| 摘要 |
A metal seal or packoff for a casing hanger has features which allow a slight downward movement of the casing hanger relative to the well head after the seal has been set. The seal ring has a base and inner and outer walls that extend upward from the base. The inner and outer walls are radially separated by an annular cavity. An energizing ring will move into this cavity to push the inner and outer walls farther apart into sealing engagement with the casing hanger and wellhead. A protective member locates below the base. A flexible section extends downward from the protective member, while joining the protective member to the base. The flexible section is located on the inner side of the base and has a radial dimension that is much less than the base. This thin section enables the base to flex if downward movement of the casing hanger occurs after the seal has been set. The flexing reduces the chance for any movement between the inner and outer walls and the wellhead and casing hanger to take place.
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