Centralizing apparatus

Abstract

A wellhead isolation tool including a cup mandrel and a centralizing device. The centralizing device will align the tool so that the cup seal at the lower end of the cup mandrel sealingly engages the production casing. The cup mandrel has an open bore for allowing service tools to pass therethrough unimpeded.

1 . A cup mandrel comprising:
 a tubular mandrel defining a bore therethrough and having first and second ends; and   a cup seal affixed to the second end thereof, the cup seal extending longitudinally and radially from the second end of the tubular mandrel and adapted to engage and seal against a casing having an inner diameter larger than an outer diameter of the tubular mandrel.   
   
   
       2 . The cup mandrel of  claim 1  wherein the bore of the tubular mandrel and the cup seal both have an inner diameter large enough to receive a service tool therethrough unimpeded for conducting downhole service operations in a wellbore. 
   
   
       3 . The cup mandrel of  claim 1 , wherein the cup seal is made of an elastomeric material. 
   
   
       4 . The cup mandrel of  claim 1 , further comprising an annular clearance between the outer diameter of the tubular mandrel and the inner diameter of the casing. 
   
   
       5 . The cup mandrel of  claim 1 , further comprising a hinge point on the cup seal, wherein the cup seal will flex inwardly at the hinge point when the cup seal is inserted into the casing to seal against the casing. 
   
   
       6 . The cup mandrel of  claim 1 , wherein the cup seal has outer and inner surfaces, and wherein the outer surface angles outwardly at a different angle than the inner surface. 
   
   
       7 . A cup mandrel comprising:
 a tubular mandrel defining a bore therethrough;   a cup seal having a first end affixed to an end of the tubular mandrel, the cup seal further comprising:
 a second end, the second end comprising a free end defining a leading edge of the cup mandrel adapted to initially engage a casing in which the cup mandrel is inserted to seal against the casing, the cup seal defining a cup seal inner diameter at least as large as the bore of the tubular mandrel. 
   
   
   
       8 . The cup mandrel of  claim 7 , wherein the cup mandrel has a low profile with an inner diameter large enough to allow a service tool to pass unimpeded therethrough. 
   
   
       9 . The cup mandrel of  claim 7 , further comprising an annular clearance between an outer diameter of the tubular mandrel and an inner diameter of the casing into which the cup seal is inserted. 
   
   
       10 . The cup mandrel of  claim 7 , further comprising a hinge on the cup seal, wherein the cup will flex inwardly at the hinge when the cup mandrel is inserted into the casing to seal against the casing. 
   
   
       11 . The cup mandrel of  claim 7 , wherein the cup seal is fabricated from an elastomeric material capable of being inserted into a casing and left in place for a plurality of wellbore operations. 
   
   
       12 . The cup mandrel of  claim 11 , wherein the cup seal is able to hold a seal against the casing up to 10,000 pounds per square inch. 
   
   
       13 . The cup mandrel of  claim 12 , wherein the cup seal is able to withstand temperatures up to 225° F. 
   
   
       14 . The cup mandrel of  claim 7 , wherein the service tool is a multistage full bore tool. 
   
   
       15 . A self-aligning wellhead isolation tool comprising:
 a tool mandrel having first and second ends;   a centralizing device mounted and extending radially outwardly and axially from the tool mandrel adapted to engage a wellhead along at least a portion of an interior thereof to align the isolation tool; and   a cup seal affixed to the second end of the tool mandrel, the cup seal extending radially and axially outwardly from the second end of the tool mandrel, wherein the cup seal is operable to seal against a bore of a top casing joint in the wellhead to protect the wellhead during treatment of a well.   
   
   
       16 . The self-aligning wellhead isolation tool of  claim 15 , wherein the tool mandrel comprises an upper mandrel and a lower mandrel connected thereto. 
   
   
       17 . The self-aligning wellhead isolation tool of  claim 16 , wherein the centralizing device is mounted to the upper mandrel, and wherein the lower mandrel and the cup seal comprise a cup mandrel. 
   
   
       18 . The self-aligning wellhead isolation tool of  claim 15 , wherein the cup seal is made of an elastomeric material. 
   
   
       19 . The self-aligning wellhead isolation tool of  claim 15 , wherein the cup seal has an inner diameter that is at least as great as an inner diameter of the lower mandrel when the cup seal is inserted into and seals against the bore of the top casing joint. 
   
   
       20 . The self-aligning wellhead isolation tool of  claim 15 , wherein the tool may be placed in a wellhead to seal against the top casing joint and remain in place for a plurality treatments of a wellbore. 
   
   
       21 . A self-aligning wellhead isolation tool comprising:
 a centralizer mandrel having first and second ends;   a centralizing device mounted to and extending radially outwardly and axially from the centralizer mandrel and adapted to engage a wellhead along at least a portion of an interior thereof to align the isolation tool;   a tubular mandrel having first and second ends, the first end being connected to the centralizer mandrel; and   a cup seal affixed at the second end of the tubular mandrel, the cup seal having a free, unprotected lower end that defines a leading edge of the isolation tool, the cup seal being operable to seal against a top casing joint in the wellhead to protect the wellhead during treatment of a well.   
   
   
       22 . The self-aligning wellhead isolation tool of  claim 21 , wherein the cup seal is made of an elastomeric material. 
   
   
       23 . The self-aligning wellhead isolation tool of  claim 22 , wherein the cup seal comprises an inner surface and an outer surface and wherein the inner surface tapers outwardly from the tubular mandrel at a steeper angle than the outer surface. 
   
   
       24 . The self-aligning wellhead isolation tool of  claim 21 , wherein the cup seal has an inner diameter, when sealingly engaged with the top casing joint that is at least as great as an inner diameter of the tubular mandrel. 
   
   
       25 . The self-aligning wellhead isolation tool of  claim 21 , wherein the isolation tool is a low profile tool having a bore sized to allow a service tool to pass unimpeded therethrough for conducting downhole service operations in a wellbore. 
   
   
       26 . The self-aligning wellhead isolation tool of  claim 21 , wherein the cup seal further comprises a hinge point, the hinge point allowing the cup seal to flex inwardly when the leading edge engages the top casing joint.