Injection of CO₂ into the subsurface for geological storage has an effect on the temperature of the storage formation and the CO₂ itself. Numerical investigations are an essential tool in describing the relevant processes that determine such changes and the impact they may have on the migration and the storage mechanisms of CO₂ in the subsurface.

This chapter focuses on the numerical simulation of such thermal effects and their consequences. Simulating the temperature changes in a storage site can be of interest for temperature-based monitoring. Determining whether or how such thermal effects change the transport of CO₂ in the formation is important for the success of a CO₂ storage effort. In particular, this chapter examines a leakage scenario and how temperature changes could affect the leakage flow.

The second part of the chapter presents results of a complex reservoir-scale simulation. The target formation forms an anticlinal structure at a depth of about 570–900 m (1870–2953 ft). Strong temperature effects can be expected because of the possible transition of the CO₂ from a high-density supercritical to a low-density gaseous state at the given depths.