EFFECT OF CORROSION INHIBITOR ACTIVE COMPONENTS ON CORROSION INHIBITION IN A SWEET ENVIRONMENT

摘要

In sweet corrosion, corrosion scales such as iron carbonate are formed on the internal surfaces of oil and gas production and transport systems. Depending on the type of corrosion inhibition program and the age of production system before chemical treatment is implemented, the presence of corrosion scale could affect the performance of the inhibitor. Previous work completed by the authors' company investigated the interaction of iron carbonate and three inhibitor actives - quaternary amine, imidazoline, and phosphate ester. This study is a continuation and examines two more generic compounds: quaternary amine dimer and alkyl pyridine quaternary amine. Linear Polarization Resistance (LPR), Electrochemical Impedance Spectroscopy (EIS) were used to measure corrosion rates and to monitor the active-scale interaction. Scanning Electron Microscopy (SEM) was used to observe the morphology of the iron scale layer.The second part of this paper explores aggregate formation for several generic inhibitor actives. Most actives are surfactants which form micelles above the Critical Micelle Concentrations (CMC). In theory, maximum inhibition should be observed around the CMC since additional surfactant molecules lead to the formation of micelles and do not contribute to inhibition. This concept is discussed and the relationship between surfactant concentration, adsorption and inhibition is analyzed.