Angle Drilling in Exploration: Why Inclined Holes Matter

A vertical hole is not always the best way to test an orebody. In many deposits, including vein-hosted and shear-hosted gold common in West Africa, mineralised zones dip steeply. Drilling at an angle makes the hole cross them more effectively.

Why angle matters

• A hole drilled roughly perpendicular to a structure crosses it over a shorter length, giving intercepts closer to the true width.
• A vertical hole in a steep zone can run along it, overstating its width, or miss it entirely.
• Inclined holes can test a structure at depth from a convenient surface position.

What angle drilling asks of the rig

• A mast that can be set and locked at the planned angle. The PRD OZ RC drills from 45° to 90°, with manual locks in 5° increments, and raises its mast with two hydraulic cylinders with a dumping arrangement for angle drilling.
• Safe rod handling when the mast is inclined: the PRD OZ RC has a jib boom arm for this, plus radio-remote rod handling.
• Stable set-up: four hydraulic levelling jacks.

Planning tips

• Set azimuth and dip from the geological model before mobilisation.
• Build pad layouts around the hole orientation.
• Plan downhole surveys: the PRD OZ RC has a survey winch (500 kg hoisting capacity, 400 m drum).

Planning an angled RC programme? See the RC drilling page and request a quote below.