Modular Low-Clearance Centralizer and Method of Making Modular Low-Clearance Centralizer

Abstract

A low-clearance bow spring centralizer ( 10 ) can be made by providing a plurality of bow spring modules ( 54 ), each having an elongate rib ( 52 ) with a first integrally-formed collar segment ( 54 ) at a first end and a second integrally-formed collar segment ( 56 ) at a second end wherein the first collar segment ( 54 ) and the second collar segment ( 56 ) are joined to adjacent first and second collar segments, respectively. The bow spring modules may be interlinked by welding a seam ( 55 ) formed between abutting sides of adjacent pairs of first collar segments and/or second collar segments. The sides ( 54 a ) of the first collar segment and the sides ( 56 a ) of the second collar segment may each be perpendicular to the axis of the centralizer bore, and seams ( 55 ) therebetween may be welded to form a first centralizer collar and a second centralizer collar, coupled one to the other by the ribs ( 52 ).

1 . A method of making a bow spring centralizer to center a tubular string within a borehole comprising the steps of:
 providing a plurality of bow spring modules having an integrally-formed and curved first collar segment at a first end of an elongate rib, and an integrally-formed and curved second collar segment at the second, opposite end of the rib; and   coupling the plurality of first collar segments together to form a first centralizer collar; and   coupling the plurality of second collar segments together to form a second centralizer collar.   
     
     
         2 . The method of  claim 1  further comprising the steps of:
 bending the first collar segment of a bow spring module to conform to a curvature of a primary forming block; and   bending the second collar segment of a bow spring module to conform to the curvature of the primary forming block.   
     
     
         3 . The method of  claim 2  further comprising the steps of:
 bending the first collar segment of a bow spring module to conform to a curvature of a secondary forming block; and   bending the second collar segment of a bow spring module to conform to the curvature of the secondary forming block.   
     
     
         4 . The method of  claim 1  further comprising the steps of:
 coupling a spacer to an uncoupled first collar segment of a module; and   coupling a spacer to an uncoupled second collar segment of a module.   
     
     
         5 . The method of  claim 1  further comprising the step of:
 heat treating the weld seams of the first centralizer collar or the second centralizer collar.   
     
     
         6 . A method of making a bow spring centralizer comprising the steps of:
 displacing a male die through a metal plate and into a female die cavity to form a bow spring module having an elongate rib, an integrally-formed and curved first collar segment at a first end of the rib and an integrally-formed and curved second collar segment at a second end of the rib;   repeating the first step to produce a plurality of bow spring modules;   welding the first collar segment to a collar segment of an adjacent bow spring module to form a first centralizer collar; and   welding the second collar segment to a collar segment of the adjacent bow spring module to form a second centralizer collar that is spaced-apart from the first centralizer collar by the plurality of ribs.   
     
     
         7 . A bow spring module to use in making a bow spring centralizer comprising:
 an elongate rib having an integrally-formed first collar segment at a first end and an integrally-formed second collar segment at a second end; and   wherein the first collar segment comprises two spaced-apart sides and the second collar segment comprises two spaced-apart sides.   
     
     
         8 . The bow spring module of  claim 7  wherein at least one of the two-spaced apart sides of the first collar segment or at least one of the two-spaced apart sides of the second collar segment are generally parallel to the axis of a bow spring centralizer that may be made by interlinking the bow spring modules. 
     
     
         9 . The bow spring module of  claim 8  wherein one of the two-spaced apart sides of the first collar segment or one of the two-spaced apart sides of the second collar segment are beveled. 
     
     
         10 . A method of making a bow spring centralizer comprising the steps of:
 providing a plurality of bow spring modules comprising an elongate rib with an integrally-formed first collar segment at a first end and an integrally-formed second collar segment at a second end, the first and second integrally-formed collar segments comprising two spaced-apart sides; and   interlinking the plurality of bow spring modules.   
     
     
         11 . The method of  claim 10  wherein interlinking each first collar segment along each of the sides to an adjacent first collar segment to form a first centralizer collar includes the step of welding, and wherein joining each second collar segment along each of the sides to an adjacent second collar segment to form a second centralizer collar includes the step of welding. 
     
     
         12 . The method of  claim 11  further comprising the step of dressing the welded joints. 
     
     
         13 . The method of  claim 10  wherein the sides are generally linear. 
     
     
         14 . The method of  claim 13  wherein the sides of the first and the second collar segments are beveled so as to form a channel when placed in an abutting position along the side of an adjacent first or second collar segment. 
     
     
         15 . A method of making a bow spring centralizer comprising the steps of:
 providing a plurality of bow spring modules,   joining each first collar segment along each of the sides to an adjacent first collar segment to form a first centralizer collar; and   joining each second collar segment along each of the sides to an adjacent second collar segment to form a second centralizer collar.   
     
     
         16 . The method of  claim 1  further comprising the step of coupling a spacer to one of the first collar segment or the second collar segment to alter the size thereof.