Assigning Block Model Grades to Planned Drillholes

When working with planned drillholes—whether generated from surface, existing drillhole locations, it is often useful to visualise the predicted grades from an existing block model along those planned holes. While nearest-neighbour (NN) estimation using block centroids is one option, Micromine also supports a workflow based on planned drillholes and block model value assignment.

This method avoids re-estimation and allows you to directly sample block model values along the planned drillhole traces.

First, save the planned drillhole collar or trace as an assay plan layer, add a From field set to 0, and rename TD (Total Depth) to To without changing its value. Then add this modified layer to the planned drillhole database as an interval file, ensuring the planned drillhole is stored in a format that supports compositing.

Next, composite the planned drillhole intervals at a suitable length (for example, 1 m), then use Block Model → Assign Blocks to assign the required block model grade fields directly to the planned drillhole composites. The block model values are written onto the composites along the planned drillhole trace, allowing predicted grades to be reviewed and visualised.

Want to learn more?

Online Help Manuals - Click here for the latest version

Learning Management System - Click here to login or here to request access