Residual Analysis Assay for Thiol-Based Volatile Corrosion Inhibitor Quantification in Top-of-Line Corrosion Environments

Carbon dioxide (CO2) Top of Line Corrosion (TLC) poses a significant problem in oil and gas fields, resulting in both economic losses and health and safety issues. The use of conventional corrosion inhibitors does not typically ensure effective protection against this particular type of corrosion, limiting the working lifetime of carbon steel pipelines. The main chemistry of inhibitors used for such application relies on volatile chemicals that can be transported through the vapor phase to reach the top of the pipeline. Studies have shown that alkanethiol compounds may form self-assembled monolayers in acid environments with good efficiency in mitigating steel corrosion. Recently, long chain thiols (> C6) have been investigated as potential volatile corrosion inhibitors (VCIs), demonstrating good efficiency. This work seeks to evaluate the efficiency, mechanism and bulk-vapor partitioning behavior of volatile thiol corrosion inhibitors through the implementation of a biochemical technique which targets sulphydryl groups, coupled with a miniature electrode configuration for real time, in situ electrochemical TLC measurements. The proposed assay results in a rapid, cost effective screening technique that can monitor thiol-based chemistries that are partitioned in the condensate. The implementation of these methods enables the performance and mechanisms of volatile inhibitors to be better characterized and understood, shedding new light on their behavior, whilst also facilitating more effective optimization of their dose rate.