SRB对20碳钢在气田采出水中腐蚀行为的影响

Effects of SRB on Corrosion Behavior of Carbon Steel 20 in Produced Water of Gasfield

为研究气田采出水系统微生物腐蚀机理,提出有效的防腐蚀措施,设计了3组气田采出水静态腐蚀挂片试验(灭菌组、空白组和SRB组)并连续测定各组试样49 d的腐蚀速率;通过测定SRB的生长曲线,并利用电化学测试和表面分析研究了SRB对20碳钢的腐蚀机理。结果显示:SRB的生长区间可分为适应期、对数生长期以及衰亡期;试验钢片浸泡49 d的平均腐蚀速率:灭菌组<空白组<SRB组;SRB在试样表面形成不均匀的生物膜易引发局部腐蚀;生物膜和腐蚀产物膜的形成可在一定程度上阻碍金属与溶液的传质过程,导致腐蚀速率减慢,但其疏松多孔且易脱落使得试样裸露出基体致使20碳钢再次被腐蚀;SRB参与20碳钢的腐蚀过程能产生FeS,SRB加速金属腐蚀是其代谢活动与金属溶解相互作用的结果。

In order to study the corrosion mechanism of microbiologically induced corrosion in produced water system of gasfield,and put forward effective anticorrosion measures,three groups of static corrosion test(sterile group,blank and SRB)were designed,and the corrosion rate of each group was determined continuously for 49 days.The corrosion mechanism of carbon steel 20 with SRB was studied by the growth curves of SRB,electrochemical measurement and surface analysis.Results showed that the growth intervals of SRB could be divided into adaptation period,logarithmic growth period and decay period,and the order of average corrosion rate of test specimen for 49 days was:sterile group<blank<SRB.In addition,SRB formed uneven biofilm on the surface of specimens,which was easy to induce local corrosion.The formation of biofilm and corrosion product film could hinder the mass transfer between metal and solution to some extent,and so the corrosion rate declined.However,the composite film with loose and porous structure was easy to fall off,which exposed some new surface of the specimen and induced carbon steel 20 to be corroded again.Furthermore,the participation of SRB in the corrosion process of carbon steel 20 could produce FeS.The enhancement effect of SRB on meal corrosion was a result of the interaction between the metabolic activities of SRB and the dissolution of metals.