Study On Flocculation Treatment Of Oily Wastewater Produced From Different Forms Of Displacement Oilfield

At present, polymer flooding technology has been implemented in many major oilfields in our country. However, a new type of wastewater produced with the injection of polymer solution, which is called poly-containing wastewater. At the same time, ASP flooding is popularized in part of the oil fields, so it produced another new oily wastewater, which is called ASP flooding wastewater. It is a problem to many large-scale fields that how to treat the poly-containing and ASP flooding wastewater by an effective and low-cost method. The flocculation treatment of different flocculants on wastewater of laboratory simulated water flooding, polymer flooding as well as ASP flooding was studied in this thesis, and conducted a comparative study among the three, so as to provide valuable reference on effectively treating the polymer flooding and ASP flooding wastewater which were difficult to deal.Three conventional flocculants were used to treat the simulated water flooding wastewater in this thesis. Coagulant treatment of water flooding wastewater achieve the best value of 99.2% when the flocculation temperature was 37℃and the dosage was 600 mg/L. Single coagulant-aid's treatment were not good, so it couldn't apply to the simulated water flooding wasterwater. Combinating coagulant and coagulant-aid 1, when the dosage of coagulant was 500mg/L, the dosage of coagulant-aid was 150mg/L and the flocculation temperature was 33℃, the light transmission can achieve 99.1%. Combinating coagulant and coagulant-aid 2, when the dosage of coagulant was 500mg/L, the dosage of coagulant-aid was 125mg/L and the flocculation temperature was 33℃, the light transmission can achieve 98.4%.Single coagulant's treatment of the simulated polymer flooding, when the dosage was 720mg/L and the flocculation temperature was 33℃, the light transmission can achieve 97.0%. For coagulant-aid 2, when the dosage was 120mg/L and the flocculation temperature was 30℃, the light transmission can achieve 81.5%. Combinating coagulant and coagulant-aid 2, when the dosage of coagulant was600mg/L, the dosage of coagulant-aid was 7mg/L and the flocculation temperature was 37℃, the light transmission can achieve 98.3%.Coagulant treatment of the simulated ASP flooding wastewater, when the dosage was 1080mg/L and the flocculation temperature was 33℃, the light transmission can achieve 87.9%. For coagulant-aid 2, when the dosage was 140mg/L and the flocculation temperature was 37℃, the light transmission can achieve86.7%. Combinating coagulant and coagulant-aid 1, when the dosage of coagulant was 880mg/L, the dosage of coagulant-aid was 80mg/L and the flocculation temperature was 37℃, the light transmission can achieve89.0%. Combinating coagulant and coagulant-aid 2, when the dosage of coagulant was 900mg/L, the dosage of coagulant-aid was10mg/L and the flocculation temperature was 37℃, the light transmission can achieve 87.5%.Only one of the three flocculants treatment of the simulated ASP flooding wastewater, the light transmission can not achieve 80.0%. Combinating coagulant and coagulant-aid 1, when the dosage of coagulant was 880mg/L, the dosage of coagulant-aid was80mg/L and the flocculation temperature was 37℃, the light transmission can achieve 88.0%. Combinating coagulant and coagulant-aid 2, when the dosage of coagulant was 900mg/L, the dosage of coagulant-aid was10mg/L and the flocculation temperature was 37℃, the light transmission can achieve 88.9%.Comparing of the treatment effect of the single-dose and combination flocculants to simulated oil field, the results were water flooding and polymer flooding better and ASP flooding was less effective. It can be seen that it is difficult to handle the ASP flooding produced wastewater with conventional water treatment agent, so it required further development of a new efficient flocculant.