Method to Study Transportability of Corrosion Inhibitors in Liquid Hydrocarbon Pipelines

Abstract Application of water-soluble (WS) continuous corrosion inhibitors in the upstream oil and gas industry has mostly been successful in systems that contain high water fraction (> 50% water are common). High water fraction facilitates physical transport of the WS inhibitor to the entire system to provide protection. In contrast to high water cut pipelines, performance of WS inhibitors in low water midstream oil pipelines (< 1% v/v water) tends to be less successful. This lack of reliable performance is due to the inability of the oil to successfully transport the WS inhibitor to all the locations where free water may be present. It also explains poor performance of WS inhibitors in pipelines where water nucleation occurs. In comparison, oil soluble (OS) inhibitors solve the transportability issue by homogeneously blending with the hydrocarbon to successfully contact all steel surfaces (AMPP-2024-21214) and partitioning to the microscopic water nucleated therein (AMPP-2024-21232). While these processes are intuitively appreciated, there has not been a practical way to evaluate an inhibitor's transportability characteristic. This paper proposes a method based on simple laboratory procedures to evaluate the combined effect of hydrocarbon partitioning and transportability to determine the efficacy of residual inhibitor present in a hydrocarbon matrix.