Inhibition of Multiphase Wet Gas Corrosion

Abstract Corrosion rates at the top and bottom of the pipe have been measured in wet gas multiphase flow at carbon dioxide partial pressures of 0.46 MPa and 0.79 MPa and temperatures of 40 C and 60 C in a high pressure 10-cm diameter system. Gas velocities up to 30 m/s and liquid velocities up to 0.5 m/s were used. The liquid consisted of a mixture of de-ionized water and low viscosity oil at two water cuts of 80% and 40%, and carbon dioxide was used in the gas phase. Corrosion inhibition studies were carried out at 50 ppm and 100 ppm dosage levels. The inhibitor used was an oleic imidazoline active compound dissolved in isopropyl alcohol and water. The corrosion rate was found to increase with increase in gas velocity, liquid velocity, temperature and CO2 partial pressure. The corrosion rate at the top of the pipe is negligible up to a gas velocity of 20 m/s. However, at a gas velocity of 30 m/s, there is substantial and measurable corrosion at the top of the pipe. This was attributed to wave spreading. Addition of inhibitors reduced the corrosion rate at the top and bottom of the pipe significantly. However, the corrosion rates are not negligible.