Downhole tool with slip elements having a friction surface

Abstract

Slip segments with a friction medium are used to anchor a downhole tool in a well. Each slip segment has a slip segment body made of a drillable material. A friction medium is applied to the outer surface of the slip segment body so that the outer surface of the slip segment has an increased holding capability in the well.

1 . Apparatus for anchoring a downhole tool in a well comprising:
 a plurality of slip segments disposed about a mandrel of the downhole tool and movable to a set position wherein the slip segments engage the well, at least one of the slip segments made of a drillable material with a friction medium applied to the outer surface thereof for increasing the gripping capability of the slip segment to the well.   
   
   
       2 . The apparatus of  claim 1 , wherein the slip segment has a sandpaper-like outer surface. 
   
   
       3 . The apparatus of  claim 1 , the at least one slip segment comprising a phenolic slip segment body, the friction medium being applied to the outer surface of the slip segment body. 
   
   
       4 . The apparatus of  claim 3 , wherein the friction medium is molded to the phenolic slip segment body. 
   
   
       5 . The apparatus of  claim 3 , wherein the friction medium comprises aluminum oxide. 
   
   
       6 . The apparatus of  claim 1 , wherein the slip segments have at least one button secured thereto and extending outwardly from the outer surface thereof for gripping the casing. 
   
   
       7 . The apparatus of  claim 1 , wherein the plurality of slip segments are comprised of a non-metallic material. 
   
   
       8 . The apparatus of  claim 7 , wherein the plurality of slip segments are comprised of a phenolic. 
   
   
       9 . The apparatus of  claim 8 , the friction medium comprising aluminum oxide applied to the outer surface of the phenolic. 
   
   
       10 . The apparatus of  claim 8 , wherein all of the slip segments include the friction medium at the outer surface thereof. 
   
   
       11 . A downhole tool for use in a well comprising:
 a mandrel;   a slip ring movable from a set to an unset position, wherein in the set position the slip ring grippingly engages the well, the slip ring comprising a drillable material with a friction medium applied on the outer surface thereof for increasing the gripping capability of the slip ring to the well.   
   
   
       12 . The downhole tool of  claim 11  wherein the slip ring comprises a plurality of slip segments, at least a portion of the slip segments having the friction medium on an outer surface thereof. 
   
   
       13 . The downhole tool of  claim 12 , wherein the friction medium comprises aluminum oxide. 
   
   
       14 . The downhole tool of  claim 12 , wherein the slip segments are comprised of a phenolic. 
   
   
       15 . The downhole tool of  claim 11  comprising an expandable packer element disposed about the mandrel and first and second slip rings, one of the slip rings positioned above the packer element and the other positioned below the packer element. 
   
   
       16 . The downhole tool of  claim 15 , wherein the first and second slip rings comprise a plurality of slip segments grippingly engageable with the well. 
   
   
       17 . The downhole tool of  claim 16 , wherein at least a portion of the slip segments comprises inserts extending outwardly from an outer surface thereof. 
   
   
       18 . The downhole tool of  claim 17  wherein the slip segments comprise a phenolic slip segment body with aluminum oxide applied to an outer surface thereof. 
   
   
       19 . A downhole tool for use in a well comprising::
 a mandrel;   an expandable element disposed about the mandrel;   a first slip ring disposed about the mandrel movable from an unset to a set position wherein the first slip ring grippingly engages the well in the set position;   a second slip ring disposed about the mandrel movable from an unset to a set position wherein the second slip ring grippingly engages the well in the set position, wherein at least one of the first and second slip rings has a friction medium on the outer surface thereof so that the gripping ability of the slip ring is greater than the gripping ability of a bare slip ring.   
   
   
       20 . The downhole tool of  claim 19 , the first and second slip rings comprising a plurality of slip segments retained on the mandrel and movable to the set position wherein an outer surface of at least a portion of the slip segments engages the well in the set position. 
   
   
       21 . The downhole tool of  claim 20 , wherein at least a portion of the slip segments comprises a phenolic slip segment body with the friction medium applied thereto. 
   
   
       22 . The downhole tool of  claim 21 , the friction medium comprising aluminum oxide. 
   
   
       23 . The downhole tool of  claim 19 , the slip rings comprising a phenolic having the friction medium applied to the outer surface thereof. 
   
   
       24 . The downhole tool of  claim 19 , the friction medium comprising aluminum oxide.