Creating a 3D model would isolate optimal zones for total reserves of economically extractable gold in mining industry, the groundwater contamination flow from waste infiltrated in environmental case, etc. - Rockware.com

1. 3D Sub-Surface Modelling
(Mining, Geology, Geophysics, Geotechnical, and Environment)
PelaGIS Office
Saturday, March 4th, 2017
By
Fakhrurrazi

2. Outline
• Introduction
• Data Management
• Lithology versus Stratigraphy
• Modelling
• Visualization
• Volumetric Computation
• Software Demo

3. Introduction
Kota Banda Aceh
How is the subsurface layer of Banda Aceh City ?
Gold Deposits ?
oil & gas ?
or waste ?

4. Introduction
How to determine the subsurface of Banda Aceh City ?
No directional survey
• Geophysics
• Geological Map Cross-Section
Directional survey
• Civil Engineering (Boring)
• Well Exploration
• Pit Testing for mineral exploration

5. Introduction
Result
No Directional Survey
Defriyanto, 2015
Directional Survey

6. Introduction
It’s only one or two data of location determination
G1
G2
D1

7. How is the subsurface model have a lot of data ?

8. 3D Modelling

9. How to create a 3D Model of Subsurface ?

10. We need :
• Data collection (e.g. Geophysics, Geology, Mining, Geotechnical, Environment)
• That data must have X, Y, Z (spatial) and others value of main parameter
• Computer and Software ( Ex: Rockworks and ArcGIS)
• Basics and advanced concept about Geostatistics
• Lithology and Stratigraphy knowledge for a Geoscientist

11. What is the advantage from a 3D-Model ?

12. • The Distribution of Soils/Rocks vertically or horizontally
• Visualization such as : cross-section, fence diagrams, block diagrams
• Calculation of Volumetrics
Important : Creating a 3D model would isolate optimal zones for total reserves of
economically extractable gold in mining industry, the groundwater contamination
flow from waste infiltrated in environmental case, etc.

13. Data Management X : 10.000 (mU)
Y : 12.000 (mT)
Z : 15 (m dpl)
Total Depth of Dowhole : 120 m
Other Information Borehole data

14. Data Management

15. Data Management
Flowchart to create a 3D Model
Rockworks Software

16. Lithology versus Stratigraphy
• Lithology : rocks description based on that characteristics (Jackson, 1985)
• Rock classification into 4 types : Igneous, Sedimentary, Metamorphic, and
Pyroclastics

17. • Viewed into a tab : listing depth to depth, and rock or material type
Rock typeIn the Field Depth to Depth (m)
Lithology versus Stratigraphy

18. • Often repeating others depth
Location 1 Location 2 Location 3
Tab Correlation
Lithology versus Stratigraphy

19. • Stratigraphy : rock layers and stratification based on lithology, environment and
depositional age
• Sub-Fields into 3 types : Lithostratigraphy, Biostratigraphy, Chronostratigraphy
Lithology versus Stratigraphy
LithostratigraphyandChronostratigraphy
Biostratigraphy and Chronostratigraphy

20. • Classification into Group, Formation, and Member
Lithology versus Stratigraphy

21. • Never repeat others depth
Tab Correlation
Lithology versus Stratigraphy

22. Modelling
• 2D/3D-Modelling is depend upon the number of independent variables
• In a two-dimensional array, the dependent variable (z) is a function of the horizontal
(x,y) coordinates. Also referred to as a “GRID MODEL”

23. Modelling
• In a three-dimensional array, the dependent variable(g) is a function of the horizontal
(x,y) and vertical coordinates (z). Also referred to as a “SOLID MODEL”

24. Geostastistics Basics
• 2D Modelling
Popular method to
Interpolate is “IDW”
Inversed Distance Weigh
Longitude
Latitude
Z Value

25. Popular method to Interpolate is “IDW”
Inversed Distance Weigh
Geostastistics Basics

26. Geostastistics Basics
• 2D Modelling
Used to model topography,
stratigraphic contacts,
isopachs, and water
levels

27. Geostastistics Basics
• 3D Modelling
There is simply the three-
dimensional version of
gridding.
The creation of Supercomputers
Used to model geochemistry, contaminants, ore
grades, metals, and geotechnical properties

28. Visualization
• Diagrams of grids and solids are more than "eye candy“
• Viewed in cross-section, fence diagrams, or block diagrams
• Comparing the original data with interpolated model

29. Visualization

30. Visualization

31. Volumetric Computation
• Model has been created
• Computing the volume : simple mathematical operation with cell values
• Usually in a “isopach map” layer selected
=
“isopach map” selected
• All cells added together (Total = 272 m), and multiplied by cell size ( 50 m x 50
m) ; referred as “Length x width” . The volume is 680.000 m3
• Then multiplied by density (Rho) of material was conversion factor (e.g. density
of coal = 1.826 metric tons per cubic meter). The tonnage is 1,2m metric tons)

32. Volumetric Computation
=
“isopach map” selected
• Volume = 272 m x 50 m x 50 m
= 680.000 m3
• Tonnage = 680.000 m3 x 1,826 metric tons / m3
= 1.241.680 metrics tons (1,2m metric tons)

33. Volumetric Computation
??

34. Future References
www.rockware.com