Geological Carbon Storage (GCS) consists in injecting CO2 into geological formations with the aim of storing it there for several hundreds of years and longer to reduce the amount of CO2 emitted in the atmosphere and to mitigate or slow down climate changes. This paper proposes to study a synthetic deep saline aquifer located in Qatar and the seismic response induced by a CO2 injection. We will describe the static geological model and the dynamic flow inside this model we used. The high-resolution model has been upscaled to reach a reasonable size for the fluid flow model. Then the methodology used to generate the seismic data is explained. A petro-elastic model has been used to transform the simulation model (pressure, saturation) into a synthetic seismic, which then allowed us to see the seismic response to the CO2 injection. The results appear to be dominate by the pressure build-up due to injection.