Effect of Muscat Oilfield Brine on the Stressed X-70 Pipeline Steel

© 2019 Elsevier Ltd Electrochemical and slow strain rate tensile tests were performed to understand the corrosion behaviour of X-70 pipeline steel in 3.5% NaCl and Muscat Oilfield brine. Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and Energy Dispersive X-ray spectroscopy (EDX) were used in the investigation. The results showed that the corrosion rate of X-70 pipeline steel significantly decreased in oilfield brine and increased in saline solution. In the oilfield environment, a fine and compact corrosion film of iron carbonate which reduced the corrosion rate was observed. It was concluded that the iron carbonate film which was formed provided protection and delayed the time to failure of the X-70 pipeline steel compared to the test performed in a 3.5% NaCl environment. This mechanism will be important not only to the petroleum industry but also to the pipeline manufacturing industry in the selection of appropriate material for steel pipe design.