Patent ID: 9181755
Filing Date: 2015-11-10
Classification: E21B

Abstract:
1. A downhole expandable roller bearing apparatus for incorporation into a drill string, the apparatus comprising: a body defining a central longitudinal axis; at least one piston mounted in the body and moveable radially relative to the central longitudinal axis between an inwardly retracted position and an outwardly deployed activated position in response to fluid pressure in the body acting on a surface of at least one said piston, the surface being disposed internally in the body; at least one roller rotatably mounted to the or each said piston, at least one said roller arranged to roll against the side of a borehole when at least one said piston is in the outwardly deployed activated position to provide stabilisation to and reduce vibration and torque in a drill string in which the apparatus is incorporated; characterised by an aperture formed through at least one piston, the aperture defining an aperture axis that is perpendicular to a radius of the body; and at least one retaining member removably mountable in the body to project into the respective aperture in both the inwardly retracted and outwardly deployed activated positions to prevent removal of the corresponding piston from the body and resist rotation of the piston relative to the body.