Diffraction enhancement in prestack seismic data

Abstract

Seismic diffractions are often considered noise and are intentionally or implicitly suppressed during processing. Diffraction-like events include true diffractions, wave conversions, or fracture waves which may contain valuable information about the subsurface and could be used for interpretation or imaging. Using synthetic and field data, we examine workflows to separate diffractions from reflections that allow enhancement of diffraction-like signals and suppression of reflections. The workflows consist of combinations of standard processing modules. Most workflows apply normal moveout corrections to flatten reflection hyperbolas, which eases their removal. We observe that the most effective techniques are the decomposition of seismic gathers into eigensections and flows based on Radon transformations.

Coal seismic diffraction fault imaging: Results from numerical modelling

“…On the basis of our testing, f-k dip filtering on NMO-corrected common-shot gathers (Bansal and Imhof, 2005) is probably the most effective method for extracting diffractions from specular reflections. Theoretically, after applying NMO corrections, the reflected events are flattened (or sub-flattened) and the diffracted events are deformed.…”

“…Landa and Fomel (2008), Reshef and Landa (2009) and Klokov and Fomel (2012) adopted the hybrid Radon transform (Trad et al, 2001) to separate reflections and diffractions using their shape differences in the migrated dipangle domain. Bansal and Imhof (2005) examined several workflows to enhance diffractions and suppress reflections in the normal-moveout (NMO)-corrected prestack data. Seven approaches are tested, including Diote and dip filtering on common-offset gathers, dip filtering for NMO-corrected shotgathers, NMO-dip-moveout filtering, eigenvector (Singularvalue decomposition -SVD) filtering and Harlan signal/noise separation and Radon filtering.…”

“…Prior to using seismic migration, seismic interpreters sought diffraction patterns as an indication of faulting structures, especially for small faults where the discontinuities in the seismic reflections are less evident. These diffractions are often attenuated by conventional seismic data processing (Khaidukov et al, 2004;Bansal and Imhof, 2005;Moser and Howard, 2008). However, the significance of these diffractions has been long recognised in fault and other discontinuity imaging by many researchers such as Krey (1952), Hagedoorn (1954), Trorey (1970), Harlan et al (1984), Landa et al (1987), Kanasewich and Phadke (1988), Neidell (1997), Khaidukov et al (2004), Shtivelman and Keydar (2004) and Landa (2010).…”

Full-azimuth anisotropic prestack time migration in the local-angle domain and its applications on fracture detection

“…(15) in which the former migration actually stands for anisotropic migration in the LAD, and the latter provides a good chance of separating and imaging diffractions (Bansal and Imhof, 2005;Koren et al, 2008;Landa et al, 2008). In this paper, we mainly study anisotropic migration in the LAD within the frame of Kirchhoff PSTM.…”

Fracture Detection via Double Beam Focusing and Image Filtering

“…Its significant difference is focusing of reflections into the virtual sources and then subtracting from the total wave field. Bansal and Imhof (2005) proposed a set of procedures to enhance the diffraction components and reduce specular reflections, which allows the efficient use of the information contained in the diffracted waves. In the paper by Fomel with co-authors (2007) there is developed a method for separating of the wave field and construction a diffraction image on the basis of the so-called plane wave destructor(PWD).…”