Expandable Tubular Centralizer

Abstract

A centralizer device that is set by expansion of an inner expandable tubular member. The centralizer is made up of either one or a plurality of centralizer bands which radially surround an inner, radially expandable tubular member. Each of the centralizer bands includes one or more expansion sections which buckles under tension to form a loop. Generally semicircular, opposing tension straps are affixed to opposite end portions of the expansion section. The tension straps underlie the expansion section and radially surround the inner tubular member in a close-fitting, snug relation. A closure mechanism is used to secure each centralizer band to the inner tubular member.

1 . A centralizer for a radially expandable tubular member having an outer radial surface with a circumference, the centralizer comprising:
 a centralizer band which radially surrounds the expandable tubular member and comprises:
 an arcuate expansion section overlying a portion of the outer radial surface of the expandable tubular member, the expansion section having first and second arcuate ends and being deformable into a loop as the first and second arcuate ends are moved toward each other; 
 a first, generally semi-circular tension band affixed to the first arcuate end and extending about a portion of the circumference of the expandable tubular member; 
 a second tension band affixed to the second arcuate end and extending about a portion of the circumference of the expandable tubular member; and 
 the first and second tension bands being secured to each other. 
   
     
     
         2 . The centralizer of  claim 1  wherein there is a plurality of centralizer bands forming the centralizer. 
     
     
         3 . The centralizer of  claim 2  wherein the expansion section of each of the plurality of centralizer bands is angularly offset from the expansion sections of other centralizer bands. 
     
     
         4 . The centralizer of  claim 3  wherein the expansion sections of the centralizer bands are generally equally angularly spaced relative to one another about the circumference of the expandable tubular member. 
     
     
         5 . The centralizer of  claim 1  wherein there is a single centralizer band having multiple expansion sections. 
     
     
         6 . The centralizer of  claim 1  wherein:
 expansion of the expandable tubular member moves the centralizer from an unset condition, wherein the expansion section of the centralizer band is not deformed into a loop, to a set condition wherein the expansion section is deformed into a loop. 
 
     
     
         7 . The centralizer of  claim 1  wherein the centralizer band is substantially formed of sheet metal. 
     
     
         8 . The centralizer of  claim 1  further comprising a closure mechanism for securing the first tension band to the second tension band, the closure mechanism comprising:
 pin retainer portions formed in each of the first and second tension bands; and 
 a retaining pin that is secured within the pin retainer portions. 
 
     
     
         9 . The centralizer of  claim 1  wherein at least one of the first and second tension bands is affixed to the expansion section by a hinge. 
     
     
         10 . A centralizer for a radially expandable tubular member having an outer radial surface with a circumference, the centralizer comprising:
 a centralizer band, said centralizer band radially surrounding the expandable tubular member and comprising:
 an arcuate expansion section overlying a portion of the outer radial surface of the expandable tubular member, the expansion section having first and second arcuate ends and being deformable into a loop as the first and second arcuate ends are moved toward each other; 
 a first, generally semi-circular tension band affixed to the first arcuate end and extending about a portion of the circumference of the expandable tubular member; 
 a second tension band affixed to the second arcuate end and extending about a portion of the circumference of the expandable tubular member; 
 the first and second tension bands being secured to each other; and 
 wherein expansion of the expandable tubular member moves the centralizer from an unset condition, wherein the expansion section of the centralizer band is not deformed into a loop, to a set condition wherein the expansion section is deformed into a loop. 
   
     
     
         11 . The centralizer of  claim 10  wherein there is a plurality of centralizer bands forming the centralizer. 
     
     
         12 . The centralizer of  claim 11  wherein the expansion section of each of the plurality of centralizer bands is angularly offset from the expansion sections of other centralizer bands. 
     
     
         13 . The centralizer of  claim 12  wherein the expansion sections of the centralizer bands are generally equally angularly spaced relative to one another about the circumference of the expandable tubular member. 
     
     
         14 . The centralizer of  claim 11  wherein there are six centralizer bands forming the centralizer. 
     
     
         15 . The centralizer of  claim 10  wherein the centralizer band has multiple expansion sections. 
     
     
         16 . The centralizer of  claim 10  further comprising a closure mechanism for securing the first tension band to the second tension band, the closure mechanism comprising:
 pin retainer portions formed in each of the first and second tension bands; and 
 a retaining pin that is secured within the pin retainer portions. 
 
     
     
         17 . The centralizer of  claim 10  wherein at least one of the first and second tension bands is affixed to the expansion section by a hinge. 
     
     
         18 . A method for centralizing an inner, radially expandable tubular member within an outer tubular member, the method comprising the steps of:
 disposing a centralizer around the inner tubular member, the centralizer comprising at least one centralizer band having:
 an arcuate expansion section having first and second arcuate ends and being deformable into a loop as the first and second arcuate ends are moved toward each other; 
 a first, generally semi-circular tension band affixed to the first arcuate end and extending about a portion of the circumference of the inner expandable tubular member; 
 a second tension band affixed to the second arcuate end and extending about a portion of the circumference of the inner tubular member; 
   disposing the inner tubular member and the centralizer within an outer tubular member; and   radially expanding the inner expandable tubular member, the radial expansion causing the centralizer bands to move from an unset condition to a set condition, thereby centralizing the inner tubular member within the outer tubular member.   
     
     
         19 . The method of  claim 18  wherein the at least one centralizer band is moved from the unset to the set condition by:
 the first and second tension bands exerting tension upon arcuate ends of each expansion section to cause the expansion section to buckle and form a loop. 
 
     
     
         20 . The method of  claim 18  wherein the step of disposing a centralizer around the inner tubular member further comprises:
 disposing multiple centralizer bands around the inner tubular member such that the expansion sections of each centralizer band is angularly offset from the expansion sections of other centralizer bands. 
 
     
     
         21 . The method of  claim 20  wherein the expansion sections of the centralizer bands are generally equally angularly spaced relative to one another about the circumference of the inner tubular member. 
     
     
         22 . The method of  claim 18  wherein the step of disposing the centralizer around the inner tubular member further comprises securing the at least one centralizer band by fastening a closure mechanism. 
     
     
         23 . The method of  claim 18  wherein the step of disposing a centralizer around the inner tubular member further comprises:
 disposing a centralizer band with multiple expansion sections around the inner tubular member.