GNGTS 2013 - Atti del 32° Convegno Nazionale

energetic than reflections, it is necessary to separate diffraction from reflections in order to perform diffraction imaging and processing. We analyzed separation of diffractions by dip-filtering in the post-stack domain and separation in the dip-angle gathers. Then a strategy for separation of diffractions from reflections in the depth migrated images has been developed, based on a combination of the previously analyzed algorithms and taking advantage of the virtues of both. The strategy has been tested with promising results on both synthetic and field data. Although separation of reflection and diffraction energy can never be exact, the proposed methodology achieves the practical purpose of enhancing diffractive response of small subsurface discontinuities. Here an example of separation of diffraction in the synthetic Sigsbee 2A dataset is shown. Future works will be focused on the study of methodologies for the actual use of diffraction for velocity analysis, both in the post-stack depth migrated image and in the dip-angle gathers. Acknowledgements. The authors wish to thank the Smaart JV consortium for releasing the Sigsbee 2A synthetic dataset. References Audebert F., Froidevaux P., Huard I., Nicoletis L. and Svay-Lucas J.; 2000: A multi-angle toolbox for restored amplitude images and AVA-Gathers . SEG Expanded Abstracts, MIG 10.4. Audebert, F., Froidevaux,P., Racotoarisoa, H., Svay-Lucas, J.; 2002: Insights into migration in the angle domain . SEG Expanded Abstracts, 1188-1191. Bienati N., Andreoletti C., Perrone F., Lipari V., Giboli M.; 2009: Limited Aperture Migration in the Angle Domain . 71st EAGE Conference & Exhibition Fomel S.; 2002: Applications of plane-wave destruction filters . Geophysics, 67, 1946–1960. Fomel S., Landa E., and Taner M.T.; 2007: Poststack velocity analysis by separation and imaging of seismic diffractions. Geophysics, 72, U89–U94 Hale D., 2007: Local dip filtering with directional laplacians. CWP Report, 567 Harlan, W. S., Claerbout J. F., and Rocca F.; 1984: Signal/noise separation and velocity estimation: Geophysics . 49, 1869- 1880. Kanasewich, E. R., and Phadke S. M.; 1988: Imaging discontinuities on seismic sections . Geophysics, 53, 334–345. Khaidukov V., Landa E., and T. J. Moser T.J.; 2004: Diffraction imaging by focusing-defocusing: An outlook on seismic superresolution. Geophysics, 69, 1478–1490 Landa E., Fomel S., and Reshef M.; 2008: Separation, imaging, and velocity analysis of seismic diffractions using migrated dip-angle gathers. SEG Expanded Abstracts, 27, 2176. Landa, E., and S. Keydar,; 1998: Seismic monitoring of diffraction images for detection of local heterogeneities . Geophysics, 63, 1093–1100. Reshef M. and Landa E.; 2009: Post-stack velocity analysis in the dip-angle domain using diffractions. Geophysical Prospecting, 2009, 57, 811–821 Reshef, M., and Ruger A.; 2005: Influence of structural dip on interval velocity analysis . 75th Annual International Meeting, SEG, Expanded Abstracts, 2245–2248. Taner M.T., Fomel S., and Landa E.; 2006: Prestack separation of seismic diffractions using plane-wave decomposition. SEG Expanded Abstracts, 25, 2401 Tsingas C., El Marfhoul B., and Dajani A.; 2010 Fracture Detection by Diffraction Imaging . 71st EAGE Conference & Exhibition van Vliet L. J., and Verbeek P. W.; 1995: Estimators for Orientation and Anisotropy in Digitized Images , ASCI, 442-450 76 GNGTS 2013 S essione 3.1