Evaluation Of Adsorption Performance Of Filter Materials And Optimization Of Its Grading Model For Pfpw Filtration Process

In the treatment of oilfield produced water,the polymer flooding produced water(PFPW)generated by carrying polymer oil-displacing agent components is a major factor affecting the efficient operation of the surface system.This oil-displacing agent is comprised of a high molecular polymer called polyacrylamide,which greatly deepens the complexity of water quality,and continuously affects and forms a series of problems such as equipment corrosion,environmental damage,operation instability and reinjection water quality reduction.Especially in the fact of the current situation of the precious clean water resources and large-scale produced waste water due to the high water-cut stage of the oil field,the problems and contradictions are further highlighted in this treatment process.Therefore,it is of great scientific significance and engineering application value to improve and optimize the PFPW treatment technology and improve the efficiency of PFPW treatment.In this paper,focusing on the two-stage filtration process of PFPW,the adsorption performance of different filter materials for PFPW filtration was evaluated founded on the characteristics of suspended particle distribution,treatment effect and pressure field through numerical simulation and laboratory experiments.At the same time,the influence of the grading mode of filling filter materials in the filter tank on the filtration and backwashing process of PFPW was studied,and finally the high-efficiency PFPW filtration process mode was optimized It provides theoretical support for increasing the filtration efficiency of PFPW.The results indicate that the filter material with small particle size,large specific surface area,obvious angularity and more surface micropores represented by magnetite have stronger adsorption and filtration effects for suspended particles in PFPW,while the filter material with large particle size and small specific surface area filter material represented by quartz sand has lower adsorption effect,but it has strong pollutant carrying capacity,which can alleviate the increase of filtration pressure difference and the impact of secondary pollution on the quality of filtered water to a certain extent.For the graded filtering mode,the filtering with the thickness of magnetite filter material layer greater than that of quartz sand filter material layer can obtain a more stable pressure field and the flow field,and have better filtering ability for small particle size suspended particles.For PFPW filtration with polymer concentration less than 300 mg/L,it is recommended to select the two-stage double-layer graded filtration mode with the filling height ratio of 1.67 to 2.20.The removal rate of suspended solids and oil can be controlled above 76%and 79%respectively.The corresponding optimized backwash intensity is 15 L/(s·m~2)to 20 L/(s·m~2)and backwash time is 15 minutes.For PFPW filtration with polymer concentration higher than 300 mg/L,it is recommended to select the two-stage double-layer graded filtration mode with the filling height ratio of 1.28 to 1.67.The removal rate of suspended solids and oil can be controlled above 75%respectively.The corresponding optimized backwash intensity is 15 L/(s·m~2)and backwash time is 17 minutes to 20 minutes.At the same time,based on the simulation result data,the relative chart of the operation the technical limit of the Graded media filtration and backwash process suitable for PFPW with different concentration of polymer is constructed.