| Title | Expanding the Thermal Conductivity Assessment of the St. Lawrence Lowlands (Quebec, Canada): A New Laboratory Dataset from Optical Scanning |
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| Authors | David Moreno, Jasmin Raymond, Stéphanie Larmagnat, Daniela Blessent |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | Thermal conductivity (TC) assessments are critical for designing ground-coupled heat pump systems. In the St. Lawrence Lowlands (SLL), Quebec, previous regional TC mapping identified systematic overestimations in laboratory measurements (obtained using divided bar and needle probe apparatus) compared to in situ thermal response tests (TRTs). This was attributed to the inability of lab measurements made on small samples to capture heterogeneities. Reservoir formations exhibited large discrepancies between lab and in situ assessments reaching up to 1.4 W/m·K. The objective of this study was to expand the SLL’s TC inventory with 102 new measurements using a Thermal Conductivity Scanner (TCS), applying the optical scanning method to outcrop samples and improving spatial coverage. The results incorporated confirm earlier trends: Cairnside and Covey Hill reservoir units remain the most conductive formations (averaging 5.3 and 4.59 W/m·K, respectively), while Caprocks show lower values. However, TC values obtained in the lab with the TCS are consistently lower than prior lab assessments, reducing disparities with TRT data. Cairnside’s average TC decreased from 6.2 W/m·K (historical lab) to 5.3 W/m·K (historical lab + TCS), aligning closely with TRT results (5.0 W/m·K). Similar adjustments occurred in the Theresa (4.3 to 3.93 W/m·K) and Covey Hill units (4.8 to 4.59 W/m·K). These updates refined internal dataset variability, enhancing representativeness. This work underscores the importance of integrating advanced laboratory methods in TC assessments. The updated laboratory inventory brings values closer to those obtained from TRT, which better reflect subsurface conditions, and contribute to a more accurate geothermal resource potential evaluation. |