Analyses of thermal conductivity from mineral composition and analyses by use of Thermal Conductivity Scanner : a study of thermal properties of Scanian rock types

Abstract: With an increase in demand for green energy the interest has grown in Geoenergy. The bedrock may function both as energy source and as energy storage, which makes it suitable for both heating and cooling. The thermal properties of the bedrock are essential when effectively planning and designing a geothermal energy well. This thesis focuses on research and study of the thermal properties of the Scanian bedrock, and on existing mineralogical data and samples accessible through Geological Survey of Sweden. Samples were chosen on the basis of the rock type and geographic location. Those rock units and areas that were not represented were sampled, if possible, during the summer of 2012. Sample preparation involved cutting them along several axes. Upon review of the results, they were then compared against the calculated values. The calculated values deviated slightly, but are considered representative for the thermal properties. The results show a grouping into 5 groups, 3 sedimentary and 2 crystalline. The amount of quartz content in the crystalline rock types defines the 2 different groups. High quartz content gives a conductivity of 3.0 W/mK, whereas the crystalline rock units that have a low quartz content, have a slightly lower thermal conductivity (2.5 W/m•k). The sedimentary rocks are divided by type and age. The youngest is limestone with a low thermal conductivity, 1 W/m•k. Following in age is a large span of rock types which have a midrange thermal conductivity around 3.0 W/m•k. The highest thermal conductivity, 6 W/m•k, are recorded in Cambrian quartzite and sandstone. With the database related to this project, makes it possible to develop an prognosis map of the thermal conductivity of Scanian rocks.