The influence of temperature and flow rate on the characterization and mechanisms of corrosion product layers from CO 2 corrosion of 13Cr stainless steel was carried out in simulated oilfield solution. Cyclic potentiodynamic polarization method as well as weight loss tests in autoclave were utilized to investigate pitting corrosion behavior at various temperatures. Weight loss tests were performed at 100 and 160°C under dynamic and static flow conditions. At the same time, the significant pitting parameters such as E corr , E pit , E pp , DE, and I pass in cyclic polarization curves at various temperatures were analyzed and compared for revealing the pitting behavior of 13Cr stainless steel. The surface measurement techniques such as SEM, XRD, and XPS were used to detect the corrosion product layers. The results showed that both temperature and flow rate had significant effects on characterization of corrosion product layers or passive films formed on 13Cr stainless steel in CO 2 corrosion system. At high temperature, lots of pits were formed at the localized corrosion areas of metal surfaces. Corrosion rates under the condition of 5 m/s were higher than those under the static condition regardless of the test temperatures.

The present work investigated corrosion behaviour of J55 tubing steels and solution equilibrium chemistry of the produced water under simulated CO 2 flooding environments at various temperatures. The corrosion rates were calculated by weight loss method carried out with or without one kind of imidazoline based inhibitor in autoclave. Surface morphologies of corrosion product films formed on samples were analysed using scanning electron microscopy (SEM). Meanwhile, the concentrations of main solution species in experimental produced water were tested. The solution equilibrium chemistry of dissolved CO 2 in the produced water was also calculated and analysed. The results indicated that corrosion rate of J55 significantly increased when temperature exceeded 55uC and greatly decreased with the effect of inhibitor especially when the imidazoline based inhibitor exceeds 150 ppm, s Fe concentration increased with the increase in temperature, especially when temperature exceeded 44uC. The H 2 CO 3 concentration declines by about 3 orders of magnitude compared to CO 2 (aq) concentration and the yielded HCO 32 concentration is about 0?2-0?35 times of the H 2 CO 3 concentration.