The Bactericidal Effect Of Chlorine Dioxide In The Oilfield Injection Water Treatment And Engineering Application

Water injection for oil exploitation is adopted widely in the petroleum exploitation in our country, and it needs a great deal of water every year. However, Corrosion and plugging caused by the microorganism in the injection water is very severe. The effective medicaments have been popularly studied and applied to the oil injection water for reducing the issues.The sterilization and anticorrosion in the rejection water from Zaoyi injection station in Dagang oil field was thoroughly studied, where chlorine dioxide medicament was applied. And then full-large test was completed successfully. A new method of determination ClO2 in the water is also provided, in which the fading agent is the AGB.This study show that using AGB to determinate ClO2 is simple and effective; it requires fewer drugs, but the color is stability, and the result is sensitive, rapid, accurate and precision, with good anti-jamming capability. In addition, the sterilization efficiencies of chlorine dioxide for sulphate reducing bacteria, heterotrophic bacteria and iron bacteria were studied in varies conditions. The results prove that ClO2 is suitable to apply in the oil rejection water to sterilize. When the dosage was 3.0 mg/L, the bacteria sterilization rates was fulfilled; when the dosage was 5.0mg/L, the Sterilization can reach or very close to 100%. The longer reaction time, the higher the rate of sterilization and only 10 min after the reaction, the residue of bacterial can meet the standards. Temperature and pH value influence reaction slightly, the best sterilization rate could be gotten at 60℃, and reached to 90% when the pH is within 7⁹. Fe^2-and S^2- could also be easily removed by ClO2, so that the corrosion of the pipeline has been significantly reduced.The field experiment indicated that the bacterial growth could be inhibited when the ClO2 dosage is 3.0mg/L, and the bacteria in the pipeline can be kill sustained with the dosage of 5.0mg/L. The corrosion of the pipeline was also improved because the perfect removal of Fe^2-and S^2-. Economic analysis shows that the annual cost savings could be 492,000 Yuan if ClO2 is applied in sterilization, which represents good economic benefits.