Determination of biocorrosion of low alloy steel by sulfate‐reducing Desulfotomaculum sp. isolated from crude oil field

Abstract

AbstractIn this study corrosion behavior of low alloy steel, in the presence of anaerobic sulfate‐reducing Desulfotomaculum sp. which was isolated from an oil production well, was investigated. In order to determine corrosion rates and mechanisms, mass loss measurements and electrochemical polarization studies were performed without and with bacteria in the culture medium. Scanning electron microscopic observations and energy dispersive X‐ray spectra (EDS) analysis were made on steel coupons.The effect of iron concentration on corrosion behavior was determined by Tafel extrapolation method. In a sterile culture medium, as the FeSO4 · 7H2O concentration increased, corrosion potential (Ecor) values shifted towards more anodic potentials and corrosion current density (Icor) values increased considerably. After inoculation of sulfate‐reducing bacteria (SRB), Ecor shifted towards cathodic values. Icor values increased with increasing incubation time for 10 and 100 mg/L concentrations of FeSO4 · 7H2O.Results have shown that the corrosion activity changed due to several factors such as bacterial metabolites, ferrous sulfide, hydrogen sulfide, iron phosphide, and cathodic depolarization effect.