Development of a Model for Mitigated Corrosion - A Mathematical Model for Evaluation of Upstream Oil and Gas Field Applications that Include Mitigation by Corrosion Inhibition

摘要

Over the past decades, several corrosion prediction models have been developed for Upstream Oil and Gas process conditions. These models provide the unmitigated corrosion rates in typical sweet or sour conditions. However, the practice of field operations is typically based on the mitigated corrosion rate. Therefore, the predicted unmitigated corrosion rates cannot directly be used to understand real-life situation unless the effect of mitigation is effectively considered. Currently, the mitigated corrosion rate is typically quantified via a very simplified method (e.g. corrosion inhibitor availability). Corrosion prediction is designed to look forward and, ideally, should also be part of corrosion and asset integrity management. For this purpose, a robust analysis of the mitigation practices and methods is essential. This paper provides an overview of aspects to be considered when predicting mitigated corrosion rate for the case of continuous corrosion inhibitor (CI) injection as the mitigation barrier. It is proposed to use a combination of models to calculate the mitigated corrosion rate in a practical and reliable way. It is recognized that partitioning of the Cl among different phases is a key aspect in relation to the field application of inhibitors. Therefore, guidance is provided to incorporate this as part of the corrosion mitigation and its prediction.