Cailiao Baohu (Apr 2022)
Study on Corrosion Resistance of Epoxy Black Ceramic Coating in Tahe Oilfield
Abstract
With the extension of oilfield production life and the complication of its service environmental conditions, the applicability of the inner coating would be being challenged. In this work, the service condition of epoxy black ceramic coating in Tahe oilfield was simulated by using high-temperature autoclave to study the corrosion resistance of coatings in gas, oil and water phases, and the electrochemical characteristics of the coating in 6 kinds of simulated working conditions such as H2S dominated, H2S / CO2 coexistence and CO2 dominated were analyzed by the electrochemical AC impedance technique (EIS). Results showed that the epoxy black ceramic coating possessed good corrosion resistance characteristics under working conditions, and the AC impedance value was higher than 107 Ω·cm2. From the filed application, the coating had good adhesion to the substrate and good cathodic stripping resistance. Moreover, the failure mechanism of coatings was discussed preliminarily, and their service life under field conditions was preliminarily predicted. Coating defects became a fast channel for the diffusion of water and various ions, electrochemical corrosion occurred at the interface between the coating and the substrate, resulting in the increase of local pressure at the interface and the blistering and cracking of the coating. Furthermore, the life of epoxy black ceramic coating predicted by quadratic polynomial of fitting curve was 517 d.
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