Method and apparatus for steering a drill string and reaming well bore surfaces nearer the center of drift

Abstract

A steerable well bore drilling device and method are disclosed. The steerable well bore drilling device comprises a drill string, a bit coupled to the drill string, a drilling motor within the drill string and driving the bit, and a pair of eccentric reamers coupled to the drill string and positioned between the bit and the motor.

1 . A steerable well bore drilling device, comprising:
 a drill string;   a bit coupled to the drill string;   a drilling motor within the drill string and driving the bit; and   a pair of eccentric reamers coupled to the drill string and positioned between the bit and the motor.   
     
     
         2 . The steerable well bore drilling device of  claim 1 , wherein the pair of eccentric reamers are diametrically opposed about the drill string. 
     
     
         3 . The steerable well bore drilling device of  claim 2 , wherein each eccentric reamer comprises multiple sets of cutting elements. 
     
     
         4 . The steerable well bore drilling device of  claim 3 , wherein each set of cutting elements are arranged along a spiral path along the surface of each eccentric reamer. 
     
     
         5 . The steerable well bore drilling device of  claim 1 , wherein the eccentric reamers are identical. 
     
     
         6 . The steerable well bore drilling device of  claim 1 , further comprising a drive shaft coupling the bit to the drilling motor, wherein the drive shaft passes through the pair of eccentric reamers. 
     
     
         7 . The steerable well bore drilling device of  claim 1 , further comprising a measure while drilling device adapted to control the rotational position of the pair of eccentric reamers about the drill string to steer the drill string. 
     
     
         8 . The steerable well bore drilling device of  claim 1 , wherein the pair of eccentric reamers are coupled to the drill string at a predetermined separation corresponding to a curvature of the well bore. 
     
     
         9 . The steerable well bore drilling device of  claim 1 , wherein the pair of eccentric reamers extend from the drill string a predetermined distance corresponding to a curvature of the well bore. 
     
     
         10 . The steerable well bore drilling device of  claim 1 , wherein the pair of eccentric reamers provide a steering force when the drill string is sliding and condition the well bore when the drill string is rotating. 
     
     
         11 . A method of drilling a well bore, comprising:
 coupling a bit to a drill string;   coupling a drilling motor positioned within the drill string to the bit;   coupling a pair of eccentric reamers to the drill string, wherein the pair of eccentric reamers are positioned between the bit and the motor;   drilling the well bore;   steering the bit by sliding the drill string within the well bore; and   reaming the well bore by rotating the drill string.   
     
     
         12 . The method of  claim 11 , wherein the pair of eccentric reamers are diametrically opposed about the drill string. 
     
     
         13 . The method of  claim 12 , wherein each eccentric reamer comprises multiple sets of cutting elements. 
     
     
         14 . The method of  claim 13 , wherein each set of cutting elements are arranged along a spiral path along the surface of each eccentric reamer. 
     
     
         15 . The method of  claim 11 , wherein the eccentric reamers are identical. 
     
     
         16 . The method of  claim 11 , wherein the bit is coupled to the drilling motor by a drive shaft that passes through the pair of eccentric reamers. 
     
     
         17 . The method of  claim 11 , further comprising controlling the rotational position of the pair of eccentric reamers about the drill string to steer the drill string with a measure while drilling device. 
     
     
         18 . The method of  claim 11 , further comprising separating the pair of eccentric reamers along the drill string at a predetermined distance corresponding to a curvature of the well bore. 
     
     
         19 . The method of  claim 11 , wherein the pair of eccentric reamers extend from the drill string a predetermined distance corresponding to a curvature of the well bore. 
     
     
         20 . The method of  claim 11 , wherein steering step and the reaming step occur at separate times.