Study On Oilfield Fracturing Backflow Liquid Treatment Based On Air Flotation-magnetic Separation Filtration

With the deepening of oilfield development,a large amount of waste liquid mainly from abandoned scattered mud,water for washing equipment testing during the drilling process and waste water generated by operations has been produced.The wastewater contains a large amount of sediment,oil substances,heavy metal pollutants and various chemical treatment agents.If these substances are not treated,Direct discharge will seriously damage surface water and crops,causing serious damage to the surrounding environment.At present,Daqing Oilfield is mainly transported by tanker to the curing pit plus curing agent for curing.The transportation of wastewater requires a special sewage transport vehicle.Once the transportation is not timely,it will have a serious impact on the local ecological environment.The exploration and development of Daqing Oilfield needs to be based on the idea of sustainable development,in order to achieve industrial upgrading,it is necessary to establish a mobile drilling operation waste liquid processing device with streamlined process,strong operability and low processing cost.Firstly,according to the water quality parameters of different waste liquids to be treated,the types of pesticides and dosages required for the treatment of returning and discharging liquid under different water quality are screened.Due to the large difference in water quality between the fracturing and returning liquids in various regions,an optimized combination of oxidizing agents,coagulants,and coagulants,and an amount of oxidizing agent and reaction time were tested.According to the experimental data analysis,it is finally determined that when the oil content is50-250mg/L and the suspended matter is 100-4000mg/L,the coagulant is selected from polyaluminum ferric chloride-S,the dosage is 1000mg/L,the coagulant is cationic polyacrylamide,the dosage is 5mg/L,the oxidant is potassium permanganate,and the reaction time is 20-40min.Secondly,by optimizing the design of the experimental scheme,the pre-oxidation dosing agent is further optimized,And the effect of viscosity on the performance of air flotation and magnetic separation treatment,the combination of the best treatment process is determined as a combination of quen ching and tempering-air flotation-magnetic separation.Make the effluent water quality reach oil content?20mg/L,suspended matter content?20mg/L,Satisfy Q/SYDQ0605-2006 standard for polymer-containing sewage high permeability layer.And establish the optimal integration technology of waste treatment equipment for on-board drilling operations.Finally,through the project research,the drilling operation fracturing and returning liquid can be processed to reach the re-injection standard,at the same time,it changed the mode of using the solidification method to treat the waste liquid in the drilling operation in Daqing Oilfield,it saves the solidification land and saves the cost of transportation waste,according to the annual processing of 300,000 m~3,the annual cost savings can reach 10 million yuan.