Effect of Sand Production and Flow Velocity on Corrosion Inhibition Under Scale Forming Conditions

Erosion, corrosion, and the combined effects of erosion-corrosion result in complex and costly problems encountered during oil and gas production. Since the current trend is to drill deeper wells in more corrosive environments, the importance of mitigating corrosion and erosion-corrosion is rapidly increasing. In some CO₂ corrosion environments, an iron carbonate (FeCO₃) scale can form that provides significant corrosion protection. Also, chemical inhibition has proven to be effective in controlling corrosion in many environments. In spite of this, sand production can reduce or eliminate the protection offered by iron carbonate scales or inhibition. In this work, corrosion rates are examined for scale-forming conditions in a flow loop circulating CO₂-saturated brine and sand. Results, obtained with and without a chemical corrosion inhibitor, were compared to evaluate the role of pre-existing iron carbonate scales in inhibitor effectiveness. Tests were conducted under highly erosive conditions in a flow loop with an impinging jet flow velocity of 42 ft/s. The material tested was AISI 1018 carbon steel and the inhibitor used was a water soluble, oil dispersible, amidoamine fatty acid. Metal loss rates were evaluated using weight loss and linear polarization resistance (LPR).