Studio 3 Geological Modeling User Guide

(1)

Geological Modeling

Studio 3 User Guide

Studio 3 Geological Modeling Concepts and Processes

TTR-MUG-ST3-0003 TTR-MUG-ST3-0003

Datamine Software Limited Datamine Software Limited 2, St Cuthbert Street

2, St Cuthbert Street

Wells, Somerset, United Kingdom Wells, Somerset, United Kingdom Tel:

Tel: +44 +44 (0) (0) 1749 1749 679299679299 Fax:

Fax: +44 (+44 (0) 0) 1749 6702901749 670290

Author:

Author: James James NewlandNewland Technical Author Technical Author Datamine Software Limited Datamine Software Limited

(2)

The core aspect of this process, and the most significant single component required to The core aspect of this process, and the most significant single component required to undertake this task, is the Block Model. This data type, a key component of Studio 3 undertake this task, is the Block Model. This data type, a key component of Studio 3

software, is described in detail, from its initial composition in the form of a prototype model, software, is described in detail, from its initial composition in the form of a prototype model, to a full resolved block model mass comprising parent and sub-cells. This guide explains each to a full resolved block model mass comprising parent and sub-cells. This guide explains each aspect of geological modelling in detail, from both a Studio 3 perspective and a real-world aspect of geological modelling in detail, from both a Studio 3 perspective and a real-world basis.

(4)

1

1 _O

_O

_VERVIEW

Purpose of this document

This document aims to provide: This document aims to provide:

!

! An understanding of the basic concepts behind geological modelling.An understanding of the basic concepts behind geological modelling. !

! An explanation of the block model An explanation of the block model data type, parent cells and sub-cells.data type, parent cells and sub-cells. !

! Details of the files and fields associated with Details of the files and fields associated with block modelling processes.block modelling processes. !

! An overview of the different techniques used An overview of the different techniques used for manipulating the block modellingfor manipulating the block modelling

processes. processes.

!

! A brief foray into the area of A brief foray into the area of Grade Estimation. This is intended as a precursor toGrade Estimation. This is intended as a precursor to

the

the ‘ ‘Studio 3 Grade Estimation User GuideStudio 3 Grade Estimation User Guide’ ’

Prerequisites

Although this document explains the concepts of

Although this document explains the concepts of geological modelling, you should havegeological modelling, you should have at least a basic understanding of real-world geological modelling

at least a basic understanding of real-world geological modelling processes.processes.

Acronyms and Abbreviations

The following Acronyms and Abbreviations are used throughout this document: The following Acronyms and Abbreviations are used throughout this document:

Acronym Description Acronym Description DTM

DTM Digital Digital Terrain Terrain ModelModel

More information

!

(5)

2

2 _I

_I

_NTRODUCTION

The purpose of a geological model is to accurately represent not just the grades of a deposit, The purpose of a geological model is to accurately represent not just the grades of a deposit, but also its boun

but also its boundaries and internal structures.daries and internal structures.

A Datamine geological model is composed of rectangular blocks, or cells, each of which has A Datamine geological model is composed of rectangular blocks, or cells, each of which has attributes such as grades, rock types,

attributes such as grades, rock types, oxidization codes, etc.oxidization codes, etc. Though many cell shapes, such

Though many cell shapes, such as polygons, distorted cubes, mathematias polygons, distorted cubes, mathematical surfaces andcal surfaces and triangulations are pos

triangulations are possible none is completely general in sible none is completely general in application. application. The simplest form The simplest form ofof three-dimensional model consists of a rectangular grid in which each cell has the same three-dimensional model consists of a rectangular grid in which each cell has the same dimensions.

dimensions. This is also This is also the most commonly used type the most commonly used type of model because it lends of model because it lends itself wellitself well to efficient handling in a computer.

to efficient handling in a computer.

For some deposits there can be elegant solutions to the problem of representing grades and For some deposits there can be elegant solutions to the problem of representing grades and geological boundaries.

geological boundaries. A comprehensive modelling system A comprehensive modelling system such as Studio 3, such as Studio 3, however,however, requires a method that is applicable without modification to the widest possible range of requires a method that is applicable without modification to the widest possible range of deposits.

deposits. The solution is to The solution is to use a block model that use a block model that allows rectangular cells allows rectangular cells of differentof different dimensions

dimensions

Cross-section through a geological model Cross-section through a geological model

Cell Size

A Parent cell is the

A Parent cell is the largest cell allowed in a largest cell allowed in a model. model. The size of these The size of these cells is defined by thecells is defined by the user and should be based on several factors such as the drillhole spacing, mining method, user and should be based on several factors such as the drillhole spacing, mining method, and

and the the geological geological structures structures hosting hosting the ore. the ore. Where Where the the model model needs needs greater greater definition,definition, such as within thin seams or at the edges of boundaries, it is possible to subdivide the parent such as within thin seams or at the edges of boundaries, it is possible to subdivide the parent cells into smaller

cells into smaller sub-cells. sub-cells. The degree of parent cell sThe degree of parent cell splitting is controlled by plitting is controlled by the user.the user.

A significant advantage of Datamine modelling is that it is not necessary to create a cell in A significant advantage of Datamine modelling is that it is not necessary to create a cell in every position within the model.

every position within the model. Only regions of interesOnly regions of interest, such as t, such as a mineralized zone, needa mineralized zone, need be modelled.

(6)

Filling plane

Cell splitting can be

Cell splitting can be done along any axis in done along any axis in the model. the model. When using a constraining boundary,When using a constraining boundary, such as a perimeter or wireframe, it is necessary to define a filling plane to control the such as a perimeter or wireframe, it is necessary to define a filling plane to control the direction of

direction of the the cell splitting. cell splitting. For example, For example, if the if the filling plane filling plane is set is set to 'XY' to 'XY' then the prthen the processocess will create the spec

will create the specified number of sub-cells in ified number of sub-cells in both the X and Y dboth the X and Y directions. irections. In the third axisIn the third axis the cell size will be c

the cell size will be calculated using seam filling. alculated using seam filling. With seam filling the cell dimensWith seam filling the cell dimension is setion is set automatically so that

automatically so that it precisely fits the perit precisely fits the perimeter or wirefrimeter or wireframe boundary. ame boundary. Careful selectionCareful selection of the filling plane is therefore important in providing the best possible modelling of geological of the filling plane is therefore important in providing the best possible modelling of geological boundaries.

(7)

Studio 3 stores the exact length of each cell in the X, Y and Z directions in 3 separate fields. Studio 3 stores the exact length of each cell in the X, Y and Z directions in 3 separate fields. This approach allows cells to be created with no cell dimension restrictions.

This approach allows cells to be created with no cell dimension restrictions.

Defining the Model

Before creating a model it is necessary to define the region it will represent and the size of Before creating a model it is necessary to define the region it will represent and the size of the parent cells

the parent cells it will contain. it will contain. This information This information is stored in a is stored in a model prototype file. model prototype file. ThisThis prototype can be an existing model or a new file created using the process

prototype can be an existing model or a new file created using the process PROTOMPROTOM

(

(Models | Create Model | Define PrototypeModels | Create Model | Define Prototype). ). A model prototype A model prototype can also can also be described asbe described as an empty model.

an empty model. The Model Fields The Model Fields Studio 3 requires the fo

Studio 3 requires the following numeric fields in every llowing numeric fields in every model file. model file. Note that instead of Note that instead of east,east, north and elevation

north and elevation Studio 3 uses Studio 3 uses the generic names the generic names 'X', 'Y' and 'Z'. 'X', 'Y' and 'Z'. This is becausThis is because it ise it is possible to align models to a local gr

possible to align models to a local grid instead of the true coordinate grid. id instead of the true coordinate grid. These fields are allThese fields are all created by the

created by thePROTOMPROTOM process. process. Field

Field Name Name Explicit Explicit or or Implicit Implicit DescriptionDescription XMORIG

XMORIG ImplicitImplicit Easting Easting coordinate coordinate of of thethe model origin

model origin YMORIG

YMORIG ImplicitImplicit Northing Northing coordinate coordinate of of thethe model origin

model origin ZMORIG

ZMORIG ImplicitImplicit RL RL coordinate coordinate of of the the modelmodel origin

origin NX

NX ImplicitImplicit Number of parent cells in theNumber of parent cells in the X direction

X direction NY

NY ImplicitImplicit Number of parent cells in theNumber of parent cells in the Y direction

Y direction NZ

NZ ImplicitImplicit Number of parent cells in theNumber of parent cells in the Z direction

Z direction XINC

XINC Explicit Explicit or or Implicit Implicit X X axis axis cell cell dimensiondimension YINC

(8)

ZINC

ZINC Explicit Explicit or or Implicit Implicit Z Z axis axis cell cell dimensiondimension XC

XC Explicit Explicit X X coordinate coordinate of of cell cell centrecentre YC

YC Explicit Explicit Y Y coordinate coordinate of of cell cell centrecentre ZC

ZC Explicit Explicit Z Z coordinate coordinate of of cell cell centrecentre

IJK

IJK ExplicitExplicit

Used by Datamine to position Used by Datamine to position parent cells within the model. parent cells within the model. Each Parent cell will have a Each Parent cell will have a unique

unique IJK IJK value. value. Sub-cellsSub-cells that

that lie lie within within the the samesame parent cell will have the same parent cell will have the same IJK value.

IJK value.

Defining The Model Origin Defining The Model Origin

Datamine sets the origin with respect to the corner of the first parent cell and NOT its Datamine sets the origin with respect to the corner of the first parent cell and NOT its centroid.

centroid.

Defining The Extent Of The Model Defining The Extent Of The Model

The extent of the model in the X, Y, and Z directions is defined by the number of cells allowed The extent of the model in the X, Y, and Z directions is defined by the number of cells allowed in each direction (NX,NY,NZ) in combination with the parent cell dimensions and the model in each direction (NX,NY,NZ) in combination with the parent cell dimensions and the model origin.

origin.

As an example, if a model had the following XMORIG, XINC, and NX values: As an example, if a model had the following XMORIG, XINC, and NX values:

! ! XMORIG = 45000XMORIG = 45000 ! ! XINC = 10XINC = 10 ! ! NX = 100NX = 100

The range of easting (X) values covered would be 45000 (XMORIG) to 46000 The range of easting (X) values covered would be 45000 (XMORIG) to 46000 (XMORIG+XINC*NX)

(XMORIG+XINC*NX) Other Fields

Other Fields

In addition to the standard Datamine model fields, the model will contain any extra fields In addition to the standard Datamine model fields, the model will contain any extra fields necessary to define the deposit. These fields are generally made up of a mixture of grade, necessary to define the deposit. These fields are generally made up of a mixture of grade, lithology, and density fields. Other common field types include dollar fields for polymetalic lithology, and density fields. Other common field types include dollar fields for polymetalic deposits and grade estimation fields recording values such as kriging variance.

(9)

3

3 _M

_M

_ODELING

_T

_ECHNIQUES

Several techniques can be used to create models in Datamine. The choice depends on the Several techniques can be used to create models in Datamine. The choice depends on the complexity of the geology, the degree of precision required and the amount of time and complexity of the geology, the degree of precision required and the amount of time and resources available for the modeling.

resources available for the modeling.

Unconstrained Modeling

The quickest way to build a model is to create the cells using an interpolation process. For The quickest way to build a model is to create the cells using an interpolation process. For interpolation it is necessary to define an empty model prototype, provide some assay data interpolation it is necessary to define an empty model prototype, provide some assay data and a set of suitable interpolation parameters. As the interpolation process runs, it scans the and a set of suitable interpolation parameters. As the interpolation process runs, it scans the centroid of each potential cell to ascertain the number of valid assays occurring within the centroid of each potential cell to ascertain the number of valid assays occurring within the search radius. If the assays do not satisfy the interpolation conditions, the process moves on search radius. If the assays do not satisfy the interpolation conditions, the process moves on to the next cell position without creating a cell. When enough assays that satisfy the to the next cell position without creating a cell. When enough assays that satisfy the interpolation constraints are present the process creates a cell at that position in the model interpolation constraints are present the process creates a cell at that position in the model and assigns it the interpolated value.

and assigns it the interpolated value.

The main disadvantage of this technique is that it is not possible to accurately model The main disadvantage of this technique is that it is not possible to accurately model geological contacts.

geological contacts.

This approach is typically used when modeling high tonnage, low grade, disseminated This approach is typically used when modeling high tonnage, low grade, disseminated deposits such as Porphyry Copper style mineralization.

deposits such as Porphyry Copper style mineralization.

Constrained Modeling

For better control over the shape and position of structures it is necessary to include a For better control over the shape and position of structures it is necessary to include a geological interpretation. This interpretation can take the form of perimeters which define geological interpretation. This interpretation can take the form of perimeters which define various boundaries of interest, or if more precision is required, a series of wireframed various boundaries of interest, or if more precision is required, a series of wireframed surfaces.

surfaces.

Modeling Using Perimeters Modeling Using Perimeters

A geological interpretation consists of section or plan drawings showing structure and mineral A geological interpretation consists of section or plan drawings showing structure and mineral boundaries. These can be created within Datamine using interactive graphics in the Design boundaries. These can be created within Datamine using interactive graphics in the Design Window, or by hand over hardcopy plots which can be digitized at a later date.

Window, or by hand over hardcopy plots which can be digitized at a later date.

As the strings are digitized codes or attributes should be assigned to distinguish the different As the strings are digitized codes or attributes should be assigned to distinguish the different zones and or rock types. Datamine can later assign these to the cells created in the block zones and or rock types. Datamine can later assign these to the cells created in the block model. Examples of attribute fields include

model. Examples of attribute fields include COLOURCOLOUR,, ROCKTYPE ROCKTYPE ,, ZONE ZONE ,, WEATHERWEATHER and and OXIDE

OXIDE ..

Using the interactive graphics in the

Using the interactive graphics in the DesignDesign Window, perimeter points can be snapped at the Window, perimeter points can be snapped at the precise three-dimensional coordinates of selected drillhole intervals.

precise three-dimensional coordinates of selected drillhole intervals.

For Datamine to fill the strings with cells they must form closed areas or perimeters. Ensure For Datamine to fill the strings with cells they must form closed areas or perimeters. Ensure that adjacent boundaries abut up against each other with no gaps or overlaps. The string that adjacent boundaries abut up against each other with no gaps or overlaps. The string editing utilities under the

editing utilities under the DesignDesign menu can be used to automatically generate outlines from menu can be used to automatically generate outlines from open overlapping strings. This means that common boundaries need to be digitized only open overlapping strings. This means that common boundaries need to be digitized only once.

once.

Note that perimeters can be digitized in a clockwise or anticlockwise manner. Note that perimeters can be digitized in a clockwise or anticlockwise manner. Once the strings are loaded into the

Once the strings are loaded into the DesignDesign Window they can be easily viewed and edited. Window they can be easily viewed and edited. Verifying the string positions and coding is critical because any incorrect values at this point Verifying the string positions and coding is critical because any incorrect values at this point

(10)

may significantly influence the validity of the final model. Some techniques used for may significantly influence the validity of the final model. Some techniques used for verification include;

verification include;

!

! Generating statistics on the strings using theGenerating statistics on the strings using the STATSSTATS and and PROPER PROPER processes. processes.

!

! Plotting the string position and attributes.Plotting the string position and attributes.

!

! Viewing the data in three-dimensions in theViewing the data in three-dimensions in the VisualizerVisualizer Window. Window.

Filling Perimeters with cells Filling Perimeters with cells

Building block models with strings is completed using the

Building block models with strings is completed using the PERFILPERFIL command (in the command (in the DesignDesign window, select

window, selectModels | Create Model | Fill Perimeters with cellsModels | Create Model | Fill Perimeters with cells). This process requires). This process requires that the perimeters be planar and lie in the 'XY', 'XZ' or 'YZ' plane. If the perimeters do not that the perimeters be planar and lie in the 'XY', 'XZ' or 'YZ' plane. If the perimeters do not meet any of these conditions, it will be necessary to create a wireframe and fill the wireframe meet any of these conditions, it will be necessary to create a wireframe and fill the wireframe with cells.

with cells.

As well as filling perimeters with cells

As well as filling perimeters with cells PERFILPERFIL creates cells perpendicular to the perimeters. creates cells perpendicular to the perimeters. The projection distance defined is generally set to half the section spacing. Care must be The projection distance defined is generally set to half the section spacing. Care must be taken to ensure that the values used do not create gaps or overlapping cells between the taken to ensure that the values used do not create gaps or overlapping cells between the sections. This method works best when the geological structure lies approximately along the sections. This method works best when the geological structure lies approximately along the orthogonal axis and the sections are closely spaced.

orthogonal axis and the sections are closely spaced. Checking the Model

Checking the Model

Once the model is created it should be checked to ensure that the cell filling has gone as Once the model is created it should be checked to ensure that the cell filling has gone as expected. This can be done visually by viewing various sections through the model at expected. This can be done visually by viewing various sections through the model at different orientations interactively in the

different orientations interactively in the DesignDesign Window. Window.

Load the drillhole data set into the Load the drillhole data set into the Design Window and then view it in Design Window and then view it in section. Colors or filters can be used to section. Colors or filters can be used to identify the assay and lithology codes identify the assay and lithology codes for each sample interval.

for each sample interval.

Adjust the view so that the screen lies at Adjust the view so that the screen lies at a selected section position. Set the a selected section position. Set the

(11)

Using the color coded samples digitize Using the color coded samples digitize the geological interpretation on the the geological interpretation on the screen. If the region is to be filled with screen. If the region is to be filled with model cells the strings must be closed. model cells the strings must be closed. Multiple zones on the same section can Multiple zones on the same section can be defined by coding them using color be defined by coding them using color or any other attribute.

or any other attribute.

Once the section is complete; move Once the section is complete; move the screen position to the next section the screen position to the next section and digitize another set of strings. and digitize another set of strings. Continue this procedure until all the Continue this procedure until all the sections are completed.

sections are completed.

Fill the planar strings with cells using the Fill the planar strings with cells using the PERFIL

PERFIL process. View the model in plan process. View the model in plan or section to ensure that the filling has or section to ensure that the filling has produced the expected result.

produced the expected result.

Modeling Using

Wireframes

The most precise way to define a geological boundary in three-dimensions is with a The most precise way to define a geological boundary in three-dimensions is with a wireframed surface

wireframed surface or wireframed solid. or wireframed solid. Both are essentially the sBoth are essentially the same except that wireframe except that wireframeame solids enclose a vo

solids enclose a volume while a wirefrlume while a wireframe surface is oame surface is open. pen. They may also They may also differ in thediffer in the techniques employed to

techniques employed to create them. create them. The use of The use of wireframes, wireframes, while giving more while giving more precisionprecision than perimeters, will require a thorough knowledge of how the deposit behaves in than perimeters, will require a thorough knowledge of how the deposit behaves in three-dimensions.

(12)

The starting point for solid wireframe modeling is usually a series of perimeters outlining the The starting point for solid wireframe modeling is usually a series of perimeters outlining the geology.

geology. These perimeters need not be planar These perimeters need not be planar and may lie at aand may lie at any orientation. They must ny orientation. They must notnot however overlap in three dimensions with themselves (forming a knot or 'twisted bowtie' however overlap in three dimensions with themselves (forming a knot or 'twisted bowtie' shape) or with adjacent perimeters.

shape) or with adjacent perimeters. Checking The Wireframes

Checking The Wireframes

Once perimeters have been created, the string linking commands available under the Once perimeters have been created, the string linking commands available under the Wireframes

Wireframes menu can menu can be used to crebe used to create the wireframe. ate the wireframe. The resulting wireframe The resulting wireframe must bemust be checked carefully to ensure that all the links are valid and they represent the desired surface. checked carefully to ensure that all the links are valid and they represent the desired surface. This can be done by viewing slices through the wireframe at various orientations or by This can be done by viewing slices through the wireframe at various orientations or by viewing the complete wireframe in the

viewing the complete wireframe in the VisualizerVisualizer Window. Window. Another tecAnother technique is hnique is to use to use thethe wireframe inters

wireframe intersections function ections function to find wto find wireframe ireframe overlaps. overlaps. A valid A valid wireframe will wireframe will notnot generate any intersection lines.

generate any intersection lines.

The wireframe can be filled with cells using the process

The wireframe can be filled with cells using the process TRIFILTRIFIL (in the (in the DesignDesign window, window, select

select Models | Create Model | Fill Wireframe with CellsModels | Create Model | Fill Wireframe with Cells). ). An An appropriate appropriate filling filling planeplane and sub-cell size based on the shape of the wireframe should be defined.

and sub-cell size based on the shape of the wireframe should be defined. The main advantages of this method over perimeters include.

The main advantages of this method over perimeters include.

!

! The resultant models are more precise in that they more accurately reflect geologicalThe resultant models are more precise in that they more accurately reflect geological

structures and zones. structures and zones.

!

! The wireframe can be sliced at any orientation.The wireframe can be sliced at any orientation.

!

! The wireframe slices can be converted to strings allowing the creation of a new set ofThe wireframe slices can be converted to strings allowing the creation of a new set of

perimeters in a new orientation. perimeters in a new orientation.

!

! Wireframe volumes can be calculated quickly and easily.Wireframe volumes can be calculated quickly and easily.

!

! Wireframes offer the clearest and most graphic way to display designsWireframes offer the clearest and most graphic way to display designs

Use the string linking commands under Use the string linking commands under the Wireframes menu to create links the Wireframes menu to create links between sections.

(13)

Once completed, it is important to check Once completed, it is important to check the

the wireframe. wireframe. This This can can be be done done byby viewing it from several directions with viewing it from several directions with hidden lines deleted or slicing the hidden lines deleted or slicing the wireframe to produce various section wireframe to produce various section profiles.

profiles.

Fill the wireframe with cells using the Fill the wireframe with cells using the TRIFIL

TRIFIL process. process. Viewed Viewed in in section section thethe model is checked to ensure that the filling model is checked to ensure that the filling has produced the expected result.

has produced the expected result.

Wireframe surfaces can be built and updated far more quickly than wireframe solids and can Wireframe surfaces can be built and updated far more quickly than wireframe solids and can be generated from hanging wall and foot wall contacts.

(14)

4

4 _S

_S

_TRUCTURE

_M

_ODELLING

Complex geological models often contain separate structures such as different lithology, Complex geological models often contain separate structures such as different lithology, intrusives and surf

intrusives and surface topography. ace topography. Managing all these and building them into Managing all these and building them into the modelthe model simultaneously can be both difficu

simultaneously can be both difficult and time-consuming. lt and time-consuming. In addition, if a change In addition, if a change isis made to one boundary position it may be necessary to repeat the whole modelling made to one boundary position it may be necessary to repeat the whole modelling process.

process. To overcome this problem, crTo overcome this problem, create a separate model for eate a separate model for each of the differenteach of the different structures.

structures. For example, build separate For example, build separate models for the dyke and the host rmodels for the dyke and the host rock throughock through which it has intruded.

which it has intruded. Construct the final model by Construct the final model by adding them so that the dyke isadding them so that the dyke is superimposed over the host ro

superimposed over the host rock. ck. Should it be necessary to rShould it be necessary to refine the position of theefine the position of the dyke, build a new dyke model and add it again over the original host rock model. dyke, build a new dyke model and add it again over the original host rock model.

Surface Topography

Topography wireframe surfaces are built using the

Topography wireframe surfaces are built using the Wireframes | Interactive DTMWireframes | Interactive DTM creation | Make DTM

creation | Make DTM (md) comma (md) command. nd. It is posIt is possible to create sible to create a DTM from a DTM from contourcontour strings, point data, c

strings, point data, closed boundary perimeters or losed boundary perimeters or any combination of the thrany combination of the three. ee. OnceOnce built the

built the TRIFILTRIFIL process is used to fill process is used to fill a model below the surface with a model below the surface with cellscells

Seams

Modeling of seams is s

Modeling of seams is similar to that of the similar to that of the surface topography. urface topography. A topographic surfaceA topographic surface can actually be cons

can actually be considered as a seam of air idered as a seam of air overlying the rock. overlying the rock. For this reason theFor this reason the techniques used for modeling are

techniques used for modeling are similar to those given in the presimilar to those given in the previous section. vious section. TheThe main difference is that now there are tw

main difference is that now there are two or more surfaces to consider.o or more surfaces to consider. As with surface topography the technique u

As with surface topography the technique used for creating the seam model dependssed for creating the seam model depends primarily on the natur

primarily on the nature of the data available and the e of the data available and the complexity of the seam. complexity of the seam. TwoTwo techniques and the conditions for their use a

techniques and the conditions for their use are outlined as follows;re outlined as follows;

Technique 1; Make DTM Technique 1; Make DTM Build a surface using the

Build a surface using the Wireframes | Interactive DTM creation | Make DTMWireframes | Interactive DTM creation | Make DTM (md) (md) command and then use

command and then use TRIFILTRIFIL ( (Models | Create Model | Fill WModels | Create Model | Fill Wireframe with Cellsireframe with Cells)) to fill wireframe with cells

to fill wireframe with cells

This method should be used when: This method should be used when:

!

! Point and/or string data (drillhole Point and/or string data (drillhole intersections, surface contours)intersections, surface contours)

!

! Information extends over the full modelInformation extends over the full model

!

(15)

!

! Information extends over the full modelInformation extends over the full model

!

! Complex surfaces (any orientation, overhangs)Complex surfaces (any orientation, overhangs)

Whatever technique is used if there are multiple seams each must be modelled Whatever technique is used if there are multiple seams each must be modelled separately and

separately and assigned the desired assigned the desired attributes and graattributes and grades. des. Add the individual modelsAdd the individual models using

using ADDMODADDMOD ( (Models | Manipulate Models | Add Two Block ModelsModels | Manipulate Models | Add Two Block Models) to produce) to produce the final combined model.

the final combined model.

Massive Deposits

Massive deposits hosting disseminated mineralization often exhibit few clear contacts or Massive deposits hosting disseminated mineralization often exhibit few clear contacts or boundaries defining the extent of

boundaries defining the extent of the mineralization. Alternatively, the boundary (e.g.the mineralization. Alternatively, the boundary (e.g. pluton) contact may l

pluton) contact may lie outside the zone of interest. ie outside the zone of interest. In such cases In such cases the model can bethe model can be considered as

considered as unconstrained. unconstrained. Cells can be Cells can be created using the created using the interpolation processinterpolation process ESTIMA

ESTIMA ( (Models | Interpolate Grade | Interpolate Grades into ModelModels | Interpolate Grade | Interpolate Grades into Model). ). A A menumenu driven version of the process called

driven version of the process called ESTIMATEESTIMATE ( (Models | Interpolate Grade |Models | Interpolate Grade | Interpolate Grades from Menu

Interpolate Grades from Menu) can be used ) can be used as an alternative to starting the processas an alternative to starting the process from the Command line.

from the Command line.

Empty

Empty Prototype Prototype Model Model Prototype Prototype Model Model with with CellsCells Interpolation

Interpolation Process Process Interpolation Interpolation ProcessProcess

Cells

(16)

There are two approaches for building a

There are two approaches for building a model with an interpolation process;model with an interpolation process;

!

! Fill the model prototype completely with cells using theFill the model prototype completely with cells using the PERFILPERFIL or or TRIFILTRIFIL

processes. Use this model as the prototype for an

processes. Use this model as the prototype for an interpolation process to assigninterpolation process to assign grades to cells.

grades to cells. Cells that do not satisfy Cells that do not satisfy the constraints for the constraints for grade interpolationgrade interpolation are left with undefined values.

are left with undefined values.

!

! UseUse ESTIMAESTIMA or or ESTIMATEESTIMATE to interpolate grades into an empty prototype to to interpolate grades into an empty prototype to

create cells (unconstrained estimation). create cells (unconstrained estimation).

Intrusive Features

Generally, intrusive features have distinct boundaries that can be interpolated from the Generally, intrusive features have distinct boundaries that can be interpolated from the drillhole information.

drillhole information. The first step is to digitize The first step is to digitize a set of sectional outlines a set of sectional outlines then create athen create a wireframe and fill it with cells.

wireframe and fill it with cells.

Open Surfaces

such as Faults

and

Supergene Horizons

.

Open surfaces ar

Open surfaces are best represented using wireframe best represented using wireframes. es. As this is another cAs this is another case of surfacease of surface modeling the techniques used for c

modeling the techniques used for creating these wireframes reating these wireframes are very are very similar to thosesimilar to those used for topographic wireframes.

used for topographic wireframes.

While creating a fault plane wireframe is generally easy, including i

While creating a fault plane wireframe is generally easy, including it in the geologicalt in the geological block model is a more

block model is a more involved procedure. involved procedure. Rather than filling a vRather than filling a volume with cells theolume with cells the cells are create

cells are created on one side of a wireframe. d on one side of a wireframe. Use the TRIFIL process Use the TRIFIL process and select an east,and select an east, west, north or south f

west, north or south filling direction. illing direction. Assign a unique zone code to the cAssign a unique zone code to the cells so that theyells so that they can be identified later.

can be identified later.

Another way in which a fault

Another way in which a fault wireframe can be used is to displwireframe can be used is to display it as a slice overlaying itay it as a slice overlaying it on geological sec

on geological sections. tions. This shows This shows the precise three-dimensionathe precise three-dimensional position of l position of the faultthe fault which can be used in

(17)

5

5 _C

_C

_OMBINING

_M

_ODELS

The ability to combine models

The ability to combine models is a powerful tool. is a powerful tool. As well as providing the As well as providing the ability toability to create complex models in simple stages, it also allows the

create complex models in simple stages, it also allows the updating and extension ofupdating and extension of existing models.

existing models.

Model Requirements

To combine two models using the process

To combine two models using the process ADDMODADDMOD ( (Models | Manipulate Models | AddModels | Manipulate Models | Add Two Block Models

Two Block Models) both input models must have the same model definition (i.e. the same) both input models must have the same model definition (i.e. the same origin, parent cell d

origin, parent cell dimensions and number imensions and number of cells). of cells). They must aThey must also be sorted on lso be sorted on thethe IJK IJK field.

field.

If the two models do not have the same model definition it is necessary to change the If the two models do not have the same model definition it is necessary to change the definition of one of the models.

definition of one of the models. The easiest way to do The easiest way to do this is by using the prothis is by using the processcessSLIMODSLIMOD

(

(Models | Manipulate Model | Put Model onto a New PrototypeModels | Manipulate Model | Put Model onto a New Prototype).).

It is necessary to supply this process with the model to be changed and a model prototype It is necessary to supply this process with the model to be changed and a model prototype file describing the

file describing the new model fnew model format. ormat. The model prototype The model prototype is created is created using the prousing the processcess PROTOM or, more conveniently, use an existing model as the prototype.

PROTOM or, more conveniently, use an existing model as the prototype.

Attribute Fields

Any attribute fields such as lithology or grades are

Any attribute fields such as lithology or grades are handled according to the followinghandled according to the following rules;

rules;

!

! If the fields are unique to each input model then all these fields are written to theIf the fields are unique to each input model then all these fields are written to the

output model.

output model. Those fields that Those fields that do not get a do not get a value from either value from either of the inputof the input models are set to absent data (-).

models are set to absent data (-).

!

! If the same fields exist in both input models the 2nd model overwrites theIf the same fields exist in both input models the 2nd model overwrites the

common fields in the 1st model. common fields in the 1st model.

Combining Cells

When models are added, the cells are first compared to find how they overlap. When models are added, the cells are first compared to find how they overlap.

!

! If cells do not overlap, or overlap If cells do not overlap, or overlap exactly, then no cell splitting is performed andexactly, then no cell splitting is performed and

only the cell attributes are updated. only the cell attributes are updated.

!

! If the cells partially overlap then they If the cells partially overlap then they are split along each cell boundary beforeare split along each cell boundary before

updating the attribute fields. As the resulting

updating the attribute fields. As the resulting cells must be rectangular thecells must be rectangular the splitting will continue throughout the full length

(18)

Adding Cells Using ADDMOD Adding Cells Using ADDMOD

Combining Individual Models

The following diagram demonstrates the processes involved in created a full geological model The following diagram demonstrates the processes involved in created a full geological model comprised of individual model data sets. Note that the direction of the black arrows denote comprised of individual model data sets. Note that the direction of the black arrows denote the order in which the models are added (e.g. Seam 1 is added on top of Seam 2), and the the order in which the models are added (e.g. Seam 1 is added on top of Seam 2), and the white arrows follow the build-up of the combined model data set:

white arrows follow the build-up of the combined model data set:

Seam

Seam 1 1 Seam Seam 2 2 Intrusive Intrusive DykeDyke

Weathered

Weathered Zone Zone Surface Surface TopographyTopography Parent Cell Parent Cell Parent Cell Parent Cell Combined Combined Adding Cells Using

Adding Cells Using ADDMOD

(19)

Optimizing a Model

When adding two models together the new output model may contain more cells than When adding two models together the new output model may contain more cells than either of the input models.

either of the input models. This is a result oThis is a result of the cells being split along smaller f the cells being split along smaller subcellsubcell boundaries.

boundaries. If the new model is becoming too larIf the new model is becoming too large due to all the new cells the procge due to all the new cells the processess PROMOD (Models | Manipulate Model | Optimise Block Model) can

PROMOD (Models | Manipulate Model | Optimise Block Model) can be used to combinebe used to combine model cells according to a set of constraints.

model cells according to a set of constraints. It is also possible to

It is also possible to minimize the creation of smaminimize the creation of small cells during modeling. ll cells during modeling. In the PERFILIn the PERFIL and TRIFIL processes set the @RESOL parameter to define

and TRIFIL processes set the @RESOL parameter to define the smallest cell size allowed.the smallest cell size allowed. This in effect forces the subcelling in the seam filling direction to be completed using This in effect forces the subcelling in the seam filling direction to be completed using subcell splitting by rounding the cell lengths to a minimum set fraction of the parent cell subcell splitting by rounding the cell lengths to a minimum set fraction of the parent cell dimension.

dimension. As an example for As an example for parent cell length of 10 in the Z direction aparent cell length of 10 in the Z direction and a RESOLnd a RESOL value of 10, the minimum cell length in the Z direction allowed will be 1/10 i.e. 1 metre. value of 10, the minimum cell length in the Z direction allowed will be 1/10 i.e. 1 metre.

(20)

6

6 _G

_G

_RADE

_E

_STIMATION

Grade estimation is the process of estimating cell values (e.g. block mo

Grade estimation is the process of estimating cell values (e.g. block model cells) baseddel cells) based on a set of three-dimensional s

on a set of three-dimensional sample data. ample data. This information usually taThis information usually takes the form ofkes the form of drillholes, surf

drillholes, surface samples or ace samples or underground grab samples. underground grab samples. There are severaThere are severall mathematical techniques available for doing the interpolation.

mathematical techniques available for doing the interpolation. For more information on grade estimation refer to the

(21)

Datamine Software Limited Datamine Software Limited

2, St. Cuthbert Street 2, St. Cuthbert Street Wells Wells Somerset Somerset Tel: Tel: +44 +44 (0) (0) 1749 1749 679299679299 Fax: +44 (0) 1749 670290 Fax: +44 (0) 1749 670290 www.datamine.co.uk www.datamine.co.uk

Studio 3 Geological Modeling User Guide

Geological Modeling

Geological Modeling

Studio 3 User Guide

Studio 3 User Guide

Studio 3 Geological Modeling Concepts and Processes

Studio 3 Geological Modeling Concepts and Processes

Contents

Contents

E

E

XECUTIVE

XECUTIVE

S

S

UMMARY

UMMARY

1

1

O

O

VERVIEW

VERVIEW

Purpose of this document

Purpose of this document

Prerequisites

Prerequisites

Acronyms and Abbreviations

Acronyms and Abbreviations

More information

More information

2

2

I

I

NTRODUCTION

NTRODUCTION

Cell Size

Cell Size

Filling plane

Filling plane

Defining the Model

Defining the Model

3

3

M

M

ODELING

ODELING

T

T

ECHNIQUES

ECHNIQUES

Unconstrained Modeling

Unconstrained Modeling

Constrained Modeling

Constrained Modeling

Modeling Using

Modeling Using

Wireframes

Wireframes

4

4

S

S

TRUCTURE

TRUCTURE

M

M

ODELLING

ODELLING

Surface Topography

Surface Topography

Seams

Seams

Massive Deposits

Massive Deposits

Intrusive Features

Intrusive Features

Open Surfaces

_O

_O

_VERVIEW

_VERVIEW

_I

_I

_NTRODUCTION

_NTRODUCTION

_M

_M

_ODELING

_ODELING

_T

_T

_ECHNIQUES

_ECHNIQUES

_S

_S

_TRUCTURE

_TRUCTURE

_M

_M

_ODELLING

_ODELLING

_C

_C

_OMBINING

_OMBINING

_M

_M

_ODELS

_ODELS

_G

_G

_RADE

_RADE

_E

_E

_STIMATION

_STIMATION