“…The Middle Jurassic (Dogger) carbonate reservoirs located at a depth of about 1.5 km were first identified in the 1980s as the most promising target for the development of geothermal energy in the Paris Basin (France) (Antics et al, 2005;Allo et al, 2021;Giot and Rojas, 1981;Housse and Maget, 1976;Lopez et al, 2010;Rojas et al, 1989). Fifty-four district heating production units with their associated wells and distribution grids exploit the heat capacity of a deep reservoir at 55-80 °C formed by the Bathonian limestones (Lopez et al, 2010;Rojas et al, 1989;Thomas et al, 2023). In order to improve our understanding of the heterogeneities in this reservoir, an NMR logging tool (Combinable Magnetic Resonance -CMR©) was deployed in two recent geothermal operations at Cachan in 2017 and Bobigny-Drancy in 2020 (Ungemach et al, 2019;Wielemaker et al, 2020).…”