Modular Tubing Seal Bore System

Abstract

A seal bore is provided in a modular form so that a desired length of continuous seal bore can be provided with modules that are preferably secured to each other with threads. The modular concept allows overall seal bore lengths to go beyond the 20 meter limit that previously existing that could be attained with honing equipment entering opposed ends of a tubular. The modules abut each other as the threaded connection is made up. A transition zone extends in opposed direction on opposed sides of a connection that retracts the contact location between modules far enough so that even if the dimensional tolerances all go to the extreme in the pin and box that make the connection, a surface irregularity will be sufficiently small as to avoid seal stack contact that can result in potential seal damage. The seal stack length spans the transition zone to preserve sealing integrity.

We claim: 
     
         1 . A seal bore assembly, comprising:
 at least a first and a second tubular modules each having an internal polished bore and configured for end to end connection such that said modules are in abutting contact at their respective internal polished bores.   
     
     
         2 . The assembly of  claim 1 , wherein:
 an end of one of said modules abuts a shoulder of an adjacent module to define a transition line.   
     
     
         3 . The assembly of  claim 1 , wherein:
 said internal polished bore in said first and second modules increases in dimension at a contact location between said first and second modules.   
     
     
         4 . The assembly of  claim 1 , wherein:
 any difference in radial dimension at a contact location between said first and second modules is recessed in a larger dimension than the balance of a polished bore dimension in said first and second modules.   
     
     
         5 . The assembly of  claim 1 , wherein:
 said abutting contact takes place at a larger internal dimension than the internal polished bore dimension that runs for the substantial length of each said module.   
     
     
         6 . The assembly of  claim 1 , wherein:
 said first and second tubular modules having a nominal polished bore dimension and an enlarged dimension adjacent at least one end thereof such that abutting enlarged dimensions of said first and second modules define a recess that is at least as deep as a dimensional difference at said abutting enlarged dimensions.   
     
     
         7 . The assembly of  claim 6 , wherein:
 said enlarged dimensions are formed with tapers extending from said nominal polished bore dimension in said first and second modules.   
     
     
         8 . The assembly of  claim 7 , wherein:
 said tapers are at an angle in the range of 0.5 to 5 degrees.   
     
     
         9 . The assembly of  claim 8 , wherein:
 said tapers are at an angle of 2 degrees.   
     
     
         10 . The assembly of  claim 6 , wherein:
 said enlarged dimension is arcuate.   
     
     
         11 . The assembly of  claim 10 , wherein:
 said enlarged dimension has at least one constant radius.   
     
     
         12 . The assembly of  claim 10 , wherein:
 said enlarged dimension has a plurality of arcs that curve in opposite directions.   
     
     
         13 . The assembly of  claim 1 , further comprising:
 a seal assembly on a mandrel insertable into said internal polished bore of said modules without contacting said modules at the location of their said abutting contact.   
     
     
         14 . The assembly of  claim 13 , wherein:
 said first and second tubular modules having a nominal polished bore dimension and an enlarged dimension adjacent at least one end thereof such that abutting enlarged dimensions of said first and second modules define a recess that is at least as deep as a dimensional difference at said abutting enlarged dimensions.   
     
     
         15 . The assembly of  claim 14 , wherein:
 said enlarged dimensions are formed with tapers extending from said nominal polished bore dimension in said first and second modules.   
     
     
         16 . The assembly of  claim 15 , wherein:
 said tapers are at an angle in the range of 0.5 to 5 degrees.   
     
     
         17 . The assembly of  claim 16 , wherein:
 said tapers are at an angle of 2 degrees.   
     
     
         18 . The assembly of  claim 14 , wherein:
 said enlarged dimension is arcuate.   
     
     
         19 . The assembly of  claim 18 , wherein:
 said enlarged dimension has at least one constant radius.   
     
     
         20 . The assembly of  claim 18 , wherein:
 said enlarged dimension has a plurality of arcs that curve in opposite directions.