Autofocusing for retrieving the green's function in the presence of a free surface

Conference paper (2014)

Authors

Satyan Singh Colorado School of Mines
R Snieder Colorado School of Mines
J Behura Colorado School of Mines
J.R. van der Neut Applied Geophysics and Petrophysics - CEG
C.P.A. Wapenaar Applied Geophysics and Petrophysics - CEG , ImPhys/Medical Imaging - AS
E.C. Slob Applied Geophysics and Petrophysics - CEG
Research Group
Applied Geophysics and Petrophysics (CEG) (TU Delft)
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Published Date

2014

Language

English

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Faculty

Civil Engineering & Geosciences

Department

Geoscience and Engineering

Research Group

Applied Geophysics and Petrophysics

Abstract

Recent work on autofocusing with the Marchenko equation has shown how the Green's function for a virtual source in the subsurface can be obtained from reflection data. The response to the virtual source is the Green's function from the location of the virtual source to the surface. The Green's function is retrieved using only the reflection response of the medium and an estimate of the first arrival at the surface from the virtual source. Current techniques, however, only include primaries and internal multiples. Therefore, all surface-related multiples must be removed from the reflection response prior to the Green's function retrieval. Here, we present a new scheme that includes primaries, internal multiples, and free-surface multiples. In other words, we retrieve the Green's function in the presence of the free surface. The information needed for the retrieval are the reflection response at the acquisition surface and an estimate of the first arrival at the surface from the virtual source. The reflection response, in this case, includes the free-surface multiples; this makes it possible to include these multiples in the imaging operator and it obviates the need for surface-related multiple elimination.