Sterilization of Oil-Field Re-injection Water by Chlorine Dioxide

Corrosion and plugging caused by sulfate reducting bacteria, total growth bacteria and iron bacteria in the reinjection water is very severe. The sterilization efficiencies of chlorine dioxide on the three kinds of bacteria above were studied in varies conditions. The results prove that ClO₂ is suitable to apply in the oil rejection water sterilizing. When the dosage was 3.0 mg/L, the bacteria remains can meet the standards, then raise the dosage up to 5.0 mg/L, the sterilization can reach or very close to 100%. Higher sterilization rates can be obtained at longer reaction time. The residue of bacterial can reach the standards just at 10 min. The influence of temperature and pH value was slightly, the best sterilization rate can be gotten at 60°C, and reach to 90% when the pH is within 7~9. Comparing with the static steel content measurements in the water before and after treatment, 1 mg/L ClO₂ can make the corrosion rate lower than the standard and the lowest corrosion rate is 0.036 mm/a when ClO₂ dosage is 4 mg/L.