Can the Viscoelasticity of HPAM Polymer Solution Make the Polymer Flooding Compete with Gel Treatment to Improve Sweep Efficiency? A Comparison with Different Polymer Gel Systems

Improving sweep efficiency from heterogenous reservoirs necessitates the injection of gel treatment and/or polymer solution to lower the degree of heterogeneity and to lower the mobility ratio, respectively. In this study, three gel systems were compared with partially hydrolyzed polyacrylamide (HPAM) solution. The purpose of this study was to show the ability of the viscoelastic properties of the HPAM to enhance the sweep efficiency compared to the selected gel systems. The model was one quarter of five- spot pattern with one injector and one producer. The injection rate was 525 bbl/day. The selected simulator to run the scenarios was UTGEL, while the selected gel systems were colloidal dispersion gel (CDG), polymer/chromium chloride gel, and polymer/chromium malonate gel. Two polymer concentrations (0.1 and 0.15 wt. %) were used and three salinities were considered (5000, 10,000, and 20,000 mg/l). This study showed interesting results regarding the ability of the viscoelastic properties of the HPAM polymer solution to yield recovery factors close or similar to those recovery factors obtained from the selected polymer gel systems. The results also revealed that lowering the salinity of post-treatment water could boost the performance of the polymer solution and make the polymer flooding more effective than gel systems. The results also showed that regardless the duration of injecting the polymer gel system, the HPAM polymer solution still yielded promising results, particularly if low-salinity water was implemented after the treatment.