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

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.