Annulus pressure referenced circulating valve

Fluid handling – Destructible or deformable element controlled – Destructible element

Reexamination Certificate

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Details

C137S599110, C137S601200, C166S323000, C166S374000

Reexamination Certificate

active

06328055

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides an annulus pressure referenced circulating valve.
It is well known in the art to operate a valve positioned in a subterranean well by applying fluid pressure to the valve. The fluid pressure may exist by virtue of the weight of fluid in the well, the fluid pressure may be applied to the valve by, for example, a pump at the earth's surface or in the well, and the fluid pressure may be a combination of these. When the valve is interconnected in a tubular string positioned in a wellbore of the well, the fluid pressure may exist in the tubular string, in an annulus formed between the tubular string and the wellbore, or the valve may be operated by a difference between fluid pressure in the tubular string and fluid pressure in the annulus.
Where a valve is operated by absolute fluid pressure in a tubular string or in an annulus exterior to the valve, the valve typically includes a chamber at atmospheric pressure or an elevated precharged pressure at the earth's surface. After positioning in the well, a fluid pressure differential (equal to the difference between the chamber pressure and the pressure in the tubular string or annulus) is generally created across a member releasably secured against displacement by, for example, one or more shear pins. When a predetermined fluid pressure differential is reached, the member is released and displaced by the differential pressure, thereby operating the valve. Unfortunately, however, it is often uncertain what pressure conditions will be experienced in the well prior to installing the valve in the tubular string, so there is a danger that the valve will be inadvertently operated due to an unexpected pressure increase in the tubular string or annulus.
Where the valve is operated in response to a pressure differential between the tubular string and the annulus, the member is typically released for displacement when the predetermined fluid pressure differential is created. While, strictly speaking, operation of this type of valve does not require prior knowledge of absolute fluid pressures in either the tubular string or annulus, it does requires prior knowledge of fluid pressures to be experienced in both the tubular string and the annulus, so that the fluid pressure differential may be determined and the valve may be set up to avoid inadvertent operation of the valve.
Solutions to the problem of inadvertent operation of pressure responsive valves have been implemented. For example, it is common for a valve to include a chamber at an elevated pressure and a member displaceable in response to a difference in pressure between the chamber and the tubular string, the annulus, or a difference between the tubular string and annulus pressures. By manipulating the tubular string pressure, the annulus pressure, or the difference between the tubular string and annulus pressures, the member is made to displace repeatedly, the member displacing sufficiently to operate the valve after a predetermined number of the pressure manipulations. The number of pressure manipulations is usually determined by a ratchet or J-slot mechanism. Unfortunately, this type of valve requires numerous pressure manipulations, and a complex and expensive ratchet or J-slot mechanism.
Therefore, it would be highly desirable to provide a valve responsive to fluid pressure in a well, which does not require numerous pressure manipulations or precise prior knowledge of fluid pressures to be experienced in the well, and which is relatively uncomplicated in its construction and use.
SUMMARY OF THE INVENTION
In carrying out the principles of the present invention, in accordance with an embodiment thereof, a circulating valve is provided which is annulus pressure referenced. The valve stores annulus pressure in an internal chamber as a variable reference. A subsequent relatively rapid increase in annulus pressure relative to that previously stored in the chamber causes the valve to operate. The valve is nonresponsive to fluid pressure in an axial flow passage formed therethrough.
In one aspect of the present invention, the valve includes a specially configured hydraulic circuit. The hydraulic circuit includes two portions interconnected in series between a fluid pressure source external to the valve, and a fluid pressure storage chamber within the valve. As fluid pressure external to the valve gradually increases and decreases, the hydraulic circuit permits the fluid pressure to be stored in the chamber. The hydraulic circuit portions permit substantially restricted fluid flow from the valve exterior to the chamber, and permit substantially unrestricted fluid flow from the chamber to the valve exterior.
However, when the external fluid pressure is relatively rapidly increased, one of the hydraulic circuit portions opens to permit substantially unrestricted flow therethrough from the valve exterior, while the other hydraulic circuit portion continues to substantially restrict fluid flow therethrough, thereby causing displacement of the hydraulic circuit portions relative to each other. Since one of the hydraulic circuit portions is incorporated in a housing assembly of the valve, and the other hydraulic circuit portion is incorporated in a structure displaceable relative to the housing assembly, displacement of the hydraulic circuit portions relative to each other causes displacement of the structure relative to the housing assembly.
In another aspect of the present invention, a structure selectively blocks and permits fluid flow through a sidewall of a housing assembly. The structure is sealingly engaged and displaceable within the housing assembly. A first hydraulic circuit portion regulates fluid flow between a fluid pressure source and a second hydraulic circuit portion across a portion of the housing assembly sealingly engaged with the structure. The second hydraulic circuit portion regulates fluid flow between the first circuit portion and a fluid pressure storage chamber across a portion of the structure sealingly engaged with the housing assembly. The second circuit portion is displaceable with the structure relative to the housing assembly.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of a representative embodiment of the invention hereinbelow and the accompanying drawings.


REFERENCES:
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patent: 5050681 (1991-09-01), Skinner
patent: 5127313 (1992-07-01), Yonezawa
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patent: 5865212 (1999-02-01), Gaines
patent: 5984014 (1999-11-01), Poullard et al.
Systems Engineering Bulletin (Oct. 9, 1990).
LPR—N Description (Undated).
Select Tester Valve Brochure (Jul. 21, 1998).

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