A new waveform inversion workflow: Application to near-surface velocity estimation in Saudi Arabia

Conclusion

We showed a new three stage waveform inversion workflow for near-surface velocity estimation:

       1) First arrival traveltime tomography.
       2) Wave-equation traveltime inversion.
       3) Early arrival acoustic waveform inversion.

The wave-equation traveltime inversion step helps correct inaccuracies in the conventional first arrival traveltime inversion result due to the inability of ray based methods to properly handle low velocity zones and large velocity contrasts.

This new workflow was evaluated using both a synthetic data example and a 2D field dataset from Saudi Arabia. Our new inversion workflow produced a superior result on the field data compared to results obtained using a more conventional strategy that did not include the wave-equation traveltime inversion step. Since the 2D field data was not acquired in a straight line, it is possible that the improvement we observed when using wave-equation traveltime inversion was partly due to the correction of the non-2D geometry. We plan to further investigate the wave-equation traveltime inversion, using a full 3D parametrization for the modeling and inversion.

A new waveform inversion workflow: Application to near-surface velocity estimation in Saudi Arabia