Nitrogen Containing Organic Compounds as Corrosion Inhibitors of Mild Steel Corrosion in Oilfield Acids

Abstract

Abstract The paper describes results of a preliminary laboratory study on corrosion protection of mild steel in 15% HCl and 3% HF used in acidization of oilwell by some N-containing organic compounds. Inhibition efficiencies were evaluated by metal loss and potentiostatic polarisation methods. The corrosion rate of mild steel decreased appreciably even in the presence of traces of the compounds. The extent of decrease in the corrosion rate was found to depend on the nature of the inhibitor and its concentration. Results of testing the additives in preventing corrosion of mild steel by the acid solution at different temperatures (30 to70°C) and exposure times (6h to 36h) at a fixed inhibitor concentration are also reported here. Thermodynamic parameters like heat of adsorption and activation energies have been calculated in the absence and presence of these organic additives. The nature of the film formed on the metal surface was analysed by infrared (IR) spectrum and relationship between structure of the organic compounds and inhibition effeciency has been explained.