Drill bit stabilizer

Abstract

A stabilizer for a drill string and drill bit is mounted behind the drill bit in the drilling assembly. The stabilizer comprises a tubular body having one or more stabilizer blades mounted thereon. The stabilizer blades extend radially outwardly from the stabilizer body. In a first position, the stabilizer blades are in vertical axial alignment behind the drill bit. Drill string pressure is utilized to release a locking mechanism permitting relative rotation between the stabilizer blades and the stabilizer body thereby rotating the stabilizer blades to a second position providing stabilization for the drill string and drill bit.

1 . A drill bit stabilizer, comprising: 
 a) a stabilizer body having an axial passage extending therethrough, said stabilizer body including a pin connector on one end and a box connecter on the other end for connecting said stabilizer body in a drill string;    b) at least one stabilizer blade mounted about said stabilizer body;    c) an actuator housing mounted in said axial passage of said stabilizer body;    d) piston means carried by said housing for coupling said stabilizer blade with said stabilizer body; and    e) conduit means providing fluid communication between said piston means and said axial passage of said stabilizer body.    
     
     
         2 . The apparatus of  claim 1  wherein said piston means comprises a piston rod having pins mounted on the distal ends thereof, and wherein said piston rod and said pins are in a transverse bore extending through said actuator housing and said stabilizer body.  
     
     
         3 . The apparatus of  claim 1  including means pivotally mounted on the periphery of said stabilizer blade for engaging the inner wall of a borehole upon rotation of said stabilizer body.  
     
     
         4 . The apparatus of  claim 3  wherein said pivotal means comprise a brake shoe mounted in a recess formed on the peripheral edge of said stabilizer blade.  
     
     
         5 . The apparatus of  4  wherein said brake shoe is pivotally secured in said recess and further including biase means providing an outward force against said brake shoe.  
     
     
         6 . The apparatus of  claim 4  wherein said brake shoe includes an axial elongate slot and a post extending through said slot and secured in said recess for limiting the outward radial movement of said brake shoe.  
     
     
         7 . The apparatus of  claim 1  including means for rotating said stabilizer body relative to said stabilizer blade from a first position to a second position.  
     
     
         8 . The apparatus of  claim 1  including at least three stabilizer blades vertically aligned on said stabilizer body.  
     
     
         9 . The apparatus of  claim 8  wherein one of said stabilizer blades is integrally formed with said stabilizer body.  
     
     
         10 . The apparatus of  claim 8  wherein said stabilizer blades are rotated from a first position to a second position for providing full gauge stabilization.