Probabilistic Modeling of Ore Lens Geometry: An Alternative to Deterministic Wireframes

Abstract

In many precious metals mining operations, resource estimation and mine planning require a model of the geometry of the high-grade lenses. These models are often developed by a manual interpretation of the drill hole data, leading to a “wireframe” solid that provides a single deterministic description of the major geological control on mineralization. An alternative approach is proposed, one that treats the problem probabilistically. Like the conventional approach, this alternative honors drill hole data; it also allows the user to represent their geological model as a wireframe solid. Two demonstrations of the method are provided, one that treats the drill hole data as “hard” information that must be honored exactly, and the other that treats some of the drill hole data as “soft” information that is honored on average over many realizations. These examples make use of a variogram model that offers the user flexible control of the degree of spatial continuity of the lenses. The results demonstrate that the technique offers all that the conventional approach offers—a wireframe that honors drill hole data—and has the advantage of offering multiple renditions of the ore lens geometry that can be used to study the impact of geologic uncertainty on resource and reserve estimates.