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SUMMARY Seismic interferometry allows one to create a virtual source inside a medium, assuming a receiver is present at the position of the virtual source. We discuss a method that creates a virtual source inside a medium from reflection data measured at the surface, without needing a receiver inside the medium and, hence, going beyond seismic interferometry. In addition to the reflection data, an estimate of the direct arrivals is required. However, no information about the medium is needed. We analyze the proposed method for a simple configuration using physical arguments based on the stationary-phase method and show that the retrieved virtual-source response correctly contains the multiples due to the inhomogeneous medium. The proposed method can serve as a basis for data-driven suppression of internal multiples in seismic imaging.
SUMMARY Using only surface reflection data and first-arrival information, we generate up- and down-going wavefields at every image point using the algorithm of Rose (2002b,a) and Wapenaar et al. (2011, 2012a). An imaging condition is applied to these up- and down-going wavefields directly to generate the image. Since the above algorithm is based on exact inverse scattering theory, the reconstructed wavefields are accurate and contain all multiply scattered energy in addition to the primary event. As corroborated by our synthetic examples, imaging of these multiply scattered energy helps illuminate the subsurface better than reverse-time migration. We also demonstrate that it is possible to perform illumination compensation using our imaging algorithm that results in improved imaging at large depths.
Focusing Inside an Unknown Medium Using Reflection Data With Internal Multiples: Numerical Examples for a Laterally-Varying Velocity Model, Spatially-Extended Virtual Source, and Inaccurate Direct Arrivals
Broggini, Filippo (Colorado School of Mines) | Snieder, Roel (Colorado School of Mines) | Wapenaar, Kees (Delft University of Technology)
SUMMARY Seismic interferometry is a technique that allows one to reconstruct the full response from a virtual source inside a medium, assuming a receiver is present at the virtual source location. We describe a method that creates a virtual source inside a medium from reflection data measured at the surface, without needing a receiver inside the medium and, hence, presenting an advantage over seismic interferometry. An estimate of the direct arriving wavefront is required in addition to the reflection data. However, no information about the medium is needed. We illustrate the method with numerical examples in a lossless acoustic medium with laterally-varying velocity and density and take into consideration finite acquisition aperture and a spatially-extended virtual source. We examine the reconstructed wavefield when a macro model is used to estimate the direct arrivals. The proposed method can serve as a basis for data-driven suppression of internal multiples in seismic imaging.
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.65)
ABSTRACT With seismic interferometry one can retrieve the response to a virtual source inside an unknown medium, if there is a receiver at the position of the virtual source. Using inverse scattering theory, we demonstrate that, for a 1D medium, the requirement of having an actual receiver inside the medium can be circumvented, going beyond seismic interferometry. In this case, the wavefield can be focused inside an unknown medium with independent variations in velocity and density using reflection data only.
- North America > United States > Colorado (0.29)
- Europe (0.28)