Abstract

Due to the surfactant properties of inhibitors, the effect of hydrocarbons on the inhibition process and inhibitor performance is a topic of interest from both an operations and a testing perspective.

Many aspects related to the presence of hydrocarbons affect corrosion itself as well as inhibition; some are often investigated when inhibitors are qualified. Certain components of crudes can be corrosive while others may have inhibiting properties; partitioning of inhibitors between the immiscible aqueous and hydrocarbon phases as well as emulsion formation is important to be reckoned with.

Among various issues with quite negative connotation with respect to water-oil-inhibitor systems, the potential beneficial effect hydrocarbons can display as synergists to inhibitors should not be overlooked. Experimental data shows that hydrocarbons can significantly improve inhibitor performance. This effect is especially important at high temperatures when even efficient inhibition may fail to reduce the corrosion rate to acceptable levels.

This paper presents results obtained in a Joint Industry Project aimed at studying corrosion inhibition at high temperatures in general and the effect of oil in particular. The results show that a model oil with no intrinsic inhibiting qualities can contribute to nearly an order of magnitude reduction in corrosion rate as compared to inhibitor alone. This was a consistent finding in several experiments performed in a jet impingement apparatus at temperatures up to 150 0C using 1% (vol.) oil. Corrosion rates lower than 0.1 mm/y were possible to achieve even at the highest temperature.

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