The objective of this thesis is to support a preliminary project for the reconversion of decommissioned offshore platforms by conducting Computational Fluid Dynamic (CFD) simulations for risk analysis. The focus of the project is to repurpose an oil platform into a carbon dioxide injection station for storage purposes, using Carbon Capture and Storage (CCS) technologies. However, due to the changes in platform layout and the presence of another hazardous substance, the previously conducted risk analyses for hydrocarbon extraction are no longer applicable. The primary focus of this thesis is to perform numerical modeling simulations of potential incidental scenarios related to the CO2 release that can occur on board the platform.