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Previous issue date: 2009-04-27 === Petr?leo Brasileiro SA - PETROBRAS === The gas injection has become the most important IOR process in the United States. Furthermore, the year 2006 marks the first time the gas injection IOR production has surpassed that of steam injection. In Brazil, the installation of a petrochemical complex in the Northeast of Brazil (Bahia State) offers opportunities for the injection of gases in the fields located in the Rec?ncavo Basin. Field-scale gas injection applications have almost always been associated with design and operational difficulties. The mobility ratio, which controls the volumetric sweep, between the injected gas and displaced oil bank in gas processes, is typically unfavorable due to the relatively low viscosity of the injected gas. Furthermore, the difference between their densities results in severe gravity segregation of fluids in the reservoirs, consequently leading to poor control in the volumetric sweep. Nowadays, from the above applications of gas injection, the WAG process is most popular. However, in attempting to solve the mobility problems, the WAG process gives rise to other problems associated with increased water saturation in the reservoir including diminished gas injectivity and increased competition to the flow of oil. The low field performance of WAG floods with oil recoveries in the range of 5-10% is a clear indication of these problems. In order to find na effective alternative to WAG, the Gas Assisted Gravity Drainage (GAGD) was developed. This process is designed to take advantage of gravity force to allow vertical segregation between the injected CO2 and reservoir crude oil due to their density difference. This process consists of placing horizontal producers near the bottom of the pay zone and injecting g?s through existing vertical wells in field. Homogeneous models were used in this work which can be extrapolated to commercial application for fields located in the Northeast of Brazil. The simulations were performed in a CMG simulator, the STARS 2007.11, where some parameters and their interactions were analyzed. The results have shown that the CO2 injection in GAGD process increased significantly the rate and the final recovery of oil === A inje??o de g?s tem sido o m?todo de recupera??o mais utilizado nos Estados Unidos e o ano de 2006 marca a primeira vez em que a produ??o proveniente dos processos de inje??o de g?s superou os de inje??o de vapor. No Brasil, a instala??o do complexo petroqu?mico, no estado da Bahia, oferece oportunidades para inje??o de g?s na Bacia do Rec?ncavo. As aplica??es de inje??o de g?s em campo foram quase sempre associadas com dificuldades operacionais e de projetos. A raz?o de mobilidade, que controla a varredura volum?trica, entre o g?s injetado e o banco de ?leo deslocado, ? tipicamente desfavor?vel devido ? baixa viscosidade do g?s. Al?m de que a diferen?a entre as densidades conduz a segrega??o gravitacional severa dos fluidos no reservat?rio e consequentemente, levando a um pobre controle na varredura volum?trica. Atualmente, grande parte dos projetos de inje??o de g?s no mundo ? do tipo WAG. Entretanto, na tentativa de resolver os problemas de mobilidade, o processo WAG causa outros problemas como o aumento na satura??o de ?gua no reservat?rio, incluindo a diminui??o na injetividade do g?s e aumento da competi??o no fluxo do ?leo. O baixo desempenho na recupera??o de ?leo deste processo no campo, na ordem de 5 a 10%, ? uma clara indica??o destes problemas. A fim de encontrar uma alternativa eficaz para o WAG, o processo de drenagem gravitacional assistida por inje??o de g?s (GAGD) foi desenvolvido. O processo GAGD ? projetado para tomar vantagem da for?a gravitacional causando assim, a segrega??o vertical entre o CO2 injetado e a reserva de ?leo devido ? diferen?a de densidades. Este processo consiste na coloca??o de po?os produtores horizontais pr?ximos a parte inferior da zona de ?leo e inje??o de g?s atrav?s de po?os verticais existentes em campo. Modelos homog?neos foram utilizados neste trabalho os quais podem ser extrapolados para aplica??o comercial em campos localizados no nordeste brasileiro. As simula??es foram realizadas no simulador da CMG STARS 2007.11, sendo analisados alguns par?metros e suas intera??es. Os resultados mostraram que a inje??o de CO2 no processo GAGD aumentou significativamente a vaz?o e a recupera??o final de ?leo
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