| Aiming at the problem of oilfield injection water quality on-way deterioration, the Ninghai area injection water in Shengli oilfield was used in this paper as the object,and the microbiological corrosion condition was studied.The results showed that the injection water microbiological corrosion was an important reason for deterioration of water quality. On this basis, the control measures---bactericide, removal nutrition and biological competition of microbial corrosion were studied.Three methods---High temperature steam sterilization, centrifugal degerming and filtration sterilization are used to investigate different changes of corrosion extent in re-injected water caused by removing bacteria and contribution rate in water corrosion by microorganism in Ninghai area re-injected water. On one hand, the results show that high temperature steam sterilization can degerm all the germs, but at the same time it change water chemical property. Through centrifugal degerming, water chemical property remains the same, but germs could't completely been removed. By filtration sterilization, water chemical property under go no change meanwhile germs are completely removed. Besides, it can better reflect the role of microorganisms in corrosion. On the other hand, the research results indicated that microorganism is a leading factor in Ninghai area water corrosion by which the contribution rate is approximately 57% to 72%.Due to corrosion led to increased water suspended matter content, therefore, the study also confirmed that microbiological corrosion is the major reason of injection water quality on-way deterioration.The microbiological corrosion control measure of adding bactericide experimental results showed that the improved quaternary ammonium bactericide BC-12B was not only better than the traditional bactericide 1227, also the dosage was only 1/2 of the latter, besides it have certain corrosion inhibition, and could reduce the injection water corrosion rate of 73.3% on average. Therefore, choosing appropriate bactericide, microbiological corrosion could be well controlled within a period of time.Application domestication of activated sludge treatment of oil field wastewater, the treatment effect was well after optimization the processing parameters.The effluent water crude oil under 1.0 mg/L, COD value was 60 mg/L, and suspended solids content was 10 mg/L.Taking activated sludge biological treatment to reduce the COD content of the injection water to remove the related nutrition of bacteria required. This removal nutrition method could completely inhibit the activity of SRB and its content was not detected, TGB and FB content is almost 0.Therefore, its could effectively inhibit the microbiological corrosion, made the injection water average corrosion rate decrease 70% and suspended solids incremental reduction 74.8%. From engineering perspective, oilfield injection water after biological treatment, the dissolved oxygen and aerobic bacteria content keep high levels in water. So its corrosion was enhanced, unfavorable directly re-injected;by biochemical treatment--filter--oxygen removal treatment, the SRB and other bacteria in water could be removed completely,and the dissolved oxygen content was reduced greatly, effectively reducing the injection water corrosion, thus sharply reduce the injection water on-way deterioration.The denitrifying bacteria was activated effectively and its content increased 15,000/mL from140/mL by adding 50 mg/L of nitrate to oilfield injection water.Denitrifying bacteria could inhibit the sulfate-reducing bacteria well, and its content was not detected. Therefore, the biological competition methods of using denitrifying bacteria to inhibit sulfate-reducing bacteria have a good effect to reduce the microbiological corrosion and the suspended solids content increased .The method could reduce the injection water corrosion rate about 30%.
|
PDF Full Text Request