Device for temporarily sealing a pipe

Fluid handling – Line condition change responsive valves – With separate connected fluid reactor surface

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Details

166317, 166321, E21B 3300, F16L 5510

Patent

active

044872216

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to a device for temporarily sealing a pipe, as for example the production tubing of an oil well.
Devices of this kind are known and are sometimes referred to as "subs". "Subs" are usually used in conjunction with plugs for production tubing; the subs are normally closed but, when open, provide a passage for the flow of oil through the plug, thus enabling a well to start or recommence production without requiring removal of the plug.
"Subs" which are openable upon the application thereto of pressure by pumping oil or mud down the production tubing are known as "pump out subs".
A previously known "pump out sub" comprises a plunger held by shear pins in a position in which it seals an opening through which oil may pass up the production tubing. The shear pins may be sheared by the pressure of the pumped fluid so that the plunger drops away from the sealing position.
A second previously known "pump out sub" comprises a disc which is sheared from the sub when a sufficient pressure of fluid is applied.
These known "pump out subs" have the disadvantage that deposition of debris, such as sand or shale, will result in formation of a plug of debris on the plunger or disc when fluid is pumped under pressure onto it. In consequence greater pressure must be applied before the pins or disc will shear than if the plug of debris were not present. Also the shear parts may be prematurely sheared by jarring the plug when it is set down inside the tubing by wireline.
A further disadvantage of the aforesaid "pump out subs" is the high pressure differential necessary to effect shearing. Thus for shear disc holding a well pressure of 2000 psi it is usually necessary to apply at least 3000 psi to produce shearing; this high pressure differential of 1000 psi necessitates the use of well Christmas trees capable of coping with the high pressures required for sub opening, and imposes restrictions on the use of subs in wells in which the Christmas trees are rigged to cope with relatively low pressures.


SUMMARY OF THE INVENTION

According to this invention there is provided a device for temporarily sealing a pipe, as for example the production tubing of an oil well, comprising a body defining a cylindrical chamber, and a piston arranged to move in the chamber; the chamber having an outlet at one end thereof, an inlet axially spaced from the outlet, and the chamber providing a passageway from the inlet to the outlet for fluid flow through the chamber; the piston being movable from a first position to a second position, characterized in that the piston has associated therewith an annular member which seals the passageway, and which is movable relative to the piston when the piston is in the second position, by the application of differential pressure, so as to open the passageway.
Devices in accordance with the present invention will be referred to herein sometimes as "pump open subs".
In devices described below the annular member is a collet mounted on the piston.
In preferred embodiments described hereunder the piston is moveable, in said chamber, from the first to the second position under the influence of fluid pressure applied to an end face thereof.
In the preferred embodiments, the device is adapted such that when installed in a pipeline the piston can be moved from the first position to the second position by increasing the fluid pressure at the outlet side of the chamber, and the moveable member may then be moved, to permit said fluid flow, by reducing the said outlet side pressure to below the pressure at the inlet(s).
In preferred embodiments of the device, the piston is resiliently biased towards the first position by for example, compression springs.
Preferably the moveable member is movable from the piston under the influence of a fluid pressure force applied to a surface thereof.
It is preferred that the devices in accordance with the invention comprise means for locking the piston into the second position.
In the embodiments described below the piston comprises at leas

REFERENCES:
patent: 1356298 (1920-10-01), McGregor
patent: 2730124 (1956-01-01), Buchanan
patent: 3130789 (1964-04-01), Alexander et al.
patent: 3183040 (1965-05-01), Gold
patent: 3306363 (1967-02-01), McZilkey
patent: 3353609 (1967-11-01), Jensen
patent: 3356140 (1967-12-01), Young
patent: 3457994 (1969-07-01), Stachowiak
patent: 3473606 (1969-10-01), Page
patent: 3485298 (1969-12-01), Kisling
patent: 3570595 (1971-03-01), Berryman

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