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The first investigation into the geothermal potential of Madagascar was compiling an inventory of the hot springs (Besairie 1959), which was followed two decades later by an assessment of the geochemical characteristics of geothermal energy sources using chemical and isotopic analysis and chemical geothermometers on samples of hot spring water (Gunnlaugsson et al. 1981). The results provided a general characterization of the geothermal regions of Madagascar (Andrianaivo 2011). The prospective areas in this study have been subject to geological assessments, including structural geology (Andrianaivo and Ramasiarinoro 2010a, b). Knowing that geothermal exploration in Madagascar is at an early stage and that there is currently no geothermal power production in the country, this study reviews the available results from previous work with the objective to better understand the factors affecting the geothermal energy source and to produce the first catalogue of geothermal systems in Madagascar. The aim of the classification is to highlight the dominant characteristics of each area.

In eastern Québec, the Sayabec Formation is a lower Silurian carbonate unit well known for its natural macro porous intervals occurring both at the outcrop scale and in the subsurface, and interpreted as hydrothermal dolomite (HTD) units. The Sayabec Formation represents a potential reservoir analog to the Albion-Scipio oil field (Ordovician, Michigan basin, USA) and has been targeted by a local oil and gas operator since 2010, which resulted in the drilling of about 6000 meters of stratigraphic wells in the Témiscouata area. This provided an ideal case study to test how conventional methods for oil and gas exploration can be applied to assess geothermal properties of reservoir units. To better understand the conventional reservoir properties (e.g. porosity and permeability variability with respect to lithofacies), their spatial heterogeneity and how these properties can be used to evaluate geothermal parameters; outcrops were revisited in the Témiscouata area to collect a consistent, although limited, new sample set of key sedimentary facies within the lower Silurian succession for this pilot project. A total of eight distinctive lithologies were defined and analysed using both an infrared thermal conductivity scanner and probe permeametry, providing critical fine scale assessment of thermophysical properties of the lower Silurian carbonates and clastics. Those preliminary field data are compared with pre-existing porosity and permeability laboratory measurements made on core samples from wells drilled in the same study area.

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