Seal With Bellows Type Nose Ring

Abstract

A wellhead assembly having concentric tubulars and a seal assembly in an annulus between the tubulars. The seal assembly includes an upper portion having an annular body with a U-shaped cross section and a nose ring seal. The nose ring seal has a bellows like cross section and provides sealing in the annulus and exerts a lockdown force onto one of the tubulars. Metal inlays are provided on the outer edges of the folds in the bellows and a compressible medium is disposed between the folds.

What is claimed is: 
     
         1 . A seal assembly for use between concentric downhole tubulars comprising:
 an annular upper portion comprising a ring like outer leg, a ring like inner leg set radially inward from the outer leg to define an annular space between the inner leg and outer leg and having a lower end attached to the outer leg; and   a nose ring assembly coupled to a lower end of the upper portion comprising an annular seal body having a bellows shaped cross section that defines folds having edges along inner and outer circumferences of the seal body, and compressible material between the folds, so that when the seal assembly is disposed between the concentric downhole tubulars and an end of an energizing ring is inserted into the annular space between the inner and outer leg, the seal body of the nose ring transfers a lock down force onto one of the tubulars and the edges extend radially inward and outward into sealing contact with the downhole tubulars.   
     
     
         2 . The seal assembly of  claim 1 , wherein the compressible material comprises encapsulated gas dispersed within a medium. 
     
     
         3 . The seal assembly of  claim 2 , wherein the encapsulated gas comprises glass microspheres and the medium comprises an elastomer. 
     
     
         4 . The seal assembly of  claim 1 , wherein the seal body comprises an elastic metal. 
     
     
         5 . The seal assembly of  claim 1 , further comprising inlays that comprise metal having a yield strength less than the downhole tubulars, so that when the edges extend into sealing contact with the downhole tubulars and discontinuities are present on the downhole tubulars, the inlays conform to the discontinuities to provide the sealing contact. 
     
     
         6 . The seal assembly of  claim 1 , wherein the seal body of the nose ring is threadingly coupled to the upper portion and further comprises a ring like lower base projecting axially downward from an end of a lowermost fold, wherein the lower base is in selective contact with a casing hanger. 
     
     
         7 . The seal assembly of  claim 1 , further comprising a lock nut mounted on an inner surface of the upper end of the upper portion, so that when the energizing ring is pulled from between the tubulars, the seal assembly is retrieved with the energizing ring. 
     
     
         8 . A wellhead assembly comprising:
 an outer tubular;   an inner tubular inserted within the outer tubular to define an annular space between the tubulars; and   a seal assembly in the annular space comprising:
 a seal body having axially projecting folds that define a bellows and edges between adjacent folds that are in sealing contact with an outer surface of the inner tubular and an inner surface of the outer tubular, and 
 an upper end engaged to one of the outer tubular or lower tubular and a lower end engaged with the one of the tubulars not engaged by the upper end, so that when the seal assembly is set in the annular space, a lock down force is transmitted between the inner and outer tubulars through the seal body. 
   
     
     
         9 . The wellhead assembly of  claim 8 , further comprising a compressible material disposed between the folds. 
     
     
         10 . The wellhead assembly of  claim 9 , wherein the compressible material comprises glass microspheres dispersed in an elastomeric medium. 
     
     
         11 . The wellhead assembly of  claim 8 , further comprising an upper portion attached to an upper end of the seal body, the upper portion comprising an annular outer leg in engagement with the outer tubular and an inner leg spaced radially inward from the outer leg that has a lower end depending from the outer leg and is in contact with the inner tubular. 
     
     
         12 . The wellhead assembly of  claim 11 , further comprising a lower base on the seal body that contacts the inner tubular and transmits the lock down force from the inner tubular to the seal assembly. 
     
     
         13 . The wellhead assembly of  claim 8 , further comprising metal inlays on the edges that conform to discontinuities on the respective surfaces of the inner and outer tubulars. 
     
     
         14 . A seal assembly for use between concentric inner and outer downhole tubulars comprising:
 an annular lockdown portion comprising a ring like outer leg, a ring like inner leg set radially inward from the outer leg to define an annular space between the inner leg and outer leg and having a lower end attached to the outer leg;   a nose ring assembly coupled to a lower end of the lockdown portion comprising:
 a bellows like annular seal body that defines folds that are obliquely angled to adjacent folds, 
 edges formed at interfaces between adjacent folds that extend along inner and outer circumferences of the seal body, and 
 compressible material between the folds that comprises an elastomeric substrate with glass microspheres dispersed in the substrate, so that when the seal assembly is disposed between the concentric downhole tubulars and an end of an energizing ring is inserted into the annular space between the inner and outer leg, the seal body of the nose ring transfers a lock down force onto one of the tubulars and the edges extend radially inward and outward into sealing contact with the downhole tubulars. 
   
     
     
         15 . The seal assembly of  claim 14 , wherein the seal body comprises an elastic metal. 
     
     
         16 . The seal assembly of  claim 14 , further comprising inlays that comprise metal having a yield strength less than the downhole tubulars, so that when the edges extend into sealing contact with the downhole tubulars and discontinuities are present on the downhole tubulars, the inlays conform to the discontinuities to provide the sealing contact. 
     
     
         17 . The seal assembly of  claim 14 , wherein the seal body of the nose ring is threadingly coupled to the lockdown portion and further comprises a ring like lower base projecting axially downward from an end of a lowermost fold, wherein the lower base is in selective contact with a casing hanger.