Residual chemical analysis of amines used as corrosion inhibitors

Main problem: Presence of acidic chemicals such as carbon dioxide and hydrogen sulphide, composition of production fluids triggers corrosion. Corrosion in oil and gas industry leads to deterioration of equipment since most of equipment is made of metal alloys. Application of inhibitors is one of the corrosion mitigation methods that needs to be controlled because it is important to identify optimal concentration of the chemicals in production fluids.Residual chemical analysis plays an important rolein identifying the appropriate dosage of corrosion inhibitors and its correction. It is imperative to find the most optimal concentration of amines due to the fact that both overdose and underdose could lead to equipment deterioration. The chemical analysis is hindered by complexity of mixtures that are applied in petroleum industry. Purpose: The main purpose of this article is to find out the most effective method of residual chemical analysis for inhibitors used against sweet and sour corrosion by studying and analyzing corresponding literature review. The analysis should be carried out with robust, sensitive, and accurate instrumentation. Methods :Theoretical study of composition and mechanism of amines used in oil and gas industry as corrosion inhibitors and selection of appropriate instrumental analytical techniques for the residual analysis. Results and their importance: After careful studying and consideration of modern instrumental analytical techniques the most optimal and efficient method in terms of robustness, time saving and cost was selected. Ion chromatography is an adequate method to carry out residual chemical analysis for amines that are used as inhibitors in oil and gas industry to prevent sweet and sour corrosion.

Long-Term Sour Corrosion of Carbon Steel in Anoxic Conditions

Coatings and cathodic protection of pipelines can fail leading to exposure of underlying steel substrate to environmental conditions. In Canada, these conditions are typically alkaline and can contain dissolved sulfides. Sulfides are known to accelerate corrosion of steel, however, the corrosion behavior may differ if a preformed oxide or oxyhydroxide is present on the steel surface. This study investigates the change in corrosion behavior of steel in anoxic alkaline conditions that is directly exposed to sulfide or has a preformed surface oxide. The electrochemical response (corrosion potential and polarization resistance) were monitored for 90 d and 120 d, while simultaneously monitoring the film composition and morphology by Raman spectroscopy and scanning electron microscopy, respectively. In the absence of a preformed oxide the mackinawite film was able to undergo anoxic aging to greigite and pyrite whereas the electrodes with a preformed film had only mackinawite present on the surface. The interconversion of mackinawite to greigite and pyrite lead to a higher relative polarization resistance than the electrode with the preformed oxide.