Investigation on Corrosion of Insulation Tubing Steel in HTHP Steam and Flue Gas Co-Injected to Enhance Heavy Oil Production

Abstract Co-injection of steam and flue gas is potentional to improve heavy oil well production. For a typical steam and gas co- generator, the flue gas content is about 10wt%-30wt% in general, the temperature usually ranges from 200℃ to 350℃ (regulated by fuel and water injection rate), and the injection pressure is up to 20MPa. More attention has to be attached to the corrosion of insulation tubing in the HTTP steam and flue gas comprised of CO2, N2 and residue O2. In this work, corrosion performance and inhibition with some additives of the insulation tubing steel in HTHP fluid of steam, CO2, N2 and residue O2 were investigated by weight loss experiment with alloy reactor. The results showed that there are another peak at 200℃ except the corrosion rate peak at 60℃ for CO2 and O2 corrosion, the corrosion rate of steel in co-injected fluid is enhanced at higher temperature. The corrosion principles are related to production of FeCO3 and Fe2O3 under different conditions. At higher temperature, corrosion rate could be reduced with addition of corrosion inhibitor and/or deoxidizer, for example, more than 90% reduction in corrosion rate could be obtained with addition of 2000mg/L selected corrosion inhibitor at 200℃. Additionally, the field testing cases show significant corrosion inhibition of insulation tubing in co- injection of steam and flue gas with addition of corrosion inhibitor.