Enhanced oil recovery (EOR) techniques have become increasingly important in the oil industry to boost oil production from mature reservoirs. Many oil fields in Oman, including the eastern half of the South Oman basin and the major brown oil field in the eastern portion of the South Oman Salt basin, have undergone polymer flooding as an EOR technique. However, the use of polymers in harsh environments with high temperatures and salinity is limited, and the effectiveness of polymer flooding can be hindered by poor injectivity, poor sweep efficiency, and gravity override. To address these challenges, a comprehensive EOR screening study was endorsed by the Petroleum Development Oman company in 2007.This study evaluated a new aqueous polymeric nanofluid to see how effectively it performed when exposed to different temperatures, salinities, and aging times in order to improve the performance of chemical EOR. The polymer used in the study was HPAM (Hydrolyzed Polyacrylamide) with a viscosity of 1000 cp and a molecular weight of 18 MD. The primary objective was to test the stability of polymeric nanofluids at high temperatures, specifically 75°C, and salinity of 16000 ppm, which are considered rare conditions in the South Oman region. Different characterization techniques were employed to evaluate the performance of the polymeric nanofluid, including dispersion and suspension of nanomaterial. The investigation results from various tests conducted showed that the polymeric nanoparticles improved the physicochemical properties of the polymer chain in harsh conditions, allowing for further stability of the polymeric solution. The initial screening tests revealed that the nanoparticles acted as a flow diversion method in the tested reservoir. Seven core plugs were subjected to core flooding recovery tests, and it was observed that injecting nanoparticles using chase water with an optimized slug size resulted in incremental oil gain. The study revealed that the optimized polymeric nanoparticle injection increased the recovery factor from 8% to 17%.These findings suggest that the use of polymeric nanofluids could be a promising approach to enhance oil recovery in harsh environments with high temperatures and salinity, such as those encountered in the South Oman region. By addressing the limitations of polymer flooding and improving the performance of chemical EOR, the utilization of polymeric nanofluids offers potential for maximizing oil production in mature reservoirs.