The role of acetic acid in FeCO3 scale deposition on CO2 corrosion of API X65 carbon steel under high temperatures

Abstract

ABSTRACT The combined effects of high temperatures and different acetic acid (HAc) concentrations on corrosion and deposition of FeCO3 scales on API X65 carbon steel in CO2-saturated brines were investigated. Conditions with the absence and presence of 100 and 600\u2005ppm of HAc were evaluated under high pressure at 90°C and 120°C. Electrochemical impedance spectroscopy, linear polarisation resistance, weight loss and characterisations through scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction were conducted. Conditions with the absence of acid presented a huge deposition of sweet corrosion products and low corrosion rates. The addition of 100\u2005ppm of acid at 90°C did not increase significantly corrosion rates; however, it retarded the precipitation of FeCO3. Higher temperatures favoured iron carbonate nucleation even in the presence of HAc. The highest corrosion rates were observed for the environment with 600\u2005ppm of HAc at 120°C.