This paper investigates the ability of different seismic modeling techniques to detect changes in reservoir properties due to waterflooding into an oil reservoir. To do so, we simulate a poorly consolidated shaly sandstone reservoir model based on a prograding near-shore depositional environment. To account for the spatial distribution of petrophysical properties, an effective porosity model is first simulated by Gaussian geostatistics. Dispersed clay and dual water models are then efficiently combined with other well-known petrophysical correlations to consistently simulate the reservoir properties. Next, the constructed reservoir model is subjected to numerical simulation of multi-phase fluid flow to predict the spatial distributions of pore pressure and water saturation due to water injection. A geologically consistent stress-sensitive rock physics model, followed with modified Gassmann fluid substitution for shaly sandstones, is then utilized to simulate the seismic elastic parameters. Here, we insert the petro-elastic model into a one-dimensional background elastic model simulating the surrounding offshore sedimentary basin in which the reservoir was embedded. Finally, we employ different seismic modeling algorithms: one-dimensional (1D) acoustic and elastic ray tracing, 1D full elastic reflectivity, 2D split-step Fourier plane-wave (SFPW), and 2D stagger grid explicit finite difference, to simulate seismic waves propagated through the model and recorded at sea level. A base and two monitor surveys associated with 5 and 10 years of waterflooding are selected and the corresponding time-lapse signatures are analyzed at different incident angles. Our analyses demonstrate that internal multiples behind the waterfront, flooded zones, partially subtract out in time-lapse differencing, so they are less significant in monitoring projects than that of reservoir characterization. We find that for time-lapse seismic modeling, acoustic modeling of an elastic medium is a good approximation up to ray parameter (p) equal to 0.2 s/km or surface incident angle of 17 degrees. But, at p = 0.3 s/km (surface incident angle of 27 degrees), difference between elastic and acoustic wave propagation is the most dominant effect other than internal multiples and converted waves. Here, converted waves are generated with significant amplitudes compared to primaries and internal multiples. We also show that time-lapse modeling of the reservoir using SFPW approach is computationally fast compared to FD, 100 times faster for our case here. It is capable of handling higher frequencies than FD. It provides an accurate image of the waterflooding process comparable to FD. Consequently, it is a powerful alternative for time-lapse seismic modeling.