Patent ID: 7549485
Filing Date: 2009-06-23
Classification: E21B

Abstract:
1. An expandable reamer for enlarging a subterranean borehole, comprising: a tubular body having a longitudinal axis and a trailing end thereof for connecting to a drill string; a drilling fluid flow path extending though the expandable reamer; a plurality of generally radially and longitudinally extending blades carried by the tubular body, each blade of the plurality of blades carrying at least one cutting structure thereon, wherein at least one blade of the plurality of blades is laterally movable; at least one blade-biasing element positioned to act laterally on the at least one laterally movable blade to hold the at least one laterally moveable blade at an innermost lateral position with a force, the innennost lateral position corresponding to an initial diameter of the expandable reamer; a structure for limiting an outermost lateral position of the at least one laterally movable blade, the outermost lateral position of the at least one laterally movable blade corresponding to an expanded diameter of the expandable reamer; and an actuation sleeve positioned along an inner diameter of the tubular body and configured to selectively prevent or allow conmunication within the tubular body from the drilling fluid flow path with the at least one laterally movable blade in response to an actuation device engaging the actuation sleeve.