APPARATUS AND METHOD FOR DIRECTIONAL DRILLING

摘要

A directional drilling system and method are provided for directional drilling a borehole by continuous rotating of the drill string in combination with an arrangement of drilling motor assemblies at the lower end of the drill string to effect drilling along a curved path and a substantially straight path. A first drilling motor assembly is coupled to a drill bit and operable to rotate the drill bit to effect drilling of the borehole. A second drilling motor assembly, positioned on the drill string above the first drilling motor assembly, is operable to rotate the first drilling motor assembly in a direction opposite the direction of rotation imparted to the drill string from the surface and to the drill bit by the first drilling motor assembly. A control system associated with the second drilling motor assembly controls fluid flow through the second drilling motor assembly so that the first drilling motor assembly is substantially rotationally stationary with respect to the rotating drill string when drilling a curved path of the borehole.