The present study is about the second part of La Itala area in the oil field of Los Perales - Las Mesetas. This deposit is located on the western flank of the San Jorge Gulf Basin, northwest of the Province of Santa Cruz in Argentina and about 45km at the north of the town of Las Heras.Synthetic seismograms were generated using sonic and density logs, which allowed to obtain time-depth tables (speed laws) that served to control the seismic-well adjustment, achieving an acceptable correlation between the geological well-tops and those interpreted in the seismic.A velocity model was made in the area using the interpreted surfaces, the geological well tops and the speed-laws of the wells, to make the conversion between time and deep of the structural elements.From this structural model, a static one was built in depth, which one was created with cells of 75x75x1. The grid was made with a model of seven facies. Variogram maps were generated to optimize the populate according to the zones and at the same time we worked with two different algorithms (Kriging and Gaussian).The difference between this model, and traditional one is about how we use the water saturation curve (Sw). The petrophysical interpretation provides, from records measured in the wells, a Sw curve conditioned and affected by different factors, such as tool type, vertical resolution and well quality. Geoscientists and engineers rely on these "biased" results to perform a well-to-well and hydraulic unit interpretation.What is proposed in this paper, and for this model, is to apply an equation on the water saturation curve using a cut-off of porosity on the hydraulic units, to work only on reservoir sands. This methodology allows to visualize a balance in the distribution of fluids, with the structure water below and hydrocarbon structure above. We also get a useful thickness more adjusted to reality.In conclusion, the numerical simulation provides better results when calculating is on the new hydrocarbon volume, showing a better fit with the production history of the wells, which implies that the OOIP estimated in 2D projects by traditional calculations is underestimate.