Erosion-corrosion is a severe problem in oil and gas producing wells due to high flow velocity and sand particles entrained in the system. Using corrosion inhibitors to reduce erosion-corrosion has recently been proposed as an economically viable solution for carbon steel piping systems [1]. In the literature, most studies using inhibitors to mitigate corrosion have been conducted under stagnant or low flow rate (<1 m/s) conditions. However severe erosion-corrosion may occur when inhibitor films are removed from the steel by high liquid shear forces under actual oil and gas production conditions.

The inhibiting effect of a commercial inhibitor (named inhibitor A [2]) on the behaviour of carbon steel in CO2 saturated media has been examined under high flow velocity with sand by electrochemical and gravimetric measurements. Experiments were performed using a Rotating Cylinder Electrode (RCE). The AC impedance technique was used to study the effect of inhibitor adsorption onto the metal surface. The study clearly reveals the fact that the addition of the inhibitor moves the corrosion potential towards positive values and reduces the corrosion rate. Changes in impedance parameters (Rct and Cdl) are indicative of adsorption of inhibitor on the metal surface leading to the formation of protective films.

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