Boundary conditions in thermal models: An application to the KTB site, Germany

Abstract

Deep temperature estimations are important for rheological studies of the crust and also for the planning of deep drill holes. Thermal modeling requires the input of realistic boundary conditions in order to obtain reliable values for the temperature at depth. Boundary conditions necessary for thermal models may be inferred from geochemical and geophysical parameters mea- sured in the field.
Numerical solutions of heat equations can be obtained through finite element and finite difference schemes in one, two or three dimensions, taking into account several assumptions regarding the medium parameters, such as homogeneity and anisotropy of thermal conductivity. In this paper we present one and two-D models and highlight the differences between them.
The Oberpfalz area was selected to test the model and boundary conditions, because geochemical and geophysical data were available to estimate the boundary conditions in our model and temperatures at depth have been actually measured at the KTB borehole. A good agreement between the calculated and measured temperatures is obtained for a 2-D model with appropriate boundary conditions from geochemical and geophysical data.