A STEERING TOOL ADAPTED TO CONTROL THE ANGLE AND DIRECTION OF A ROTARY WELL DRILLING STRING IN THE DRILLING OF A WELL BORE THROUGH EARTH FORMATION

摘要

Well bore drilling apparatus has a steering tool operable to stabilize the drill string above the drill bit and to selectively cause a lateral force to be applied to the bit to deflect the drill in a selected direction. The apparatus includes master sensors, in the form of pistons, which sense the lateral force of the drill stem on the low side of the hole and apply fluid pressure to selected slave pistons which are circumferentially spaced above the drill bit to apply lateral thrust in the selected direction. The slave pistons are selected by valves in the apparatus which are opened or closed, as desired, either before running the tool into the well bore or by a wireline manipulator tool while the tool remains in the well bore.