Packoff Sealing Assembly

Abstract

A packoff assembly for sealing a space between an inner well member and an outer well member. The packoff assembly has a packoff body, and a sealing mechanism with a U-shaped cross-section, including a packoff body leg and a well component leg extending substantially downward from a transverse connecting section. The well component leg is elastically bendable so that it resists inward deflection toward the packoff body and so that the sealing mechanism can be set without the use of an energizing ring. The packoff body leg is configured for engagement with the packoff body, and the well component leg has a sealing surface configured for sealing engagement with the inner or the outer well member.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This technology relates to oil and gas wells, and in particular to sealing mechanisms in packoff assemblies for use in oil and gas wells.[0003]2. Brief Description of Related Art[0004]Typical oil and gas wells have a wellhead. Strings of casing, each supported by a casing hanger, are lowered into the wellhead. Typically, the casing hanger is threaded, and is attached to a threaded upper end of the casing string. The casing hanger lands on a landing shoulder in the wellhead, or alternatively, may land on a previously installed casing hanger having a larger diameter. With the casing string in place, cement may be pumped down the casing until it comes back up the annulus around the casing. After the cement is pumped, a packoff assembly may be positioned between the wellhead and an upper portion of the casing hanger to seal the casing hanger annulus.[0005]Some older wellheads include packoff seals that are elastomeric, and ...

AI Technical Summary

Benefits of technology

This patent is about a packoff assembly used in oil and gas drilling operations. The assembly includes features such as wiper rings to prepare surfaces for sealing, upper seals to shield from pressures and a retainer plate to keep the sealing mechanisms in place. These features improve the performance and reliability of the packoff assembly.

Problems solved by technology

Furthermore, many older oil wells are now being extended past the original design life of such packoff seals, and some are experiencing long term gas migration out to the larger diameter annuli, such as those where the packoff seals are located.

In addition, this older equipment has often been in use for long periods of time, and drilling operation damage to surfaces of the wellhead and / or the casing hanger is possible.

The packoff seals originally installed in the wells are often not suitable for overcoming these problems.

For example, elastomeric seals are susceptible to degradation in their mechanical properties over time.

Thus, as the life of the well becomes extended, the packoff seal may not be reliable.

However, replacement and reinstallation of the packoff seals can be complicated, requiring the use of complex running tools and procedures.

Furthermore, elastomeric seals are still subject to degradation when exposed to high pressure and temperature in the well.

In addition, because surfaces of the well components may be damaged, achieving an adequate seal with a replacement packoff sealing assembly can be difficult.

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