Estudo do mecanismo de corrosão pelo CO2 em aço carbono via técnicas eletroquímicas em condições que incluem alta pressão e temperatura

Abstract

CO2 corrosion is one of the major forms of deterioration of carbon steel in the oil and gas industry. The presence of the carbon dioxide accelerates the corrosion of carbon steel if compared to the medium containing strong acid with the same pH and this scenario makes even more relevant the development and improvement of corrosion models used to predict corrosion rate of steels. In this context, the role of CO2 in the anodic dissolution mechanism of carbon steel was investigated through measurements of electrochemical impedance, local pH and mass loss tests. Tests under high partial pressure of CO2were carried out in order to increase the dissolved CO2concentration, allowing to evaluate the possible influence of this gas on steel corrosion. In addition, the influence of salt concentration on carbon steel corrosion was investigated. An experimental apparatus consisting of a two-electrodes cell, adapted for autoclave, was used for the first time in the literature to perform electrochemical measurements in water saturated with CO2. The results support the non-action of CO2 directly on the free iron surface. The investigation of the influence of NaCl concentration on carbon steel corrosion suggests that the increase in the concentration of this salt leads to a decrease in steel corrosion.