Targeted loci analysis from a hydrocarbon reservoir microbiome

Having access to a sample set representing the production history of an oil field from primary oil production, through secondary oil production with seawater injection and nitrate treatment for souring control, we have been able to demonstrate that oil production practices trigger successive shifts in the petroleum reservoir's microbiome. Initially dominated by slow growing anaerobes adapted to living on hydrocarbons and complex refractory organic matter, the microbial community progressively changes, as seawater injection delivers oxidants, to fast growing opportunists with energetically efficient metabolisms associated with detrimental effects on the oil production system. These findings provide a new conceptual framework for understanding the petroleum reservoir biosphere and have consequences for developing strategies to manage and mitigate microbiological problems in the oil industry.