Unfaulting for Unfaulted Interpolation of Faulted Deposits

Unfaulting, in the context of geological modeling and resource estimation, is a space transformation and partitioning technique that transforms drill hole composites back to its unfaulted space. Block Model Interpolation happens in the unfaulted space and the interpolated blocks are then transformed back to the faulted space. This technique is best suited for faulted deposits where the fault network was formed after the orebody had been deposited. Since the orebody is assumed to have existed prior to faulting, interpolation in the unfaulted space would tend to result in a more accurate resource estimate.

The pre-requisite for using Unfaulting is to create a Fault Network. A fault Network in GeoMine is a group of faults acting together as a space partitioner. A fault object in a Fault Network can be either infinite or finite and it can be dynamically activated and deactivated on the fly. Custom Fault Interactions or Relations can be added between pairs of faults within a Fault Network. The following screenshot shows the Fault Network Manager in GeoMine-GeoModeler:

Unfaulting in GeoMine-GeoModeler entails the following six steps:

1. A faulted Composites object (created using the original drill hole records) and a Fault Network object are selected.
2. Coordinates of the Composites’ points are partitioned and transformed by the selected Fault Network object.
3. Block Model is partitioned and transformed by the selected Fault Network object.
4. The user performs Variogram Modeling using the corresponding Unfaulted Composites object to determine the search ellipsoid in the unfaulted space.
5. Interpolation of attributes for each unfaulted block is performed in the unfaulted space.
6. Interpolated blocks are transformed (aka faulted) back to the original faulted space.

The picture below shows an example block model interpolated w/o any considerations of the existing faults:

The picture below shows an example block model interpolated with Unfaulting on the same Composites object as above:

Unfaulting can also be combined with Dynamic Anisotropy or Unfolding for even more accurate resource estimation in GeoMine:

Unfaulting, Unfolding and Dynamic Anisotropy are currently available in the Ordinary Kriging and Inverse Distance Weighted Interpolation methods in GeoMine-GeoModeler.