Stability and Reactivity of Iron Sulfide Passive Films in Sour Environments
Bilge Yildiz (Massachusetts Institute of Tec)
Engineering Mechanics and Materials in the Oilfield
Wed 10:45 - 12:15
CIT 227
Iron sulfide scales form on steels in the presence of H2S, notably in the extreme environments that exist in the oil and gas fields. They form a passivating surface layer that protects the structure from pitting and stress corrossion cracking. Our research aims to provide a quantitative, atomic-scale description of the growth mechanisms, barrier properties and stability of iron sulfide corrosion films in such aggressive conditions. This is necessary for enabling more accurate predictions of corrosion lifetimes for components used in the petroleum industry. We investigate the unit processes that govern the reactivity and stability of iron sulfide films using in situ surface sensitive probes, and electronic and atomic scale simulations. In this talk, I will present our quantitative assessment of the formation of sulfur vacancy sites on the surface, correlation of the electronic structure of defective surfaces with their chemical reactivity towards H2S and H2O, and the mechanisms by which hydrogen defects alter the mechanical stability of the critical iron sulfide films.