Metal to metal packoff for use in a wellhead assembly

Abstract

A wellhead assembly having an inner tubular insertable into an outer tubular. A packoff is provided on an outer surface of the inner tubular for sealing between the inner and outer tubulars. The packoff includes an energizing ring, a U-shaped seal member, and a nut for retaining the seal member against the energizing ring. The seal member includes legs that are spaced apart by interaction with the energizing ring. The outer tubular has a bore wall that is profiled so that when the inner tubular is inserted into the outer tubular, an outer leg of the seal member is spaced radially outward from the bore wall until the inner tubular is landed in the outer tubular. When the inner tubular member is landed, a portion of the bore wall adjacent the outer leg tapers radially inward into sealing contact with the outer leg of the seal member.

What is claimed is: 
     
         1 . A wellhead assembly comprising:
 an outer tubular having a bore that defines a bore wall;   an inner tubular insertable into the bore and selectively set in a landed position in the bore;   a packoff on the inner tubular;   a taper strategically located in the bore, so that when the inner tubular is inserted into the bore, the packoff is in sealing contact with the bore wall when the inner tubular is proximate the landed position, and the packoff is set radially inward from the bore wall when the inner tubular is above a location proximate the landed position.   
     
     
         2 . The wellhead assembly of  claim 1 , wherein the packoff comprises an energizing ring with a protrusion, a seal element having spaced apart legs that terminate on opposing sides of the protrusion, and a retaining nut threaded to the inner tubular and on a side of the seal element distal from the energizing ring. 
     
     
         3 . The wellhead assembly of  claim 2 , wherein the seal element is a generally annular member. 
     
     
         4 . The wellhead assembly of  claim 3 , wherein one of the legs is spaced radially outward from the protrusion when the when the inner tubular is above a location proximate the landed position, and wherein the one of the legs is wedged between the taper and the protrusion when the when the inner tubular is proximate the landed position. 
     
     
         5 . The wellhead assembly of  claim 2 , wherein one of the legs projects radially outward to define a seal between the outer tubular and the seal element and wherein another one of the legs projects radially inward to define a seal between the inner tubular and seal element. 
     
     
         6 . The wellhead assembly of  claim 1 , wherein the inner tubular is a tubing hanger and wherein the outer tubular is a tubing head. 
     
     
         7 . The wellhead assembly of  claim 1 , wherein the bore wall projects radially inward at an axial location below the taper to define a shoulder on which the inner tubular lands. 
     
     
         8 . A wellhead assembly comprising:
 an outer tubular having an axial bore;   a taper formed in the bore where a surface of the bore projects radially inward;   a shoulder formed in the bore below the taper;   an inner tubular landed on the shoulder; and   a packoff having, an outer radius in sealing contact with the taper and set radially inward from a portion of the bore between the taper and an upper end of the bore, and an inner radius in sealing contact with the inner tubular.   
     
     
         9 . The wellhead assembly of  claim 8 , wherein the packoff comprises an energizing ring, a seal element with legs spaced apart by the energizing ring, and a retaining nut for urging the seal element against the energizing ring, and beads on the legs that form a seal against the inner and outer tubulars. 
     
     
         10 . The wellhead assembly of  claim 9 , wherein the seal element comprises metal. 
     
     
         11 . The wellhead assembly of  claim 9 , wherein the energizing ring comprises a protrusion on which the legs are supported. 
     
     
         12 . The wellhead assembly of  claim 8 , wherein the inner tubular comprises a tubing hanger and the outer tubular comprises a tubing head. 
     
     
         13 . A method of sealing between tubulars in a wellhead assembly comprising:
 providing an inner tubular having a packoff circumscribing a portion of the inner tubular;   providing an outer tubular having a bore with a taper so that a portion of the bore above the taper has a radius greater than a radius of the packoff, and a portion of the bore below the taper has a radius less than the packoff; and   sealing between the packoff and the bore by inserting the inner tubular into the outer tubular at least to a depth that the packoff contacts the portion of the bore having a radius less than the packoff.   
     
     
         14 . The method of  claim 13 , further comprising landing the inner tubular in the outer tubular. 
     
     
         15 . The method of  claim 13 , wherein the packoff comprises an energizing ring with a protrusion, a seal element having spaced apart legs that terminate on opposing sides of the protrusion, a soft metal coating on the seal element, and a retaining nut threaded to the inner tubular and on a side of the seal element distal from the energizing ring.