撑计划项目2012BAC24B03;中央高校基本科研业务费专项资金项目14CX05020A;山东省自然科学基金项目ZR2010EM034资助~~

摘　　要：利用高温高压CO2模拟实验及SEM,EDS,XRD等分析技术,研究了超临界CO2/油/水系统中J55钢的腐蚀速率、腐蚀形态和腐蚀产物膜的结构特征,建立了不同含水率下的腐蚀模型,并阐述其腐蚀机制.结果表明：含水率低于30%时,原油浸润整个金属表面,J55钢发生均匀腐蚀,处于耐蚀状态;含水率在30%~75%之间时,腐蚀速率近似线性增长,原油吸附不均匀性及在腐蚀膜沉积部位水优先润湿导致局部孔蚀;含水率高于75%以后,水相浸润整个金属表面,原油的缓蚀作用被屏蔽,腐蚀膜局部破坏引发台地腐蚀,腐蚀速率急剧增加.含水率达到100%时,超临界CO2溶于水形成的强腐蚀环境导致整个金属表面的均匀腐蚀.原油能够削弱超临界腐蚀介质对腐蚀膜的溶解,改变腐蚀膜晶粒尺寸、堆积形态及化学组成,提高腐蚀膜的保护性能.The supercritical CO2 corrosion problems of oil country tubular goods （OCTG） become increasingly prominent along with the application of CO2 flooding enhanced oil recovery （EOR） technique and the exploitation of deep oil wells under high temperature and high pressure. Actually, OCTG steel often suffers from multiphase fluid corrosion of crude oil, water and supercritical COs at different stages of oil and gas production. However, studies about CO2 corrosion of carbon steel used for oil and gas production generally are carded out considering only the aqueous phase without proper consideration of the oil phase that may be present. The crude oil in crude oil/ water production environments is a key factor affected the corrosion behavior of carbon steel. Corrosion rate and corrosion type of J55 steel were investigated under the conditions of different oil/water ratios saturated with supercritical CO2. SEM, EDS and XRD were employed to analyze the morphology and characteristic of corrosion scale on the steel. The corrosion models were developed to understand the corrosion mechanism with consideration of a variation of oil/water ratio in reality. The results show that uniform corrosion occurs along with the lower corrosion rate due to the protection of crude oil when the water cut of crude oil is within the range, i.e., 0~30% and the water-in-oil fluid is formed. But the local corrosion rate of the steel increases rapidly due to the itthomogeneous adsorption of crude oil with the fluid changing from water-in-oil to oil-in-water emulsion when the water cut is between 30% and 75%. The corrosion products deposited on the steel surface change the wettability of oil and water phase, therefore, water phase can preferentially wet the localized deposited scale, leading to the development of pitting corrosion under the scale. However, when the water cut is higher than 75% and the oil-in-water fluid is formed, water phase infiltrates the metal surface that blocks the corrosion inhibition of crude oil for the steel, hence,

关 键 词：CO2腐蚀 超临界CO2 原油 含水率 J55钢 

分 类 号：TG172.9[金属学及工艺—金属表面处理]