Microbial community analysis of three hydrocarbon reservoir cores provides valuable insights for the assessment of reservoir souring potential. (January 2018)

• Record Type: Journal Article
• Authors: Tsesmetzis, Nicolas; Alsop, Eric B.; Vigneron, Adrien; Marcelis, Fons; Head, Ian M.; Lomans, Bart P.
• Is Part Of: International biodeterioration & biodegradation. Volume 126(2018)
• Page Start: 177
• Page End: 188
• Publication Date: 2018-01
• Subjects: Reservoir core -- Microbial profile -- Reservoir souring -- Next generation sequencing -- Hydrocarbons -- Souring potential assessment; MIC microbially influenced corrosion -- SRBs sulfate reducing bacteria -- NRBs nitrate reducing bacteria; Biodegradation -- Periodicals; Bioremediation -- Periodicals; Biodegradation -- Periodicals; Biodégradation -- Périodiques; Biorestauration -- Périodiques; Electronic journals; 620.11223
• DOI: 10.1016/j.ibiod.2016.09.002
• Languages: English
• ISSNs: 0964-8305

Abstract

Abstract: Three hydrocarbon reservoir cores were obtained from a high temperature non-waterflooded offshore reservoir. All three cores were taken from a 56-m section of the same well. Under sterile conditions, DNA was recovered from the inner section of each core and the microbial community profiles were deduced by sequencing the 16S rRNA marker gene. Taxonomic analysis of the Operational Taxonomic Units (OTUs) recovered, identified a high proportion of members from the Oxalobacteraceae family (38.5%) followed by members from the Pseudomonadaceae and Comamonadaceae families (29.1% and 12.8% respectively). Representatives of all these families are known to degrade hydrocarbons as well as to use nitrate as a terminal electron acceptor under anaerobic conditions. Assuming these predominant microorganisms are indigenous to the reservoir and have not been introduced with the drilling fluids they might exhibit a relatively rapid response to nitrate injection for souring control. On the contrary, very few sulfate reducing bacteria (SRBs) were detected in these cores (<0.01%) suggesting unfavorable conditions to SRB growth. This however may well rapidly change upon seawater injections in the absence of nitrate addition. This study sets the microbial profiling "baseline" for the prediction of souring through modelling as well as for any upcoming biomonitoring surveys. Highlights: Microbial profiling can assist with the assessment of reservoir souring potential. Nitrate reduction may be a substantial in-situ process in an oil reservoir. Sulfate reduction potential in a pristine oil reservoir was very low. Nitrate reduction might occur at a higher temperature than previously thought.