WP 1.3
Storing excess electricity in form of H2 or CH4 (“power to gas”) is an important approach to regard the fluctuating energy production of regenerative sources. Gas storage actions utilize the geologic formations present in the subsurface, while these storage actions can influence the properties of the structures and the deep groundwater. The deep geological subsurface represents a space, where its geological structures and properties are distributed heterogeneously, equivalent to the near-surface underground. Within the geological formations, but also in between these, parameters of properties are distributed for instance as a consequence of sedimentation processes. Since in general the investigation of geological formations requires drillings, only a limited number of data points are available. Therefore it is not possible to acquire an area-wide knowledge regarding parameter distributions.
Due to the limited data quantity of subsurface parameters, which are furthermore focusing on regions of hydrocarbon deposits, numerical simulation of processes induced by gas storage actions (WP 3.1, WP 3.2 and WP 3.3) requires the knowledge of either site specific or generally valid data regarding the properties of the geological formations. For this reason, simple statistical approaches are applied using an existing database which is comprising hydraulic, geochemical, and mineralogical data of the deep subsurface (> approx. 500m depth). Second, approaches of multivariate statistics and/or geostatistics are applied to conduct correlation analyses for instance between porosities and permeabilities of potential reservoir formations or of deep groundwater compositions and geochemical constituents of the sediments. Both approaches aim at evaluating typical hydraulic and geochemical conditions of the deep subsurface. Exceeding the current scope of the database, it is planned to extend it with respect to mechanical (modules of rigidity), geophysical (seismic modules and velocities, electric water and rock conductivities), and thermal (heat capacities and heat conductivities) parameter groups. The data acquisition regards national sites, but also international site data are used, if these can complement to the national data based on existing analogies.
Results of this work package, such as statistic descriptions of parameter sets including correlation lengths in vertical and horizontal directions, are utilized in ANGUS+ simulations in order to define statistically supported, realistic variation ranges of parameters (WP 3.1, WP 3.2 and WP 3.3). The presented work package is furthermore linked to WP 1.1 and WP 1.2, which also focus on the acquisition and evaluation of subsurface parameters.
