Downhole traction

Abstract

An apparatus for use in drilling a high angle or horizontal borehole has a body for coupling to a drill string and one or more traction members mounted for rotation on the body. The apparatus defines a first, passive, configuration and a second, active, configuration in which the traction member urges the apparatus along the inner wall of the borehole.

1 . An apparatus for use in drilling a high angle or horizontal borehole, the apparatus comprising:
 a body for coupling to a drill string; and   a traction member mounted for rotation on the body, the apparatus having a first, passive, configuration and a second, active, configuration in which the traction member urges the apparatus along an inner wall of the borehole.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . The apparatus of  claim 1 , wherein the traction member is adapted for mounting on the body at a skew angle relative to a longitudinal axis of the body. 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . The apparatus of  claim 1 , wherein the apparatus is configured so that the traction member is offset from the borehole wall in the passive configuration. 
     
     
         14 . The apparatus of  claim 1 , wherein the apparatus is configured so that the traction member contacts the borehole wall in both the passive and active configurations. 
     
     
         15 . The apparatus of  claim 1 , wherein the apparatus further comprises an activation arrangement for moving the traction member from the passive configuration to the active configuration. 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . (canceled) 
     
     
         25 . (canceled) 
     
     
         26 . (canceled) 
     
     
         25 . (canceled) 
     
     
         26 . The apparatus of  claim 1 , wherein the traction member comprises a roller or journal. 
     
     
         27 . (canceled) 
     
     
         28 . The apparatus of  claim 1 , wherein the traction member is of sufficient diameter that the central longitudinal axis of the body lies within the diameter of the traction member. 
     
     
         29 . The apparatus of  claim 6 , wherein the axis of the skewed traction member may lie within less than half its diameter from the central longitudinal axis of the body. 
     
     
         30 . The apparatus of  claim 1 , wherein the apparatus comprises one traction member. 
     
     
         31 . The apparatus of  claim 1 , wherein the apparatus comprises a plurality of traction members arranged around the body. 
     
     
         32 . The apparatus of  claim 1 , wherein the body comprises a cylindrical mandrel. 
     
     
         33 . (canceled) 
     
     
         34 . (canceled) 
     
     
         35 . The apparatus of  claim 1 , wherein a recess or pocket is provided in the body. 
     
     
         36 . (canceled) 
     
     
         37 . The apparatus of  claim 1 , wherein the traction member is adapted for mounting in the body directly. 
     
     
         38 . The apparatus of  claim 1 , further comprising a carrier into which the traction member is rotatably mounted. 
     
     
         39 . (canceled) 
     
     
         40 . (canceled) 
     
     
         41 . (canceled) 
     
     
         42 . (canceled) 
     
     
         43 . (canceled) 
     
     
         44 . (canceled) 
     
     
         45 . (canceled) 
     
     
         46 . The apparatus of  claim 1 , wherein the traction member is provided with one or more pressure-compensated radial bearing. 
     
     
         47 . The apparatus of  claim 1 , wherein lubricant is held within a reservoir in the retention block. 
     
     
         48 . (canceled) 
     
     
         49 . (canceled) 
     
     
         50 . (canceled) 
     
     
         51 . (canceled) 
     
     
         52 . (canceled) 
     
     
         53 . The apparatus of  claim 1 , wherein the apparatus further comprises at least one further traction member. 
     
     
         54 . (canceled) 
     
     
         55 . The apparatus of  claim 1 , wherein the apparatus forms or forms part of a downhole stabiliser. 
     
     
         56 . (canceled) 
     
     
         57 . A downhole assembly for use in a high angle or horizontal borehole, the assembly comprising a drill string and at least one apparatus according to  claim 1 . 
     
     
         58 . (canceled) 
     
     
         59 . An apparatus for use in high angle or horizontal drilling applications, the apparatus comprising:
 a body for coupling to a drill string; and   a traction member mounted for rotation on the body, the traction member mounted on the body by means of at least one latch locked retention block.   
     
     
         60 . (canceled)