Effect of Antimicrobial Halophilic Plant Extracts on Microbiologically Influenced Corrosion (MIC)

Offshore oil production is susceptible to internal corrosion, which can occur through microbiologically influenced corrosion (MIC) caused by biofilm-forming sulfate-reducing prokaryotes (SRP). The oil and gas industry relies primarily on biocides and mechanical cleaning to mitigate MIC. Halophytes (salttolerant plants) produce a variety of bioactive compounds, some of which have antimicrobial activity. MIC was studied on UNS S31600 stainless steel coupons in flasks with three extract types, from four halophytes, at three different concentrations. Flasks were inoculated batch-wise with anaerobic sediment from the Wadden Sea (Denmark) to mimic North Sea oil production MIC. Using H2S as activity indicator for SRPs initial trials showed a >99.5% reduction in H2S concentration in samples treated with 20% (v/v) Type B extracts compared to extract-free controls, indicating a significant reduction of SRP. ATP concentrations were only lowered by ≥15% (v/v) concentrations of extracts. Next-generation 16S rRNA amplicon sequencing of DNA from Bacteria and Archaea showed a significant shift away from SRPs in the microbial composition in inoculations with extracts. Visual reduction in corrosion was observed on the coupons treated with 20% Type B extract from halophytes 3 and 4.