Corrosion of Steel Tank for Treatment of Oil-Water Transition Layer with ClO2-Oxidation Process

The separation of oil/water transition layer in settling tank becomes deterioration during the late oil production. For improving the dehydration of oil - water layer in settling tank, the oxidation technique by chlorine dioxide was adopted for the demulsification. Chlorine dioxide typically is strong oxidizing reagent. The touched materials would be corroded by the chemical. Therefore, it is necessary to evaluate the corrosion of chlorine dioxide for the steel in the settling tank. In this paper, the research was made to the determination of corrosion rate and corrosion morphology of steel equipped for oil/water transition layer treated with Chlorine dioxide oxidation. The experiments showed that, in the oil/water transition layer after treatment, water phase has the highest corrosion rate of up to 0.151 mm/a and lower than the company-formulated standard of 1.0 mm/a, which falls into the permission range (0.1-1.0 mm/a) of the corrosion standard Class 3. From steel-hanging corrosion morphology, it can be seen that the steel corrosion is weaker before the treatment while becoming stronger with the addition of ClO2 system and acidic solution. The reaction and mechanism were also explained on the corrosion chemistry of oil/water transition layer treated by oxidation process. With the experimental data, the oxidation and corrosion performance of chlorine dioxide can be controlled effectively to play an important role for stable production of oilfield.