| 摘要 |
A steerable oil and/or gas well drilling method comprises: - inducing top drive equipped with a drill string rotation modulation system to cyclically modulate a rotational speed of an upper end of a drill string (1) during each revolution thereof to steer a drill bit (10) with a tilted toolface into a curved steering direction; - inducing a Measuring While Drilling Device (MWD), to divide each revolution of a Bottom Hole Assembly (BHA) at a lower end of the drill string (10) into a plurality of angular intervals and to transmit average percentages of time that the BHA rotates through the angular intervals to the modulation system thereby providing the modulating system with real time information about the angular orientation of the curved steering direction and obviating a need to provide the modulation system with calibrated models and ongoing torque and/or drill string drag measurements to estimate effects of static and dynamic amounts of drill string twist on the difference between the annular orientations of the upper end of the drill string and the drill bit. |
