Influence of fluid flow in microbiological corrosion failures in oil field injector well tubing

Abstract

Several API J55 steel tubings failed due to localized corrosion, after a year in service in water injector wells at an oil field. Microscopy observations, chemical analyses and computational fluid dynamic (CFD) numerical simulations were performed to determine the degradation mechanisms. Sulfate-Reducing Bacteria (SRB) activated the localized corrosion mechanism: pitting corrosion and cracking. Numerical flow rate results at failure locations were compared with those obtained in laboratory by different researchers, showing a particularly good correlation. Corrosion rates by SRB were found to be particularly high beneath calcareous deposits in watertight areas between packers, where the punch is located, and when flow rates are less than 0.17 m/s. Unfortunately, avoiding fluid stagnation is not feasible; cathodic protection with sacrificial electrodes is most effective to prevent localized SRB-induced corrosion in the tubing.