Crude Oil Chemistry Effects on Inhibition of Corrosion and Phase Wetting

The effect of crude oil chemistry on corrosion processes is poorly understood. A simple mechanistic model that takes into account the combined effects of corrosion inhibition and wettability alteration, due to the adsorption of polar molecules onto the steel surface, is proposed. While the inhibition effect is dominant in oil-water stratified flow, the wettability alteration is dominant in turbulent flow. Consequently, both effects have to be taken into consideration in order to predict corrosion in oil-water pipe flow. The objective of this study is to identify chemicals present in crude oil which have an effect on inhibition and wettability. The likeliest molecules to adsorb onto a metal surface are polar compounds. Nine polar compounds containing nitrogen, sulfur and oxygen have been studied. Corrosion rates were recorded, the change of the steel wettability has been quantified and the mass adsorbed onto the metal surface measured with a quartz-crystal-microbalance. Results show that certain groups of chemicals have strongly inhibitive effect on corrosion and wettability while others had only a negligible effect.