Abstract: A push-the-bit steering tool for drilling deviated wellbores comprises a steering head mountable to the bottom of a drill string and having steering pads extendable and retractable by fluid-actuated pistons; a fluid manifold co-rotatingly mounted to the steering head for delivering fluid to the pistons; a rotationally geostationary primary valve for delivering fluid to the fluid manifold; and a secondary valve for delivering fluid to the primary valve. The primary valve has a flow restrictor for regulating fluid flow to the pistons such that the steering pads will be sequentially actuated as the drill string rotates, and the steering force exerted against the wellbore by each sequentially-actuated steering pad will be in a constant selected direction. All of the pistons are hydraulically connected, thereby enabling dependent control of steering pad extension and dependent and positive control of steering pad retraction.

Abstract: A push-the-bit steering tool for drilling deviated wellbores comprises a steering head mountable to the bottom of a drill string and having steering pads extendable and retractable by fluid-actuated pistons; a fluid manifold co-rotatingly mounted to the steering head for delivering fluid to the pistons; a rotationally geostationary primary valve for delivering fluid to the fluid manifold; and a secondary valve for delivering fluid to the primary valve. The primary valve has a flow restrictor for regulating fluid flow to the pistons such that the steering pads will be sequentially actuated as the drill string rotates, and the steering force exerted against the wellbore by each sequentially-actuated steering pad will be in a constant selected direction. All of the pistons are hydraulically connected, thereby enabling dependent control of steering pad extension and dependent and positive control of steering pad retraction.