Downhole Filter Tool

Abstract

Apparatus for downhole filtration in a wellbore The apparatus has a diverter and a filter slidably mounted on a mandrel. The diverter has a circumferential wiper element between the mandrel and the casing within which the apparatus is run. When fluids are reverse circulated, or the tool is being pulled out, the diverter shifts to a downward position, wherein it seals against an upper end of the filter, filtering out solids in the fluids and retaining them in a chamber between the sleeve and mandrel. When running the tool into a wellbore, the diverter shifts to an upper position to permit fluids to bypass the filter sleeve. The filter sleeve bears against a spring loaded seat, which permits creating a gap between the diverter and an upper end of the filter sleeve to allow fluids to bypass the filter sleeve should the filter sleeve slots become plugged.

1 . An apparatus for downhole filtration of completion fluids in a wellbore, comprising:
 a) a central mandrel;   b) a diverter slidably disposed on said mandrel, with an annulus between said mandrel and said diverter forming a flow passage therebetween, said diverter comprising an exterior circumferential wiper in an annulus between said diverter and a casing wall, said diverter slidable between an upper position and a lower position; and   c) a filter sleeve having fluid filtering openings therein, disposed on said mandrel below said diverter, with an annulus between said filter sleeve and said mandrel forming a chamber for retention of solids,   
     whereby when said diverter is in said upper position, fluid can flow through said annulus between said mandrel and said diverter, and when said diverter is in said lower position, said diverter seals against said filter sleeve, whereby fluid moving downhole with respect to said apparatus flows through said fluid filtering openings in said filter sleeve. 
   
   
       2 . The apparatus of  claim 1 , further comprising an outer assembly disposed on said mandrel above said diverter, and wherein:
 said diverter comprises flow passages therethrough, above said wiper, and   said diverter in said upper position seals against said outer assembly.   
   
   
       3 . The apparatus of  claim 2 , further comprising:
 a shoulder on said mandrel which limits movement of said diverter on said mandrel in a downhole direction; and   a seat below said filter sleeve and against which a lower end of said filter sleeve presses, said seat spring biased in an uphole direction, whereby when said filter sleeve moves in a downhole direction with respect to said mandrel under the influence of fluid forces sufficiently great to overcome said spring bias, said seat moves in a downhole direction from an upper position to a lower position, moving said filter sleeve from an upper position to a lower position, creating a gap between said diverter and an upper end of said filter sleeve, through which fluids can flow.   
   
   
       4 . The apparatus of  claim 3 , wherein:
 said filter sleeve comprises one or more ports proximal a lower end thereof, and   with said filter sleeve in its upper position, said seat in its upper position blocks flow through said ports, and said seat in a lower position permits flow through said ports.   
   
   
       5 . The apparatus of  claim 3 , wherein said fluid filtering openings comprise slots. 
   
   
       6 . The apparatus of  claim 3 , wherein said outer assembly comprises a stabilizer. 
   
   
       7 . The apparatus of  claim 3 , wherein said outer assembly comprises a mill. 
   
   
       8 . An apparatus for downhole filtering of fluids in a wellbore, and retrieval of solids from said wellbore, comprising:
 a) a central mandrel with an outer assembly mounted thereon;   b) a diverter slidably disposed on said mandrel, with an annulus between said mandrel and said diverter forming a flow passage therebetween, said diverter comprising an exterior circumferential wiper in an annulus between said diverter and a casing wall and flow passages therethrough above said wiper, said diverter slidable between an upper position wherein said diverter seals against said outer assembly, and a lower position, movement of said diverter on said mandrel limited by a shoulder on said mandrel;   c) a filter sleeve having fluid filtering openings therein, disposed on said mandrel below said diverter, with an annulus between said filter sleeve and said mandrel forming a chamber for retention of solids, and comprising one or more ports proximal a lower end,   
     whereby when said diverter is in said upper position, fluid can flow through said annulus between said mandrel and said diverter, and when said diverter is in said lower position, said diverter seals against said filter sleeve, whereby fluid moving downhole with respect to said apparatus flows through said fluid filtering openings in said filter sleeve;
 d) a seat below said filter sleeve and against which a lower end of said filter sleeve presses, said seat spring biased in an uphole direction, whereby when said filter sleeve moves in a downhole direction with respect to said mandrel under the influence of fluid forces sufficiently great to overcome said spring bias, said seat moves in a downhole direction from an upper position to a lower position, moving said filter sleeve from an upper position to a lower position, creating a gap between said diverter and an upper end of said filter sleeve, through which fluids can flow, 
 
     and wherein with said filter sleeve in its upper position, said seat in its upper position blocks flow through said one or more ports, and said seat in a lower position permits flow through said one or more ports.