A great deal of effort has been expended in the last decade to model carbon dioxide (CO2) sequestration processes. Data on a variety of scales and understanding of a number of processes is necessary in order to develop a consistent understanding of the important mechanisms of CO2 transport and reactivity with the aim of understanding the long-term fate of CO2 in underground formations. The reactions are often described using equilibrium models, which may or may not be relevant on the time scale of the simulation. In the first part of this paper, we evaluate the various equilibrium and kinetic models used and their implication on the ultimate fate of CO2. It has often been observed in natural CO2 reservoirs that the type of mineralogical changes observed in the laboratory or predicted in models are only partially seen in the field. The reasons for this and possible model modifications necessary to adjust for these phenomena are discussed next. Impact of the mineralogical changes on injectivity are discussed next. The transport and of CO2 in the reservoir depends on reservoir properties, on rock-fluid interactions (capillary pressures and relative permeabilities), and on the interactions of CO2 with the fluid (brine) and the rock. We take a comprehensive look at all these effects together in light of our findings on reactivity and injectivity. These findings are examined in the context of the validation data available on CO2 injections on a variry of scales.