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 O-2 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.