Elastic interferometry for ocean bottom cable data: Theory and examples < sup/ >

• Published in: Geophysical Prospecting Vol. 58; no. 3; pp. 347 - 360
• Main Authors: Gaiser, J E, Vasconcelos, I
• Format: Journal Article
• Language: English
• Published: 01-05-2010
• ISSN: 0016-8025
• DOI: 10.1111/j.1365-2478.2009.00825.x

Elastic imaging from ocean bottom cable (OBC) data can be challenging because it requires the prior estimation of both compressional-wave (P-wave) and shear-wave (S-wave) velocity fields. Seismic interferometry is an attractive technique for processing OBC data because it performs model-independent redatuming; retrieving 'pseudo-sources' at positions of the receivers. The purpose of this study is to investigate multicomponent applications of interferometry for processing OBC data. This translates into using interferometry to retrieve pseudo-source data on the sea-bed not only for multiple suppression but for obtaining P-, converted P to S-wave (PS-wave) and possibly pure mode S-waves. We discuss scattering-based, elastic interferometry with synthetic and field OBC datasets.Conventional and scattering-based interferometry integrands computed from a synthetic are compared to show that the latter yields little anti-causal response. A four-component (4C) pseudo-source response retrieves pure-mode S-reflections as well at P- and PS-reflections. Pseudo-source responses observed in OBC data are related to P-wave conversions at the seabed rather than to true horizontal or vertical point forces. From a Gulf of Mexico OBC data set, diagonal components from a nine-component pseudo-source response demonstrate that the P-wave to S-wave velocity ratio (VP-VS) at the sea-bed is an important factor in the conversion of P to S for obtaining the pure-mode S-wave reflections.