An experimental study on retention characteristics under two-phase flow considering oil saturation in polymer flooding

Abstract

This study presents experimental results on polymer retention under two-phase flow considering oil saturation. To analyze polymer retention in porous media, core flooding experiments were conducted using unconsolidated cores without clay minerals. From the results, the presence of oil in cores showed an increase in the polymer retention values (from approximately 17 to 25μg/g). Parametric experiments were performed to investigate the retention characteristics by varying the polymer concentration and injection rate. When the polymer concentration was increased from 500 to 2000ppm, the polymer retention values increased owing to interference between the polymer molecular chains; however, the delay factor decreased from 0.184 to 0.135. This indicates that the slug size of the polymer affects the delay factor because more additional polymer volume could be required when a lower concentration of polymer is used. Owing to the hydrodynamic force, the delay factor was increased by more than ten times when the polymer injection rate was increased. This implies that increasing the polymer slug size should be considered for maintaining the sweep efficiency in polymer flooding. Therefore, polymer injection rate is a more sensitive parameter than polymer concentration for designing the injection conditions in polymer flooding.