Exploration Success … What’s the Drill?


Uncovering the real potential of an exploration target heavily relies on the capacity of an exploration team. The primary objective is to take a mineral target and soon transition it into an asset, which is valued by the market, or to walk away with confidence that exploration risks and uncertainties were properly dealt with. A skillful exploration team should be able to dynamically redirect exploration dollars based on real time analysis of the risks and uncertainties within a given portfolio.

Nevertheless, if you want to consistently drill for exploration success, take note of the following: drill into the mineral body, not the mineral target!

The discovery hole and the holes that follow must reveal the most reliable information to allow for an accurate valuation of a mineral property. The collection of mineral intersections created by drilling is the result of the interplay between two distinct geometries: the drilling configuration and the mineral body. I call this cloud of piercing-points mineral intersection geometry or MIG. MIG is not to be confused with the mineral envelope. MIG is about the orientation, distribution, quantity and quality of the mineral intersections provided by a drilling campaign. MIG is the set of mineral intersections used to produce a mineral envelope. Different exploration teams will surely come up with diverse MIGs and therefore they would be susceptible to create different mineral envelopes. Some mineral envelopes will be very good and some others will require additional drilling to approach a reasonable MIG. The best MIGs are the result of a real-time and dynamic review of each borehole that cuts through the mineral envelope. Necessary changes should be carried out to the next borehole and so forth – so the drilling geometry must be highly interactive, otherwise the MIGs will be poor. Well configured MIGs are more predictive and less expensive than the poor ones and will speak volumes about the experience and strengths of the exploration team. A mineral body with a reliable estimate of grade distribution and geometry is a required product to raise interest and investments.

How can one accomplish an effective drilling workflow task, which allows the drilling results to generate the best MIG possible, in a timely manner, within budget and thereby deliver value to investors?

In order to tackle this question one must recognize the power of drilling into the mineral body – a three-dimensional entity, to understand the grade distribution in the context of a particular geometry. This may seem simple and straightforward, but good exploration practices need to be followed to maximize value and minimize risk. The broad framework of such workflow is already out there in the industry (Vearncombe, J. & Vearncombe, S., 1998; Marjoribanks, R., 2010; Davis, B., 2012; Holcombe, R., 2014; and Monteiro, R.N., 2015).  However, it needs to be reconfigured in such a way that it would allow for early predictionsabout the shape of the mineralization, and its continuity and grade distribution. In this context, I expect that if the current industry XYZG Exploration System is augmented with the addition of mineralization-related structural vectors to build the concept of the XYZGV Exploration System the reward should be significant – as it will be explained ahead. By adopting this practice, and optimizing the MIG, exploration geologists should be able to better manage their exploration time and budget, while reducing risk and controlling uncertainties.

The XYZG stands for (x, y, z) coordinates of a sample that returns G, which is the grade. The G of the XYZG is just a scalar property! This is the traditional geochemical or assay sample we collect from core. It is a one-dimensional value that has no directional information to be projected into the three-dimensional space – unless, for instance, it can be vectorized by variography; however, such vectorization requires a large amount of mineral intersections – increasing time and investments – before spatial inferences can be drawn.

On the other hand, XYZGV is geometry-based at each sample site. XYZGV stands for (x, y, z) coordinates that returns not only G but also V, which is a type of vector (Allemendinger, Cardozo and Fisher, 2012) – a structural vector! The XYZGV implies that a grade value, obtained from a sample at (x, y, z) coordinates can be described as a vector or axis.Therefore, this grade can be projected along the mineralization-related structural vector. It not only empowers the exploration geologists to early detect and understand the hidden architecture of the mineralization and continuity, but also prompts them to fast redirect drilling to better intersect the mineral body (Figure 1). Vektore has improved such practices (Monteiro, 2013a and c) with proven record of significant successful applications.

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