Transcript SEAM Phase I Model

SEG 2009 Workshop
SEAM Phase I Model
SEAM Phase I Model
Outline
Model Overview - Structural Macro view
Model scale and domain
The Salt
Major Sedimentary Surfaces
Special surfaces (i.e. Salt, sutures, sediment raft, faults )
Adding fine layered properties within macro structure
Construction process
From Surfaces to Stratigrphic Grids
Rock Properties.
Rock Physics and Reservoirs
Model properties
SEAM Phase I Model
Model Overview – Components
I) Provenance
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A deep water Gulf of Mexico salt domain analogue.
II) Major Structural Features
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1 Complex salt body with a rugous top, a root, and overhangs
9 Horizons that extend across the entire model
12 Radial faults arrayed under salt and near to the salt root stock
1 Overturned sediment raft proximate to salt root
2 internal sutures in salt and a heterogeneous salt cap
III) Special Features in the model
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Reservoirs, Difractors, SEG stamp, Fine layering, Multiple properties
SEAM Phase I Model
Model Overview - Volume of Interest
• Size and Orientation
35km EW x 40km NS x 15km Depth (27 x SEG Salt)
E-W = X
N-S = Y
Depth=Z
• XYZ Origin = (0,0,0)
• Grid Size
properties were built on 10m and 20m grid spacing
10m 84.1gb/property (21 billion cells = 220x SEG Salt)
20m 10.52gb/property
x-y-z storage order
Phase I Model – A complex deep water salt model
35 Km
Top View
40 km
View from west
40 km
View from east
SEAM Phase I Model
Model Overview - The major sediment horizons
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8.
9.
Basement
Top Mother Salt
MCU (Mid Cretaceous Unconformity)
Top Olicoene/Paleogene “4_Oligocene”
Top Lower Miocene “5_Miocne_1”
Top Mid Miocene “6_Miocene_2”
Miocene Pliocene Unconformity “8_Mio_Plio_UNCF”
Top Pliocene
Water Bottom
A Blank Canvas
Flat Basement, Z=14858m
Top Mother Salt
MCU – Top Cretaceous
MCU – with radial faults
MCU – with salt removed
Oligocene
Miocene_1, top of lower Miocene
Miocene_2, top mid Miocene
Mio-Plio Unconformity - uncut
Pliocene - uncut
Water Bottom
SEAM Phase I Model
Model Overview – Other Special Surfaces
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2.
3.
Salt Sutures – entrained thin sediment
Overturned sediment raft
Radial Faults
Salt suture sufaces
Salt suture sufaces - zoom
Radial fault surfaces (12)
Overturned sediment raft
Sediment raft relative to salt - density
SEAM Phase I Model
- Going from macro structure to fine layered detail -
Model Construction Work Flow
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Build salt surface
- Construct patches from top and base interpretations
- Merge salt patches into hermetically sealed surface.
- Iterative revisions to address concerns
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Construct sediment surfaces for a cellular version of the model
- used both triangulated and regular 2D gridded objects
- Introduce faults into surfaces and make consistent with faults
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Build indicator volume to flag model regions
Form stratigraphic reservoir grids from bounding surfaces
For 7 major sedimentary units and each property (Vp,Vs, r, Rn, Rt )
- Morph properties from a local cartesian grid to a strat-grid
- Transfer property from the strat grid to the global cartesian grid
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Mask in salt & overturned sediment raft after property set on major units
Interpolate | average | smooth to final 10m grid
SEAM Phase I Model
Indicator Volume
Basement
1
Mother Salt
2
Cretaceous
3
Oligocene-Paleo
4
Lower Miocene
5
Middle Miocene
6
Upper Miocene
7
Pliocene
8
Pleistocene
9
Water
10
Inv. Lower Mio.
11
Inv. Olig-Paleog.
12
Inv. Cretaceous
13
Salt Suture
14
Salt
15
Hetero Salt
17
10
9
17
14
15
13
12
11
2
Bounding surfaces to define Pliocene reservoir grid
Pliocene density on UVW grid
Pliocene density morphed from UVW to XYZ strat-grid
421 million cells – 1 of 7 grids
Density transferred to Cartesian global grid
turbidite fan
salt
channel
SEAM Phase I Model
Model Overview – Reservoirs and Statisitics
Catalogue
Pleistocene
Pliocene
Upper Miocene
Middle Miocene
Lower Miocene
5 small turbidite fans
2 E-W trending braided channel systems
2 N-S trending braided channels in eastern half
2 Large turbidite fans that enter from North
2 Large turbidite fans that enter from North
SEAM Channel and Turbidite Reservoirs
SEAM Phase I Model
Rock Properties & Physical Properties
• Conceptual Framework
•Rock Properties
•Statistics
•Channel Procedure
•Turbidite procedure
Rooting the seismic simulation back into the rock properties
( Conceptual Framework for SEAM Model )
Elastic parameter modeling
from Rock properties
Seismic modeling from
Elastic parameters
Rock Properties
Elastic Parms
Seismic Waves
Vshale, Porosity, Fluids,
Sat, Pressure, Resis, …
Vp, Vs, Dn, Cij, Q
P, S, qP,S, atten/disp; EM
response, Gravity
(and their reflectivities)
Elasticity inversion
for rock/reservoir properties
Interest group on this end:
Reservoir characterization and
Monitoring
AVO reflectivity inversion
for elastic parameters
Interest groups on this end:
Imagers, Tomographers, Processors
The Rock Property Is The Root of Seismic Behavior
The earth model is rooted in the rock properties to force physical consistency across derived
elasticity parameters!
Several independent rock properties form the “basis functions” from which all elastic
parameters are consistently derived via rock physics + well statistics!
Properties(X,Y,Z) in ~ order of significance:
Vshale: varies from 0 to 1 and indicates the relative volume of sand and shale
lithologies; in this case shales are taken to be interbedded with sands.
Porosity of the Sand endmember: variable and germane to fluid substitution
Porosity of the Shale endmember: variable but not involved in fluid substitution
Pore Fluid: (type and saturation) affects bulk modulus of sand via Gassmann
Resistivity: bed-normal and bed-parallel anisotropy
Net Pressure: most important for soft sands, but not significant in model
Rock physics & well statistics information:
Porosity Depth Trend: scaffold on which porosity variation is superposed
Cementation/Diagenesis: provides the steep modulus vs porosity trend
Deposition (sorting etc.): provides the shallow modulus vs porosity cross-trend
Gassmann & simple contact theory: fluid and overpressure effects
Porosity retention with burial/uplift: V contours parallel neither structure nor seafloor
Archie’s Law: for ionic flow in porous sand, also ~ modified for shales
SEAM STRATIGRAPHY
•Rock properties based on generated statistics
•Could base properties on real data statistics
sheet turbidites
sheet turbidites
Plio
Up Mio
stacked channels
Md Mio
stacked channels not in section
Lo Mio
leaf turbidites
Pal Olig
marl streaks
Cret
leaf turbidites
Pleisto
Stratigraphic vshale section (white=sandier)
Cross-section shows vshale statistics on flat UVW grid
SUMMARY OF
CHANNEL RESERVOIR ARCHITECTURE
Channels at one depth level. Channels are 20 m thick, and top rectangle is 35 km long (EW) X 10 km wide (NS). Two channels
per depth level, 12 depth levels in the channel complex for a total complex thickness of 240 meters. Each level of the 12 has
a different but statistically similar pair of channels.
The main statistical features of the channels (length, width, thickness,
sinuosity, vshale distribution) come from real world measurements of hires seismic and outcrop observations.
Zoom of above, ~ 11 km long. Individual channels average ~180 m across
*Within* channels, red ~ 5% vsh, light green ~ 25% vsh, blue ~ 60% vsh;
Outside of channels = background shale from main model
SAME upper panel as in previous slide.
Image of the average vshale vertically averaged through all 12 depth levels of the channel complex. Now, red ~ 50% vsh, blue ~
80% vsh (because of partial averaging contribution from background vsh of ~100%) . The complex is just over one wavelength
thick, so this image represents what a medium wavelength wave could sense. Individual channels are from 150 to 220 m wide;
entire channel complex about 2 to 3 km wide
Zoomed on next slide
Zoom of previous panel. ~ 5 km left to right. The blue-green part of the channel complex is about 1.6 km
across . The individual 20 m cells are visible at this scale. Blue disk represents a dominant wavelength of
about 200 meters (3000 m/s / 15 Hz). Effective imaging resolution will be poorer given noisy data, subsalt
illumination, and inaccurate velocity model.
Find the sweet spots in the channels.
SUMMARY OF
TURBIDITE RESERVOIR ARCHITECTURE
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4.
Turbidite channels digitized from high-resolution, near surface seismic images of recent turbidites.
This and two other templates rotated and stretched to produce multiple turbidite complexes.
Each filamentary channel “dressed up” with vshale and width variations.
Full turbidite complexes superposed and scattered across the various reservoir strat levels.
200 m vertical average of “dressed” turbidite vshale: white=sandier, blue=shalier
Channel elements narrow distally: start at 240 m width in throat, end up 70 m wide
Superposed on salt for orientation. Entire 35 km width of model shown. Yellow bars = 10 km
Mid Miocene Reservoirs: vshale
(red = sand, white = shale)
Multiple turbidite complexes. Similar
fans superposed over 4 consecutive 20m layers (80 m thick complex), followed
by 40 m of shale, followed by another
similar 80 m thick complex.
10 km
SAMPLE WELL LOGS
Central Model. NOTE: depths = strat cell X 20m, so gradients are not “perfect” due to lack of absolute depth warping
Well x=900 y=983 cells (eroded)
9Pleist
8Plio
7UpMio
6MdMio
5LoMio
0.8
4OligPaleo
3Cret
oil
oil
gas
oil
1
Two Reservoir Penetrations
vshnorm
Vpnorm
Por
0.6
Reflecnorm
Vptomonorm
0.4
0.2
MioPlioUNCF
Normalized Units
Dnnorm
turbidite
reservoirs
0
0
2000
4000
6000
8000
Depth BML (m)
10000
12000
14000
Example
Seismic
Section
1D (0-offset) Reflectivity convolved with 0-3-12-25 Hz 0-phase Ormsby bandpass filter Y=cell 1000
< Small Reservoir
< Channel Reservoir
(not visible here)
7UpMio
8Plio
9Pleist
Chaotic Pleistocene
< Small Reservoir
< Channel Reservoir
3Cret 4OligPaleo
5LoMio
6MdMio
< Turbidite Reservoir
NOTE: These were created separately and glued together, so in this figure there is *no* reflectivity present at the macrolayer boundaries.
< Top overpressure
< Turbidite Reservoir
< Bot overpressure
< Olig marlstones
< Low coherency, low
amp Paleogene
< Hi amp sandy
carbonates in Cret
Special Features – SEG density logo
Special Features – deep density difractors
Special Features – radial faults
Special Features – shallow difractors
Shallow difractors in density
SEAM Phase I Model
Existing Model Properties
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Vp
P-wave velocity
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r
R n, R t
Vs
density
normal and transverse resistivity
Shear velocity
Distinctive Nature of SEAM model
• Geophysical Properties based on Rock properties
• Scale of model and fine scale statistics
• To elasticity and beyond - Vs is future aspiration
SEAM Phase I Model
Acknowledgments
•
Many thanks to Joe Stefani, Dean Stoughton, Edward
Naylor, Joachim Blanche, Jacques Leveille for time
spent constructing the model
• Mike Fehler for managing a distributed process
• To the management of sponsor companies that allowed
their employees to contribute to this industry project.
• The SEG for providing assistance and guidance.