During the operation of a geological carbon storage project, verifying that the CO2 plume remains within the permitted zone will be of particular interest both to regulators and to operators. We demonstrate a model selection algorithm that refines an initial suite of subsurface models representing the prior uncertainty to create a posterior set of subsurface models that reflect injection performance consistent with that observed. Such posterior models can be used to represent uncertainty in the future migration of the CO2 plume. Because only injection data is required, the method provides a very inexpensive method to map the migration of the plume and the associated uncertainty in migration paths. We illustrate the method using a field data set.