Investigation of microbial souring mechanisms and testing natural antibiotics for prevention of microbiologically influenced corrosion (MIC)

Offshore oil production facilities are subjectable to internal corrosion, which can occur through microbiologically influenced corrosion (MIC) and souring (sulphide production by sulfate-reducing prokaryotes, SRP). Seawater contains sulfate (up to 25-30 mM in the North Sea), thus allowing prominent SRP; sulphate-reducing bacteria (SRB), sulphatereducing archaea (SRA) and methanogens to attack as an embedded matrix (often with bioinorganic matrixes) referred to as biofilms. The petroleum industry relies on biocides to avoid MIC, souring and biofouling.
Active phytochemicals including strong antimicrobials from halophytes were applied in this study to combat contamination by inhibiting MIC microorganisms such as methanogens and SRP. A bioreactor system for biofilm production was setup and inoculated with production well fluids/biofilm samples to emulated onsite MIC. Next generation sequencing (NGS) of DNA from bacteria and archaea will help identify the strains and study the effects of antimicrobials on these strains. The inhibitory effect of using selected halophyte plant extracts on SRB, SRA and methanogens was studied. Significant inhibition of MIC bacteria was observed in liquid samples from the reactors treated with extractive mix. Biofilm formation was reduced by three times on carbon steel and four times on stainless steel coupons in reactors treated with extractive mix. Visible and measurable reduction in pitting and corrosion damages on carbon steel coupons was observed with the help of 3D scanning. Use of natural antibiotics resulted in inhibiting the growth of SRP. Long -term solutions to prevent MIC and souring using natural antibiotics are proposed.