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Microbiologically influenced corrosion(MIC)is quite a harmful form of corrosion in gas and oil pipelines.Therefore,the aim of this experiment was to investigate the corrosive microbial communities in gas and oil pipes,and distinguished them from oil reservoirs in situ microorganisms.Samples were collected from three oil production regions located in Liaohe Oilfield which using water flooding(WF),chemical flooding(CF),steam flooding(SF),steam soak(SS)and steam-assisted gravity drainage(SAGD)exploitation methods,respectively.The total OTUs and the types of microorganisms were analyzed by the total DNA extraction,PCR amplification and high-throughput sequencing analysis.Results showed that the abundance of corrosion-induced microorganisms accounted for 20.28%in the total OTUs.From totally about 170 genera reported related to corrosive microorganisms up to now,58 genera were detected in these samples.According to the data,it could be easily found: In figure 1,there were different distributions of corrosive microbial communities in different wells using different exploitation methods,especially SAGD.Compared with other modes,the microbial communities of corrosion were significant different.With the conditions of SAGD,Thermomonas,a genus of iron oxide bacteria,occupied the first station in most samples,then the Nitrosomonas,supplemented by other species less or no content.Nitrosomonas would produce nitrate and nitrite,reduce pH in the pipelines,thereby accelerating corrosion.While other exploitation methods,Pseudomonas,a genus of iron oxide bacteria,was dominated corrosive microbial flora.With the exploitation method of SAGD conditions,the abundance of corrosive microbial communities was different from different geological conditions.According to figure 2,it was easily found that 11 samples were divided into three groups.Group A(including L2YSD291,L2YSD 16 and L2YSD 17)was mainly dominated by Pseudomonas,then Desulfurella and Acinetobacter.While Group B(L2YSD44,L2YSD14,L2YSD47,L2YSD42 and L2YSD11 five samples,circled),the corrosive microbes were mainly Nitrosomonas and Thermomonas,less Bacteroides genus,lower content of other communities.As to Group C(L2YSD281,L2YSDH3001 and L2YSD48),Nitrosomonas,Pseudomonas,Nitrosospira,Flavobacterium and Hyphomicrobium were averaged at 10%~40%.