A 3D model of an ancient sand-rich and mixed mud-sand ramp deep-water sedimentary environment, outcropping near Apiuna, Santa Catarina State, Brazil, is presented. This research contributes in the following way to the upstream sector of the petroleum industry: i) with a 3D conceptual model of reservoirs in ramp deep-water systems and ii) with 2D synthetic seismograms based on real outcrops. The first contribution refers to a more refined 3D conceptual model for the reservoirs. The proposed architectural model is more complicated than the previous interpretations which saw the deposits of Apiuna unit as a channel-lobe system in a deep-water fan. In this new model, two type of ramp are recognized. One, sand-rich, is characterized by extensive sandy-sheet reservoirs, not linked to proximal channels and showing an apparent casuality of construction. The sandy sheets vary downcurrent their lithologic features as function of a density-stratified flow: debris flow s.l. in the lower part of the sedimentary flux and turbidity current in the upper part. The second type of ramp, mixed sand-mud, is characterized by a channel-levee complex. The two mentioned ramp systems represent the variation of the depositional environment controlled probably by tectonic-morphologic factors. Construction of synthetic seismograms by using extensive 2D geologic models evaluated from outcrop data is the other part of this work. The properties needed for constructing the synthetic seismograms, which are densities and P-wave velocities of each stratigraphic unit, are evaluated from appropriate petrophysical tables. Synthetic seismograms are then used to qualitatively analyse the seismic response of a stratigraphic column. Correlation of each generated seismogram with the respective stratigraphic column allows identifying small-scale features not visible within the range of seismic frequencies.