Performance Variation Of Polymer Solution By Near - Well Site And Its Effect On Oil Displacement Efficiency

As the fast development of polymer flooding technology, the orientation of polymer flooding is high temperature, high salinity and high oil viscosity reservoirs. Before entering bottom hole and arriving at formation of interest in the reservoir, the polymer solution have to undergo a series of high-speed shearing in immediate vicinity of wellbore.For high permeability strata conditions in bohai, these links are composed of wire wrapped screen, gravel packing zone, perf, skin and near wellbore undisturbed formation. During this process, high-speed shearing can produce strenuous influence on apparent viscosity, viscoelasticity, microstructure of polymer solution, and seepage characteristics.It is more important to study the performance of polymer solution through near wellbore and their impact on the performance of flooding. It can be known from the mechanism of the polymer flooding, injecting the polymer can control flow ratio, to expand the sweep efficiency, and improve the efficiency of microscopic oil displacement. All or one of the performance of polymer solution is studied by mechanism in privious study, it is showed that apparent viscosity, viscoelastic, resistance factor and residual resistance factor have great influence on displacement efficiency by lots of theoretical and experimental research, therefore this several performance are studied as key performance indicators in this paper.According to the actual conditions of Bohai SZ36-1oilfield, with near wellbore simulator to shear the polymer solution, the determination of the main properties of the polymer solution in shear before and after change. the result show the apparent viscosity solution decline drastically, in the condition of reservoir temperature, along with the shear strength increase, the stability of the apparent viscosity weaken; After the shear polymer solution viscoelastic get lower, solution before and after the shear can establish flow resistance in high-permeability porous media, but the resistance factor and residual resistance factor decreased; microscopic changes in the structure of the solution before and after the shear get significant. Also by the shear strength of the increase in near wellbore, have a research on dendritic polymer and HPAM solution apparent viscosity and residual resistance factor of the impact of flooding characteristics. With the intensification of the shear strength, the flow control ability of two polymer solution get weaken in the displacement process, polymer flooding volume reduce more, high penetration of heavy oil reservoirs in polymer flooding displacement effect Impact seriously, eventually lead to degradation of polymer flooding performance.Near wellbore shearing have great influence on oil displacement key performance indicators of dendritic polymer and HPAM solution, and it is compared with the field apparent viscosity, the results are basically identical. It is reasonable and meaningful using the model to evaluate oil displacement key performance indicators, and this is of reference significance to analyze polymer go into and flow status in the formation.