EFECTO SINÉRGICO DE LAS BACTERIAS SULFATO-REDUCTORAS Y EL CO2 EN AGUA DE PRODUCCI ÓN SOBRE LA CORROSIÓN DEL ACERO AL CARBONO/SYNERGIC EFFECTS OF SULFATE-REDUCING BACTERIA AND CO2 IN PRODUCED WATER ON CARBON STEEL CORROSION

The effects of CO2 and of a mixed culture of sulfate-reducing bacteria (SRB) isolated from an oil industry field on general and localized corrosion of carbon steel in synthetic produced water were analyzed. The experiments were carried out in a rotating cage. The synthetic produced water was saturated with various CO2 concentrations. During the trials the pH was measured, planktonic SRB were counted and the concentrations of sulfur, sulfate, Fe, Ca and Mg ions were measured in the solution. After the experiments, sessile SRB and mass loss in the carbon steel coupons were measured, the corrosion products were identified by scanning electron microscopy and X-ray diffraction, while the corrosion morphology was determined by optical microscopy, scanning electron microscopy and also using a laser profilometer. It was found that the general and localized corrosion rate of carbon steel are doubled in solutions containing 10% CO2 and 10% SRB in comparison with the solutions containing either CO2 or SRB (synergistic effect). High CO2 concentrations inhibited planktonic and sessile SRB growth. [PUBLICATION ABSTRACT]