Varied rpm drill bit steering

Abstract

A method of steering a drill bit while drilling a wellbore can include periodically increasing a rotational speed of the drill bit while drilling the wellbore, with the rotational speed being increased when an axis of the drill bit is oriented in a desired azimuthal direction relative to a drill string axis. A directional drilling system can include a drill string having a bend interconnected therein, a drill bit, and a controller which selectively increases a rotational speed of the drill bit when an axis of the drill bit is oriented in a desired azimuthal direction relative to an axis of the drill string above the bend. Another method of steering a drill bit while drilling a wellbore can include interconnecting a brake in a drill string, and periodically decreasing a braking force of the brake as the drill bit is rotated.

1 . A method of steering a drill bit while drilling a wellbore, the method comprising:
 periodically increasing a rotational speed of the drill bit while drilling the wellbore; and   the rotational speed of the drill bit being increased when an axis of the drill bit is oriented in a desired azimuthal direction relative to an axis of a drill string.   
     
     
         2 . The method of  claim 1 , wherein the rotational speed of the drill bit is decreased when the drill bit axis is oriented away from the desired azimuthal direction. 
     
     
         3 . The method of  claim 1 , wherein the drill bit axis rotates about the drill string axis while the rotational speed of the drill bit varies. 
     
     
         4 . The method of  claim 1 , wherein the rotational speed of the drill bit is increased only when the drill bit axis is oriented in the desired azimuthal direction relative to the drill string axis. 
     
     
         5 . The method of  claim 1 , wherein the rotational speed of the drill bit is increased when the drill bit axis is oriented within a selected range of the desired azimuthal direction relative to the drill string axis. 
     
     
         6 . The method of  claim 1 , further comprising periodically delivering an impact to the drill bit as the drill bit is rotated. 
     
     
         7 . The method of  claim 6 , wherein the impact is delivered by an impact tool interconnected in the drill string. 
     
     
         8 . The method of  claim 6 , wherein the impact is delivered to the drill bit when the axis of the drill bit is oriented in the desired azimuthal direction relative to the axis of the drill string. 
     
     
         9 . The method of  claim 1 , further comprising changing the desired azimuthal direction of the drill bit axis from a remote location. 
     
     
         10 . The method of  claim 9 , wherein changing the desired azimuthal direction is performed in part by transmitting a command from the remote location via a telemetry signal. 
     
     
         11 . A directional drilling system, comprising:
 a drill string having a bend interconnected therein;   a drill bit; and   a controller which selectively increases a rotational speed of the drill bit when an axis of the drill bit is oriented in a desired azimuthal direction relative to an axis of the drill string above the bend.   
     
     
         12 . The system of  claim 11 , wherein the controller selectively decreases the rotational speed of the drill bit when the axis of the drill bit is oriented away from the desired azimuthal direction. 
     
     
         13 . The system of  claim 12 , wherein the controller selectively decreases the rotational speed of the drill bit by selectively increasing a braking force applied to the drill string. 
     
     
         14 . The system of  claim 11 , wherein the controller selectively increases the rotational speed of the drill bit when the axis of the drill bit is oriented within a selected range of the desired azimuthal direction. 
     
     
         15 . The system of  claim 11 , wherein the controller selectively increases the rotational speed of the drill bit by selectively decreasing a braking force applied to the drill string. 
     
     
         16 . The system of  claim 11 , further comprising an impact tool which delivers an impact to the drill bit. 
     
     
         17 . The system of  claim 16 , wherein the impact tool delivers the impact to the drill bit when the axis of the drill bit is oriented in the desired azimuthal direction. 
     
     
         18 . The system of  claim 16 , wherein at least one sensor interconnected in the drill string senses the azimuthal direction of the axis of the drill bit relative to the axis of the drill string above the bend. 
     
     
         19 . The system of  claim 11 , wherein the desired azimuthal direction is changeable from a remote location. 
     
     
         20 . The system of  claim 19 , wherein the desired azimuthal direction is changed in part by transmission of a command from the remote location to the controller via a telemetry signal. 
     
     
         21 . A method of steering a drill bit while drilling a wellbore, the method comprising:
 interconnecting a brake in a drill string; and   periodically decreasing a braking force of the brake as the drill bit is rotated.   
     
     
         22 . The method of  claim 21 , wherein the braking force is decreased when an axis of the drill bit is oriented in a desired azimuthal direction relative to an axis of the drill string. 
     
     
         23 . The method of  claim 22 , further comprising changing the desired azimuthal direction from a remote location. 
     
     
         24 . The method of  claim 23 , wherein changing the desired azimuthal direction is performed in part by transmitting a command from the remote location via a telemetry signal. 
     
     
         25 . The method of  claim 21 , wherein a rotational speed of the drill bit is increased as a result of decreasing the braking force. 
     
     
         26 . The method of  claim 25 , wherein the rotational speed of the drill bit is increased while an axis of the drill bit is oriented in a desired azimuthal direction relative to an axis of the drill string. 
     
     
         27 . The method of  claim 26 , wherein the rotational speed of the drill bit is increased while the axis of the drill bit is oriented within a selected range of the desired azimuthal direction. 
     
     
         28 . The method of  claim 21 , further comprising periodically delivering an impact to the drill bit as the drill bit is rotated. 
     
     
         29 . The method of  claim 28 , wherein the impact is delivered by an impact tool interconnected in the drill string. 
     
     
         30 . The method of  claim 28 , wherein the impact is delivered to the drill bit when an axis of the drill bit is oriented in a desired azimuthal direction relative to an axis of the drill string.