Time-lapse- or SD-seismic monitoring of producing reservoirs can improve reservoir management. A high-speed simulation was developed that combined streamline-fluid-flow and ray-Born-seismic models to examine the feasibility and uncertainty of such monitoring, The seismic-amplitude change as a result of water injection is large enough to be visible in the high-porosity regions of the reservoir, but the change in low-porosity regions is small and may be masked if the signal/noise (S/N) ratio is small. Also, the pore-pressure change is a critical reservoir property that influences the seismic amplitude.