| Title | X-rays and thermal conductivity: towards 3D heat transfer modelling |
|---|---|
| Authors | Mathieu Des Roches, Stéphanie Larmagnat, Jasmin Raymond, Christine Rivard, Pierre Francus |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | The performance of geothermal systems is highly dependent on rock properties. For deep (>1 km) open-loop systems, the critical reservoir properties to assess include porosity, permeability, and thermal conductivity (TC). Various methods can be used to characterize the heterogeneous distribution of porosity and permeability at difference scales, but limited options are available for measuring TC. In situ heat injection tests made at the meter scale are hardly feasible in deep wells, and the divided bar method used with core plugs integrates heterogeneities at the centimeter scale. Infrared thermal conductivity scanner (TCS) measures variations of TC at the millimeter scale, but is limited to 1D surface measurements that are not necessarily representative of the sample’s internal structures. To overcome this issue, X-ray tomography was used to produce 3D images of the sample’s structure. The typical image resolution for a medical CT-scanner is in the sub-millimeter range. The level of X-ray attenuation mainly depends on three material characteristics: density, chemical composition, and porosity. The measurement obtained, in Hounsfield Unit (HU), combines these three properties which are known to influence rocks TC. A comparison of the two measurements was performed on a set of sedimentary rock samples (> 30) to provide a better understanding of how heterogeneity impacts TC. To achieve this, a code had to be developed to precisely locate the two measurement types. Promising correlation has been obtained, opening up the possibility to map the distribution of TC in 3D using X-ray imaging. |