Patent ID: 6644422
Filing Date: 2003-11-11
Classification: E21B

Abstract:
An underreamer for forming a cavity within a well bore, comprising:a housing adapted to be rotatably positioned within the well bore; an actuation rod slidably positioned in the housing; at least one first cutter, each first cutter having a first end and a second end, each first end pivotally coupled to the housing; and at least one second cutter, each second cutter pivotally coupled to a respective first cutter, each second cutter having a first end and a second end, the first end of each second cutter pivotally coupled to the actuation rod, wherein an axial force applied to the actuation rod is operable to slide the actuation rod relative to the housing and extend the second ends of the first and second cutters radially outward relative to the housing from a retracted position to form the cavity when the housing is rotated relative to the well bore.