Patent ID: 7588100
Filing Date: 2009-09-15
Classification: E21B

Abstract:
1. A method of drilling along a desired trajectory for at least a portion of a borehole in a subterranean formation comprising: establishing an angular reference point of a drill string at the surface, the drill string extending downhole along the borehole; rotating the drill string from the surface; supporting a drill bit at a distal end of the drill string, the drill bit being angularly deviated from an axis of the distal end of the drill string; rotating the drill bit relative to the drill string for drilling the borehole; and continuously rotating the drill string in one direction by varying the angular velocity of the rotation of the drill string within each revolution between at least a fast and a slow angular velocity, the varying of the angular velocity having a velocity profile relative to the angular reference point, and applying the velocity relative to the angular reference point substantially similarly for each of a plurality of revolutions wherein the drilling of the borehole is steered along the desired trajectory.