A Novel Method to Mitigate Top-of-the-Line Corrosion in Wet Gas Pipelines: Part I—Proof of Concept

Conventional injection methods for delivery of corrosion inhibitors in wet gas pipelines are incapable of providing consistent inhibitor coverage for the entire inside pipe wall, if the flow dynamics are not favorable. Such limitation becomes particularly crucial where Top of the Line Corrosion (TLC) is an issue due to water condensation at the 12 o’clock position, in particular in presence of volatile organic acids. Currently the most common inhibitor delivery methods rely on periodic pigging or batch treatment to control TLC. Such methods can be expensive and at times unavailable.   
A novel idea is to inject the corrosion inhibitor within a foam matrix.  The foam slug is formed and carried along the pipeline by the produced gas, therefore contacting the whole circumference of the pipe along a given distance. The foam can be broken before the separation stage using a de-foamer, if it does not naturally break. This process ensures homogeneous delivery of the inhibitor to the pipe wall along pipe sections suffering from TLC. This technique does not interrupt production and can potentially be more cost effective than the classical methods of treating TLC using pigging or batch inhibition. This paper addresses the chemistry work relating to screening various foaming agents and corrosion inhibitors for compatibility issues and foam stability criteria. A laboratory prototype apparatus of the foam formation and application is described and corrosion data is presented as a proof of concept of the new method.
 

Key words: TLC, foam, inhibitor, gas pipeline: TLC, foam, inhibitor, gas pipeline: TLC, foam, inhibitor, gas pipeline