The effect of acetic acid on the localized corrosion of 3Cr steel in the CO2-saturated oilfield formationwater was investigated using weight loss tests, surface characterization, and electrochemicalmeasurements. Weight loss tests revealed that acetic acid and increased concentration can dramaticallyaccelerate the general rate of 3Cr steel when the general corrosion rate increased from 0.2841 to 1.2236mm/y in tandem with an increase in the acetic acid concentration from 0 to 5,000 ppm. Surfacecharacterization measurements were performed by scanning electron microscopy, energy-dispersive Xray spectroscopy, X-ray powder diffraction, and three-dimensional profilometry. The results revealedthat FeCO3 and Cr compounds dominated the corrosion scales and that the corrosion scales graduallybecame looser and shed off with increased acetic acid concentration. The localized corrosion rateincreased from 0.2663 to 4.2416 mm/y in tandem with an increase in acetic acid concentration from 0to 5,000 ppm. The electrochemical measurements showed that the reduced reaction of undissociatedacetic acid in the solution participated in the cathodic reaction process. Moreover, acetic acid was shownto affect the adsorption process of the corrosion product scales, with the entire corrosion reactiondrastically accelerating. In this paper, the localized corrosion mechanism of 3Cr steel in the CO2-saturated oilfield formation water is discussed. Acetic acid significantly contributes to the generation oflocalized corrosion. Moreover, the combined effect of Cl?stimulates the formation and development oflocalized corrosion on 3Cr steel’s surface..
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