Halophilic plant extracts for prevention of microbiologically influenced corrosion (MIC)

Offshore oil production is subjectable to internal corrosion, which can occur through microbiologically influenced corrosion (MIC). In pipelines, sulfur-reducing bacteria (SRB) such as Desulfovibrio, Desulfobacterium, Dethiosulfovibrio can thrive in the sulfate-rich produced waters, forming a MIC promoting biofilm. To mitigate MIC, the oil and gas industry relies primarily on biocides and mechanical cleaning. Halophytes (salt-tolerant plants), produce a variety of bioactive compounds that ensures their survival in an environment low in nutrition and high in free radicals and some of these compounds have antimicrobial activity. MIC was studied on carbon steel coupons inoculated with anaerobic sediment from the Wadden Sea (Denmark) to mimic MIC from oil production facilities in the North Sea. The coupons were treated with extracts from selected halophytes. Using H2S as activity indicator for SRBs and ATP for general microbial activity in the liquid phase, initial trials have shown a significant reduction in H2S and unchanged ATP concentrations in experiments treated with extracts compared to untreated controls, indicating a reduction of SRB species. Biofilm formation on carbon steel coupons from a bioreactor was reduced by two-thirds with the addition of extracts. Furthermore, next generation 16S rRNA amplicon sequencing of DNA from Bacteria and Archaea, proved a significant shift in the microbial composition when compared to samples not treated with extracts. Lastly, visual and measurable reduction in corrosion was observed with 3D surface scanning. Long-term solutions to prevent MIC using natural antimicrobial compounds from halophyte plants are discussed and proposed in this study.