Method for enabling movement of a centralized pipe through a reduced diameter restriction and apparatus therefor

Abstract

A centralizer for laterally positioning a pipe in an opening larger in diameter than an opening through which the centralizer may freely pass is disclosed. The centralizer includes a plurality of helically shaped spring blades affixed at each end thereof to a slip collar. The slip collars are adapted to slide and rotate about the exterior surface of the pipe. The retaining sleeve is disposed axially between the slip collars, the retaining sleeve and is adapted to be affixed to the pipe so as to limit axial motion of the slip collars.

What is claimed is:  
     
         1 . A centralizer for laterally positioning a pipe in an opening larger in diameter than an opening through which the centralizer may freely pass, comprising: 
 a plurality of helically shaped spring blades affixed at each end thereof to a slip collar, the slip collars adapted to slide and rotate about the exterior surface of the pipe; and    a retaining sleeve disposed axially between the slip collars, the retaining sleeve adapted to be affixed to the pipe so as to limit axial motion of the slip collars.    
     
     
         2 . The centralizer as defined in  claim 1  wherein an axial outermost edge of at least one of the slip collars comprises a taper adapted to reduce sticking of the slip collar as it is moved through the opening through which the centralizer may freely pass.  
     
     
         3 . The centralizer as defined in  claim 1  wherein the retaining sleeve includes a plurality of set screws therein to affix the sleeve to the pipe, the set screws arranged in a pattern substantially conforming to a shape of the spring blades whereby the set screws may be accessed through the blades.  
     
     
         4 . The centralizer as defined in  claim 1  wherein the spring blades define an angle of about 15 to 20 degrees with respect to a longitudinal axis of the pipe.  
     
     
         5 . The centralizer as defined in  claim 1  further comprising an anti-friction bearing disposed between an edge of the sleeve and at least one of the slip collars.  
     
     
         6 . The centralizer as defined in  claim 1  further comprising an anti-friction bearing surface disposed between at least one of the slip collars.  
     
     
         7 . The centralizer as defined in  claim 1  wherein the spring blades are affixed to the slip collars in corresponding grooves on an exterior surface thereof, the corresponding grooves having a depth selected to make an exterior surface of the spring blades substantially flush with an exterior surface of the slip collars.  
     
     
         8 . The centralizer as defined in  claim 7  wherein the depth of the corresponding grooves is selected so that a material thickness of the slip collar therein is substantially equal to a thickness of the retaining sleeve.  
     
     
         9 . The centralizer as defined in  claim 7  wherein sides of the grooves are radiused.  
     
     
         10 . The centralizer as defined in  claim 1  wherein the slip collars comprise mud channels in an exterior surface thereof.  
     
     
         11 . The centralizer as defined in  claim 1  wherein the spring blades and the slip collars are formed from a single piece of material.  
     
     
         12 . A method for laterally positioning a pipe in an opening larger in diameter than an opening through which the pipe may freely pass, comprising: 
 sliding a bow spring centralizer and a retaining sleeve onto an exterior surface of the pipe, the centralizer comprising a plurality of helically shaped spring blades affixed at each end thereof to a slip collar, the slip collars adapted to slide and rotate about the exterior surface of the pipe, the retaining sleeve disposed axially between the slip collars, the retaining sleeve adapted to be affixed to the pipe so as to limit axial motion of the slip collars;    affixing the retaining sleeve to the exterior surface of the pipe; and    inserting the pipe having the centralizer and retaining sleeve attached thereto into the opening through which the pipe may freely pass and thence into the opening having the larger diameter.    
     
     
         13 . The method as defined in  claim 12  wherein an axial outermost edge of at least one of the slip collars comprises a taper adapted to reduce sticking of the slip collar as it is moved through the opening through which the centralizer may freely pass.  
     
     
         14 . The method as defined in  claim 12  wherein the retaining sleeve includes a plurality of set screws therein to affix the sleeve to the pipe, the set screws arranged in a pattern substantially conforming to a shape of the spring blades whereby the set screws may be accessed through the blades.  
     
     
         15 . The method as defined in  claim 12  wherein the spring blades define an angle of about 15 to 20 degrees with respect to a longitudinal axis of the pipe.  
     
     
         16 . The method as defined in  claim 12  further comprising an anti-friction bearing disposed between an edge of the sleeve and at least one of the slip collars.  
     
     
         17 . The method as defined in  claim 12  further comprising an anti-friction bearing surface disposed between at least one of the slip collars.  
     
     
         18 . The method as defined in  claim 12  wherein the spring blades are affixed to the slip collars in corresponding grooves on an exterior surface thereof, the corresponding grooves having a depth selected to make an exterior surface of the spring blades substantially flush with an exterior surface of the slip collars.  
     
     
         19 . The method as defined in  claim 18  wherein the depth of the corresponding grooves is selected so that a material thickness of the slip collar therein is substantially equal to a thickness of the retaining sleeve.  
     
     
         20 . The method as defined in  claim 18  wherein sides of the grooves are radiused.  
     
     
         21 . The method as defined in  claim 12  wherein the slip collars comprise mud channels in an exterior surface thereof.  
     
     
         22 . The method as defined in  claim 1  wherein the spring blades and slip collars are made from a single piece of material.