Abstract Reservoir maps are amongst the most important data necessary for oil exploration and development. Reservoir mapping through seismic data at San Jorge Basin has always been difficult due to the low thickness of the individual sandstones. The techniques of seismic reservoir mapping based on the integration of the top and base reflection amplitudes and the seismic isopach map allowed us to map successfully reservoirs in the order of system tracts in those cases where sand and shale thickness were beyond the tuning thickness. The technique involves a detailed well tying through synthetic seismograms at the control wells. This allows to obtain the phase of the seismic data and to identify the seismic response of the different lithologies. Based on this tying the top and base of the reservoir interval are carefully picked. From these picks the reflection amplitudes at the top and base of the interval and their isopach map are extracted, quality controlled for tuning and calibrated. The final reservoir thickness is obtained from the integration of the data and it is quality controlled against the existing wells. This methodology allowed us to map reservoirs at the Salamanca and Yacimiento El Trébol Fm. at the North Flank of San Jorge Basin and at Mina El Carmen Fm. at the north and west flanks of the basin. As a summary, this technique allows us to map reservoirs at the system tract level at the northern flank of Golfo San Jorge Basin in those cases where there is poor well control and results are not interfered by tuning. Although there are more sophisticated techniques (seismic inversion, geostatistical inversion), this one let us do a fast mapping of the reservoirs. On the other hand, the tying and picking involved in this technique can be applied as an input to the most sophisticated techniques.