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Residual Analysis Assay For Thiol-Based VCI Quantification In Top-Of-Line Corrosion Environments

Residual Analysis Assay For Thiol-Based VCI Quantification In Top-Of-Line Corrosion Environments
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Top of line corrosion (TLC) is a degradation mechanism predominantly encountered in the oil and gas industry. Initiation of TLC requires a stratified flow regime with wet gas transportation and the existence of a significant temperature gradient between the hot fluid inside the pipeline and the colder external environment.1,2,3 This temperature difference results in the condensation of water vapor, present in the gas phase, onto the cooler, upper internal section of the pipeline. The condensed water can be particularly aggressive as it lacks dissolved salts (e.g. bicarbonates), some of which are able to buffer the bulk electrolyte, increasing the pH and suppressing corrosivity.4,5,6 The absence of such salts typically results in a very low pH condensate (<pH 4), often containing dissolved acidic gases, such as carbon dioxide (CO2) and hydrogen sulfide (H2S), and also acetic acid (HAc), which can cause severe degradation, particularly in the form of localized corrosion.5 

Product Number: 51322-17918-SG
Author: Mariana Costa Folena, José Antônio da Cunha Ponciano Gomes, Hanan Alshareef Farhat, Iain Manfield, Joshua Owen, Anne Neville, Richard Barker
Publication Date: 2022
Industry: Coatings
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$20.00
$20.00

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. 

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. 

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Picture for Dual Functional Corrosion Inhibitor Design And Testing For Top-Of-Line And Bottom Of Line Corrosion
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Dual Functional Corrosion Inhibitor Design And Testing For Top-Of-Line And Bottom Of Line Corrosion

Product Number: 51322-17787-SG
Author: Larry Chen, Nihal Obeyesekere, Jonathan Wylde, Michael Sim
Publication Date: 2022
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TOL corrosion is reported to occur in large diameter wet gas pipeline in stratified flow conditions
due to low fluid velocities1. With increasing distance from the inlet, the wet gas pipeline becomes
cooler as it loses heat to the environment. Such cooling causes water, hydrocarbon, and other
high vapor pressure species to condense on the pipe wall. The upper part of the pipe will
constantly be supplied with freshly condensed water while the less corrosive water saturated
with corrosion products will be drained along the pipe wall to the bottom of the line.
Picture for Prediction And Mitigation Of Top Of Line Corrosion Risk Due To Damages In External Pipeline Coating
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Prediction And Mitigation Of Top Of Line Corrosion Risk Due To Damages In External Pipeline Coating

Product Number: 51321-16789-SG
Author: Marc Singer, Nick Bardsley, Julie Morgan, Stuart Kegg, Adam Darwin, Peter Cossins, Anthony Kwong, Jason Biddlecombe, Jo Yetman, Joe Bullen
Publication Date: 2021
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A visual inspection of a subsea field development, transporting wet gas, containing approximately 1.5 to 2 mol% of CO2 to shore, was conducted via ROV (remotely operated vehicle). The pipeline system is largely carbon steel with only short lengths of CRA (corrosion resistant alloy) piping from the wellhead to the production/pigging manifold. Downstream of the pigging manifold the system has 20” carbon steel spools leading to the FTA (flowline termination assembly) and then 20” carbon steel flowlines to the riser platform.
Picture for Top-of-Line Corrosion Inhibiton and Proposal of an Inhibition Mechanism
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51318-11117-Top-of-Line Corrosion Inhibiton and Proposal of an Inhibition Mechanism

Product Number: 51318-11117-SG
Author: Alyn Jenkins / Ian Gilbert / Aiman Kamaruzaman / Astrid Lone
Publication Date: 2018
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The work carried out to develop test methods suitable for assessing inhibitor performance in controlling TOL corrosion. New corrosion inhibitors have been developed that effectively mitigate TOL corrosion.
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