Abstract
In the present study, a comprehensive thermodynamic model, depicted by Pourbaix diagrams, has been developed with the relatively narrow focus on corrosion of mild steel in oil and gas field conditions. This thermodynamic model focuses on predicting the formation of metastable or stable corrosion products in sour environments at elevated temperature up to 250 0C, which includes mackinawite (FeS), greigite (Fe3S4), the pyrrhotite group (Fe1-xS, x = 0 to 0.17) and pyrite (FeS2). The model is based on theoretical thermodynamic calculations and data collection from open literature. As known, the appearance of Pourbaix diagram is significantly affected by temperature since thermodynamic properties are highly sensitive to temperature. Therefore, specific corrosion experiments at two different temperatures (25 0C and 80 0C) were designed to compare the predictions of corrosion products made by the Pourbaix diagrams to those formed during experiments. It was observed that the experimental results generally agreed with the predictions made by the Pourbaix diagrams.
