The objective of this work is to study the effect of sulphide ion on the corrosion behaviour of X52 steel in the simulated solution containing sulphate reducing bacteria metabolic products species. Linear polarisation resistance and electrochemical impedance spectroscopy results show that the addition of 50 ppm sulphide ions increased the rate of X52 steel corrosion. However, with addition of 200 and 400 ppm sulphide, the corrosion rate decreased. The increase in corrosion rate is due to the increase in the cathodic reaction in the presence of sulphide, while the corrosion protection was related to FeS film formed, typically mackinawite and pyrite.

Purpose -The purpose of this paper is to develop an empirical equation of SRB corrosion based on their metabolic species. Design/methodology/approach -Solution containing SRB metabolic species was simulated using abiotic chemistry approach. Linear polarization technique was used to measure the corrosion rate of X52-sample in simulated solution containing SRB metabolic products species. The curve obtained from LPR data was then fitted using multiple non-linear regression method by Minitab 15 w software. Findings -Statistical analysis shows that sulphide and sulphite have significant effect on the X52 corrosion rate. Originality/value -Using abiotic chemistry approach, an empirical equation that considers SRB metabolic species has been developed. The equation could be used to predict carbon steel corrosion rate by SRB.

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Microbiologically influenced corrosion (MIC) is a serious problem in the oil and gas industry. The most common microorganism responsible for MIC is sulfate-reducing bacteria (SRB) which produces detrimental sulfide ions into the environment. Currently, there are some prediction models that develop to predict corrosion rate caused by SRB. However, among the models, the prediction is limited to predict the general corrosion rate, whereas, SRB caused localized corrosion. Thus, the objective of this work is to predict the pitting depth caused by SRB using available empirical equation. The study showed that the pitting depth increased with the increasing of sulfide concentration. In contrast, the pitting depth decreased with increasing sulfite concentration. The decreasing of pitting depth is related to the inhibitive FeS film formed, while the increasing of pitting depth is caused by the decreasing of the film thickness in the presence of sulfite.