Study On Advanced Treatment Of Polymer-Flooding Produced Water And Control Of Viscosity Loss Of Preparing Polymer Solution

Polymer flooding technology has become an important measure to improve the recovery rate of crude oil in the high water cut stage of oil field,and to ensure the continuous and stable production of oil field.Polymer flooding is refers to the injection water with polyacrylamide,to increase the viscosity and water retention time,caused by permeability decreased so as to improve the mobility ratio between oil and water,adjust the water injection profile,improve the actual spread coefficient method to improve oil recovery.However,due to the influence of mechanical shearing,water quality and microorganism,the polymer solution will cause a certain degree of loss of polymer solution,which will affect the effect of polymer flooding.Therefore,how to keep the viscosity of polymer solution in the course of preparation,transportation and injection of polymer solution is an important support to ensure the effect of polymer solution flooding.In the polymer hybrid injection process,namely polymer solution and dilution water static mixer was prepared by mixing polymer to liquid and injection wells to process factors on viscosity of polymer solution is diluted water,flow regulator(a pump wells flow),static mixer and injection pipe.In order to improve the viscosity of polymer solution in mixed injection system,this paper studies the main influencing factors.First of all,in order to reduce the cost and improve the utilization rate of resources,for the recovery of dilution water,sewage treatment and reuse after polymer flooding,studied the high polymer bearing oily wastewater treatment technology to improve the quality of dilution water depth;secondly,in order to reduce the polymer solution in the configuration and transportation process by mechanical shear stress caused by the viscosity loss of the development and application of research and development and application of low shear static mixer and low shear liquid flow regulator;finally,studied the microbial viscosity loss inhibitor development pipeline and application and so on.In this paper,the process of “dissolved gas purification ? dissolved gas biological purification ?biological enhanced treatment ? solid-liquid separation”.When the processing capacity reaches 3000 m3/d,the residence time is about 21.6 h.In this experiment,the oil content of solid-liquid separation is 5.2 mg/L,the suspended matter content is about 9.6 mg/L,and the median particle size is about 1.2 ?m.When the solid-liquid separation is used,the oil content of effluent is 0.4 mg/L,and the content of suspended matter is about 3.4 mg/L,and the suspended particle size is about 1.2 ?m.The water quality is significantly better than that of 5mg/L oil content,the content of suspended matter is lower than 5 mg/L,and the median particle size is less than 2 mg/L,which is the standard of advanced treatment of wastewater quality.In addition,the treatment process can significantly reduce the COD in wastewater(COD),the concentration of ammonia,sulfide and other pollutants,improve water quality toreduce the viscosity loss of polymer,which can fully satisfy the requirements of polymer flooding diluted water.In polymer injection system,the viscosity loss rate caused by static mixer is more than8%,which is one of the main causes of polymer viscosity loss.This paper analyzed the conventional static mixer mechanism,clear the root cause of the mixing uniformity of low viscosity,high loss rate,and based on the design and development of the spiral type low shear static mixer.Parallel multi spiral mixing unit using mixed medium radial separation and convective fluid flow around and through the action of centrifugal force,the method compared with the conventional static force mergesplit mixing way has advantages of higher mixing uniformity,lower shear rate.The practical application indicates that the average polymer viscosity loss caused by static mixer low shear rate was 3.06%,the average unmixedness is 5.06%,the conventional static mixer respectively than SX and SK mixed units decreased by 3.64% and 4.78%.The viscosity loss of polymer which is caused by the liquid flow regulation was 5%,is also an important link of the viscosity loss of polymer.Based on the advantages and disadvantages of this paper in-depth analysis of the characteristics of non Newtonian fluid of polymer mother liquor and conventional liquid flow regulator,design a spindle rod low shear liquor flow regulator,and the flow regulator internal distribution simulation.By adjusting the viscosity loss rate performance and field test of low shear flow regulator solution were evaluated.The results showed the average low shear viscosity loss of polymer mother liquor liquor flow regulator in 2.49%,with the same conditions of the conventional Venturi liquor flow regulator decreased by 2.04%.Different from the above two caused by the mechanical action of viscosity loss is in the pipeline,widespread sulfate reducing bacteria,the corrosion of pipes produced with iron and sulfide,but also one of the reasons causing the viscosity loss of polymer solution.In this study,through the competition of nitrate reducing bacteria(NBR)and sulfate reducing bacteria(SRB),NRB was used to inhibit the growth of SRB through substrate competition.In this study,the nitrate reducing bacteria Alccligenes sp.JNS05 was screened from the oil field wastewater,and the inhibition effect on sulfate reducing bacteria was verified.After the strain was expanded,the culture fluid was injected into the oil field polymer injection system.The results showed that the growth and metabolism of nitrate reducing bacteria JNS05 can effectively inhibit the sulfate reducing bacteria,harmless SRB.The JNS05 medium is injected into the oil polymer injection pipeline,can effectively reduce the sulfide injection well and total iron content.It can significantly improve the injection viscosity of injection well and reduce the viscosity loss of polymer by more than 10%.The polymer solution has a longer retention time,and the pipeline viscosity is more serious,and the inhibition effect of nitrate reducing bacteria is more significant.To sum up,in order to improve the viscosity of polymer solution in mixed injection system,this paper studies the influence factors of viscosity loss.By improving water quality of dilution water,reduce the mechanical effect of injection process,injection pipe of microbial inhibition viscosity associated with the loss of a series of tests,reduce the viscosity loss ofpolymer formed in all aspects of injection process,and achieved significant results,with great potential.