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Copyright © Gemcom Software International Inc.
The mining solutions you expect. From the people you trust.
Geological Modeling of Stratified DepositsDamian Baranowski – Principal Consultant (Asia)
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Grid Model vs Block Model2
Grid Model Block Model
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Grid ModelModel generated directly from data source (borehole and geometry)Grids honour data and follow trends smoothlyQuick model updateMaintain seam sequence
Block ModelManual digitising of points on sections Generate surface from strings (DTM or Wireframing) Block assigningProblem with seam overlapping and cross-overs
3
Grid Model vs Block Model
Cross sectionSeam A
Surfaces are fitted automatically to data
Grids are regularised surface incorporatng trending (smooth) They are NOT triangles.
Seam B
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Grid ModelAdequately represents thin seamsMore accurate modelsBetter handle variation of seam thicknessDesign for deposit large in lateral extentBetter represents faulted and folded structureMore accurate volume reporting Quicker validation
Block ModelLess accurate modelsSub-blocking is memory intensiveMuch higher storage capacity required Long processing time (impractical)Not suitable for faultingInaccurate modeling leads to incorrect assessment of project value
4
Grid Model vs Block Model
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5
Modeling Operations – Ply Splitting
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
SS SS SSSS
SS
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
BS BS BS BS BS
A
A1
A2
A11
A12
A21
A22
A111
A112
A12 A12
A112
A111
A21
A22
A2
BH1 BH2 BH3 BH4 BH5
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6
Modeling Operations – Ply Splitting
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
SS SS SSSS
SS
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
MD
BS BS BS BS BS
A111(E)
A12
A21
A22
A111
A112
A12 A12
A112
A111
A21
A22
A112(E)A111(E)
A112(E)
A111(E)
A112(E)
A12(E)
A21(E)
A22(E)
A12(E)
A21(E)
A22(E)
A21(E)
A22(E)
BH1 BH2 BH3 BH4 BH5
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7
Modeling Operations – Father/Son
CO
CO
CO
CO
CO
CO
CO
CO
CO
SSSS SS SS SS
MDMD
MD
MD
MDBS
BS BS
BS
BS
B BU
BH1 BH2 BH3 BH4 BH5
BB
BU
B
BL
B
BU
BL
CO
CO
SS
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8
Modeling Operations – Father/Son
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
SSSS SS SS SS
MDMD
MD
MD
MDBS
BS BS
BS
BS
B BU
BH1 BH2 BH3 BH4 BH5
BL
BB
BU
B
BL
B
BU
BL
SS
CO
BU(E)
BU(E)
BL(E)BL(E)
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9
Modeling Operations – Interpolator
CO
SS
CL
BS
A
BH1
BH2
B
C
D
CL
CO
CO
MD
CO
CO
SS
CL
BS
A
B
C
D
CL
CO
CO
MD
CO
BH3
CO
SS
A
CCO
CO
SS
A
BH4
CCO
MD
CL
CL
BS
BH5
B
C
CL
CO
CO
MD
CL
BH6
B
C
D
CL
CO
CO
MD
CO
MD
CL
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10
Modeling Operations – Interpolator
CO
SS
CL
BS
A
BH1
BH2
B
C
D
CL
CO
CO
MD
CO
CO
SS
CL
BS
A
B
C
D
CL
CO
CO
MD
CO
BH3
CO
SS
A
B(I)
C
D(I)
CO
SS
A
BH4
B(I)
C
D(I)
CO
MD
CL
BS
BH5
B
C
CL
CO
CO
MD
CL
A(I)
BH6
B
C
D
CL
CO
CO
MD
CO
MD
A(I)
D(I)
CO
CLCL
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11
Modeling Operations – Parameters
Splitting– validation– average or area factors – borehole & seam selection– data classification
Interpolator – searching parameters (scan distance, sectors, max. points)– borehole & seam selection– seam priority– setting seam thickness to zero– data classification
Father/Son– validation – area selection – borehole & seam selection– data classification
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12
Modeling Operations – User input
User’s interpretation is required (important factor)The results cannot be more accurate than input dataGood visualisation – helps with the interpretationCheck result graphically and numerically
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Fault Modeling13
Coal deposits are subject of complex faultingCritical aspect of modelingModeling of inclined or curved faults in normal or reverse environmentInput data: fault strings (or fault surface) with dip and throw
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14
Fault ModelingUn-faulting boreholes in chronological sequenceModeling operations, generating modelRe-faulting the model to its current faulted position.
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Growth Technique Features
Best suited for Structural modelling (Seam roofs and floors)May be used for quality attributes (thickness, ash etc)Honours the data pointsExtrapolated values (estimates outside data value range)Expansion outside data area (by distance or “Fill Area”)Declusters data (Averaging and redistribution)Produces accurate and smooth displays (Contour maps etc)Various data type support (spots, break lines, faults, trends)
15
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Growth Technique – Interpolation Methods
Growth Technique uses a combination of interpolation methods1. Inverse Distance estimation,2. Secant plane estimation and3. Tangent plane estimations at each mesh point
Stage 1 (Regional grid generation) uses methods 1 and 2Stage 3 (Final gridding) uses methods 2 and 3.**
The Secant Plane is determined using a least squares fit using data from the surrounding 8 sectorsThe Tangent Plane is determined from a first order differential equation from immediate “known” points
** Where there is lack of data (< 5 sectors) Stage 3 will resort to Methods 1 and 2.
16
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Growth Technique – Interpolation Methods17
Previously Estimated points
Tangent Plane Estimations
Secant Plane Estimation
Tangent Planes
Estimation Point
Secant Plane
Actual Surface
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Growth Technique – Input data18
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Growth Technique – Initial Gridding 19
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Growth Technique – Final Gridding 20
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Growth Technique – Final Grid21
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Thank you for your attention 22
To learn more, visit www.gemcomsoftware.com
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