Development of a numerical 3D geothermal model for Denmark

Abstract

A regional 3D subsurface thermal model for Danish onshore areas is being developed. Structural and lithological information, data on rock thermal properties and current information on borehole temperatures and heat flow are integrated into a numerical model. By applying combined numerical forward modelling and inverse calibration methodology, model thermal parameters may be constrained to ensure consistency between temperature predictions and measured borehole temperatures. Some first results are presented and discussed including temperatures of potential geothermal reservoirs. Geothermal gradients across the country broadly range between 20 and 35 °C/km depending on location and depth. Variations are found to be largely due to differences in thermal conductivity between lithological units. In large parts of the country, sandstone reservoirs are found at depths and temperatures suitable for exploitation of low enthalpy geothermal resources. Thermal models, like the present, facilitate risk reduction in regional and local geothermal exploration, and model results are easily integrated into web-based platforms to provide information on subsurface geothermal conditions to a broader public.