Downhole closed loop control of drilling trajectory

Abstract

A method for drilling a borehole, comprising transmitting a directional signal to a downhole processor, and maintaining the desired drill bit azimuthal direction by using the downhole processor to evaluate an actual drill bit azimuthal direction relative to the desired drill bit azimuthal direction, and using the downhole processor to adjust the actual drill bit azimuthal direction by controlling the directional drilling device.

What is claimed is:  
     
         1 . A method for drilling a borehole, comprising: 
 transmitting a directional signal to a downhole processor; and    maintaining the desired drill bit azimuthal direction by using the downhole processor to evaluate an actual drill bit azimuthal direction relative to the desired drill bit azimuthal direction, and using the downhole processor to adjust the actual drill bit azimuthal direction by controlling a directional drilling device.    
     
     
         2 . The method of  claim 1 , further comprising maintaining the desired drill bit inclination by using the downhole processor to evaluate an actual drill bit inclination relative to the desired drill bit inclination, and using the downhole processor to adjust the actual drill bit inclination by controlling the directional drilling device.  
     
     
         3 . The method of  claim 2 , wherein the directional signal comprises a desired drill bit inclination and a desired drill bit azimuthal direction.  
     
     
         4 . The method of  claim 2 , wherein the directional signal is transmitted to the downhole processor before the downhole processor is placed in the borehole.  
     
     
         5 . A method for drilling a borehole, comprising: 
 transmitting a directional signal to a downhole processor; and    maintaining the desired drill bit azimuthal rate of curvature per unit time by using the downhole processor to evaluate an actual drill bit azimuthal rate of curvature per unit time relative to the desired azimuthal rate of curvature per unit time and using the downhole processor to adjust the actual drill bit azimuthal rate of curvature per unit time by controlling a directional drilling device.    
     
     
         6 . The method of  claim 5 , further comprising maintaining the desired drill bit inclination rate of curvature per unit time by using the downhole processor to evaluate an actual drill bit inclination rate of curvature per unit time relative to the desired inclination rate of curvature per unit time and using the downhole processor to adjust the actual drill bit inclination rate of curvature per unit time by controlling the directional drilling device.  
     
     
         7 . The method of  claim 6 , wherein the directional signal comprises a desired drill bit inclination rate of curvature per unit time and a desired drill bit azimuthal rate of curvature per unit time.  
     
     
         8 . The method of  claim 6 , wherein the directional signal is transmitted to the downhole processor before the downhole processor is placed in a borehole.  
     
     
         9 . A bottom hole assembly, comprising: 
 a drill bit;    a directional drilling device operatively coupled to the drill bit;    a first orientation sensor set disposed proximate to the drill bit; and    a second orientation sensor set disposed at a known axial distance from the first orientation sensor set.    
     
     
         10 . The bottom hole assembly of  claim 11 , further comprising a processor operatively coupled to the directional drilling device, the first orientation sensor set, and the second orientation sensor set, and adapted to control the directional drilling device.  
     
     
         11 . The bottom hole assembly of  claim 12 , wherein the processor is operatively coupled to at least one of the first orientation sensor set and the second orientation sensor set by a short-hop telemetry device.  
     
     
         12 . The bottom hole assembly of  claim 11 , wherein the directional drilling device comprises a bent housing and a mud motor.  
     
     
         13 . The bottom hole assembly of  claim 11 , wherein the directional drilling device comprises a rotary steerable system.  
     
     
         14 . A method for drilling a curved well path, comprising: 
 transmitting a directional signal to a downhole processor operatively coupled to a bottom hole assembly, the bottom hole assembly comprising a plurality of sensors spaced by a known axial distance and a directional drilling device; and    maintaining an at least one of an inclination rate of curvature per unit distance and an azimuthal rate of curvature per unit distance by using the downhole processor to control the at least one of the inclination rate of curvature per unit distance and an azimuthal rate of curvature per unit distance.    
     
     
         15 . The method of  claim 14 , wherein the directional signal comprises a desired drill bit inclination rate of curvature per unit distance and a desired drill bit azimuthal rate of curvature per unit distance.  
     
     
         16 . The method of  claim 14 , wherein the directional signal is transmitted to the downhole processor before the processor is placed in a borehole.  
     
     
         17 . The method of  claim 14 , wherein the directional drilling device comprises a bent housing and a mud motor.  
     
     
         18 . The method of  claim 14 , wherein the directional drilling device comprises a rotary steerable system.  
     
     
         19 . The method of  claim 14 , wherein maintaining at least one of the inclination rate of curvature per unit distance and the azimuthal curvature per unit distance comprises using the downhole processor to evaluate an actual drill bit inclination rate of curvature per unit distance relative to the desired inclination rate of curvature per unit distance and using the downhole processor to adjust the actual drill bit inclination rate of curvature per unit distance by controlling the directional drilling device.  
     
     
         20 . The method of  claim 14 , wherein maintaining at least one of the inclination rate of curvature per unit distance and the azimuthal curvature per unit distance comprises using the downhole processor to evaluate an actual drill bit azimuthal rate of curvature per unit distance relative to the desired azimuthal rate of curvature per unit distance and using the downhole processor to adjust the actual drill bit azimuthal rate of curvature per unit distance by controlling the directional drilling device.  
     
     
         21 . A method for drilling a borehole, comprising: 
 loading trajectory data for each of a plurality of drilling segments into a downhole processor;    maintaining a desired drill bit inclination by using the downhole processor to evaluate an actual drill bit inclination relative to the trajectory data for each of the plurality of drilling segments and by using the downhole processor to control a directional drilling device; and    maintaining a desired drill bit azimuthal direction by using the downhole processor to evaluate an actual drill bit azimuthal direction relative to the trajectory data for each of the plurality of drilling segments and using the downhole processor to control the directional drilling device.