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