Influence of thermophilic sulfate-reducing bacteria and deposited CaCO3 on the corrosion of water injection system

Herein, a schematic model was established to assess the combined effect of deposited CaCO3 and thermophilic sulfate-reducing bacteria (SRB), at high CO2 and low O2 dissolution levels on the corrosion behavior and growth of corrosion scale on X65 pipeline carbon steel. Field emission scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction, confocal laser scanning microscopy, open circuit potential, and electrochemical impedance spectroscopy were used to characterize the corrosion pattern of water injection pipe. The results showed that a synergistic effect exists between CaCO3 and thermophilic SRB, both uniform and localized corrosion of CaCO3-coated X65 steel were promoted when inoculated with SRB. The corrosion process was comprised of three stages depending on the metabolism of SRB.