Design And Optimization Analysis Of Viscosity Reduction-Coalescence Device Of Polymer-Flooding Produced Liquid

Polymer flooding technology is widely used in major oil fields with high water content due to its advantages of easy operation,low cost and readily available raw materials.However,the addition of polymers increases the viscosity of the aqueous phase,resulting in increased viscosity of the produced fluid and exacerbating the oil-water emulsification phenomenon.Emulsified oil droplets in polymer-flooding produced fluids have strong stability,which is unfavorable for subsequent oil-water separation.Therefore,it is urgent to reduce the viscosity of the polymer-flooding produced fluid.However,the degree of oil-water emulsification in the produced fluid after viscosity reduction is high.Spiral flow aggregation treatment of the polymer-flooding produced fluid after viscosity reduction can alleviate the degree of oil-water emulsification.The study of viscosity reduction and aggregation treatment of polymer-flooding produced fluids is of great significance for the development of polymer flooding technology in oil fields and the subsequent efficient separation of oil and water.An orthogonal experimental design method was used to optimize the structure of a viscosity-reducing device for non-Newtonian fluids through numerical simulation,and a single-factor analysis was conducted to further investigate the main influencing factors of the structural parameters.The optimal design had a flow area of 400 mm~2,a pressure drop of0.011MPa and reduced the viscosity from 4.35m Pa·s to 2.181m Pa·s.For the coalescence device,a population balance model was used to optimize the structure through single-factor analysis and orthogonal experimental design,identifying the significant structural factors and their influence order on droplet coalescence.The optimal design achieved a coalescence rate of 17.82,which improved by 15.8%compared to the initial structure and reduced the pressure drop to0.0133MPa.The structural optimization of the viscosity-reducing and coalescence device provides valuable insights for efficient oil-water separation in extraction processes.The viscosity characteristics of a viscosity-reducing device were analyzed using a Malvern rheometer.The study found that the viscosity reduction effect improved with an increasing number of shear layers.The experimental values and simulated values were in good agreement for polymer concentrations ranging from 200 to 500mg/L and the viscosity increased gradually with an increasing polymer concentration.The degree of oil-water emulsification in the viscosity-reducing device was measured using a Malvern particle size analyzer and it was found that the oil droplets were severely broken at the outlet of the device.Under a 4%oil concentration,the large-sized oil droplets were almost completely broken down into smaller-sized ones,which was used as the basis for setting the coalescence inlet parameters.These findings provide valuable insights for the optimization of the structure and operation of viscosity-reducing and coalescence devices for efficient oil-water separation.The coalescence performance of a composite device was analyzed in terms of flow field characteristics such as velocity,oil droplet size,pressure drop and coalescence rate.The study found that a higher processing capacity led to a higher tangential velocity inside the coalescence unit,which was conducive to the central aggregation of oil droplets.Particle size measurement experiments at varying oil concentrations showed that the experimental values were generally lower than the simulated values due to measurement errors.However,the simulation and experimental results were consistent,with both showing that the coalescence rate decreased first and then increased with an increasing oil concentration.The optimal coalescence performance was achieved at an oil concentration of 1%,validating the coalescence performance of the composite device and the reliability of the simulation.These findings provide useful insights for the optimization of the structure and operation of composite devices for efficient oil-water separation.