Shallow or deep geothermal resources can be used to produce different energy services: district heating, electricity and cooling. The combined production of these services is done using conversion technologies, such as flash systems, binary cycles or heat pumps. In order to identify the optimal exploitation schemes of geothermal resources, the overall system, including the potential resources, the technologies and the demand profiles, has to be considered. The interactions within these three sub-systems have to be modelled and the decision variables have to be identified. Decision variables are the technological alternatives and their associated operating conditions, but also the different potential resources and their exploitation mode, which include not only the heat extraction, but also the heat injection and its seasonal storage. Energy integration techniques are used to integrate together the three subsystems of resources, technologies and demand. Multi-objective optimization is then performed to identify the optimal ranges of the decision variables, which allows for selecting which resources have to be used and how, with which technologies. Considered performance indicators are economical profitability, life-cycle environmental impacts, resource sustainability and thermodynamic efficiencies. The developed strategy includes the multi-period character of the demand and of the resource exploitation.