Centraliser segment and centraliser

Abstract

A centraliser segment ( 11 ) which can, by itself or in combination with one or more corresponding centraliser segments, be used to form a centraliser ( 13 ) which can in use be clampingly engaged around an element ( 10 ) which is receivable in a borehole, said centraliser segment comprising a first collar portion ( 15 ), a second collar portion ( 17 ) and at least one bow element ( 19 ) extending between said first collar portion and said second collar portion to maintain the collar portions in spaced relation to each other, wherein the collars have an inner face which in use is to bear against the element and wherein said bow element has a curvature along its length to define an intermediate portion which extends laterally from the centraliser segment away from the inner faces of the collars, at least the intermediate portion of the bow elements having a convex transverse profile, a first connection element ( 21 ) provided at one end of the collar portions and second connection element ( 23 ) provided at the other end of the collar portions, wherein in use said first connection element are engagable with said second connection element of the same or another centraliser segment such that one or more said centraliser segments are connectable together to form a centraliser which in use is capable of being received around the element whereby the intermediate portions are radially outermost, said first and second connection element having an adjustment means which can cause the diameter of the centraliser to be varied.

1 . A centraliser segment which can, by itself or in combination with one or more corresponding centraliser segments, be used to form a centraliser which can in use be clampingly engaged around an element which is receivable in a borehole, said centraliser segment comprising a first collar portion, a second collar portion and at least one strap-like resiliently flexible bow element extending between said first collar portion and said second collar portion to maintain the collar portions in spaced relation to each other, wherein the collars have an inner face which in use is to bear against the element and wherein said bow element has a configuration such as to define an intermediate portion which extends laterally from the centraliser segment away from the inner faces of the collars, said bow elements having a convex transverse profile and having a varied width along their length which is greatest at the intermediate portion, a first connection element provided at one end of the collar portions and a second connection element provided at the other end of the collar portions, wherein in use said first connection element are engagable with said second connection element of the same or another centraliser segment such that one or more said centraliser segments are connectable together to form a centraliser which in use is capable of being received around the element at which position the intermediate portions are radially outermost, said first and second connection element having an adjustment means which can cause the diameter of the centraliser to be varied. 
     
     
         2 . A centraliser segment as claimed at  claim 1  wherein each bow element is configured to have a curvature along its length. 
     
     
         3 . A centraliser segment as claimed at  claim 1  wherein the collar portions are curved along their longitudinal axis to have a curvature which at most approaches the curvature of the element to which the centraliser is to be applied. 
     
     
         4 . A centraliser segment as claimed at  claim 1  wherein the first connection element comprises a passage formed along the respective collar portion to extend inwardly from the respective end and the second connection element comprises an elongate element which in use is able to be received in the passage, the elongate element formed with a set of serrations spaced along at least a portion of its length, the passage associated with a pawl element which is positioned to resiliently engage the serrations to control the longitudinal movement of the elongate portion when received in the passage. 
     
     
         5 . A centraliser segment as claimed at  claim 4  wherein the engagement of the pawl member with the serrations is such as to permit relative movement between the pawl and the passage to cause a reduction in diameter of the centraliser but to resist an increase in the diameter of the centraliser. 
     
     
         6 . A centraliser segment as claimed at  claim 4  wherein outer face of the collar is provided with a pair of transversely spaced retention lugs located in spaced relationship from the passage, the retention lugs configured and arranged to receive the portion of the elongate element passing from the passage on application of the centraliser to the element to hold the portion in close abutting relationship with the outer face of the collar. 
     
     
         7 . A centraliser segment as claimed at  claim 6  wherein a plurality of pairs of retention lugs are provided. 
     
     
         8 . A centraliser segment as claimed at  claim 1  wherein at least two bow elements extend between said first and second collar portions. 
     
     
         9 . A centraliser segment as claimed  claim 1  wherein said first and second collar portions are substantially parallel. 
     
     
         10 . A centraliser segment as claimed at  claim 1  wherein said first and second collar portions are provided as strap-like members. 
     
     
         11 . A centraliser segment as claimed  claim 1  wherein said centraliser segment is made of a corrosion resistant material. 
     
     
         12 . A centraliser segment as claimed at  claim 1  wherein the inner face of the collars between the connection element is provided with a protrusion at spaced intervals along the length of the collars. 
     
     
         13 . A centraliser segment as claimed at  claim 12  wherein the protrusions comprise a rib-like formation extending transversely across the inner face of the collars. 
     
     
         14 . A centraliser for an element comprising a centraliser segment of the form as claimed at  claim 1  wherein the ends of one or more centraliser segments are connected together via said first and second connection element around the element to provide a centraliser for the element.