CO2 storage in geological formation, especially in deep aquifers, is considered as a compromising technology to reduce the impact of CO2 on the greenhouse effect. Practically, large-volume of CO2 could be injected at a high rate into a system which consists of a highly porous host aquifer covered by a very low permeable sealing caprock. The caprock may undergo significant deformation and geomechanical instabilities, such as caprock failure and fault reactivation. In addition, the temperature of the injected CO2 is often lower than the in-situ temperature, providing an additional degree of complexity to the system. The interaction between temperature, fluid flow and mechanical reaction of geomaterials gives rise to a complexly coupled system. It is crucial to understand such thermo-hydro-mechanical processes in order to secure the injection. We investigate the geomechanical effects induced by CO2 injection on the aquifer and the related interactions with the caprock. The proposed simulator incorporates real physical properties of supercritical CO2 and elastic behaviour of involved geomaterials. A conceptual storage system is modelled to investigate the state of caprock deformation during the injection of CO2, accounting changes in most influential thermo-hydro-mechanic properties. We benchmark the In-Salah CO2 storage surface uplift measurement with the proposed model. A good agreement has been found between the measurement and the simulation. The failure risk of the aquifer are also assessed and the analysis indicates that both caprock and aquifer are subjected to high shear failure potential.