Modellkonzepte zur Optimierung und Risikominimierung der Untergrundnutzung im Kontext der Energieversorgung
The natural subsurface is already utilised in many ways and is gaining in importance for a variety of engineering applications related to energy supply. On the one hand, the subsurface with its groundwater system represents the most important and usually the cleanest source of drinking water, on the other hand, it contains natural resources such as petroleum, natural gas and coal. In addition, it can serve as a short-, medium- or long-term storage medium for energy in various forms and even as a temporary or final disposal site for waste or natural substances. Among these latter uses of the subsurface are the storage of energy, e.g. in the form of methane (CH4), as well as the permanent storage of carbon dioxide (CO2) for climate protection. The subsurface is also attracting increasing interest as a natural source of energy. Keywords in this connection are, for instance, the extraction of fossil methane by hydraulic fracturing or the utilisation of geothermal energy as a renewable energy source. In recent years, the Department of Hydromechanics and Modelling of Hydrosystems (LH2) has participated intensively in research on CO2 storage, with several projects funded mostly in the framework of the BMBF/DFG special R&D programme GEOTECHNOLOGIEN (www.geotechnologien.de). The focus of these projects at LH2 was initially on the development of modelling concepts for simulating multiphase flow that can reproduce the - sometimes high - complexity of the underlying processes. The mathematical and numerical representation of thermodynamic processes such as density and viscosity changes dependent on temperature, pressure and concentration etc. are essential, as is the description of solubility and mutual miscibility in a multiphase-multicomponent system. Since 2008, these approaches have been implemented within the software package DuMuX (TODO: LINK ZU www.dumux.org). The application of the model concepts mentioned above is of great importance with respect to feasibility, risk, storage capacity and sensitivity issues. The work at LH2 on these topics also includes the description of large-scale, complex geometries and their cross-linkage with powerful and efficient mesh generators. In the meantime, the range of our research work has broadened to include the investigation of applications such as hydraulic fracturing and the chemical storage of energy in the subsurface, e.g in the form of methane. For this purpose, the conceptional requirements have to be expanded. Geomechanical processes such as deformation and fracture creation as well as flow through fractured porous media must also be considered to a greater extent. Moreover, geochemical processes induced by the utilisation of the subsurface have to be taken into account, as they have great influence on the hydraulic properties of porous media by dissolving or precipitating minerals. Similarly, the temporal and spatial coupling of models of varying complexity (multi-physics / multi-scale) is important to reduce the computational cost of simulations with large temporal and spatial scales. Accordingly, the models in DuMuX are constantly developed in the scope of various research projects.
Focal point of research activities