Geological storage of CO2 in deep saline aquifers is considered as option for reducing anthropogenic greenhouse gas emissions into the atmosphere. Most often the same aquifers might allow for provision of geothermal energy potentially resulting in a competitive situation. Within the frame of the present study we evaluated the feasibility of synergetic utilisation of a reservoir suitable for both, CO2 storage and geothermal heat exploitation, by 3D numerical simulations of simultaneous CO2 and brine (re-) injection and brine production. Based on structural and petrophysical data from a prospective storage site in the North East German Basin different scenarios were investigated taking into account reservoir permeability anisotropy and varying flow related descriptions of existing faults. Simulation results show that for an isotropic horizontal permeability distribution synergetic use is feasible for at least 30 years. Nevertheless, permeability anisotropy and open faults do have an impact on the CO2 arrival time at the brine production well and should be taken into account for implementation of a synergetic utilisation in the study area.