Corrosion at Higher H2S Concentrations and Moderate Temperatures

Abstract

Abstract During the past decade, a number of research facilities have conducted investigations of H2S corrosion under conditions that have produced mackinawite as the corrosion product. Field experience with oilfield equipment has frequently found the corrosion product to be pyrrhotite under conditions that appear similar to these laboratory studies. A review of publications that were able to produce pyrrhotite revealed that pH, temperature and the length of exposure all appear to play a role in the development of the FeS corrosion product. In longer term exposures, there also appears to be a multi-stage film growth mechanism where mackinawite forms first and then ruptures. Following film rupture, a second stage of FeS film growth occurs and it is during this second phase where several forms of FeS can form, depending upon pH, temperature and mass transfer characteristics of the system.