[en] After having recalled the objective of CO₂ geological storage, and the different forms of storage and perspectives in France, this report summarizes theoretical elements related to the evolution of a storage in time. It presents the different stages of storage lifetime, from the regional synthesis to the evolution on the long term, with the associated operational and administrative milestones. Then, the reports details the storage components: geological objects, well, surface installation, injected fluid. It determines the limitations of a storage complex. It defines five safety functions for a storage: to ensure the confinement of the injected fluid within a specified part, to foresee a massive or diffuse gas release at the soil surface or at its vicinity and susceptible to affect workers and public health, to prevent a displacement of dissolved fluids and substances which may have undesirable effects of the ecosystem or resources (notably drinking water), to limit mechanical, hydraulic and chemical disturbances brought to geological formations at the regional scale. A third part presents the safety management principles for a CO₂ storage which depend on characteristics of the chosen site. Safety is based on an iterative approach which is itself based on the return on experience. Risk analysis is based on numerical simulation. Safety principles are then applied to the different stages of storage lifetime. Recommendations are then made on guiding principles and technical arrangements regarding geological characteristics, the quality of the injected CO₂, the maximum pressure, wells, and control systems.

[en] This set of 10 detailed scientific documents notably reports geological studies performed within the framework of the Clastiq and Clastiq 2 programmes which aimed at assessing the geothermal resource of deep clayey-sandstone reservoirs of the French metropolitan territory within an energy perspective of heat production and, if possible, electric power production (low to medium temperature geothermal in sedimentary basins), and at assessing problems of re-injection in clayey-sandstone aquifers (based on successful or failed experiences in Europe and in France). Some specific regions are considered: the Upper Rhine Plain, the Paris Basin, the Bresse basin