Seal for a Wellbore

Abstract

A seal apparatus for closing a wellbore, the apparatus being universally deployable and capable of closing the wellbore even in the case of damage located beneath a present blowout preventer. The apparatus is based on the idea of introducing a seal into the wellbore in order to close it off to avoid damage from a rising fluid. For this purpose, the seal has at least one apron, or a capsule. An opening of the apron, or distending of the capsule, causes a non-positive and/or positive connection to be produced in respect to the wall of the wellbore such that the wellbore is closed.

Description

FIELD OF THE INVENTION[0001]The invention relates to a seal for a wellbore in which a fluid, for instance oil or gas, flows up.Prior Art[0002]So-called blowout preventers are known from the prior art. The term blowout preventer is used for various shut-off valves that are fitted directly over the wellbore in the case of a drilling operation. Blowout preventers serve to prevent a fluid from flowing out of the wellbore. This is necessary, in particular, if the drill string is damaged or if the drilling operation encounters a pressurized zone.[0003]While a drilling operation is being performed, the drill string extends through the blowout preventer. If, in this case, there is an outflow of the fluid that cannot be stopped by other means, a two-stage mechanism comes into effect in the blowout preventer. In a first stage, seals are activated, which seal off the outer space around the drill string. Should this not suffice to stop an outflow of the fluid, the drill string is severed inside...

AI Technical Summary

Benefits of technology

[0021]The fluid rising in the wellbore flows at a certain flow velocity. Once a particular threshold value of the flow velocity is attained, the at least one apron unfolds. If the flow velocity is too great, the at least one apron can be destroyed during the change from the state in which it is folded towards the pipe to the state in which it is unfolded away from the pipe and towards the wall. In order to prevent this, an advantageous development of the invention has a plurality of aprons. These are disposed in succession along the pipe. At least one apron thereof is preferably provided with a passage for the fluid. This passage reduces the kinetic energy of the rising fluid. An apron that is located above, or behind, the apron provided with the passage can protect the latter from being destroyed.

Problems solved by technology

This is necessary, in particular, if the drill string is damaged or if the drilling operation encounters a pressurized zone.

In particular cases, however, it is questionable whether the dimensioning of the blowout preventer used is adequate for severing the drill string.

The incident in the Gulf of Mexico has shown that the known methods used have considerable weaknesses and are highly susceptible to faults in respect of deployment and operation.

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