| US 7,588,100 B2 | ||
| Method and apparatus for directional drilling with variable drill string rotation | ||
| James F Hamilton, Calgary (Canada) | ||
| Assigned to Precision Drilling Corporation, Calgary, Alberta (Canada) | ||
| Filed on Sep. 06, 2007, as Appl. No. 11/851,384. | ||
| Prior Publication US 2009/0065258 A1, Mar. 12, 2009 | ||
| Int. Cl. E21B 7/04 (2006.01) | ||
| U.S. Cl. 175—61 [175/73; 175/74] | 17 Claims |
| 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.
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