The study attempts to infer the characterization of subsurface reservoirs by enlightening the petrophysical properties prediction through the integration of petrophysical characteristic and the three-dimensional (3D) seismic observations at Simian gas field in the northern part of Egypt. This goal is accomplished using regression analysis on the seismic post stack inversion properties, a well-made relationship between the measured porosity log and the seismic inversion properties derived at the well location. After extraction the relationship, the porosity cube can be derived reasonably from the results of inversion properties. Being controlled by the physical properties and annotations at the well, the resulting porosity estimations from inversion properties are suitable for making reservoir management decisions. Finally, the predictable porosity can deliver a geologically realistic porosity distribution that helps to trace the reservoirs heterogeneities within the study area