Understanding Inhibition of Sour Systems with Water Soluble Corrosion Inhibitors

Corrosion Inhibitors have been successfully applied in sour oil and gas systems for over 40 years. While working effectively, little is understood about their inhibitive mechanisms and their interaction with sour corrosion product layers. The nature of the inhibition process and the ability to reduce corrosion, in particular localized corrosion is yet to be established.
The existence of corrosion product layers and the ability of the corrosion inhibitor to interact with those layers determine the effectiveness of the inhibitor and its ability to prevent pitting. The performance of the inhibitor is determined not only by adsorption to the steel surface but by its ability to bind into the product layer providing protection and by changing the morphology of future scale growth.
Comparison of film persistency on bare steel surfaces and pre-corroded surfaces under differing corrosion environments was tested in high pressure autoclaves.  Corrosion rate analysis is conducted by weight loss, electrical impedance spectroscopy.  Scale analysis is conducted by SEM/EDX and XRD