西南石油大学学报(自然科学版)

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Corrosion Perforation of CaCl2 Produced Water to Bottom Plate of
Crude Oil Storage Tank

Liu Yucheng, Zhang Yinlong, Liao Sicheng, Xu Junzhong   

  1. College of Chemistry & Chemical Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,China
  • Online:2014-10-01 Published:2014-10-01

Abstract:

An analysis of process and influening factors in Tuha oilfield was made,aiming to solve the problems in oil production
and safety issues caused by perforation leakage on tank bottom. After exposing coupons in the storage tank for 120 days,
corrosion rate of weight loss was calculated. Scanning electron microscope(SEM)was employed to observe the microscopic
corrosion morphology of coupons,and the composition of water and steel at the bottom of the storage tank were analyzed.
The corrosion process was researched through electrochemical method and the influence of Ca2+ and Cl− on corrosion rate was
tested. The results show that the irregular pitting corrosion appears on the surface of coupons hung at the bottom of the storage
tank. The corrosion rate of weight loss is 0.22 mm/a and the corrosion rate tested by electrochemical method is 0.15 mm/a. The
instantaneous corrosion rate presents a trend of gradual increase. Repetitive passivation and solubility of surface film occurs
on carbon steel. Ca2+ and Cl− will accelerate corrosion in water solution in oil tank bottom. The research lays a foundation for
analyzing and solving leakage of tank bottom.

Key words: storage tank, bottom plate, corrosion perforation, CaCl2, electrochemical analysis