Rock-Type Underreamer

Overview Product Sheets

Underreamer for open holes, casing programs, and sidetracking

The rock-type underreamer (RTU) features three specially designed arms with large cones that enable it to deploy and underream to nearly twice its original diameter. A wide selection of cones is available.

Operated hydraulically, the cutting arms lock into the open position while pressure is maintained and collapse into the body automatically when pressure is relieved. Cutter arms are changeable quickly on the rig floor.

Tailored for specific downhole conditions

The RTU is easily tailored to specific formation conditions with a range of milled tooth and tungsten carbide insert (TCI) cutting structures available. Milled tooth cutters are available in both open- and sealed-bearing configurations to match project economics. Polycrystalline diamond compact (PDC) cutters are available on request. Orifices are available in different sizes to tailor performance to mud volume and specific downhole conditions.


  • Underreaming for openhole gravel-pack completions
  • Accommodating special casing programs in heaving shales or fault zones
  • Opening a section in preparation for sidetracking

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Underream to Nearly Twice Original Diameter

Rock-Type Underreamer
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RTU Specifications

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