Influence of geological structure and geophysical parameters on the geothermal field below the city of Berlin, Germany

Abstract

The goal of this study is to analyze the influence of the geological structure of model units on conductive and fluid-driven heat transport in the subsurface of the city of Berlin, Germany, as calculated by 3D numerical simulations.
The results show that the structural configuration (i.e. thickness distribution) of the Rupelian clay aquitard has the strongest impact on the shallow and deep geothermal field. In the purely conductive environment, a general increase of the thermal blanketing effect exerted by increased thicknesses of the lowly conductive Rupelian, could be identified. In a coupled hydrothermal environment, a reduction of forced convective cooling induced by a relatively continuous appearance of the Rupelian led to generally warmer predicted temperatures of the models compared to previous studies (up to ± 23 K at -1000 m.a.s.l.). The structural refinement also reduces the influence of the hydraulic boundary condition (BC) and associated gradients to ± 11 K at -1000 m.a.s.l.. Modifications of the upper temperature BC relate to temperature differences up to only ± 2 K at -1000 m.a.s.l. since the implementation of the latter according to measured data has only little impact on the fluid flow system.