EIS measurement for corrosion monitoring under multiphase flow conditions

The electrochemical behavior of carbon steel in ASTM saltwater saturated with carbon dioxide (CO2) with/without an imidazoline based inhibitor under different flow conditions was studied using Electrochemical Impedance Spectroscopy (EIS). The effects of the addition of a light refined oil on the inhibitor performance were examined. Experiments were carried out in a 101.6 mm I.D., 15 m long acrylic flow loop. The system was maintained at a pressure of 0.136 MPa and temperature of 40 degrees C, Experiments were conducted at water cuts of 100 and 80%. Inhibitor concentrations of 25 ppm and 100 ppm were used. Results show that the EIS technique can be used to study mechanisms of corrosion and its inhibition in turbulent multiphase flow conditions. It was seen that the high rate of shear stress and turbulence in multiphase flows can significantly enhance the corrosion rate and reduce the inhibition performance of corrosion inhibitors. (C) 1999 Elsevier Science Ltd. All rights reserved.