Category: How-to

Dimensions and decisions: Mineral resource risk

By Mike O’Brien

 

10% and 90% Probability Shells for a Model of a Kimberlite Pipe

10% and 90% probability shells for a model of a Kimberlite Pipe

Mineral Resources and Reserves are not easy things to define. Qualified Persons (QP – NI43-101) and Competent Persons (CP – JORC, SAMREC etc) exist to do difficult things independently and provide a level of comfort to investors, clients and regulatory authorities.

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Modelling with the offset surface tool

By Jason McIntosh

Leapfrog has a new surface modelling tool available in the Geological modelling toolset! The offset surface tool will be available to users who have the latest version of Leapfrog Geo or Geothermal. It’s designed to enable a greater degree of flexibility when modelling complex stratified geology, particularly from heterogeneous data. The offset surface tool appropriates all the current dynamic functionality available in the existing geological modelling surface options.

So how can the new tool be used to model such deposits? Users of Geo 2.2.1 and earlier may already be familiar with the existing offset tool that was located in the meshes folder. The new tool incorporates much of the same functionality but supersedes the earlier version with improved algorithms and additional editing options. The new functionality is well suited for modelling faulted, stratified deposits.

Folded and faulted offset surface stratigraphy.

Folded and faulted offset surface stratigraphy.

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Making the most of Leapfrog for flow modelling: Part 2

By Jason McIntosh

Continued from part 1 – Making the most of Leapfrog for Flow Modelling.

Generate and evaluate a finite element grid

Finally to generate a FEFLOW model right click ‘Flow Models’ in the project tree and select ‘New 2D FEFLOW Model’. Set the element size and boundary from either a GIS line, polyline or a GM. Next expand the grid, right click ‘grid’ and select ‘New feature’. Within the dialogue add any ‘Point’, ‘Line’ or ‘Polygon’ features you wish to refine the grid with. Select ‘Simplify Feature’ to reduce or increase the number of points used for the boundary prisms. Next double click the grid, in the ‘Features’ tab and activate any features you wish to build detail around and the number of refinement steps. Within the ‘Boundary’ tab select either a rectangular boundary or a custom boundary by selecting ‘From another object’.

2D FEFLOW grid with refined cells about the collar locations.

2D FEFLOW grid with refined cells about the collar locations.

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Making the most of Leapfrog for flow modelling: Part 1

By Jason McIntosh

Simulating fluid flow, mass and heat transfer requires the synthesis of geological models with a multitude of parameters, the process is complex. So how can Leapfrogs modelling functionality be used to streamline it? 

Interoperability with FEFLOW and MODFLOW allows Leapfrog Hydro, Geothermal and Hydrology module users to interpolate initial simulation parameters and apply them to geologically constrained finite element and finite difference grids. For the purpose of this blog I will demonstrate the capabilities by modelling an aquifer system in Leapfrog Geo, simulating it in FEFLOW and viewing the time series in Leapfrog.

Aquifer systems are comprised of permeable porous water bearing aquifers and impermeable aquitards. Both have variable permeability and porosity within the sedimentary units they are comprised of, the units themselves pinch-out and diverge within stratified layers of sediment. Stratified drift aquifers are among the most challenging of such systems, as a result of the complex depositional environments they derive from.

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Optimum performance with Leapfrog projects

By Tim Schurr

Have you noticed the “.aproj_data” folder that always appears along-side your Leapfrog project file?

 aproj_data-folder in Leapfrog Geo

If you’ve ever had to move or copy a project to another location, you’ve probably come across it, opened folder using explorer and discovered a whole raft of sub-folders and files and thought “What’s all of this?  Is this really my Leapfrog project?”

.aproj_data folder beside Leapfrog project

In this article, I will explain the reason why Leapfrog saves projects in seemingly such a bizarre way, then I’ll give you a couple of tricks on how to get the best performance and reliability out of your Leapfrog projects.

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Creating accurate vein systems from complex data

By Jason McIntosh

Modelling multiple thin intersecting veins in 3D can be an arduous task, luckily the Leapfrog vein modelling tool is perfect for visualising thin intersecting vein systems. Complex vein systems are common in many geological settings, but for the purpose of this blog I’m going to focus on shear zone vein systems. So bear with me as I attempt to sum up the characteristics of metalliferous shear zone ore deposits and how they can be modelled using Leapfrog Geo in an easily digestible blog.

A shear zone is a discontinuity surface in the Earth’s crust and upper mantle. Depending on the characteristics of the shear zone genesis and later regional tectonics, shear zones can form economic gold, silver, copper, lead, zinc and molybdenum deposits. However, the formation of large mineral deposits is dependent on a number of factors.

Shear zones form in brittle/ductile transition zones as metamorphic facies are uplifted during orogenic collisions. They are mineralized throughout successive cycles consisting of increased and decreased fluid pressure phases. Metamorphic compression pressurizes the fluid and seismic activity reduces the pressure by allowing the fluid to invade the country rock along grain boundaries and fractures. The successive cycles allow fluid to disperse and regenerate, therefore allowing for incremental precipitation of incompatible elements such as gold within fractures and along grain boundaries.

Characteristic veins within the Brittle-Ductile transition zone. (Image sourced from USGS).

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Creating a continuous overburden surface

By Lorraine Tam

Often, generating a continuous overburden surface with uniform thickness from limited drilling is difficult, especially when it is not logged in a consistent manner.  Simply extracting the bottom contact of drillholes may produce a patchy result which will require a significant amount of manual editing.

Project area.

Plan view of the project area. Drillhole collar locations are shown in red. The overburden surface (in yellow) does not extend to where there is no data.

2D slice through the model.

A 2D slice through the model. The overburden is patchy because where there is no data, it crosses above the topography (shown in light green).

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Modifying intrusion surfaces – Effect of Value Clipping on intrusions (part 2/2)

By Lisa Swinnard

Continued from part 1.

Adjusting the value clipping has an effect on the volume of the intrusion, as well as its continuity. The volume of the intrusion can be determined by right clicking the Output Volume > Properties, and the continuity of an intrusion is represented by the number of parts it comprises (fewer parts = greater continuity). Below is a series of examples that show how value clipping affects the volume and continuity of this intrusion.

Automatic Clipping (Lower and Upper Bound Equal +/- 21.66)

Automatic Clipping (Lower and Upper Bound Equal +/- 21.66)

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Modifying intrusion surfaces – effect of value clipping on intrusions (part 1/2)

By Lisa Swinnard

There are several ways to edit and modify an “Intrusion” surface within a GM; of them, value clipping is often overlooked. This document is part one of two and will outline the procedure for modifying intrusion surfaces by value clipping, describe the importance and relevance of volume points, and explain how the two are connected.

1. Modifying intrusion surfaces by Value Clipping

Step 1 – Create a new geological model and intrusion surface

  • Within the GM, create a new intrusion surface.
  • Edit the surface accordingly, add a trend if necessary.

Step 2  – Modify the value clipping

  • To modify the value clipping, double click the intrusion surface in the project tree.
  • In the dialogue box that appears, click on the surfacing tab and check the “Show additional surfacing options” box.

Value clipping. Dialogue box. Surfacing tab. Leapfrog 3D.

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Drillhole planning in Leapfrog Geo

By Andrew Cantwell

One of the major costs of an exploration project is the drilling program. Planning drillholes in 3D based on existing knowledge is an easy way to maximise the value of any future drilling, and can be achieved quickly and easily in Leapfrog Geo. This blog post will take you through the steps required to plan a drilling campaign in Leapfrog Geo, then set up a scene file so the field team can see where each drillhole should be going, as well as what lithology and grade it is expected to intercept, in 3D.

  • The first step is to define your project area – a good start is to import any existing data. This could include a topography surface, any existing drillholes, an aerial photograph or geological map, and GIS data such as lakes, rivers, access roads and tenement boundaries.
  • Once you have imported the existing data, you’ll be able to start visualising in 3D where an appropriate location is to place your collar. If you’ve created any geological or grade models, you can also visualise where your potential target is.
  • To create a planned drillhole, right click on the ‘Planned Drillholes’ folder, and click ‘Plan Drillhole’.
  • There are two options you can choose; you can either specify a collar location or a target location. We’ll specify a collar location as it is more common to have a known point on the topography to place your collar.

Example 1.

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