Abstract
Elemental sulfur corrosion has become one of the most important risks during production in highly sour gas fields and one of the most complex corrosion issues due to the co-existing sulfur, H2S and CO2. According to the condition of downhole and surface system in sour gas field, the interactive effects of H2S and elemental sulfur on the corrosion behavior were investigated through corrosion simulation test and electrochemical measurements. The corrosion products were also studied by SEM and XRD methods. The results show the corrosion rate of X65 increased with the H2S concentration at 90 °C in S-H2O-H2S system, but it is lower than that in S-H2O under the same condition. The corrosion products are mainly composed of mackinawite and pyrrhotite crystals, and S element content decreases from outside to inside of the corrosion product film. Electrochemical measurements shows that trace H2S restrict the corrosion effect of element sulfur while higher content of H2S promote the corrosion reaction.