Sealing method and apparatus for wellheads

A seal assembly for sealing an annulus between concentric spaced apart inner and outer generally cylindrical surfaces, each surface having an upper and a lower portion, the seal assembly adapted to be disposed within the annulus, comprising:

• an upper ring-shaped seal member formed of a metallic material and adapted to be disposed adjacent the upper portions of the surfaces, the upper seal member having a generally U-shaped configuration with inner and outer downwardly extending leg members, with an inner seal disposed on the inner leg member and an outer seal disposed on the outer leg member;
• a lower ring-shaped seal member formed of a metallic material and adapted to be disposed adjacent the lower portions of the surfaces, the lower seal member having a generally U-shaped configuration with inner and outer upwardly extending leg members, with an inner seal disposed on the inner leg member and an outer seal disposed on the outer leg member;
• an energizing ring member, disposed between the upper and lower seal members, for energizing the upper and lower seal members to engage, and seal against the surfaces;
• means for causing relative motion between the energizing ring member and the upper and lower seal members;
• and
• the inner seals on the upper and lower inner leg members are interference type seals and sealing between the inner seals and their adjacent inner surfaces is accomplished by an interference fit of the inner seals, disposed on the inner leg members, with their adjacent inner surfaces;
• and the outer seals are wedge type seals, and the sealing between the outer seals and their adjacent outer surfaces is accomplished by the outer seals being wedged into sealing engagement with the adjacent outer surfaces.

A seal assembly for sealing an annulus between an outer surface of an oil and/or gas well tubing or casing hanger and an inner surface of a well head housing, the seal assembly adapted to be disposed within the annulus in sealing engagement with the outer and inner surfaces of the hanger and the wellhead housing, comprising:

• an upper ring-shaped seal member formed of a metallic material and having a generally U-shaped configuration with inner and outer downwardly extending leg members, with an inner seal disposed on the inner leg member and an outer seal disposed on the outer leg member;
• a lower ring-shaped seal member formed of a metallic material and having a generally U-shaped configuration with inner and outer upwardly extending leg members, with an inner seal disposed on the inner leg member and an outer seal disposed on the outer leg member;
• an energizing ring member, disposed between the upper and lower seal members, for energizing the upper and lower seal members to engage and, seal against, the surfaces;
• means for causing relative motion between the energizing ring member and the upper and lower seal members;
• and
• the outer surface of the hanger has a first tapered surface adjacent the inner leg member of the upper seal member, which first tapered surface tapers downwardly and outwardly toward the upper seal member to provide the hanger with a first enlarged diameter adjacent the inner seal of the inner leg member of the upper seal member;
• and
• the outer surface of the hanger has a second tapered surface adjacent the inner leg member of the lower seal member, which second tapered surface tapers downwardly and outwardly toward the lower seal member to provide the hanger with a second enlarged diameter adjacent the inner seal of the inner leg member of the lower seal member.

A seal assembly for sealing an annulus between concentric spaced apart inner and outer generally cylindrical surfaces, the seal assembly adapted to be disposed within the annulus, comprising

• a ring-shaped seal member formed of a metallic material and having a generally U-shaped configuration with inner and outer upwardly extending leg members with an inner seal disposed on the inner leg member adjacent the inner surface and an outer seal disposed on the outer leg member adjacent the outer surface;
• an energizing ring member for energizing the inner and outer seals to engage, and seal against, their adjacent inner and outer surfaces;
• means for causing relative motion between the energizing ring member and the seal member;
• and
• means for staging the energizing of the inner and outer seals to cause one of the seals to completely engage, and seal against, its adjacent surface, before the other seal completely engages, and seals against, its adjacent surface.

A method for sealing an annulus between concentric, spaced apart inner and outer generally cylindrical surfaces, each surface having an upper and a lower portion, comprising the steps of:

• a) providing a seal assembly, having upper and lower metallic seal members, within the annulus adjacent the inner and outer surfaces, the lower seal member having an inner seal for engaging, and sealing against, the lower portion of the inner surface and an outer seal for engaging, and sealing against, the lower portion of the outer surface;
• b) energizing the seal assembly to first cause one of the seals of the lower seal member to completely engage, and seal against, one of the lower portions of one of the surfaces, before the other seal of the lower seal member completely engages, and seals against, the other lower portion of the other surface, and before the upper seal member has engaged, and sealed against, the upper portions of the surfaces;
• and
• c) energizing the seal assembly to then cause the upper seal member to engage, and seal against, the upper portions of the surfaces.

A method for sealing an annulus between concentric, spaced apart inner and outer generally cylindrical surfaces, each surface having an upper and a lower portion, comprising the steps of:

• a) providing a seal assembly having upper and lower metallic seal members, within the annulus adjacent the inner and outer surfaces, each seal member having first and second seals thereon;
• b) providing an energizing ring member disposed between the upper and lower seal members;
• c) disposing the first seals of the upper and lower seal members against adjacent upper and lower portions of the inner surface;
• d) disposing the second seals of the upper and lower seal members against adjacent upper and lower portions of the outer surface;
• e) utilizing interference fit seals as one of the seals for the upper and lower seal members;
• f) utilizing wedge type seals as the other seals for the upper and lower seal members;
• and
• g) causing relative movement between the energizing ring member and the upper and lower seal members to energize the seal assembly to cause the first and second seals of the upper and lower seal members to engage, and seal against, the inner and outer surfaces.