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. A retaining device is disposed axially between the slip collars and is adapted to limit axial motion of the slip collars. One embodiment of the retaining device is a sleeve which is adapted to be affixed to the exterior surface of the pipe at a selected axial position.

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 an exterior surface of the pipe; and    a retaining device disposed axially between the slip collars at a selected axial position along the exterior surface of 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 device comprises a sleeve including 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 retaining device comprises a sleeve adapted to be affixed to the exterior surface of the pipe.  
     
     
         5 . The centralizer as defined in  claim 4  wherein the sleeve is formed from a plurality of circumferential segments.  
     
     
         6 . The centralizer as defined in  claim 5  wherein the segments comprise interlocking structures on circumferential ends thereof.  
     
     
         7 . 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.  
     
     
         8 . The centralizer as defined in  claim 1  further comprising an anti-friction bearing disposed between an edge of the retaining device and at least one of the slip collars.  
     
     
         9 . The centralizer as defined in  claim 1  further comprising an anti-friction bearing surface disposed between the retaining device and at least one of the slip collars.  
     
     
         10 . 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.  
     
     
         11 . The centralizer as defined in  claim 10  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.  
     
     
         12 . The centralizer as defined in  claim 10  wherein sides of the grooves are radiused.  
     
     
         13 . The centralizer as defined in  claim 1  wherein the slip collars comprise mud channels in an exterior surface thereof.  
     
     
         14 . The centralizer as defined in  claim 1  wherein the spring blades and the slip collars are formed from a single piece of material.  
     
     
         15 . The centralizer as defined in  claim 1  wherein the retaining device is adapted to fit on a pipe section having a smaller outer diameter than an outer diameter of the pipe to be laterally positioned.  
     
     
         16 . The centralizer as defined in  claim 15  wherein the slip collars are adapted to fit on the pipe section.  
     
     
         17 . The centralizer as defined in  claim 16  wherein the slip collars and the spring blades are adapted to compress to at most the outer diameter of the pipe to be laterally positioned.  
     
     
         18 . The centralizer as defined in  claim 1  further comprising a pipe section having an outer diameter smaller than an outer diameter of the pipe to be laterally positioned, and wherein the retaining device is disposed on the pipe section.  
     
     
         19 . The centralizer as defined in  claim 18  wherein the slip collars are disposed on the pipe section.  
     
     
         20 . 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 device 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 device to the exterior surface of the pipe; and    inserting the pipe having the centralizer and retaining device attached thereto into the opening through which the pipe may freely pass and thence into the opening having the larger diameter.    
     
     
         21 . The method as defined in  claim 20  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.  
     
     
         22 . The method as defined in  claim 20  wherein the retaining device comprises a sleeve including 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.  
     
     
         23 . The method as defined in  claim 20  wherein the spring blades define an angle of about 15 to 20 degrees with respect to a longitudinal axis of the pipe.  
     
     
         24 . The method as defined in  claim 20  further comprising an anti-friction bearing disposed between an edge of the retaining device and at least one of the slip collars.  
     
     
         25 . The method as defined in  claim 20  further comprising an anti-friction bearing surface disposed between the retaining device and at least one of the slip collars.  
     
     
         26 . The method as defined in  claim 20  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.  
     
     
         27 . The method as defined in  claim 26  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 device.  
     
     
         28 . The method as defined in  claim 26  wherein sides of the grooves are radiused.  
     
     
         29 . The method as defined in  claim 20  wherein the slip collars comprise mud channels in an exterior surface thereof.  
     
     
         30 . The method as defined in  claim 20  wherein the spring blades and slip collars are made from a single piece of material.  
     
     
         31 . The method as defined in  claim 20  further comprising a pipe section having an outer diameter smaller than an outer diameter of the pipe to be laterally positioned, and wherein the retaining device is disposed on the pipe section.  
     
     
         32 . The method as defined in  claim 31  wherein the slip collars are disposed on the pipe section.  
     
     
         33 . The method as defined in  claim 32  wherein the spring blades and slip collars are adapted to compress to a diameter at most equal to the outer diameter of the pipe to be laterally positioned.  
     
     
         34 . 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 an exterior surface of the pipe; and    a retaining device disposed axially between the slip collars, the retaining device formed integrally with the exterior surface of the pipe so as to limit axial motion of the slip collars.    
     
     
         35 . The centralizer as defined in  claim 34  wherein the pipe comprises reduced diameter segments on an exterior surface thereof, the reduced diameter segments adapted to receive the slip collars about an exterior surface thereof, the retaining sleeve formed by retaining at least part of an exterior diameter of the pipe in a location axially disposed between the reduced diameter segments.  
     
     
         36 . The centralizer as defined in  claim 34  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.  
     
     
         37 . The centralizer as defined in  claim 34  wherein the spring blades define an angle of about 15 to 20 degrees with respect to a longitudinal axis of the pipe.  
     
     
         38 . The centralizer as defined in  claim 34  farther comprising an anti-friction bearing disposed between an edge of the retaining device and at least one of the slip collars.  
     
     
         39 . The centralizer as defined in  claim 34  further comprising an anti-friction bearing surface disposed between the retaining device and at least one of the slip collars.  
     
     
         40 . The centralizer as defined in  claim 34  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.  
     
     
         41 . The centralizer as defined in  claim 40  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 device.  
     
     
         42 . The centralizer as defined in  claim 40  wherein sides of the grooves are radiused.  
     
     
         43 . The centralizer as defined in  claim 34  wherein the slip collars comprise mud channels in an exterior surface thereof.  
     
     
         44 . The centralizer as defined in  claim 34  wherein the spring blades and the slip collars are formed from a single piece of material.  
     
     
         45 . The centralizer as defined in  claim 34  wherein the slip collars and the spring blades are adapted to compress to at most the outer diameter of the pipe to be laterally positioned.