Reverse circulation junk basket

Abstract

An apparatus and method for capturing debris and metal cuttings downhole in a wellbore. Fluid is reverse circulated through a tubing positioned in the wellbore. An aperture opens to a larger space within the tubing interior and creates a pressure drop which separates the debris from the fluid. The debris is separated from the fluid and is collected by an interior space within the tubing. The tubing can be retrieved from the wellbore so that the debris is separated from the interior space.

What is claimed is:  
     
         1 . An apparatus for capturing debris downhole in a wellbore when fluid is reverse circulated through the wellbore and through a hollow tubular positioned in the wellbore, comprising: 
 a hollow basket housing attached to said tubular;    a basket member positioned within said basket housing to define an interior volume between said basket housing and said basket member for capturing the debris; and    an aperture in said basket member for permitting reverse circulated flow of the fluid and debris therethrough, wherein said aperture has a dimension smaller than an interior dimension of the hollow tubular to generate a pressure drop proximate to said basket member to facilitate separation of the debris from the fluid.    
     
     
         2 . An apparatus as recited in  claim 1 , wherein said basket housing is detachable from the tubular to permit removal of the debris from said interior volume.  
     
     
         3 . An apparatus as recited in  claim 1 , wherein said basket member is substantially cylindrical.  
     
     
         4 . An apparatus as recited in  claim 1 , wherein said basket member further comprises a sloped surface proximate to said aperture for guiding fluid and debris through said aperture.  
     
     
         5 . An apparatus as recited in  claim 1 , wherein said interior volume is substantially toroidal with a closed end and an open end for permitting entry of the debris into said interior volume.  
     
     
         6 . An apparatus for capturing debris downhole in a wellbore when fluid is reverse circulated through the wellbore, comprising: 
 a hollow tubular operable from the wellbore surface;    a cutter head; and    a basket attached between said cutter head and said tubular, wherein said basket comprises an exterior housing and an interior member having an aperture for permitting flow of the fluid and debris therethrough, and wherein said interior member and said exterior housing form an interior volume for capturing the debris as the fluid and debris are reverse circulated through said aperture.    
     
     
         7 . An apparatus as recited in  claim 6 , wherein said basket is detachable from said tubular to facilitate removal of the debris from said basket interior volume.  
     
     
         8 . An apparatus as recited in  claim 6 , wherein said basket is detachable from said cutter head to facilitate removal of the debris from said basket interior volume.  
     
     
         9 . An apparatus as recited in  claim 6 , wherein said interior member is substantially cylindrical.  
     
     
         10 . An apparatus as recited in  claim 6 , wherein said interior member further comprises a sloped surface proximate to said aperture for guiding fluid and the debris through said aperture.  
     
     
         11 . An apparatus as recited in  claim 6 , wherein said interior member further comprises a ring having a threadform for detachable engagement with said exterior housing.  
     
     
         12 . A method for capturing debris downhole in a wellbore, comprising the steps of: 
 attaching a basket housing to a tubular to define an interior volume within said tubular, wherein said basket housing includes an aperture for permitting fluid flow therethrough;    positioning said tubular and basket housing downhole in a wellbore;    reverse circulating fluid to move the debris through said aperture; and    separating the debris from the fluid as the debris and fluid passes through said aperture so that the debris is captured within said basket housing interior volume.    
     
     
         13 . A method as recited in  claim 12 , wherein said basket housing is positioned at a selected location within the wellbore.  
     
     
         14 . A method as recited in  claim 12 , further comprising the steps of withdrawing said basket housing from the wellbore and of removing the debris from said basket housing interior.  
     
     
         15 . A method as recited in  claim 12 , further comprising the steps of operating a mill to generate metal cuttings within the wellbore and of capturing the metal cuttings within said basket housing interior volume.  
     
     
         16 . A method as recited in  claim 12 , further controlling the flowrate of the circulating fluid to control the density of debris captured within said basket housing interior volume.  
     
     
         17 . A method as recited in  claim 12 , further comprising the step of selecting the aperture dimension to control the fluid pressure drop though said aperture as the debris and fluid flows therethrough.  
     
     
         18 . A method as recited in  claim 12 , further comprising the step of selecting the aperture configuration to direct the debris toward said basket housing interior volume.