Prestack Depth Migration and Velocity Model Derived from First Break Tomography at Long Offsets

First break tomography at long offsets is used to build up velocity model for prestack depth migration. Processing of refracted and diving waves forming first breaks allows obtaining of velocity information in complex geological structures where reflection seismic fails. That, first of all, concern cases of smooth velocity anomalies which are not related with horizons. The advantage of the approach proposed is demonstrated at test models and Pechora Sea survey where multichannel seismic data and wide angle profiling data were acquired independently along one line. Velocity model derived from first break tomography of wide angle data was used for multichannel data prestack depth migration. The final seismic image is compared with ones obtained with standard algorithms)