Most ancient fluvial systems are analyzed by detailed measurements of outcrop on cliffs that intersect paleochannel and floodplain deposits (2D outcrops). Only in exceptional conditions is the plan view of paleochannel belts coincident with the current land surface (= exhumed paleochannels) to allow detailed reconstructions of downstream changes in the fluvial pattern (3D outcrops). Exhumed paleochannels are related to a frequent geomorphological process in Patagonia, called relief inversion. The main attribute of exhumed paleochannels is to allow the measurement in plant of fluvial morphological parameters such as orientation, wavelength, sinuosity, width of channels, radius of curvature, etc., directly on satellite images. These observations are comparable to seismic geomorphologic analyses made on time slices to characterize fluvial reservoirs in the sub surface of productive basins.This work consisted in mapping more than 2000 segments of exhumed paleochannels over an area of ~20.000 km2, contained in rocks of the Chubut Group of the Cañadón Asfalto basin, Chubut, Argentina. The rocks that contain this type of outcrop correspond to the Cerro Barcino and Puesto Manuel Arce formations, lithostratigraphic equivalents of the Castillo and Bajo Barreal formations in the Golfo San Jorge basin respectively. The fluvial paleochannel network shows a wide variability in the sandbody dimensions and fluvial styles. The morphological pattern of the paleochannels allowed to define its sinuosity with great precision in the majority of cases. Low-sinuosity fluvial styles are the most commonly paleochannel pattern, although excellent examples of high sinuosity channels were described. We measured 1581 paleocurrents on tractive sedimentary structures to define local and regional paleoflow directions, source areas, depocenters, etc. The number of interpreted paleo channels and the extension of the study area provide a rare regional representation in paleoenvironmental and paleogeographic reconstructions.The similarities between exhumed paleochannels (Chubut Group, Cañadón Asfalto basin) and channalized geoforms in the subsurface of the Golfo San Jorge basin, allow us to establish very good analogies from different observation scales (individual sandbodies, local, semi-regional to regional paleochannel arrangements). For this reason, this exceptional worldwide example represents: 1) a unique opportunity to characterize paleochannels in three dimensions, 2) the fact to understand the variability of fluvial lithofacies and their petrophysical qualities as reservoir rocks and 3) the use of outcropped analogues in seismic geomorphologic analyses of productive fluvial sandbodies.