BP AIT 2004 2D velocity benchmarkFrederic Billette – AIT Houston
Copyright s BP America Inc. - No release, transfer, license, sell, trade or otherwise disclosure permitted outside of Queen’s U.
Legal issuesData release agreement dated February 3rd, 2004 and
confidentialityagreement dated September17th, 2004 specify that:
• You can:– use the dataset internally for any purpose.
– Publish / show results using this dataset.
– Show these slides internally.
– Publish / show your result compared to the exact model after specific permission to be obtained from BP ([email protected]).
• You can not:– Release, distribute or sell the dataset.
– Show, release, distribute or sell any material extracted form this presentation to a third party (exception specified above).
Agenda
• Model, data, challenges, …
• Queen’s U. contribution
• Velocity model comparison
• PSDM image comparison
• Feedback & ranking
Timeline
Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
2003 2004
Model generation
Data generation
QC
Data offered tothe industry
Exact model revealedResults collected
Resultsanalyzed
Feedback to contractors
Feedbackprovided
Results distributed to the network
Model Generation
Velocity
Density
67km wide, 12km deep, build on a 6.25m x 6.25m grid
Salt 1 - Shot migration no SRME
overpressurezones
sedimentinclusion
complexoverhangs
Complex/brokenreflectivity
Challenges 1/3
rugose top salt
multiples
steepdips
Salt 2 - Shot migration no SRME
poorly imagedflanks
shallow HVanomaly
channels
Challenges 2/3
Extra salt - Shot migration with SRME
HV anomalies onstructure flanks
shallow LV anomalies
mud volcano
shallow gas
Challenges 3/3
Data generation
• 2D Finite difference acoustic modeling (variable velocity & density).
• Free-surface multiples are present.
• Data shot split-spread (streamer data provided), every surface point recording data. Shot every 50m, receiver every 12.5m. 6ms sampling.
• Frequency peak is 27Hz and data can be whitened up to 54Hz.
• The wavelength is causal and has not been 0 phased (see typical trace below), time delay can be estimated considering the zero offset traces.
Data transfer
• Tape or ftp download available.
• Document with experiment details provided.
• 15km of offset..
• Model to be returned by June 9, 2004 when the exact model was revealed.
Data recipients
• 1 oil company
• 13 seismic contractors
• 7 universities
• 3 research institutes
• 1 software company
Total: 25
Presented results publicly at the EAGE
• 0 oil company
• 5 seismic contractors: CGG, Veritas, GXT, Paradigm, and Data Modeling Inc. (Calgary)
• 2 universities: KACST (Riyadh) and Queen’s (Kingston)
• 2 research institutes: SINTEF (Trondheim) and OPERA (France).
• 0 software company..
Total: 9
Participating to BP benchmark
• 0 oil company
• 8 seismic contractors: CGG, Veritas, WesternGeco, PGS, GXT, Fairfield, Paradigm, Data Modeling Inc. (Calgary)
• 2 universities: DIG (Paris), Queen’s (Kingston)
• 2 research institutes: SINTEF (Trondheim) and OPERA (Pau)
• 0 software company..
Total: 12
Queen’s University contributors
Small team work in an university lab
Professor:
Gerhard Pratt
Student:
Drew Brenders
Queen’s U. processing flow• Reduced the dataset:
1 - 7.5Hz, 1/8 shots and 1/8 receivers, 2km – 15km offset
• Initial smooth model using first-arrival travel time tomography
• Automatic velocity update without migration using waveform tomography
• No salt interpretation, all automatic
• Did not request feedback
Part1: velocity models
Display information
• All images are vertically exaggerated 3 times
• DX=25m ; Dz=6.25m
• Images are 67km wide and 12 km deep
• Velocity scale goes from 1429m/s to 4790m/s
(min & max in the exact model)
Exact model
Exact model: velocity contours
Queen’s University
A
B
C
Note: C did not deliver the right part of the model on time.
C
Note: C delivered the right part of the model on September 1st, 2004.
D
E
Note: E estimated the model extra-salt only
F
Note: left and right part have been updated independently.
H
I
J
Note: J estimated the sediment velocities only
K
L
Note: L estimated the model extra-salt only
Part2: migrations
Display information
• All images are vertically exaggerated 3 times
• DX=25m ; Dz=6.25m
• Images are 67km wide and 12 km deep
• Model have been expanded or reduced if necessary
• 2D SRME has been applied
• No other pre or post-processing applied
• 2D wave-equation migration (downwards propagation only)
• For display purposes, low frequency outputs are presented
• Exact water layer has been inserted.
Exact density model
Exact model
Exact model
Queen’s University
A
B
C
Note: C delivered the right part of the model on September 1st, 2004.
D
E
Note: E estimated the model extra-salt only
F
Note: left and right part have been updated independently.
H
I
J
Note: J estimated the sediment velocities only
K
L
Note: E estimated the model extra-salt only
Queen’s University: strengths
• Good long & short wavelength updates in the shallow section.
• Impressive resolution for some shallow anomalies.
• Good image of the top salt without interpretation.
• Good delineation of the overhangs without interpretation.
• See glimpses of the base salt.
+
Queen’s University : weaknesses
• Deep part of the model not estimated.
• Variable velocity in salt.
• Too high frequency. Regularization/smoothing issues?
• Imaging issues with several targets, even shallow.
-
Ranking Process
• Ranking along 2 axes: 1) salt & sub-salt ; 2) extra salt sediment
update.
• Ranking is an average after ~12 peer review.
• Only results provided on time were considered.
• Ranking is based on this test only.
Ranking
B
IA
K
J
E
L
Quality of salt and sub-salt model building
Acc
ura
cy o
f extr
a-s
alt
sedim
ent
update
F
H
C
D
Ranking
IA
K
J
E
L
Quality of salt and sub-salt model building
Acc
ura
cy o
f extr
a-s
alt
sedim
ent
update
F
Tier 1Tier 2Tier 3
Tier 1
Tier 2
Tier 3
H B
C
D
Questions?