Corrosion of Advanced Steels: Challenges in the Oil and Gas Industry

Abstract

Drill pipe steels are in contact with CO₂ and H₂S environments, depending on the oil and gas field. These steels have to be resistant to various in-service conditions including aggressive environments containing CO₂, H₂S, O₂, and chlorides, in addition to static and dynamic mechanical stresses. In this respect stress corrosion cracking susceptibility of two grades of drill pipe steel in CO₂ environment have been studied simulating the bottom hole oil and gas well conditions. SSRT results show that SCC susceptibility or loss of ductility changes with temperature and increasing temperature increases the loss of ductility. No FeCO₃ is observed below 100 °C, and density of FeCO₃ is higher in grip section than gauge length and this is due to strain disturbance of growth of iron carbonate crystals. Material selection for down hole in CO₂ containing environments needs has been reviewed and probability of SCC occurrence in higher temperatures has been included.

In another critical application, during oil and gas operations, steel pipeline networks are subjected to different corrosion deterioration mechanisms, one of which is microbiologically influenced corrosion (MIC) that results from accelerated deterioration caused by different microbial activities present in hydrocarbon systems. Bacterial adhesion is a detrimental step in the MIC process. The tendency of a bacterium to adhere to the metal surface can be evaluated using thermodynamics approaches via interaction energies. Thermodynamic and surface energy approaches of bacterial adhesion will be reviewed. In addition, the subsequent physical-chemical interaction between the biofilm and substratum and its implication for MIC in pipeline systems will be discussed. Further, a new development of an advanced grade of cast austenitic stainless steel for application as drill collar will be highlighted.