Understanding the Corrosion Inhibitor Partitioning in Oil and Gas Pipelines

Abstract

Abstract The use of corrosion inhibition has been a common practice in industry to protect oil and gas pipelines made of carbon steel and exposed to wet hydrocarbons containing CO2 and H2S. It is however important to emphasize that the inhibitor efficiency is highly dependent on its capability to be present in the water phase and reach the pipe wall. Therefore, for a given corrosion inhibitor injection rate, there is a need to quantify the amounts of the active components present in the water and the oil phases as well as any loss to the solid surfaces, particularly to scale and corrosion products or sand if present. This paper focuses on the use of an in-house developed laboratory method to quantify the partitioning of the corrosion inhibitor between the oil, water and solid phases and evaluate its performance as such. The partitioning of the inhibitor is evaluated using a modified standard LPR (Linear Polarization Resistance) corrosion test, followed by an analysis of the corrosion inhibitor residuals in the various phases using an LC-MS (Liquid Chromatography-Mass Spectroscopy) analytical method (Blumer and Johlman, 2008). The major active components of the inhibitor are traced using such analysis. The paper presents an illustration of the testing method and the obtained results.