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Seismic imaging in the curvelet domain: achievements and perspectives. Hervé Chauris (1) & Jianwei Ma (1,2) EAGE 2009 - Amsterdam. Centre de Géosciences, Mines ParisTech, France Institute of Seismic Exploration, School of Aerospace, Tsinghua University, Beijing, China.
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Seismic imaging in the curvelet domain: achievements and perspectives Hervé Chauris(1) & Jianwei Ma(1,2) EAGE 2009 - Amsterdam • Centre de Géosciences, Mines ParisTech, France • Institute of Seismic Exploration, School of Aerospace, Tsinghua University, Beijing, China
Locally coherent events Time common-offset section Same section after depth migration
Locally coherent events Context : seismic modeling / migration Diffraction point Globally coherent event Locally coherent event
Curvelets and other …lets Taking into account band-limited data: Curvelet Ridgelet Contourlet Shearlet Wavelet EPW Surfacelet Seislet Bandlet, …
Potential of curvelets Seismic data Single curvelet
Introduction – Curvelets Curvelets for different coefficients cμ(x,z) shift rotation stretch
Content Introduction – what are curvelets Curvelets and seismic processing tasks • pre-/post-processing • seismic migration • seismic demigration/migration – velocity estimation Conclusions
Curvelets and seismic applications Review: • Ma and Plonka, 2009 • Workshop EAGE 2007 (London), Chauris and Douma Data denoising, interpolation and compression • Hennenfent and Herrmann, 2006 Droujinine et al., 2007 • Herrmann et al., 2008a Sacchi et al., 2007 • Herrmann et al., 2008b Fomel, 2007 • Lin and Herrmann, 2007 • Neelamani et al, 2008 Seismic modeling and migration • Douma and de Hoop, 2007 • Chauris, 2006 Velocity model estimation • Chauris and Nguyen, 2007 • Chauris and Nguyen, 2008 redundant transform
Seismic propagation/migration Theoretical results • Candes and Donoho, 2003 Practical results • Douma and de Hoop, 2006 • Douma and de Hoop, 2007 • Chauris, 2006
Use of digital curvelets Fast curvelet transform Migrated section in initial model Curvelet processing Fast inverse curvelet transform Perturbed section
Migration in heterogeneous models Smooth heterogeneous 2-D model Kirchhoff migration First-order curvelet migration
Migration in heterogeneous models First-order curvelet migration Kirchhoff migration
Kirchhoff migration of a few curvelets Migration in heterogeneous models First-order approximation not good enough
Demigration/migration Sensitivity of the migrated result with respect to the velocity model Initial velocity model Triplicated ray field Velocity perturbation (up to 200 m/s)
Demigration/migration Sensitivity of a migrated image with respect to the background velocity model Given velocity model Migration ? Local velocity perturbation Migration
Input data Ray+Born 2-D synthetic data set (offsets from 0 to 2 km) Offset 600 m Initial image
Initial image Predicted image Exact image Demigration/migration Sensitivity of the migrated result with respect to the velocity model
Demigration/migration Depth difference reduced from 60 m to less than 2 m Initial / exact Predicted / exact
Demigration/migration Sensitivity of the migrated result with respect to the velocity model Unperturbed part Modified part
Common Image Gathers The prediction takes into account the lateral velocity variations Prediction with curvelets Exact Reference image
Demigration/migration Sensitivity of a migrated image with respect to the background velocity model Given velocity model Migration ? Local velocity perturbation Migration
Velocity estimation Sensitivity of a migrated image with respect to the background velocity model Given velocity model Migration Improved seismic section ? Optimal velocity perturbation? Migration Cost function
DSO in curvelet domain Feasibility study 2-D synthetic ray+Born data set Initial After 1 iteration Exact
DSO in curvelet domain Stack of offsets between 100 and 800 m Initial After 1 iteration Exact
Conclusions & perspectives Seismic imaging operators: • Curvelets more suited for demigration/migration than for migration or demigration (modeling) alone • Applications limited to smooth background velocity models A similar analysis should be conducted for (non-smooth) general background velocity models (without the use of geometrical optics) Perspectives: new transform (e.g. with explicit curvature)?
Acknowledgements We would like to thank F. ten Kroode (Shell E&P) for fruitful discussions and support M. Noble and P. Podvin (Mines ParisTech) Shell E&P for partly funding the project