Effect of CO ₂ Partial Pressure on the Corrosion Inhibition of N80 Carbon Steel by Gum Arabic in a CO ₂-Water Saline Environment for Shale Oil and Gas Industry

Abstract

The effect of CO ₂ partial pressure on the corrosion inhibition efficiency of gum arabic (GA) on the N80 carbon steel pipeline in a CO ₂-water saline environment was studied by using gravimetric and electrochemical measurements at different CO ₂ partial pressures (e.g., ${\mathrm{P}}_{{\mathrm{CO}}_2}$ = 1, 20 and 40 bar) and temperatures (e.g., 25 and 60 °C). The results showed that the inhibitor efficiency increased with an increase in inhibitor concentration and CO ₂ partial pressure. The corrosion inhibition efficiency was found to be 84.53% and 75.41% after 24 and 168 h of immersion at ${\mathrm{P}}_{{\mathrm{CO}}_2}$ = 40 bar, respectively. The surface was further evaluated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), grazing incidence X-ray diffraction (GIXRD), and X-ray photoelectron spectroscopy (XPS) measurements. The SEM-EDS and GIXRD measurements reveal that the surface of the metal was found to be strongly affected by the presence of the inhibitor and CO ₂ partial pressure. In the presence of GA, the protective layer on the metal surface becomes more compact with increasing the CO ₂ partial pressure. The XPS measurements provided direct evidence of the adsorption of GA molecules on the carbon steel surface and corroborated the gravimetric results.