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 re-injection water sterilizing. When the ClO2 dosage was 3.0 mg/L, the bacteria remains can meet the standards, and then raise the dosage up to 5.0mg/L, the sterilization rates 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 degrees C, and reach to 90% when the pH is within 7 similar to 9. Comparing with the static steel content measurements in the water before and after treatment, 1g/L ClO2 can make the corrosion rate lower than the standard and the lowest corrosion rate is 0.036mm/a when ClO2 dosage is 4mg/L.