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We have performed a series of laboratory rock physics testing under various pressure and temperature conditions to test the seismic response to different CO$_2$ phases on two tight sandstone samples of the sedimentary basin of the St. Lawrence Lowlands in Qu\'ebec, Canada. Results show that the seimic velocity and amplitude can be used to detect the CO$_2$ phase transition. Laboratory These laboratory  measurements have been used to calibrate a stochastic numerical  geological model used to generate synthetic seimograms reproducing the vertical seismic profiling response to CO$_2$ injection in the reservoir formations. Results show that substitution of brine by 100\% CO$_2$ is responsible for a time-delay in the seismic traces despite very low permeabilities and porosities. Keywords: CO$_2$, ultrasonic measurements, seismic modeling, VSP, low porosity sandstones, Gassmann's model.