J. Adachi, T. Hartman, L. Lomas & R. PlumbSchlumberger, Houston, TX, USAI. Gil & M. SanchezItasca Houston, Inc., Houston, TX, USAR. TaghaviItasca Consulting Group, Inc., Minneapolis, MN, USA

Problem statementPETRELFLAC3D & the 3DShop optionImporting horizons into 3DShopOct‐tree grid generationPETREL grid extractionPETREL Property extractionSample calculationsWorkflow

Advanced Three Dimensional Continuum Modeling for Geotechnical Analysis of Rock, Soil, and Structural ElementsNew in FLAC3D: Speed, Virtually Unlimited Model Size and Geometrical Flexibility.New in 3DShop: Tetrahedral meshing, Oct‐tree meshing, Boolean operations on meshes

The 3DShop option of FLAC3D is composed of:

ModelDesign from C4W Solid ModelingKUBRIX®, from Simulation Works  Automatic Hex Meshing

ModelDesign

Auto-meshing

3DShop

KUBRIX® FLAC3D

Modelling Simulation

FLAC3D Grids

CAD data

3DEC Blocks

Given a PETREL database (grid, horizons, faults), need workflow software tools to build a FLAC3D model.Populate the FLAC3D model with properties extracted from the PETRELComplement missing information by adding them to the FLAC3D data file

Petroleum data files may be very large.Range of sizes (30 to 3,000 m) requires a non‐traditional meshing approachProperty transfer should be conservativeWorkflow should be simple and robust

In PETREL, export horizons in Zmap formatUse KUBRIX to decimate & translate them into STL filesRead the resulting STL files into 3DShop

Details are conservedShortest

edges are sorted and collapsed until a threshold feature angle is reached

111,976 to 1727 triangles: a 99% reduction

The geometry features size variations from 30 to 3,000 meters.Traditional grid generation approaches: tradeoff between grid size and distortionFLAC3D is one of the only packages that accepts dangling nodesOct‐tree meshing is forgiving with bad geometry

Unbalanced Balanced

Regions + Boundary Regions only

U: N ( n + 1 ) = 4 x N ( n)

1

10

100

1000

10000

100000

1000000

0 1 2 3 4 5 6 7 8

UB

If a property is available, it is readPETREL cell properties are weighed by volume of intersection (rezone) and assigned to FLAC3D elementsKUBRIX writes out an ASCII file the contains the propertiesKUBRIX writes out the local normal of all zones intersecting surfaces (for ubiquitous joint)FLAC3D reads the property file with FISH and assigns them to each element

FLAC3D element Φ PETREL cell

PΦ = PA VA + PB VB + PC VC + PD VD + PE VE + PF VF + PG VG + PH VH

PA

PF

PC

PG

PD

PB

PI

PE

PH

mudstone

sandstone

1

2

3

1

2

Water

joint

mudstone

sandstone

1

2

3

1

2

joint

PETRELgrid file

(contains properties)

zmap file of horizons

Zmap Translator

Volume Property Translator

Octree grid generator Property

fileMesh

(.flac3d) file

3DShop

FLAC3D

Result

Translates & coarsens

Zmap files into triangular patches in 3DShop

Reads volume properties from the

grid file and assigns them to

individual FLAC3D zonesUses an Octree

method to refine a coarse mesh in areas of interest

FLAC3D data file

Written by user & containing FISH to read Property file

1. Collect the following items1. Grid file (must contain properties: porosity, density, etc…)2. Horizons in the zmap format (must cover the same 

geographic region, all dimensions in feet)2. Run:

Kubrix –i waterbottom –it zmap –translate stl (This produces a file called x.stl)Rename x.stl to w.stlKubrix –i pleist1 –it zmap –translate stlmv x.stl p1.stl…………

1. Run 3DShop1. Create a new document2. Insert w.stl, p1.stl, p2.stl, u1.stl, u2.stl3. Save the complete model as: a1.stl4. Reflect the entire model with respect to the z = 0 plane5. Save the complete model, again, as: a1.stlYou have created the input geometry

2. Determine the box containing the FLAC3D mesh…• The box must not extend beyond the portion of the reservoir 

represented in the grid file

Run 3DShop…1. Read in a1.stl2. Select Applications|kubrix|Hexahedral Meshing. The Hexahedral 

Meshing dialog box opens…3. Click on Default to enter default values in all fields4. Enter the following string in the field marked New Keywords:

-mode octree -olevel 5 -obox 1646200 9733000 -5220 5800 4100 4000 -app petrel

1. Mode: specifies the custom Octree mesh type2. Olevel: specifies the level of Octree mesh generation3. Obox: specifies the position of the box: the first 3 floats 

are the coordinates of the center of the box and the next 3 indicate the dimensions of the box

4. app: specifies the custom application

Click on Compute…1. 3DShop reads a1.stl2. Creates and octree mesh that fits in the box specified by 

oboxwith olevel number of levels3. Parses the grid file, extracts the cells4. Extracts the properties5. Computes the contribution of each PETREL cell to each 

FLAC3D element6. Outputs PetrelProperties.dat7. Outputs a1.flac3d

PetrelProperties.dat a1.flac3d

1. Run FLAC3D2. Run ReadPetrelProperties.fis3. Remove water4. Attach face tol 1

5. Complement missing properties6. Manage model through FISH

• Reading PETREL in native format• Workflow simplification• Speedup