Gas shale reservoirs are characterized by pore systems, associated with a heterogeneous spatial distribution of mineral and organic phases at multiple scales. This high heterogeneity requires a multi-scale & multi-tool approach to characterize the pore network. Such an approach has been developed on 7 cores from the Vaca Muerta formation (Argentina), which belong to areas with various hydrocarbon maturities, but with comparable mineral compositions. 3D µtomography and quantitative 2D mapping of the connected porosity by autoradiography have been applied at the core scale, in aim to localize and analyze the spatial heterogeneities, and to identify similar homogenous areas for localizing comparable sub-samples.The correlative coupling of various techniques was applied to achieve quantitative balance of porosity and pore size distribution, from mm to nm scales on representative sub-samples and for the first time, on preserved blocks rather than crushed powders, even for nitrogen gas adsorption experiments. Results of autoradiography are in very good agreement with other total bulk porosities, indicating that all pores are connected and accessed by the 14C-MMA used for impregnation. Decreased total porosity and pore throat/body sizes were also observed as organic matter maturity increased. An innovative approach for electron microscopy images acquisition and treatment provided large mosaics, with the distribution of mineral and organic phases at the cm scale. The correlative coupling with the autoradiography porosity map of the same zone, revealed the spatial correlations between mineralogical variations and porosity.