It’s astonishing how many exploration companies are missing out on a very powerful method of geological investigation (3D geological modelling) that can be integrated into their traditional methods of geological mapping and core observations. Even though it’s 2014, most companies are operating as if they’re still stuck in the 1990s and as a result, they’re wasting millions of investment dollars.

In the current low investment climate, public companies can’t afford to waste money, so I want to explain why accurate geological modelling (using rapid 3D geological modelling methods) is needed.

A good example of combining high quality data acquisition and geologically sensible modelling to benefit exploration is shown in Figure 1.  In this case implicit geological modelling was used as a geological investigation technique where small-scale observations made in the field and from core are married with large scale structural geometries that can be interpreted from drill core.  Observations made at one scale cannot always be scale up or down, but the patterns observable at different scales must make sense when building a geological model.  Only when all information at different scales fit in like a puzzle, we can then make inferences about exploration targets and what are the structural features controlling the grade distribution at the minable scale.

 

Figure 1: An example of good industry practice by a mining company where good quality data is routinely gathered from core and field mapping (both structural and lithological data) and are analysed with structurally sensible 3D implicit modelling.  This modelling did not depend on just modelling using default settings in Leapfrog software but required geological analysis during the modelling process.  Geological observations from the field and from core could then be understood in the context of first-order geometry of the deposit which translated to exploration and resource estimation benefits.

Traditional geological modelling is usually left to the so-called ‘computer geologist’ (i.e. geologists with little field experience) who digitises sectional strings for resource estimation purposes. To explain why I consider rapid 3D modelling an essential process of exploration, I’ll draw analogies with methods of exploration before drilling takes place.

2D workflow vs 3D workflow

The issue is to do with the scale of geological investigation. In 2D we do it right as that’s the way it’s been done and refined over many years, but when it comes to using 3D methods, most of the industry is yet to take advantage of the advanced tools we have now—tools that just weren’t available a little more than a decade ago.

Essentially in 2D-based exploration investigations, geologists:

1. Walk on the ground, gathering geological and structural data and making observations
2. Produce a map based on the data gathered in step (1)
3. Analyse the mapped patterns and then make large-scale inferences
4. Generate exploration targets based on the information above.

In 3D, when dealing with drillhole (DH) data, geologists tend to:

1. Analyse DH data and make observations usually in sections (along drillhole fences)
2. Completely skip the geometric 3D modelling of DH data (which is effectively step (2) and (3) of the 2D-based workflow) and often don’t use the structural data (because of poor data quality, or because adequate data was not measured or even observed) 
3. Try to generate regional exploration targets by core-scale observation and regional geophysics data alone (eg., aeromag, gravity) without even trying to figure out intermediate deposit-scale geometrical patterns which are absolutely critical for exploration.

Often, structural geological consultants, like us, are given a scope of works that’s identical to the second workflow above that skips 3D modelling. It is assumed by many companies that intelligent targeting can be achieved without 3D modelling, because for decades ‘we’ve always done it that way’.

This is a crazy workflow, especially as we’ve had implicit modelling capabilities for more than a decade. I don’t think we’re close to the tipping point yet of the industry using 3D modelling as a geological assessment tool, but I’m hopeful that the next boom will see 3D modelling taking its rightful place in the realm of geological analysis.

When I first started working for SRK onsulting in 1999 as a geological consultant, GIS products were considered the greatest thing since sliced bread. Companies loved them, and they were all enthusiastically using MapInfo and ArcGIS. For the first time, GIS products (as opposed to paper-based maps), allowed geologists to summarise mapped data easily and edit and update it efficiently, and that led to the formulation of geological models (at least in 2D).

A similar workflow in 3D—the speedy summarisation and 3D modelling of drillhole data—hadn’t yet happened because of how geological modelling has developed over the last 20 years. And for more than a decade, geological 3D modelling has been stuck in the time-consuming 2D digitisation paradigm. Speedy production of accurate geological models from 3D drillhole data wasn’t possible, so exploration managers didn’t see 3D modelling as part of an exploration analysis workflow. However, the workflow used in 2D should also be applied in 3D. While most geologists agree with this, many aren’t able to make that change. At Orefind we have come across many consulting work scopes that reflect this dated view. Most geologists are unaware that detailed and accurate 3D assessment of their drilling data can be done quickly and effectively to bridge that gap between core data and regional data. Even though drilling data is often the most expensive data that any company has, companies are routinely skipping the analysis of core data (such as structural data [as Brett has covered in previous blog posts]) and the modelling of this data in 3D.

However, the mining and exploration industry is unlikely to remain complacent about this issue. A complete change in approach is expected to slowly sweep through the industry after the recent release of the second edition of AusIMM’s Best Practice Volume.

AusIMM’s Best Practice Volume

Recently AusIMM released Monograph 30 which is the second edition of their best-seller Mineral Resources and Ore Reserve Estimation – the AusIMM Guide to Good Practice, originally published in 2001 (originally Monograph 23). The geological modelling chapter (which I had the privilege to edit) includes nine papers that discuss current best practices in geological modelling. In 2001 when Monograph 23 was published, the only way 3D geological models could be produced was by traditional sectional digitisation methods, which were slow and time-consuming (it was impractical to produce geological models in a day or even in a week).

Implicit modelling software did not exist in 2001; in April 2001 I was just helping to start developing Leapfrog, and the first implicit modelling software products were released in late 2003. In Monograph 30, six of the nine papers specifically mention or champion the use of implicit modelling as a cornerstone geological modelling method, demonstrating that implicit modelling is now part of mainstream mining and exploration best practice. As it is now possible to build geological models immediately as new drillhole data is obtained, the time factor is no longer relevant.

Thus, in 2014, there is no need to skip the modelling stage.  Companies who are informed are taking advantage of incorporating good data collection practice with 3D modelling to assist with their exploration and resource evaluation needs (Figure 1).  Just like GIS revolutionised 2D geological analysis, implicit modelling—if used appropriately with geological knowledge—will enable mining and exploration companies to completely change their exploration and resource evaluation approach.

But beware…

Although 3D modelling has become easier and faster, the introduction of implicit modelling has had some scary unintended consequences, mostly related to modelling by those without suitable geological knowledge or experience. A major emphasis of AusIMM’s Monograph 30, is ‘putting geology first’ (i.e. before software), so I only advocate geologically intelligent use of implicit modelling software such as Leapfrog. If your geological interpretation is wrong, there will be disastrous consequences for your exploration investment.

Unfortunately, often the application of implicit modelling software is left wanting, especially when it is taught by employees of software companies who know how to press the buttons to make the software run, but who often have no experience in geological theory or experience to intelligently apply the software in the real world.

So, how do you tell which software companies are suitable to teach you or provide an implicit modelling service? One simple way is to visit software company websites, where you may discover that some companies are unfamiliar with even simple geological terminology—a clear indication that geologists are not leading the software development or are part of the executive team.

If you are receiving training from these companies, or getting them to model your deposit, make sure they can actually build sensible models effectively, and can also explain the geological and structural significance of what they built. 

With implicit modelling software, there are infinite ways to construct a model from drillhole data, and a good modeller must be able to justify the geological reason for their modelling approach. 

You can test this by giving them some of your data before you agree to their services. If they are good, they should be able to build a model from your data for you within an hour—in front of you.

If implicit modelling software companies claim that geological models can be built quickly using their software, let them demonstrate first on real data (your own) before you pay for their services.

There will be more posts that discuss the application of implicit geological modelling in mining and exploration, but if you require more information on how this new geologically integrated 3D modelling approach can benefit your company, contact me at jun.cowan@orefind.com. We will gladly give you a live demonstration (with your data) to explain the benefits of rapid 3D geological modelling for exploration.