MECHANISTIC AND KINETIC STUDIES OF MICROBIOLOGICALLY INFLUENCED CORROSION(MIC) IN THE PRESENCE OF DOMINANT SULPHATE REDUCING BACTERIA (SRB) METABOLIC SPECIES

Microbiologically influenced corrosion (MIC) is a serious problem in the oil andgas
industry. The most common microorganism responsible for MIC is sulphate reducing
bacteria (SRB) which produces detrimental sulphide ions into the environment.
Therefore, many studies have been conducted to study the effect of sulphide ions on
the corrosion rate of mild steel using inorganic solution chemistry but ignored the
possible effects of other SRB metabolic species which are produced along with
sulphide such as sulphite, lactate, acetate, pyruvate and thiosulphate. The exclusion of
other metabolic species implies some deficiency of the current understanding of MIC
problem. Thus, the objective of this work is to elucidate the mechanistic and kinetic of
MIC with the presence of dominant SRB metabolic species by which a better MIC
prediction could be formulated. The work was conducted in simulated solution
containing dominant SRB metabolic species of sulphide, sulphite, lactate, acetate,
pyruvate and thiosulphate. Three electrochemical measurement methods were used in
this work i.e. linear polarization resistance (LPR) test, Tafel polarization (TP) and
electrochemical impedance spectroscopy (EIS).