Patent ID: 7594552
Filing Date: 2009-09-29
Classification: E21B

Abstract:
1. An expandable reamer for drilling a subterranean formation, comprising: a tubular body having a longitudinal axis; a drilling fluid flow path extending through the expandable reamer for conducting drilling fluid therethrough; a plurality of generally radially and longitudinally extending blades carried by the tubular body, each blade carrying at least one cutting structure thereon, wherein at least one blade of the plurality of blades is laterally movable and includes structure associated therewith responsive to one of a biasing force and a pressure; at least one blade-biasing element configured for providing the biasing force oriented substantially transversely to the longitudinal axis and in contact with the associated structure for holding at least one laterally movable blade at an innermost lateral position with a force, the innermost lateral position corresponding to no more than an initial diameter of the expandable reamer; and an actuation structure positioned within the tubular body and configured to selectively allow actuation of the at least one laterally movable blade of the plurality of blades directly by the associated structure to effect lateral movement thereof.