The main objective of the study was to develop and calibrate the thermal model of the Grog Schonebeck test site in Northeastern Germany, and to perform sensitivity analyses based on the availability of high-quality temperature data from deep wells. A 3D geological model of the area was constructed and then discretized into a finite element mesh that included 13 different lithologic units of variable thickness. Forward numerical calculations of the temperature field were performed based on measured and assumed data and properties. Finally, inverse modeling was used to improve parameter estimation and to obtain comprehensive statistic information. The results of the computations indicate some spatial thermal conductivity inhomogeneities in the different geologic layers and imply that the basal heat flux in the area is about 60 mW m(-2). (c) 2009 Elsevier Ltd. All rights reserved.