Experimental Treatment Of Waste Fracturing Fluid From Oilfields By Oxidation-Coagulation-Filtration Process

As an effective technology,fracturing is widely adopted in every oil and gas field especially including ones with low pressure to improve oil/gas production.The speed of flowback during fracturing influences the damage of liquid invading when taking a fracture measure to a low permeability condensate reservoir.Waste fracturing liquid contain crude petroleum and underground water is considered to be a pollution source in oil and gas field,own to high volume,compositional complexity.Waste fluid will do a great damage without proper treatment,so oilfield fracturing fluid in-depth research is urgent to be carried out.This paper mainly researches on the waste fracturing liquid from a sump in an oil production plant of Daqing.Through the analysis on many pollutants on the waste fracturing fluid,it is determined crude oil,SS and organics are the main pollutants.According to the degradation of COD,treatment method combine with primary and advanced technology were carried out,and every method were optimized to the best experimental conditions in each processing.OCF treatment processes consist of sodium hypochlorite oxidation,bleaching powder oxidation and tempering,flocculating and settling,filtration.In the stage of sodium hypochlorite oxidation we adopt F2+ to enhance the antioxidant abilities.Cationic-type polyacrylamide is added in the process of flocculation.The COD removal rate of each stage is 25.79%?11.70%?24.93%,the total removal rate is 62.42%.Through the best process combination the outlet water is clear,pH value is ranging from 9.8 to 10.6,Chemical Oxygen Demand was reduced from 2245mg/L to 840 mg/L.