Corrosion inhibitor studies in large flow loop at high temperature and high pressure

Abstract

The performance of an imidazoline based inhibitor for carbon steel in a large diameter flow loop system with saltwater–oil two-phase flow under 90°C and 300 psi was studied by electrochemical impedance spectrum technique. It is found that the corrosion resistance is increased when the inhibitor is added in the solution. Experimental results show that the Warburg impedance coefficient, σ, and the charge transfer resistance, R t, increase with increase in exposure time until 8 h and then become stable. It is suggested that, before 8 h, the inhibitor film becomes more compact at longer exposure time. After 8 h, a stable inhibitor film is reached. From this work, it is also found that the values of σ and R t measured in the solution containing 100 ppm inhibitor is not significantly different from those in the solution containing 50 ppm. This fact implies that increase in inhibitor concentration from 50 to 100 ppm does not give a good performance of inhibitor and a high corrosion resistance.