Utilization of CO2 for enhanced oil recovery (EOR) and sequestration processes not only reduces greenhouse emissions, but also awards economic benefits. Enhancing oil recovery using sequestration is an optimization process that requires careful analysis. In CO2 EOR, the main purpose is to maximize oil recovery using the minimum quantity of CO2 while at the same time, sequestering the maximum amount of CO2 in the field. The Kartaltepe Field, having 32 degrees API gravity oil in a carbonate formation, in southeast Turkey has been considered in this study. Reservoir rock and fluid data were evaluated and merged into CMG's STARS simulator. A history matching study was done with production data to verify the results of the simulator with field data. From the results of the simulation runs, it was realized that CO2 injection can be applied to increase oil recovery, but sequestering high amounts of CO2 was found out to be inappropriate for the Kartaltepe Field. Therefore, it was decided to focus on oil recovery while CO2 was sequestered within the reservoir. Oil recovery was about 23% of OOIP for the field in 2006. It reached 43% of OOIP by injecting CO2 after properly defining production and injection scenarios.