Damage tolerant casing hanger seal

A wellhead assembly comprising:

• a wellhead housing having a bore with an axis;
• a casing hanger landed in the bore, defining an annular seal pocket between the casing hanger and the wellhead housing;
• a deformable metal-to-metal seal in the seal pocket having inner and outer surfaces that sealingly engage the casing hanger and the wellhead housing, respectively, when energized;
• an extension member depending from the metal-to-metal seal;
• a seal retainer ring having annular upward facing inner and outer shoulders, the seal retainer ring having a lower end that engages a landing shoulder between the casing hanger and the wellhead housing;
• a cylindrical member having a lower end joined to the seal retainer ring and extending upward from a location between the inner and outer shoulders;
• an outer seal stack carried on the outer shoulder and having an inner surface in engagement with an outer side of the cylindrical member, the outer seal stack having compliant members that seal between the outer side of the cylindrical member and the wellhead housing when energized;
• an inner seal stack carried on the inner shoulder and having an outer surface in engagement with an inner side of the cylindrical member, the inner seal stack having compliant members that seal between the inner side of the cylindrical member and the casing hanger when energized;
• and
• a slip joint connection assembly that connects the cylindrical member to the extension member, allowing downward movement of the extension member relative to the cylindrical member, such that downward movement of the metal-to-metal seal and the extension member after the seal retainer ring lands on the landing shoulder applies downward forces through the extension member to the inner and outer seal stacks to cause the inner and outer seal stacks to set.

A wellhead assembly comprising:

• a wellhead housing having a bore with an axis;
• a casing hanger landed in the bore, defining an annular seal pocket between the casing hanger and the wellhead housing;
• a metal-to-metal seal within the seal pocket and having an inner leg and an outer leg separated by an annular slot;
• an energizing ring that when moved downward within the slot, pushes the inner leg into engagement with the casing hanger and the outer leg into engagement with the wellhead housing;
• an extension member depending from the metal-to-metal seal;
• a cylindrical member carried by the extension member and extending downward therefrom;
• a seal retainer ring at a lower end of the cylindrical member;
• an inner seal stack supported by the seal retainer ring and located between and in sealing engagement with the casing hanger and the cylindrical member, the inner seal stack comprising chevron shaped rings;
• an outer seal stack supported by the seal retainer ring and located between and in sealing engagement with the wellhead housing and the cylindrical member, the outer seal stack comprising chevron shaped rings;
• an inner spring on an inner side of the cylindrical member below the extension member and above the inner seal stack;
• an outer spring on an outer side of the cylindrical member below the extension member and above the outer seal stack;
• and
• the cylindrical member, inner seal stack and outer seal stack being configured such that downward movement of the energizing ring and the metal-to-metal seal relative to the seal retainer ring applies downward forces through the extension member to the inner and outer springs and to the inner and outer seal stacks to cause the inner and outer seal stacks to set, the downward forces bypassing the cylindrical member;
• and wherein
• continued downward movement of the energizing ring after the inner and outer seal stacks have set causes the energizing ring to move downward in the slot to set the inner and outer legs.