We quantify the evolution of the CO2 plume during the injection process. We use TKRISK to model the displacement of original fluids (brine, hydrocarbon) in the geological formation with injected CO2. We are able to quickly build a simple radial flow model of the injection process and propagate key uncertainties (average porosity, injection rate as an example) to model the radius of the CO2 plume as a function of time. This example shows how one can build a graph based model of a transient variable using time as a deterministic input.