LAUSR

Geothermal resource quantification requires underground temperature and volume information, which can be challenging to accurately assess at the regional scale. The analytical solution for steady-state heat conduction with internal heat generation is often used to calculate temperature at depth, while geological models can provide volume information. Both approaches were originally combined in a single 3D geological model, in which the underground temperature is directly computed, to accurately evaluate geothermal resources suitable for power generation in the St. Lawrence Lowlands sedimentary basin covering 18,000 km 2 in Quebec, Canada, and improve methods for geothermal resource quantification. This approach, used for the first time at such a large scale, allowed to determine the volume of each thermal unit providing a detail assessment of resource depth, temperature and host geological formation. Only 5% of geothermal resources at a temperature above 120 °C that is suitable for power generation were shown to be hosted in the Cambro-Ordovician sedimentary rock sequences at a depth of 4 to 6 km, while 95% of the resource is hosted by the underlying Precambrian basement.