The corrosion behaviour of 13Cr-Martensitic Stainless Steel was investigated in CO2-H2S-Cl- environments, typical of oil and gas wells, under different CO2 and H2S partial pressures, with NaCl content of 50 g/L, pH = 2.7 and 4.8, T = 80°C. The 13Cr steel was highly corrosion resistant as far asphenomena induced by CO2 presence (general corrosion and carbonatic SSC), while the presence of H2S caused high SSCC (Sulphide Stress Corrosion Cracking) susceptibility and high corrosion rates. Moreover, CO2 in CO2-H2S-Cl- systems was evidenced to inhibit general corrosion and SSCC phenomena by favouring the formation of a protective film. XPS analysis of the films grown in different environmental conditions showed the following experimental evidences: - CO2 favours the growth of a Cr-oxide rich protective film with a low Fe-oxide-sulphide content; the presence of H2S favours the formation of less protective Fe-sulphide and Fe-oxide rich layers. A protectiveness index Ip = Cr3+/Cr3+ + Fe2+ was defined and related to the environmental parameter E_H2S-CO2 = pCO2/pH2S + pCO2 and to the actual reaction rates.
XPS INVESTIGATION ON THE CORROSION BEHAVIOUR OF 13-Cr MARTENSITIC STAINLESS STEEL
FIERRO G;INGO GM;
1989
Abstract
The corrosion behaviour of 13Cr-Martensitic Stainless Steel was investigated in CO2-H2S-Cl- environments, typical of oil and gas wells, under different CO2 and H2S partial pressures, with NaCl content of 50 g/L, pH = 2.7 and 4.8, T = 80°C. The 13Cr steel was highly corrosion resistant as far asphenomena induced by CO2 presence (general corrosion and carbonatic SSC), while the presence of H2S caused high SSCC (Sulphide Stress Corrosion Cracking) susceptibility and high corrosion rates. Moreover, CO2 in CO2-H2S-Cl- systems was evidenced to inhibit general corrosion and SSCC phenomena by favouring the formation of a protective film. XPS analysis of the films grown in different environmental conditions showed the following experimental evidences: - CO2 favours the growth of a Cr-oxide rich protective film with a low Fe-oxide-sulphide content; the presence of H2S favours the formation of less protective Fe-sulphide and Fe-oxide rich layers. A protectiveness index Ip = Cr3+/Cr3+ + Fe2+ was defined and related to the environmental parameter E_H2S-CO2 = pCO2/pH2S + pCO2 and to the actual reaction rates.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
