Shrinkage compensated seal assembly and related methods

Abstract

Shrinkage compensated seal assemblies and methods of compensating for shrinkage of a seal due to temperature variations, are provided. According to an exemplary shrinkage compensated seal assembly, the assembly includes a seal, a first compression member for engaging the upper surface of the seal, a second compression member for engaging the lower surface of the seal, and a plurality of pin members each having an elongate body and a head portion. The elongate body of each separate one of the plurality of pin members slidably extends through a different one of a plurality of sets of apertures in the first compression member, the seal, and the second compression member to provide for maintaining a substantially constant pressure on the seal at given pressure under varying temperature conditions that result in variations in the volume size of the seal.

That claimed is: 
     
         1 . A shrinkage compensated seal assembly, comprising:
 a seal;   a first compression member having a first surface for engaging a first surface of the seal and a second surface opposite the first surface;   a second compression member having a first surface for engaging a second surface of the seal and a second surface opposite the first surface; and   a plurality of pin members each having an elongate body including a first end, a second end opposite the first end, and a head portion connected to the first end of the elongate body, the elongate body of each separate one of the plurality of pin members slidably extending through a different one of a plurality of sets of apertures in the first compression member, the seal, and the second compression member to provide for maintaining a substantially constant pressure on the seal at given pressure under varying temperature conditions that result in variations in volume size of the seal.   
     
     
         2 . A shrinkage compensated seal assembly as defined in  claim 1 , wherein the head portion of each pin member has a diameter along a radial axis thereof substantially larger than a diameter along the radial axis of the elongate body, wherein each head portion of each pin member of the plurality of pin members has an engagement surface positioned to engage the second surface of the first compression member when the shrinkage compensated seal assembly is operationally employed, and wherein each of the plurality of pin members maintains compressive engagement with the seal during shrinkage thereof due to a temperature change when in situ force applied to a surface of the head portion opposite the engagement surface of the head portion exceeds force applied to an end surface of the second end of the elongate body of the respective pin member. 
     
     
         3 . A shrinkage compensated seal assembly as defined in  claim 1 , wherein the plurality of pin members are oriented substantially vertically when the shrinkage compensated seal assembly is operationally employed, and wherein the first end of the elongate body and head portion connected thereto are positioned below the second end of the elongate body. 
     
     
         4 . A shrinkage compensated seal assembly as defined in  claim 3 , wherein the seal is an annular seal, wherein the first and second compression members are or form corresponding first and second annular compression plates, wherein the annular seal has a first engagement surface oriented to engage an outer surface of a casing extending through a bore of a casing head and a second engagement surface opposite the first engagement surface and oriented to engage inner surface portions of the casing head circumscribing the bore extending therethrough, and wherein the plurality of pin members are positioned to be actuated to compress the annular seal responsive to pressure in an annulus between the outer surface of the casing and an inner surface of the casing head. 
     
     
         5 . A shrinkage compensated seal assembly as defined in  claim 1 , wherein the head portion of the elongate body of each pin member has a maximum axial length, and wherein each respective head portion is positioned within a recess extending into a casing hanger slip bowl positioned in contact with the second surface of the first compression member, each recess having an axial length substantially exceeding the maximum axial length of the respective head portion positioned therein to provide for slidable movement thereof. 
     
     
         6 . A shrinkage compensated seal assembly as defined in  claim 5 , further comprising:
 a plurality of clamping members each having elongate bodies extending through a corresponding different one of a plurality of sets of apertures in the first compression member, the seal, and the second compression member, said plurality of sets of apertures being different than those receiving the plurality of pin members, each of the plurality of clamping members engaging the second surface of the first compression member and fixedly connected to an upper surface of the casing hanger slip bowl to thereby maintain the seal in a constant state of compression at given pressure and given temperature.   
     
     
         7 . A shrinkage compensated seal assembly as defined in  claim 1 , further comprising:
 a plurality of fasteners each separately connected to an outer surface portion of the second end of the elongate body of a different one of the plurality of pin members.   
     
     
         8 . A shrinkage compensated seal assembly as defined in  claim 7 , wherein each fastener includes an engagement surface positioned to engage the second surface of the second compression member when the shrinkage compensated seal assembly is operationally employed and when a sum of force applied to a surface opposite the engagement surface of the respective fastener and the force applied to the surface of the second end of the elongate body of the respective pin member exceeds the force applied to the surface of the head portion of the respective pin member opposite the engagement surface thereof. 
     
     
         9 . A shrinkage compensated seal assembly as defined in  claim 1 , wherein the seal is an annular seal, wherein the annular seal has a first engagement surface oriented to engage an outer surface of a casing extending through a bore of a casing head and a second engagement surface opposite the first engagement surface and oriented to engage inner surface portions of the casing head circumscribing the bore extending therethrough, wherein the annular seal is positioned within an annular recess extending into the inner surface of the casing head, wherein an axial length of each pin member is smaller than an axial length of a portion of the recess adjacent thereto when positioned therein, and wherein the plurality of pin members are positioned to be actuated to compress the annular seal responsive to pressure between the outer surface of the casing and inner diameter portions of the casing head. 
     
     
         10 . A shrinkage compensated seal assembly as defined in  claim 9 , wherein the pin members are a first plurality of pin members, wherein the plurality of sets of apertures is a first plurality of sets of apertures, the seal assembly further comprising:
 a second plurality of pin members each having an elongate body including a first end, a second end opposite the first end, and a head portion connected to the first end of the elongate body, the head portion of each pin member having a diameter along a radial axis thereof substantially larger than a diameter along the radial axis of the elongate body, each head portion of each pin member of the second plurality of pin members having an engagement surface positioned to engage the second surface of the second compression member when the shrinkage compensated seal assembly is operationally employed,   the elongate body of each separate pin member of the second plurality of pin members slidably extending through a different one of a second plurality of sets of apertures in the first annular compression member, the annular seal, and the second compression member to provide for maintaining a substantially constant pressure on the annular seal at given pressure under varying temperature conditions when force applied to a surface opposite the engagement surface of the head portion of each respective pin member of the second plurality of pin members exceeds force applied to an end surface of the second end of the elongate body of the respective pin member.   
     
     
         11 . A shrinkage compensated seal assembly for a casing head member, comprising:
 an annular seal having a first engagement surface, a second engagement surface, a first compression member engagement surface, and a second compression member engagement surface, the first engagement surface oriented to engage an outer surface of a tubular member positioned within a bore of a casing head, the second engagement surface oriented to engage inner surface portions of the casing head circumscribing a bore extending therethrough, the annular seal varying in volume size as a result of changes in temperature at given pressures;   a first annular compression member having a first surface for engaging the first compression member engagement surface of the annular seal and a second surface opposite the first surface;   a second annular compression member having a first surface for engaging the second compression member engagement surface of the annular seal and a second surface opposite the first surface;   a plurality of pin members each having an elongate body including a first end, a second end opposite the first end, and a head portion connected to the first end of the elongate body;   the elongate body of each separate one of the plurality of pin members slidably extending through a different one of a plurality of sets of apertures in the first annular compression member, the annular seal, and the second annular compression member to provide for maintaining a substantially constant pressure on the annular seal at given pressure under varying temperature conditions that result in variations in volume size of the annular seal.   
     
     
         12 . A shrinkage compensated seal assembly as defined in  claim 11 , wherein the head portion of each pin member has a diameter along a radial axis thereof substantially larger than a diameter along the radial axis of the elongate body, wherein each head portion of each pin member of the plurality of pin members has an engagement surface positioned to engage the second surface of the first compression member when the shrinkage compensated seal assembly is operationally employed, and wherein each of the plurality of pin members maintains compressive engagement with the annular seal during shrinkage thereof due to a temperature change when in situ force applied to a surface of the head portion opposite the engagement surface of the head portion exceeds force applied to an end surface of the second end of the elongate body of the respective pin member. 
     
     
         13 . A shrinkage compensated seal assembly as defined in  claim 12 , wherein the plurality of pin members are oriented substantially vertically when the shrinkage compensated seal assembly is operationally employed, and wherein the first end of the elongate body and head portion connected thereto are positioned below the second end of the elongate body. 
     
     
         14 . A shrinkage compensated seal assembly as defined in  claim 13 , wherein the tubular member is a casing extending through the bore of the casing head, and wherein the plurality of pin members are positioned to be actuated to compress the annular seal responsive to pressure in an annulus between the outer surface of the casing and an inner surface of the casing head. 
     
     
         15 . A shrinkage compensated seal assembly as defined in  claim 11 , wherein the head portion of the elongate body of each pin member has a maximum axial length, and wherein each respective head portion is positioned within a recess extending into a casing hanger slip bowl positioned in contact with the second surface of the first annular compression member, each recess having an axial length substantially exceeding the maximum axial length of the respective head portion positioned therein to provide for slidable movement therein. 
     
     
         16 . A shrinkage compensated seal assembly as defined in  claim 15 , further comprising:
 a plurality of clamping members each having elongate bodies extending through a corresponding different one of a plurality of sets of apertures in the first annular compression member, the annular seal, and the second compression member, said plurality of sets of apertures being different than those receiving the plurality of pin members, each of the plurality of clamping members engaging the second surface of the first annular compression member and fixedly connected to an upper surface of a casing hanger slip bowl to thereby maintain the annular seal in a constant state of compression at given pressure and given temperature.   
     
     
         17 . A shrinkage compensated seal assembly as defined in  claim 11 , further comprising:
 a plurality of fasteners each separately connected to an outer surface portion of the second end of the elongate body of a different one of the plurality of pin members.   
     
     
         18 . A shrinkage compensated seal assembly as defined in  claim 17 , wherein each fastener includes an engagement surface positioned to engage the second surface of the second compression member when the shrinkage compensated seal assembly is operationally employed and when a sum of force applied to a surface opposite the engagement surface of the respective fastener and the force applied to the surface of the second end of the elongate body of the respective pin member exceeds the force applied to the surface of the head portion of the respective pin member opposite the engagement surface thereof. 
     
     
         19 . A shrinkage compensated seal assembly as defined in  claim 13 , wherein the tubular member is a casing extending through the bore of the casing head, wherein the annular seal is positioned within an annular recess extending into the inner surface of the casing head, wherein an axial length of each pin member is smaller than an axial length of a portion of the recess adjacent thereto when positioned therein, and wherein the plurality of pin members are positioned to be actuated to compress the annular seal responsive to pressure between the outer surface of the casing and inner diameter portions of the casing head. 
     
     
         20 . A shrinkage compensated seal assembly as defined in  claim 19 , wherein the plurality of pin members are a first plurality of pin members, wherein plurality of sets of apertures is a first plurality of sets of apertures, and wherein each of the plurality of pin members maintains compressive engagement with the annular seal during shrinkage thereof due to a temperature change when the in situ force applied to the surface of the head portion opposite the engagement surface of the head portion of the respective pin member exceeds force applied to the end surface of the second end of the elongate body of the respective pin member, the seal assembly further comprising:
 a second plurality of pin members each having an elongate body including a first end, a second end opposite the first end, and a head portion connected to the first end of the elongate body, the head portion of each pin member of the second plurality of pin members having a diameter along a radial axis thereof substantially larger than a diameter along the radial axis of the elongate body, each head portion of each pin member of the second plurality of pin members having an engagement surface positioned to engage the second surface of the second compression member when the shrinkage compensated seal assembly is operationally employed,   the elongate body of each separate pin member of the second plurality of pin members slidably extending through a different one of a second plurality of sets of apertures in the first annular compression member, the annular seal, and the second compression member to provide for maintaining a substantially constant pressure on the annular seal at given pressure under varying temperature conditions that result in variations in volume size of the annular seal when in situ force applied to a surface of the head portion opposite the engagement surface of the head portion of each respective pin member of the second plurality of pin members exceeds force applied to an end surface of the second end of the elongate body of the respective pin member.   
     
     
         21 . A method of compensating for shrinkage of a seal for a casing head member due to temperature variations at given pressures, the method comprising the steps of:
 providing a seal assembly comprising a seal, a first compression member having a first surface for engaging a first surface of the seal and a second surface opposite the first surface, a second compression member having a first surface for engaging a second surface of the seal and a second surface opposite the first surface, and a plurality of pin members each having an elongate body including a first end, a second end opposite the first end, and a head portion connected to the first end of the elongate body;   slidably extending the elongate body of each separate one of the plurality of pin members through a corresponding different one of a plurality of sets of apertures in the first compression member, the seal, and the second compression member; and   maintaining a substantially constant pressure on the seal at given pressure under varying temperature conditions that result in variations in volume size of the seal.   
     
     
         22 . A method as defined in  claim 21 , wherein the head portion of each pin member has a diameter along a radial axis thereof substantially larger than a diameter along the radial axis of the elongate body, wherein each head portion of each pin member of the plurality of pin members has an engagement surface positioned to engage the second surface of the first compression member when the seal assembly is operationally employed, and wherein the step of maintaining a substantially constant pressure on the seal includes each of the plurality of pin members maintaining compressive engagement with the seal during shrinkage thereof due to a temperature change when in situ force applied to a surface of the head portion opposite the engagement surface of the head portion of the respective pin member exceeds force applied to an end surface of the second end of the elongate body of the respective pin member. 
     
     
         23 . A method as defined in  claim 21 , wherein the plurality of pin members are oriented substantially vertically when the seal assembly is operationally employed, wherein the first end of the elongate body and head portion connected thereto of each pin member are positioned below the second end of the elongate body, wherein each of the plurality of pin members includes or carries a fastener connected to an outer surface portion of the second end of the elongate body, the method further comprising the step of:
 engaging the second surface of the second compression member with an engagement surface of each fastener when a sum of force applied to a surface opposite the engagement surface of the respective fastener and the in situ force applied to the surface of the second end of the elongate body of the respective pin member exceeds the force applied to the surface of the head portion of the respective pin member opposite the engagement surface thereof, thereby maintaining a substantially constant pressure on the seal by each of the plurality of fasteners at given pressure under varying temperature conditions.   
     
     
         24 . A method as defined in  claim 21 , wherein the plurality of pin members is a first plurality of pin members, and wherein the step of maintaining a substantially constant pressure on the seal is performed when in situ force applied to a surface opposite the engagement surface of the head portion of the respective pin member exceeds force applied to an end surface of the second end of the elongate body of the respective pin member, each head portion of each pin member of the first plurality of pin members having the engagement surface positioned to engage the second surface of the second compression member, the method further comprising the steps of:
 providing a second plurality of pin members each having an elongate body including a first end, a second end opposite the first end, and a head portion connected to the first end of the elongate body, the head portion of each pin member having a diameter along a radial axis thereof substantially larger than a diameter along the radial axis of the elongate body, each head portion of each pin member of the second plurality of pin members having an engagement surface positioned to engage the second surface of the first compression member;   slidably extending the elongate body of each separate pin member of the second plurality of pin members through a corresponding different one of a second plurality of sets of apertures in the first compression member, the seal, and the second compression member; and   maintaining a substantially constant pressure on the seal at given pressure under varying temperature conditions that result in variations in volume size of the seal, by each of the second plurality of pin members when in situ force applied to a surface opposite the engagement surface of the head portion of the respective pin member exceeds force applied to an end surface of the second end of the elongate body of the respective pin member.