VTI migration velocity analysis using RTM |

Compared with the true model, our initial model (Figure 5(a)) has negative perturbation of about 50% in the shallower part. Because a perfect velocity model is used in this case, the moveout at large angles is so small that it is almost undetectable to human eyes (Figure 5(b)). However, our inversion scheme is very sensitive to the residual moveout and successfully updates the model in the correct direction. Figure 6 shows the inverted model and the corresponding angle-domain common-image gathers after 40 iterations. Comparing with the initial angle gathers (Figure 5(b)), we can see that the slightly curving events at large angles are flattened and the inverted model is closer to the true one.

epssm,dltsm
(a) True
model and (b) true
model used to generate the synthetic data.
Figure 4. |
---|

initeps,init-e-image
(a) Initial
model and (b) initial angle-domain
common-image gathers using initial
model. Gathers are taken at every 10 common image point from
km to
km.
Figure 5. |
---|

inveps,inv-e-image
(a) Inverted
model and (b) final angle-domain
common-image gathers using inverted
model in (a). Compared with Figure 5(b), panel (b) shows more even
energy across different angles. Gathers are taken at every 10 common image point from
km to
km.
Figure 6. |
---|

VTI migration velocity analysis using RTM |

2012-05-10