Dual-Pole Magnetic Attraction Downhole Magnetic Retrieval Apparatus

Abstract

A magnetic retrieval tool used for collecting metallic debris and material from within a wellbore or other surrounding downhole tubular. The tool includes a tool mandrel with a removable insert which contains one or more magnets. The insert is formed such that both the north and south magnetic poles of the one or more magnets are able to attract metallic debris.

1 . A magnetic retrieval tool for collecting metallic material from a surrounding tubular, the tool comprising:
 a tool mandrel;   a magnet with north and south magnetic poles disposed upon the tool mandrel; and   wherein the tool presents a first outer attraction surface to attract metallic debris using the north magnetic pole of the magnet and a second outer attraction surface to attract metallic debris using the south magnetic pole of the magnet.   
     
     
         2 . The tool of  claim 1  wherein the tool further comprises:
 an outer radial surface having at least one outwardly radially-projecting fin having two lateral sides; 
 the magnet is located inside of the fin; and 
 the first outer attraction surface is located on one lateral side and the second outer attraction surface is located on the other lateral side. 
 
     
     
         3 . The tool of  claim 2  wherein the outer radial surface comprises a plurality of outwardly radially-projecting fins having two lateral sides;
 a magnet is disposed within each of said fins; and wherein 
 a radially exterior recess is disposed between each two of said plurality of fins for collection of metallic debris. 
 
     
     
         4 . The tool of  claim 3  wherein at least one magnet disposed within a fin comprises a non-magnetic tube containing a plurality of magnets. 
     
     
         5 . The tool of  claim 2  further comprising:
 an insert disposed upon the tool mandrel, the fin being defined upon the insert; and 
 wherein the magnet is disposed within a magnet-retaining cavity that is located at least partially within the fin. 
 
     
     
         6 . The tool of  claim 5  wherein the insert is substantially formed of non-magnetic material. 
     
     
         7 . The tool of  claim 5  further comprising a cover that is removably attached to an inner radial surface of the insert to retain the magnet within the cavity. 
     
     
         8 . A magnetic retrieval tool for collecting metallic material from a surrounding tubular, the tool comprising:
 a tool mandrel;   an insert disposed upon the tool mandrel, the insert containing a magnet with north and south magnetic poles; and   wherein the insert presents a first outer attraction surface to attract metallic debris using the north magnetic pole of the magnet and a second outer attraction surface to attract metallic debris using the south magnetic pole of the magnet.   
     
     
         9 . The tool of  claim 8  wherein the insert further comprises:
 an outer radial surface having at least one outwardly radially-projecting fin having two lateral sides; 
 the magnet is located inside of the fin; and 
 the first outer attraction surface is located on one lateral side and the second outer attraction surface is located on the other lateral side. 
 
     
     
         10 . The tool of  claim 9  wherein:
 the outer radial surface comprises a plurality of outwardly radially-projecting fins having two lateral sides; and 
 a magnet is located inside of each fin. 
 
     
     
         11 . The tool of  claim 10  wherein a radially exterior recess is disposed between each two of said plurality of fins for collection of metallic debris. 
     
     
         12 . The tool of  claim 8  wherein the insert is substantially formed of non-magnetic material. 
     
     
         13 . The tool of  claim 8  wherein the magnet is disposed within a magnet-retaining cavity that is located at least partially within the fin. 
     
     
         14 . The tool of  claim 13  further comprising a cover that is removably attached to an inner radial surface of the insert to retain the magnet within the cavity. 
     
     
         15 . The tool of  claim 8  wherein the tool mandrel includes an exterior fluid flowpath defined upon an outer radial surface to permit fluid in a surrounding tubular to flow past the tool. 
     
     
         16 . An insert for use with a magnetic retrieval tool, the insert comprising:
 an insert body that is shaped and sized to removably reside within a complimentary pocket on a tool mandrel;   the insert body containing a magnet with north and south magnetic poles; and   the insert body presenting a first outer attraction surface to attract metallic debris using the north magnetic pole of the magnet and a second outer attraction surface to attract metallic debris using the south magnetic pole of the magnet.   
     
     
         17 . The insert of  claim 16  further comprising:
 an outer radial surface having at least one outwardly radially-projecting fin having two lateral sides; 
 the magnet is located inside of the fin; and 
 the first outer attraction surface is located on one lateral side and the second outer attraction surface is located on the other lateral side. 
 
     
     
         18 . The insert of  claim 17  wherein the outer radial surface comprises a plurality of outwardly radially-projecting fins having two lateral sides;
 a magnet is disposed within each of said fins; and wherein 
 a radially exterior recess is disposed between each two of said plurality of fins for collection of metallic debris. 
 
     
     
         19 . The insert of  claim 18  wherein a radially exterior recess is disposed between each two of said plurality of fins for collection of metallic debris. 
     
     
         20 . The insert of  claim 16  wherein the insert body is substantially formed of non-magnetic material. 
     
     
         21 . The insert of  claim 17  wherein the magnet is disposed within a magnet-retaining cavity that is located at least partially within the fin. 
     
     
         22 . The insert of  claim 21  further comprising a cover that is removably attached to an inner radial surface of the insert to retain the magnet within the cavity.