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Geomechanical Performance of Hydrate-Bearing Sediments in Offshore Environments
Schlumberger PlansRichard A. PlumbN.E.T.L, Morgantown W.Va.January 19, 2007
© 2006 Schlumberge All rights reserved.
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Objectives
Develop the capability of building 4D Geomechanical models of the near-seafloor deep-marine hydrate-bearing sediments.
Interface Petrel framework model with FLAC3D
Develop 4D geomechanics models of the near-wellbore region of hydrate-bearing deep-marine sediments
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Scope of work 2006
H1 2006Review the geological structures on the U.S. continental margins characteristic of the gas hydrate stability zone (GHSZ).Determine whether Petrel’s framework modeling tools can reproduce realistic fault and sedimentary structures of the (GHSZ)
H2 2006Evaluate the capability to interface Petrel with FLAC3DRecommend improvements to Petrel developersContract ITASKA to interface Petrel to 3DShop and FLAC3DSelected Keathley Canyon as a field test siteBuild a small Petrel modelExported Petrel surfaces and geological properties to ITASKA software
© 2006 Schlumberge All rights reserved.
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Geological environment
~ Hydrate Stability Zone
Complex structure due to salt diapirism
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Gulf of Mexico Gas Hydrates Joint Industry Participation Project
Petrel ModelPetrel Model
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Modelling challenges seen in seismic section at Keathley Canyon
BSR
PossibleHydrate mound
Waterbottom4260 feet BMSLClays, coarsergrained lenses,slope fans.
Sand-shales,channel levee systems.
LST slope fans,channeling, slopefailures, chaoticevents.
unconformity
HST
HST
LST
HST
LST
Unconfomity
Sand-shalelaminates, slopefan deposits.
HST shales andsand layer laminates.
LST
SBSB
SB
SB
?
Keathley Canyon Inline 5591
Pleist1
Line 5591
Depth TVDSS(ft)
4694
5254
5823
6445
7108
BSR
PossibleHydrate mound
Waterbottom4260 feet BMSLClays, coarsergrained lenses,slope fans.
Sand-shales,channel levee systems.
LST slope fans,channeling, slopefailures, chaoticevents.
unconformity
HST
HST
LST
HST
LST
Unconfomity
Sand-shalelaminates, slopefan deposits.
HST shales andsand layer laminates.
LST
SBSB
SB
SB
?
Keathley Canyon Inline 5591
Pleist1
Line 5591
BSR
PossibleHydrate mound
Waterbottom4260 feet BMSLClays, coarsergrained lenses,slope fans.
Sand-shales,channel levee systems.
LST slope fans,channeling, slopefailures, chaoticevents.
unconformity
HST
HST
LST
HST
LST
Unconfomity
Sand-shalelaminates, slopefan deposits.
HST shales andsand layer laminates.
LST
SBSB
SB
SB
?
Keathley Canyon Inline 5591
Pleist1
Line 5591
Depth TVDSS(ft)
4694
5254
5823
6445
7108
Depth TVDSS(ft)
4694
5254
5823
6445
7108
4694
5254
5823
6445
7108
Faults
Unconformities & Pinchouts
Salt bodies
Hydrate mounds
Discordant contacts-e.g. BSR
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Geomechanical Property Modelling Workflow
PetrelProperty Modeling
PetrelProperty Modeling
Vp
Bulk Density
Pp
GeophysicalLogs
3D seismic volumes (time domain)
Framework model
Bulk density
Lithology
Porosity
Elastic parameters
Strength parameters
Pp
FLAC3DGeomechanics
Simulator
FLAC3DGeomechanics
Simulator
3D geo-property volumes (depth domain)
PetrelProperty Modeling
PetrelProperty Modeling
VpVp
Bulk DensityBulk Density
PpPp
GeophysicalLogs
3D seismic volumes (time domain)
Framework model
Bulk density
Lithology
Porosity
Elastic parameters
Strength parameters
Pp
Framework modelFramework model
Bulk densityBulk density
LithologyLithology
PorosityPorosity
Elastic parametersElastic parameters
Strength parametersStrength parameters
PpPp
FLAC3DGeomechanics
Simulator
FLAC3DGeomechanics
Simulator
3D geo-property volumes (depth domain)
Interactive, Seismic volume extraction
Digitize faults in,3D Seismic volume
Model complexgeobodies
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Keathley Canyon Horizons in Petrel
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Keathley Canyon- preliminary bulk density volume
Gardner’s relationship: RhoB= a(Vp)^b
Coefficients for mudstone: a=1.75, b=0.265
Coefficients for sandstone: a=1.66, b=0.261
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Simplifiled Keathley Canyon model in Petrel
Faults are not explicitly modeled in ITASKA’s initial surfaces data set
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ITASKA’s Modelling Workflow
PETREL
Base3DShop
FLAC3D
Local Octree Refinement
Zmap Translator
Volume Property Translator
Result
Reads volume properties from the grid file and assigns them to individual FLAC3D zones
Translates Zmapfiles into triangular patches in 3DShop
Uses an Octree method to refine a coarse mesh in areas of interest
PETREL
Base3DShop
FLAC3D
Local Octree Refinement
Zmap Translator
Volume Property Translator
Result
Reads volume properties from the grid file and assigns them to individual FLAC3D zones
Translates Zmapfiles into triangular patches in 3DShop
Uses an Octree method to refine a coarse mesh in areas of interest
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Geologic Horizons in ITASKA’s 3DShop
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Proposed Next Steps 2007
ITASKARead Petrel property volumeDesign the software interfacePerform a sample geomechanical calculation in FLAC3D
SchlumbergerRefine the input velocity modelIntroduce well log data and perform log-guided seismic inversionConstruct geomechanical property volumesPerform a sample geomechanical calculation in FLAC3D
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Questions/Discussion