Corrosion investigation of J55 steel under simulated enhanced oil recovery conditions using CO_2 flooding

摘要

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 55℃ and greatly decreased with the effect of inhibitor especially when the imidazoline based inhibitor exceeds 150 ppm, σ Fe concentration increased with the increase in temperature, especially when temperature exceeded 44℃. The H_2CO_3 concentration declines by about 3 orders of magnitude compared to CO_2(aq) concentration and the yielded HCO_3~- concentration is about 0.2-0.35 times of the H_2CO_3 concentration.