Diversity And Enumeration Of Hydrogen Sulfide-producing Bacteria In Oilfield

Souring caused by H₂S derived from microbial activity can lead to various production and environmental problems in petroleum industry.In-depth understanding of the diversity of hydrogen sulfide-producing bacteria(SPB)in the oilfield environment and improving their quantitative detection accuracy are of great significance for effective control of souring.In this study,five types of produced water were collected from oilfield located in Northwest China(A),Bohai Bay(B),and Northeast China(C to E),respectively,and the SPB diversity and community composition in the produced water were analyzed by high-throughput sequencing method and anaerobic pipe method.Besides,the effects of eight culture media(NUMBER SP1?SP8)on SPB counting and diversity in the produced waters were explored.The main results were:(1)totally,2,7,14,19 and 20 genera of SPB were detected from A?E water samples,respectively,including Shewanella,Petrotoga,Clostridium,Desulfurispirillum,and Desulfuromonadaceae,with relatively high abundance;(2)four SPB species were isolated,and the 16S r RNA gene sequences of representative strains LLB,LLNS,SZB and SZH were closely related to Citrirobacter freundii strain JMC 1657,Desulfovibrio alaskensis strain Al1,Desulfomicrobium thermophilum strain P6.2,and Soehngenia saccharolytica strain DSM 12858,respectively,with sequence similarity of 99.51%,99.35%,98.80%and 98.39%;(3)Medium SP7 gave the highest number of SPB in A,C,D,E produced water,reaching the order of magnitude 10~9,10~5,10~7and 10~9cell/ml levels,respectively.The highest number of SPB at 1.5×10~4cell/ml was detected by Medium SP2 in produced water B sample.Commercial test bottles(medium SP8)gave relatively lower estimation of SPB,varying in the range of 10~2to 10~5orders of magnitude;(4)The relative abundance of Shewanella and Petrotoga and Clostridium significantly increased in the media enrichment cultures,while Desulfurispirillum and Desulfuromonadaceae decreased,and Desulfitobacteriales disappeared,compared with those in produced waters.In summary,this study shows that the diversity of SPB and population composition in the extracted water are significantly different,the existing commercial test bottle(SP8)significantly underestimates the numbers of SPB in the extracted waters,and different culture media show complex impact on the microbial diversity and composition of the extracted waters.The findings of this study deepen the understanding of SPB diversity and enumeration in oilfields in China,and are of significance for effectively improving the detection of SPB and souring control in oilfields.