Estudo da eficiência de um inibidor à base de amina nos sistemas de CO2 E CO2-O2 em meio contendo cloreto.

Abstract

Metallic materials present a wild field of application in the most diverse industries. One of them is oil and gas, which uses carbon steel for pipelines in transport and material extraction. However, the environment in which these materials are located are quite corrosive, bringing costs with maintenance and replacement of components. Some measures are used to improve corrosion resistance of the metals. The most widely used is based on corrosion inhibitors, which slow down the degradation reactions increasing the life-time of the components. In this sense, the present work aims to study the efficiency of an amine-based inhibitor in chloride-containing media in two environments found in the oil industry: (i) - carbon dioxide and (ii) - carbon dioxide with oxygen contamination. The metallic material used in the study was carbon steel AISI 1018. To measure the corrosion properties, electrochemical tests were performed: open circuit potential monitoring, electrochemical impedance spectroscopy and linear polarization. Inhibitor concentrations were 10 ppm, 25 ppm and 50 ppm. From the results obtained it was observed that for the system containing CO2 the best inhibition efficiency was at the concentration of 25 ppm with 97.42%. In the condition containing O2 as a contaminant, the best efficiency was observed at the concentration of 50 ppm with 97.28%. In addition to the electrochemical tests, mass loss tests were carried out, which aim to analyze the corrosion rate of the material under conditions with CO2 and CO2-O2. The results indicated that the lowest rate was in the medium containing CO2 with 0.08 mm/year for 25 ppm. The surface aspect of the electrode after the electrochemical tests was obtained through optical microscopy, and it is possible to verify that in the condition with carbon dioxide at 25 ppm the electrode showed better results and in the condition with oxygen at 50 ppm.