Introduction to velocity model building

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Palestra apresentada por Luís Fernando Cypriano (CGG), durante a IV Semana de Inverno de Geofísica, IMECC/Unicamp, 2013

Palestra apresentada por Luís Fernando Cypriano (CGG), durante a IV Semana de Inverno de Geofísica, IMECC/Unicamp, 2013

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  • 1. Introduction to velocity model building IV Semana de Geofísica - UNICAMP July 2013 Luís Fernando Cypriano
  • 2. Outline  Who we are?  Seismic processing overview  Velocity analysis  Velocity model inversion  Layer striping  Three examples of CGG model inversion technologies
  • 3. Who we are? 3
  • 4. Delivering advanced geoscience solutions Full range of products and clear market leadership onshore, offshore and downhole:  Technology leadership  Large installed base  A cornerstone for CGG integrated solutions Full range of seismic and other geophysical methods for acquisition:  Land  Marine  Seabed*  Airborne**  Subsurface Imaging  Reservoir Software & Services  Geological Services  Exploration & Appraisal  Satellite Mapping  Multi-Client Data Library (Seismic, Grav-Mag, Geological)  Data Management Services Geology, Geophysics & Reservoir AcquisitionEquipment  9,800 employees  70 locations worldwide  $4.2 Bn 2011 pro-forma revenue *Through the Seabed Geosolutions joint venture owned 60 % by Fugro % and 40 % by CGG **Airborne will be integrated once operating licenses and administrative authorizations have been received4
  • 5. Passion for Innovation 1930 1940 1950 1960 20201970 1980 1990 2000 2010 Creation of CGG Wide Azimuth Acquisition Long-Offset Marine Acquisition Digital Innovation Processing on Micro Sercel 408 2D Innovation UltraSeis Kirchhoff PSDM 3D SRME BroadSeis RTM 3D Gather HPVA Sercel 428 Nautilus Sentinel Reflection Seismic 3D Innovation Sercel 348 UNITE StagSeis  A unique history of innovation leadership  R&D commitment  Technology partnerships and centers – Saudi Aramco (Al Khobar) – Petrobras (Rio) 5
  • 6. CGG Brazil 6
  • 7. Seismic processing overview 7
  • 8. Where are the hydrocarbons? Fonte: http://diariodopresal.files.wordpress.com
  • 9. Exploring the Earth’s subsurface Fonte: http://tle.geoscienceworld.org 𝑍 = 𝜌𝑉 𝑑 = 𝑉𝑡
  • 10. From seismograms to 3D structural images Preprocessing • Static Correction • Noise and Multiple attenuation • Amplitude Correction • Regularization Model Building • RMO/Dip picking • Layer interpretation • Initial velocity flood • Model inversion • Velocity update • Migration Final Migration • Technique • Pre-Stack • Post- Stack • Domain • Time • Depth • Algorithm • Kirchhoff • RTM • CBM • W.E.
  • 11. Velocity analysis 11
  • 12. Common Image Gather constriction tempo offset 𝑇2 = 𝑇0 2 + 𝑥2 4𝑉2 𝑇0 = 𝐿 𝑉 𝑥 𝑳
  • 13. Moveout correction tempo offset 𝑇0 𝑇 tempo offset 𝑇0 𝑇2 − 𝑥2 4𝑉2 = 𝑇0 2 What if we remove the exact amount of travel time caused by the source-receiver offset?
  • 14. Moveout correction over real seismic gathers Before moveout correction After moveout correction
  • 15. Velocity model inversion
  • 16. 16 Migration with the Initial velocity model INITIAL MODELMigrated session * These images are for illustration purposes only
  • 17. Take Common Image Gathers on a regular grid trough the entire session. 17 Residual Moveout (RMO) Analysis and Picking Are the gathers flat? Can we improve the initial velocity? INITIAL MODELMigrated session * These images are for illustration purposes only
  • 18. Take Common Image Gathers on a regular grid trough the entire session. 18 Velocity update INITIAL MODEL There are several methods for velocity inversion. We shall try a standard tomography. UPDATED MODELMigrated session * These images are for illustration purposes only
  • 19. 19 New Migration to confirm UPDATED MODELNew Migrated session * These images are for illustration purposes only
  • 20. 20 Conclusion: Image Before Update INITIAL MODEL Migrated session CIG gathers * These images are for illustration purposes only
  • 21. 21 Conclusion: Image After Update UPDATED MODEL * These images are for illustration purposes only Migrated session CIG gathers
  • 22. Layer striping 22
  • 23. Update from WB and below 23 - Stack & CIGs QC. - Top layer interpretation. - Update velocity below layer top. Top-down velocity model building 1.Sediment flood 2.Sediment update 3.Velocity Contrast Update 4.Final Bottom Update
  • 24. Summary 24 Initial model for new layer Migration RMO pick Velocity Update for new layer Repeat for new layer Last Layer Update
  • 25. Examples of CGG model inversion technologies 25
  • 26. Integrated Imaging Solutions 26 STREAMER Conventional BroadSeisTM OCEAN BOTTOM OBC, OBN WIDE AZIMUTH WAZ , RAZ MAZ, StagSeisTM LAND Imaging algorithms Single arrival (Kirchhoff) Anisotropy (VTI, TTI, HTI, Ortho) Wave field (WEM, RTM) Model Inversion Full Wave solutions (FWI) High Definition Q Migrations Multi-layer inversion Visualisation Tornado Hybrid model Salt handling Tomography (Time & Depth) Time and Depth Amplitude & Q Multi arrival (CBM, APCBM, Beam)
  • 27. 27 Multi-layer tomography – North Sea Dutch sector 1st pass updated model – Kirchhoff migration1st pass updated model – Kirchhoff migration
  • 28. 28 Multi-layer tomography – North Sea Dutch sector Final model – Kirchhoff migrationFinal model – Kirchhoff migration
  • 29. High Definition Tomography (TOMOHD) – West Africa (2) 29 1.5 2.5 3.5 4.5 5.5 km/s 2 km 500m Initial Vint & Final PreSDMInitial Vint & Final PreSDM
  • 30. High Definition Tomography (TOMOHD) – West Africa (2) 30 2 km 500m TOMOHD Vint & Final PreSDMTOMOHD Vint & Final PreSDM 1.5 2.5 3.5 4.5 5.5 km/s
  • 31. Initial velocity model and Kirchhoff PSDM BROADSEISTM
  • 32. FWI updated model and Kirchhoff PSDM BROADSEISTM
  • 33. Thank you! Aknowledgements: Tadeu Vidal, Mathieu Reinier, Luís D’Afonseca, Raquel Mauler, Yamen Belhassen, Olivier Garde and Roger Taylor.