Upscaling of geological properties in a world-class carbonate geothermal system in France: From core scale to 3D regional reservoir dimensions

•Construction of heterogeneous 3D geothermal reservoir using data from 168 wells.•Facies, porosity and permeability modeled in 12 million cells covering 360 km3.•20% of the oolitic and bioclastic facies have good reservoir quality.•Permeable layers form kilometer-scale patches (X, Y) of about 4 m thickness (Z).•The 3D model reduces the geological risk of future doublets in the Paris Basin.