An Effective 3D Kirchhoff PSDM and MVA Procedure from Rugged Topography

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.