THE EFFECT OF SLUG ARRANGEMENT ON HPAM POLYMER INJECTIVITY AND RETENTION IN SANDSTONE

The flow of polymer solutions through porous media is an intriguing issue with applications in several fields. Polymer flooding is a well-established technique to enhance oil production from hydrocarbon reservoirs. The key idea behind this technique is to maintain a stable displacement front between the injected polymer solution and oil to improve sweep efficiency. However, the injectivity of the polymer solution into oil reservoirs faces several challenges, which might limit the use of polymer flooding. Therefore, assessing polymer injectivity is crucial for successfully implementing polymer flooding projects. This study investigated the effect of injecting polymer slugs in different sequences on polymer injectivity and retention in porous media. Two core flooding experiments were conducted utilizing synthetic hydrolyzed polyacrylamide (HPAM) polymer solutions of different concentrations, injected in different sequences into sandstone core samples. In the first experiment, four slugs were injected in descending order of polymer concentration at a constant injection rate. Following each slug, chase water was injected at varying injection rates. In the second, the four polymer slugs were injected in ascending order, and each was separated by chase water. The results demonstrate that the order in which the polymer slugs were injected significantly impacts polymer injectivity. Lower injectivity was observed when the polymer slugs were injected in a descending concentration order than in an ascending order. Furthermore, the sequence in which the polymer slugs were injected had minimal effects on the final permeability reduction of the porous media and polymer retention. Both experiments showed similar final permeabilities and polymer retention.