One of the tasks involved mapping the flow simulator output onto a regular Cartesian grid appropriate for seismic modeling. The flow simulator results are defined on a stratigraphic coordinate system with variable block sizes, usually larger than the seismic blocks. The porosity which is defined at the geologic model scale is also on an irregular stratigraphic coordinate system but with blocks smaller than the seismic scale. For upscaling the porosity to the seismic scale, a simple volumetric block averaging was used. The flow simulator outputs were downscaled to the seismic blocks by linear interpolation, first along the depth direction, and then in each horizontal layer. This exercise highlighted the need for better methods of upscaling not only the rock and reservoir properties, but also the rock physics relations between these properties and the seismic observables.