Pressure Control Devices for Sealing Around Tubular Members

Abstract

A pressure control device for sealing about a tubular string comprises: a flange disposed about a central axis, an annular extension extending from the flange and an annular seal element coupled to the annular extension. The seal member includes a through-passage for receiving the tubular string and an annular recess in which the annular extension is disposed. The annular extension includes a radially-inward facing surface that includes a tapered region that is nonlinear in an axial cross-section for reducing mechanical stresses in the seal member.

What is claimed is: 
     
         1 . A pressure control device for sealing about a tubular string, comprising:
 a flange disposed about a central axis, the central axis disposed on an axial plane;   an annular extension extending from the flange and having a radially-inward facing surface; and   an annular seal element coupled to the annular extension, the seal member having a through-passage for receiving the tubular string and an annular recess in which the annular extension is disposed;   wherein the radially-inward facing surface comprises a tapered region that is nonlinear in an axial cross-section formed on the axial plane.   
     
     
         2 . The pressure control device of  claim 1  wherein the radially-inward facing surface flares outwardly, away from the through-passage as the radially-inward facing surface extends axially from flange. 
     
     
         3 . The pressure control device of  claim 1  wherein the radially-inward facing surface includes a first end extending from the flange and a second end spaced from the first end, and wherein the second end is further from the central axis than the first end. 
     
     
         4 . The pressure control device of  claim 3  wherein the radially-inward facing surface comprises a first region extending from the first end and a second region extending from the first region, and wherein the second region is continuously curved in an axial cross-section formed on the axial plane. 
     
     
         5 . The pressure control device of  claim 4  wherein the second region has a constant radius in an axial cross-section formed on the axial plane. 
     
     
         6 . The pressure control device of  claim 3  radially-inward facing surface comprises a first region extending from the first end and a second region extending from the first region, and wherein the second region, in the axial cross-section, has a radius that has a value selected from the range 0 to 30 inches. 
     
     
         7 . The pressure control device of  claim 1  wherein the annular seal element comprises:
 a seal first end adjacent the flange; 
 a seal second end axially spaced apart from the flange; and 
 a radially outermost surface having first and second regions; 
 wherein the first region extends from the seal first end; and 
 wherein the second region extends from the seal second end toward the seal first end and is frustoconical. 
 
     
     
         8 . The pressure control device of  claim 8  wherein on the radially outermost surface, the second region intersects the first region. 
     
     
         9 . The pressure control device of  claim 1  wherein the radially-inward facing surface lacks a radially inward annular protrusion. 
     
     
         10 . A pressure control device for sealing about a tubular string, comprising:
 a central axis;   an annular insert; and   an annular seal element coupled to the annular insert, the annular seal element comprising:
 a seal first end disposed adjacent the annular insert; 
 a seal second end axially spaced apart from the annular insert; 
 a through-passage extending through the seal first and second ends for receiving the tubular string; and 
 a radially outermost surface including a first region extending from the seal first end and a second region extending from the seal second end toward the first region; 
   wherein the second region tapers as it extends in a direction away from the annular insert.   
     
     
         11 . The pressure control device of  claim 10  wherein second region on the annular seal element intersects the first region. 
     
     
         12 . The pressure control device of  claim 10  wherein the second region on the annular seal element is frustoconical. 
     
     
         13 . The pressure control device of  claim 10  wherein the annular insert comprises:
 an annular flange disposed about the central axis; 
 an annular extension extending from the flange; and 
 a radially-inward facing surface extending along the annular extension; 
 wherein the annular seal element includes an annular recess in which the annular extension is disposed, annular recess extending from the seal first end; and 
 wherein radially-inward facing surface of the annular insert includes a tapered region that expands radially outwardly as it extends axially away from the flange. 
 
     
     
         14 . The pressure control device of  claim 13  wherein the radially-inward facing surface further comprises a cylindrical region extending from the flange to the tapered region. 
     
     
         15 . A pressure control device for sealing about a tubular string, comprising:
 a central axis disposed on an axial plane;   an annular insert comprising:
 a flange disposed about the central axis; 
 an annular extension concentric with the flange and extending from the flange; and 
 a radially-inward facing surface extending along the annular extension; and 
   an annular seal element coupled to the annular extension, the annular seal element comprising:
 a seal first end disposed adjacent the flange; 
 a seal second end axially spaced apart from the flange; 
 a through-passage extending through the seal first and second ends for receiving the tubular string; 
 an annular recess in which the annular extension is disposed, the annular recess extending from the seal first end; and 
 a radially outermost surface including a first region extending from the seal first end and a second region extending from the seal second end toward the first region; 
   wherein the radially-inward facing surface of the annular insert includes a tapered region that expands radially outwardly as it extends axially away from the flange.   
     
     
         16 . The pressure control device of  claim 15  wherein the second region on the annular seal element intersects the first region. 
     
     
         17 . The pressure control device of  claim 15  wherein the tapered region is continuously curved on the axial plane. 
     
     
         18 . The pressure control device of  claim 17  wherein the tapered region of the annular insert has a constant radius on the axial plane. 
     
     
         19 . The pressure control device of  claim 15  wherein the radially-inward facing surface of the annular insert comprises:
 a first end coupled to the flange, 
 a second end spaced from the first end; and 
 a cylindrical region extending from the first end; 
 wherein the tapered region extends from the cylindrical region toward the second end. 
 
     
     
         20 . The pressure control device of  claim 19  wherein the tapered region of the radially-inward facing surface intersects the second end at a fillet; and
 wherein on the axial plane, the tapered region intersects the fillet at a tangent line that is disposed at angle between 5 and 45 degrees, inclusive, with respect to the central axis.