Halliburton Energy Services, Inc.

David Wayne Cawthon

Bradley David Dunbar

Olivier Mageren

John Gerard Evans

Jean-Pierre Lassoie

Kazi M Rashid

Luk Servaes

William Browning Bradford

A well tool apparatus comprises a control arrangement configured to control response of the downhole tool by varying a bore-annulus pressure difference. The control arrangement includes a valve piston longitudinally slidable in a generally tubular controller housing that is in operation substantially co-axial with the wellbore, to open or close a valve port to a fluid flow connection between the drill strings interior and the tool. A latch mechanism is configured to latch the valve piston against movement in one axial direction, keeping the valve piston in an open or a closed condition. Unlatching of the valve piston requires displacement thereof in the other axial direction to a mode change position. A stay member is automatically displaceable under hydraulic actuation responsive to bore-annulus pressure differences above a trigger threshold value, to obstruct movement of the latched valve piston under hydraulic actuation to the mode change position.

Hydraulic control of downhole tools

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Tomball, TX, United States of America

David Wayne Cawthon