Schlumberger

Pressure Shear Sub

Supplemental drillstring pressure for tool activation

Our pressure shear sub is run in the drillstring to apply temporary pressure for actuating tools such as a near-bit reamer. The sub addresses the need for a reliable source of pressure within the drillstring to activate certain downhole tools.

The tool consists of a one-piece body with an internal inner- and outer-sleeve arrangement. The tool is run in the initial position, enabling flow through the string. When additional pressure is needed inside the drillstring, the ball is dropped and landed on the inner sleeve. Pressure builds up behind the ball to activate another other tool above the pressure shear sub. Once the other tool has been actuated, the driller increases fluid pressure until the predetermined shear pressure is reached. The inner sleeve then shears and moves downward, reestablishing flow to the bit.

Features

  • One-piece, full-strength body
  • Full pressure integrity—no holes or ports in body
  • Ball retained on seat in tool

Advantage

  • Enables pressure to be applied to other tools in the string when required

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