Although a phase of energy transition is taking place in the world, with high growth in interest and consumption of renewable energies, oil is still the world's leading energy matrix. In Brazil, oil accounts for almost half of the available energy supply, which makes clear the importance of the oil industry in the country. National oil and gas production has had a significant increase in the last 21 years and this was mainly due to the production of Brazilian Pre-salt. Due to the great potential of pre-salt production, Brazil is today one of the protagonists in the production of oil and gas in the offshore environment. A relevant characteristic of the oil produced in this province is the high concentration of carbon dioxide (CO₂) in its composition and this motivated the injection of this gas in reservoirs of some fields, such as Lapa. In this field the method of water alternating gas injection (WAG) is already used in order to prevent the emission of CO₂ into the atmosphere as well as to facilitate the arrival of oil in producing wells. An alternative and innovative method to WAG injection that has been studied is polymer alternating gas injection (PAG). In this context, this work aimed to apply the PAG injection in a reservoir with pre-salt characteristics through numerical simulation, as well as the comparison of the results between the PAG and WAG injections. To simulate the methods in question, the GEM simulator from CMG (Computer Modeling Group) was used. The parameters to be used for PAG injection were obtained by analyzing the results of continuous CO₂ flooding and continuous polymer flooding separately. Then the injections PAG and WAG were also simulated and their results compared. By observing the results obtained, the PAG injection was technically better than the WAG injection, increasing accumulated oil production by 8.54% over a 10-year injection interval, by 11.10% over a 4-year injection interval and 10.18% for a 2-year injection interval.