Synthetic seismogram of the well model. The figures on the left show the P-wave velocity, S-wave velocity, density, and synthetic seismogram from left to right, whereas the figures on the right show the P-wave velocity, S-wave velocity, density, synthetic seismogram and difference between the seismograms (the synthetic seismogram on the left is subtracted from that on the right). In each row, the left panel shows the original synthetic seismogram, and the right panel shows the synthetic seismogram with a consistent porosity after fluid substitution.