Lowrank seismic wave extrapolation on a staggered grid

Example of BP model

Finally we test the proposed methods in a complex velocity model. Figure 13 shows a part of the BP-2004 model, which is a complicated model containing a salt body and sharp velocity and density contrasts on the flanks of the salt body (Billette and Brandsberg-Dahl, 2004). We use a Ricker-wavelet at a point source with a dominant frequency of $20 Hz$ $(f_{max} \approx 60Hz)$ . Both of the horizontal grid size $\Delta x$ and vertical grid size $\Delta z$ are $12.5m$ , and the time step is $1.5ms$ , thus, $\alpha \approx 0.57$ and $\beta \approx 1.98$ . Figure 14 shows the wavefield snapshot in the BP model generated by SGL method and 6th order SGLFD with a rank of 3. This experiment confirms that the staggered grid lowrank methods are able to handle sharp velocity and density variations.

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Figure 13. BP model: (a) velocity, (b) density.

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Figure 14. Wavefield snapshot modeled through for BP Model using (a) SGL method and (b) SGLFD method.

Lowrank seismic wave extrapolation on a staggered grid