Patent ID: 6595302
Filing Date: 2003-07-22
Classification: E21B

Abstract:
An underreamer for forming a cavity within a well bore, comprising:a housing adapted to be rotatably disposed within the well bore; a plurality of cutting blades pivotally coupled to the housing; a piston slidably disposed within the housing and adapted to engage the cutting blades, the piston operable to receive a downwardly disposed force operable to slide the piston relative to the housing, the sliding of the piston extending the cutting blades outwardly from a retracted position relative to the housing; a passage disposed within the piston and operable to communicate a fluid received via an annulus of the housing to the cutting blades, the passage comprising an inlet and an outlet, the outlet operable to be disposed in alignment with a circulation port of the housing; and a deformable member disposed proximate the inlet, and wherein a predetermined pressure of the fluid is operable to deform the member to provide fluid communication between the inlet and the circulation port, the deformable member comprising an elastomer object.