The main challenges of prestack seismic imaging and migration velocity analysis(MVA) in the piedmont areas are the severe variations of the move-out among traces and the low signal to noise ratio (SNR). Both of them are caused by rugged topography and strong near-surface lateral velocity variations. Traditional poststack/prestack migration procedures fail to work well in those regions. We generalize a 3D travltime calculation method to the rugged topography and propose a new Kirchhoff prestack depth migration (PSDM) scheme from rugged topography. We found that choosing a suitable and smooth datum can remove the high wavenumber variation of the move-out among traces. The remaining move-out part can be controlled by the PSDM and MVA from the choosed datum. Both synthetic and field data examples demonstrate that the procedure is quite effective.


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