Course holding method and apparatus for rotary mode steerable motor drilling

Abstract

A drilling machine for a wellbore is provided. The drilling machine may include one or more dynamic lateral pads (or simply “pads”) that are movable between an extended and retracted position. Generally, the pad(s) are deployed on the bend side of the drilling machine proximal to the drill bit and distal of the bend of the housing. While drilling, the drill bit may experience a deviation force that causes the drill bit to become misaligned with its original course. By extending the pad(s), however, the drilling machine can counteract the deviation force. Deployment of the pad(s) can produce a restorative force in opposition to the deviation force, thereby reducing or eliminating the directional tendency resulting from the deviation force.

What is claimed is: 
     
         1 . An apparatus configured to attach to a drill string of a drilling assembly, the apparatus comprising,
 a bent housing including a lower mandrel section configured to accept a drill bit,
 the lower mandrel section including at least one camming surface; and 
   at least one mandrel-activated dynamic pad mounted generally on a bend side of the bent housing proximal the lower mandrel section and distal a bend of the bent housing,
 the at least one mandrel-activated dynamic pad being configured to extend out at least to an extent equal to or greater than a diameter of the drill bit, and 
 the at least one mandrel-activated dynamic pad capable of exerting a restorative force to the drilling assembly when the drilling assembly experiences a deviation bias. 
   
     
     
         2 . The apparatus of  claim 1  further comprising at least one dynamic pad blade, each dynamic pad blade being situated around an outer periphery of a corresponding dynamic pad. 
     
     
         3 . The apparatus of  claim 1  further comprising two or more dynamic pad blades, each dynamic pad blade incorporating at least one dynamic pad. 
     
     
         4 . A method comprising:
 configuring a bent housing of a directional drilling assembly to include an extensible, mandrel-driven dynamic pad, the dynamic pad having an extended length capable of engaging a wall of a rotary-drilled well;   drilling in a slide mode or a rotary mode with the directional drilling assembly until a chosen path is achieved; and   drilling ahead in the rotary mode with the dynamic pad engaging the wall of the rotary-drilled well and supplying a restoration force to the directional drilling assembly when the directional drilling assembly is biased by a deviation bias.   
     
     
         5 . The method of  claim 4  further comprising:
 employing a measurement assembly to verify course holding of the directional drilling assembly during drilling. 
 
     
     
         6 . The method of  claim 5  further comprising:
 employing a slide correction to return the directional drilling assembly to the chosen path following a failure of the restoration force to filly overcome the deviation bias. 
 
     
     
         7 . The method of  claim 4  further comprising:
 measuring a location of the directional drilling assembly in the rotary-drilled well to verify a failure to fully overcome the deviation bias; 
 altering an operating parameter to alter a cycle or a location of the engagement of the dynamic pad with the wall of the rotary-drilled well; and 
 drilling ahead a specified distance and then remeasuring the location of the directional drilling assembly in the rotary-drilled well to determine if the alteration of the operating parameter improved effectiveness of the restoration force. 
 
     
     
         8 . The method of  claim 7  further comprising:
 adjusting the operating parameter until an improved response to the deviation bias is obtained; 
 performing a slide correction to return to the chosen path; and 
 upon returning to the chosen path, drilling ahead in the rotary mode. 
 
     
     
         9 . The method of  claim 7  wherein the operating parameter is a rotary speed of the mandrel or a flow rate of the directional drilling assembly. 
     
     
         10 . An apparatus for a drilling assembly, the apparatus comprising:
 a drill bit having at least one cutting structure for forming a hole, the drill bit being connected to a distal end of a drive shaft;   a housing that encircles at least a portion of the drive shaft, the housing including a proximal segment and a distal segment separated from the proximal segment by a bend;   a recess formed in the distal segment along a bend side of the housing; and   a pad positioned within the recess, the pad being configured to move from a retracted position to an extended position in which the pad contacts a wall of the hole to produce a restorative force responsive to the drilling assembly being subjected to a deviation force that alters a drilling path of the drill bit.   
     
     
         11 . The apparatus of  claim 10  further comprising:
 a mandrel connected to a distal end of the second segment of the housing, the mandrel including a cavity for receiving the drill bit. 
 
     
     
         12 . The apparatus of  claim 11  wherein the mandrel drives the pad from the retracted position to the extended position. 
     
     
         13 . The apparatus of  claim 11  wherein the pad is configured to move from the retracted position to the extended position and then back to the retracted position at least once per revolution of the mandrel. 
     
     
         14 . The apparatus of  claim 11  wherein the pad is configured to move from the retracted position to the extended position and then back to the retracted position at least four times per revolution of the mandrel. 
     
     
         15 . The apparatus of  claim 10  wherein when the pad is in the extended position, a surface of the pad extends past a diameter of the drill bit. 
     
     
         16 . The apparatus of  claim 10  wherein the pad is one of multiple pads, and wherein each pad is positioned within a separate recess formed in the distal segment of the housing. 
     
     
         17 . The apparatus of  claim 16  wherein each pad of the multiple pads is configured to independently move from the retracted position to the extended position to produce a separate restorative force. 
     
     
         18 . The apparatus of  claim 10  wherein the recess is formed in a blade that extends outward from an outer perimeter of the distal segment of the housing. 
     
     
         19 . The apparatus of  claim 10  wherein the restorative force is sufficient to counter the deviation force, thereby causing the drill bit to return to the drilling path. 
     
     
         20 . The apparatus of  claim 10  wherein a location of the contact of the wall by the pad is based on rotational speed of the housing, rotary speed, flow rate, or any combination thereof