Título: Pre­stack depth migration of P ­S converted waves using tomographycally estimated velocities

Autor: D'Agosto, C.; Donati, M.; Michelena, R. J.

Fuente: IX Congreso Venezolano de Geofísica: CD-ROM Memorias

Editor: Sociedad Venezolana de Geofísicos (SOVG)

Año: 1998

País de publicación: Venezuela

Tipo de documento: CD-rom Memorias

Resumen:

We show in this paper that P ­ and S­wave velocity models estimated by tomographic inversion of P ­S, converted waves, traveltimes are adequate to perform pre­stack depth migration. Examples of velocities estimated directly from converted waves field data, exhibit lateral and vertical changes in both velocities (P and S) and Vp=Vs ratio. Even though the migrations results are sensitive to subtle changes in velocity models, smooth, velocity maps obtained from P ­S, reflection tomogra­ phy yield well focused converted wave images. These results suggest that tomographic velocity estimation and pre­stack depth migration may be the way to image converted waves in cases when the conventional imaging techniques based in common conversion point gathering, dip moveout, and post­stack time migration fail due to differences in resolution between P and P ­S waves, lateral and vertical changes in both velocities and Vp=Vs ratios, or a combination of both.