Thermal Modeling in the Oslo Rift, Norway

Abstract

In stable continental regions, local variations of heat flow are usually related to variations in radiogenic heat production. Depending on the location of the heat source and the geological structure, areas with high heat flow might be suitable for geothermal prospecting. Given that transient effects can be neglected, the thermal structure of the continental basement can be modeled with a steady state conductive model based on primarily the radiogenic heat production and the variation of thermal conductivity. The Oslo rift is situated on the Fennoscandian Shield and compromises a complex lithology. It has been subjected to extensive geological and geophysical studies; however, there are no boreholes exceeding 1000m within the region. Therefore, temperature and properties at depths relevant for geothermal energy have to be extrapolated from shallow measurements. This is further complicated by palaeoclimatic effects. In this study a published geophysical model of the Oslo rift developed by the Geological Survey of Norway has been used. The model is based on integration of geophysical data such as magnetic and gravity data with geological models, and has been used as basis for thermal modeling. The results from the thermal modeling can be used both to evaluate geothermal potential and as a further constraint for the geophysical model.