4:29 The challenge
- →Drill a dewatering borehole from surface and physically intercept a defined underground target (a "cuddy") ~3,800 ft (1,160 m) below surface, without interrupting active mining.
- →Active workings, energized infrastructure, conveyors and mobile equipment produced severe magnetic interference (~8,000–30,000 nT) that corrupted conventional MWD surveys.
- →By ~5,100 ft (1,555 m) TD, accumulated survey uncertainty reached ±19 ft (5.8 m) vertically and ±56 ft (17.2 m) on the major axis, far too coarse for a physical intercept.
Our solution
Gunnar deployed at-bit rotating-magnet ranging alongside conventional directional surveys, with underground magnetic beacons distributed through the workings for spatial reference, collision avoidance and final target guidance. A project-specific signal-processing and inversion algorithm isolated the rotating-magnet signature inside the highly distorted field, while high-frequency triaxial sensing and multi-shot acquisition fed the composite survey workflow to continuously refine the trajectory.
Penetrated the underground target on design, mining never stopped
The result
~213 ft
ranging detection (65 m) through severe mine interference
- ·Gunnar’s first rotating-magnet ranging deployment in an underground mining intercept
- ·Magnetic beacons enabled real-time collision avoidance and target guidance
- ·A custom inversion algorithm resolved the ranging signal within an 8k–30k nT distorted field
- ·Borehole intersected the marked cuddy wall on design, with mining operations ongoing
Ranging
AMR (rotating magnet)
Deployment
BHA While Drilling
Re-entry
Yes
Location
Australia
Year
2025
Watch, related footage
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