Glass cell experiments were conducted to investigate kinetics of iron sulfide and mixed iron sulfide/carbonate scale precipitation in CO2/H2S corrosion. Weight gain/loss (WGL) method was used to investigate the scale formation using X65 carbon steel as substrates. Scanning Electron Microscopy (SEM/EDS), X-ray Diffraction methodology (XRD), X-ray Photoelectron Spectroscopy (XPS), and Electron Probe Micro-analyzer (EPMA) were used to analyse the scale. The experimental results show that the corrosion products formed in CO2/H2S system depend on the competitiveness of iron carbonate and mackinawite. At high H2S concentration and low Fe2+ concentration, mackinawite was the predominant scale formed on the steel surface. At low H2S concentration and high Fe2+ concentration, both iron carbonate and mackinawite form. It was also found that ferrous ions forming mackinawite scale mainly come from Fe2+ released from the steel surface.

Subject
Steel surfaces, Precipitation (solids), Iron sulfide films, Hydrogen concentration, Corrosion rate, Iron sulfides, Carbon steel surfaces, Corrosion scales, Sulfide concentration, Film formation, Iron carbonate scale, Scale formation, Scale
Keywords:
kinetics, iron sulfide, iron carbonate, scale, precipitation, CO2/H2S corrosion
Government work published by the Association for Materials Protection and Performance (AMPP) with permission of the author(s). Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2006
GOV
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