Patent ID: 7036611

Claim:
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, 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 configured for providing a biasing force oriented substantially transversely to the longitudinal axis and in contact with the at least one laterally movable blade for holding the 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; structure for preventing lateral movement of the at least one laterally movable blade beyond an outermost lateral position 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 allow communication of drilling fluid passing through the tubular body with the at least one laterally movable blade to effect outward lateral movement thereof responsive to a force or pressure of drilling fluid passing through the tubular body.