Corrosion mechanism for water injection system of Chengdao Offshore Oilfield

Key words:  Chengdao Oilfield  water injection  corrosion mechanism  electrochemistry  seawater

Abstract:

Standard test method for weight loss and electrochemical methods were used to investigate the corrosion of metal in water injection system of Chengdao Offshore Oilfield. The results show that the corrosion rate of coupon is parabolic shape against time and it comes to its maximum at 50-60 X.. Besides, the corrosion rate increases with the soluble oxygen content increasing. The water samples are well water, produced water, sea water in discending order of corrosion rate of coupon. The corrosion processing in three water samples is mainly dependent on the negative electrode. The corrosion of coupon in seawater is uniform corrosion, while pitting corrosion happens in well water and produced water. In addition, the corrosion rate of coupon in produced water is smaller than that of well water- The water re-injection system with good compatibility can reduce the corrosion rate of coupon to a certain extent.