In the Golfo San Jorge Basin, Argentina, the main traditional reservoirs are fluvial sandstones, which are thin and usually fall below seismic tuning frequency. The need for an aggressive development of the reserves and the need to open new areas led to a pilot job in a zone of approximately 100 km2, assuming the possibility to go vertically across structural and stratigraphic traps and their combination, using high technology added to the proved workflow. After the carefully traditional seismic structural interpretation of faults and horizons in the area and using seismic attributes, the seismic reservoir characterization was aimed toward the processing and analysis of a seismic geostatistical inversion. Using this technique improved the knowledge of the emplacement, behavior, and occurrence of the reservoir sand bodies, opening new zones and determining development drilling. The method includes geostatistical inversion and its interpretation, results, and improvement of the sequence. Time thickness of the reservoirs, sand probability, and effective-porosity maps for each separate layer were generated and interpreted at the end of the sequence. The results in proposed wells are based on this technique.