This case study explores rock physical properties of heavy oil reservoirs subject to the Steam Assisted Gravity Drainage (SAGD) thermal enhanced recovery process. Previously published measurements (e.g. Wang et. al, 1990, and Eastwood, 1993) of the temperature dependant properties of heavy oil saturated sands are extended by fluid substitutional modeling and wireline data in order to assess the effects of pore fluid composition, pressure and temperature changes on the seismic velocities of unconsolidated sands. Rock physics modeling is applied to the shallow McMurray reservoir within the bituminous Athabasca oil sands deposit in order to construct a petrophysical velocity model of the SAGD process. Although the injected steam pressure and temperature controls the fluid bulk moduli within the pore space, the stress dependant elastic frame modulus is the most poorly known yet most important factor governing the changes of seismic properties during this recovery operation. The results of the fluid substitution are used to construct a 2-D synthetic seismic section in order to establish seismic attributes for analysis and interpretation of the physical SAGD process. The findings of this modeling promote a more complete description of 11 high resolution time-lapse 2-D seismic profiles collected over a shallow oil sands reservoir undergoing SAGD.