• Intro.
• New Technology
  • Seismic Experiment
  • Phase Shift Migration
  • Reverse Time Migration
• Classic Seismic
  • Physical Background
  • Seismic Acquisition
  • CDP, Stacking
    • Hyperlink 4.3.1
    • Hyperlink 4.3.2
    • Hyperlink 4.3.3
• Hyperlink 5

Reverse Time Migration: Imaging.

We will use the t = it*dt; x = ix*dx; z = iz*dz coordinates

V(ix, iz) is the velocity field.

U(ix, iz, it) is the wave field at the present time.

U(ix, iz, it-1) is the wave field at the time past by one time step.

U(ix, iz, it+1) is the wave field at the time, one step forward in the future.

At the beginning U(ix, iz, it-1) is zero. U(ix, iz, it) is also zero, except for the place of the force, where we enter the first sample of our forced-wave.

It should be noticed here, that the time sampling of the seismic trace, or the time sampling of a source wavelet is usually larger, than the dt time step; so some clever interpolations must be used.

Next we compute the U_xx(ix, iz, it) and U_zz(ix, iz, it) second derivates from the data in the U(ix, iz, it) buffer.

Now we can compute the U(ix, iz, it+1) wave field for one time step forward.

At last we move U(ix, iz, it) into U(ix, iz, it-1), U(ix, iz, it+1) into U(ix, iz, it). We can repeat this procedure for any length.