CO2 in atmosphere levels can be reduced by sequestering it directly to the underground. High amounts of CO2 can be safely stored in underground media for very long time periods. Storage in depleted gas reservoirs provides an option for sequestering CO2. CO2 sequestration in Kuzey Marmara field has been considered in this study as an alternative to the gas storage projects. The reservoir still contains producible natural gas. Four scenarios were prepared by considering this fact with variations in the regional field properties and implemented into a previously built simulation model. Reservoir porosity and permeability maps were prepared and merged with Kuzey Marmara production information to create an input file for a computer modeling group-full equation of state compositional reservoir simulator (CMG-GEM) simulator, and a three-dimensional model of the reservoir was created. After analyzing the results from the scenarios it is realized that CO2 injection can be applied to increase natural gas recovery of Kuzey Marmara field but sequestering high rate CO2 emissions is found to be inappropriate.