Research On Biomanipulation Of Oil Field Effluent Containing Sulfate Reducing Bacteria

Since the Shengli Oil Field comes into a middle and late period, much more wastewater is produced. Organic matter rich in wastewater gave rise to a great quantity of corrosive microorganism such as sulfate reducing bacteria (SRB), which could bring serious material corrosion and environmental pollution. Common disposal method of control SRB of addition of chemical agent has faced a lot of problems. Biomanipulation by injection of denitrifying bacteria and nitrates become the focus of material and environment research on controlling of SRB.Analysis of waste water quality and microbial population show that the wastewater in Shengli Oil Field Hekou initial stateion contains a lot of SRB, is a typical sulfate reduction system; there is no nitrate or nitrite in the wastewater, as well as denitrifying bacteria. Static method and dynamic electrochemistry method are used to evaluate the effect and mechanism of biomanipulation on SRB by Thiobacillus denitrificans. It concluded that the addition of TD and inorganic activator can effectively control local corrosion caused by SRB, improve the system oxido-reduce electric potential. Reduced form inorganic sulphide and nitrate were used as energy, which finally converted to sulphur, oxygen compounds of sulphur(SO₃^2-,SO₄^2-)and nitrogen. The lowest feeding amount was confirmed to be 30ml/L in wastewater with 20 mg/L sulphide content, and the corrosion rate can drop to 0.018mm/a. The experiment results of the formulated chemical agent of inhibitor, bactericide and TD biostat shows that the inhibitor and bactericide had no effect on the growth of TD in certain concentration; the addition of the formulated chemical agent can reduce the corrosion rate in blank to 28.6% and reach to 0.016mm/a; the amount of bacteria can be controlled under 10 per milliliter.The oilfield sewage treated by TD biological can keep the viscosity of HPAM solution. The results showed that when the content of TD biological agent was 10ml/ L 60ml/ L, there was little difference on the viscosity of HPAM solution prepared by oilfield clean water and diluted by diluents. The HPAM solution prepared by oilfield wastewater treated by biomanipulation can keep viscosity for a long time at the hermetic stage. Therefore, raising oil recovery and highly reducing the clean water dosage used for diluting the polymer solution. We also put forward a special injection method by separately add concentrated cell and concentrated activator which proved to be effective.