Reconstruction of the near-surface temperature field in southern Germany: data, methods, patterns

To systematically assess Germany’s near-surface geothermal potential and support the energy transition through an expanded geothermal database, the Wärmegut project, conducted in cooperation with the Geological Surveys, collects and evaluates geothermally relevant information, integrating them into the Geothermal Information System (GeotIS), originally designed for deep geothermal applications. Based on about 3,000 measurements from more than 1,500 wells in Rhineland-Palatinate and Baden-Württemberg, this paper presents a methodology to reconstruct the near-surface temperature field. The shallow temperature-elevation regression line is used as a Kriging drift term to capture the strong influence of topography and is extended to include surface sealing effects. The analysis focuses on 50 m depth as a reference level, independent of seasonal variations, providing a baseline relevant for shallow geothermal applications and subsequent studies. Two complementary approaches are applied: extending satellite-based land surface temperatures using bottom-hole temperatures, and independent evaluation of temperature logs. A correction procedure further allows the use of extraction logs, whether operational or shut-in logs which are affected by prior pumping, to estimate the undisturbed subsurface temperature field.