In this research, a petroleum field (Field-A) having approximately 23.2 API gravity oil in a carbonate formation from southeast Turkey was studied. Field-A was put on production in 1989 and produced till now, which is very close to its economic lifetime. Thus, it was considered as a candidate for enhanced oil recovery and water injection. Reservoir rock and fluid data were first interpreted with available well logging, core, and drill stem test data. The data were then merged into CMG/STARS simulator. A history matching study was done with production data to verify the results of the simulator with field data. After obtaining a good match, the different scenarios were realized by using the simulator.