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Subsea pressure relief devices and methods

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20120305262 patent thumbnailZoom

Subsea pressure relief devices and methods


A device for relieving pressure in a subsea component comprises a housing including an inner cavity, an open end in fluid communication with the inner cavity, and a through bore extending from the inner cavity to an outer surface of the housing. In addition, the device comprises a connector coupled to the open end. The connector is configured to releasably engage a mating connector coupled to the subsea component. Further, the device comprises a burst disc assembly mounted to the housing within the through bore. The burst disc assembly is configured to rupture at a predetermined differential pressure between the inner cavity and the environment outside the housing.

Browse recent Bp Corporation North America Inc. patents - Houston, TX, US
Inventors: Adam Lee Ballard, Robert Winfield Franklin, Paul Wilhelm Gulgowski, JR., Tony Oldfield, Martin Julio Pabon
USPTO Applicaton #: #20120305262 - Class: 166363 (USPTO) - 12/06/12 - Class 166 
Wells > Submerged Well >With Safety Or Emergency Shutoff



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The Patent Description & Claims data below is from USPTO Patent Application 20120305262, Subsea pressure relief devices and methods.

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CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent application Ser. No. 61/493,752 filed Jun. 6, 2011, and entitled “Subsea Pressure Relief Device,” which is hereby incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND

1. Field of the Invention

The disclosure relates generally to systems and methods for managing over pressurization of subsea equipment. More particularly, the disclosure relates to burst disc assemblies and methods of using such assemblies to relieve excessive fluid pressure in subsea equipment such as conduits, pipelines, and fluid containment devices.

2. Background of the Technology

In producing oil and gas from offshore wells, an offshore production system includes flowing hydrocarbons from a subterranean formation through a production string to a wellhead at the sea floor. From the wellhead, hydrocarbons may flow into tubular risers that provide a fluid conduit from the wellhead to the surface, where the hydrocarbons and other fluids may be collected in a receiving facility located on a platform or other vessel. Alternatively, intermediate components may be connected between the wellhead and risers, such as a choke/kill manifold, containment disposal manifold, capping stack, or other various types of subsea equipment. At times, temporary flow lines from the wellhead to a receiving facility or other containment target, such as an existing reservoir, may be installed.

The transfer of fluids from the wellhead to a receiving facility or other containment target often involves flow from a high pressure system to a relatively low pressure system. Normally, the flow of hydrocarbons from a subsea formation is controlled by a primary pressure containment system, such as a series of valves installed on the wellhead, risers, and the receiving facility at the surface designed to withstand anticipated operating pressures emanating from the wellhead. However, such pressures may be erratic, resulting in unanticipated high fluid pressures entering the production system and possibly over pressurizing components of the pressure containment system.

For instance, offshore oil production may take place at depths thousands of feet below the surface, where the ambient water pressure may exceed several thousand pounds per square inch (PSI) at temperatures below 50° F. Such pressure and temperature conditions lead to the formation of hydrocarbon gas hydrates, which may enter the production system. As the hydrates flow up the riser towards the surface, decreasing pressure within the riser at shallower depths allows the hydrates to disassociate into water and gas and rapidly expand, violently ejecting fluid from the riser at the surface. Moreover, back pressure within the pressure containment system may be generated by closing valves or from other processes, which may lead to an over pressurization of equipment in the system. In all such instances, it may be important to prevent pressure from building up in any interconnecting flow lines. Such an imbalance of pressures could also build up due to hydrate formation, sudden pressure changes in the well bore, or back pressure from valve closings or other processes performed on the system.

Many primary pressure containment systems are active in nature, requiring operator monitoring and intervention, and the use of hydraulic, electrical, or acoustic signals to activate the system in the case of an unanticipated over pressurization. The reliance on operator intervention may be problematic in certain situations, such as when inclement weather due to a tropical storm or hurricane forces the evacuation of a production platform, limiting the ability of operators to monitor and manage any unanticipated pressurizations.

Further, because of the immense depths and associated hydrostatic pressures, effectuating repairs of subsea equipment in the production system often requires that equipment and tools be handled by deep diving, remotely operated vehicles (ROVs). Due to the need for ROVs, repairing or replacing subsea equipment damaged by an unanticipated over pressurization may be cumbersome, time consuming and expensive. Thus, in the case of an unanticipated over pressurization, in order to reduce costs and quicken the time frame of repair it is necessary to ensure that the amount of subsea equipment damaged by the over pressurization is minimized and may be quickly and easily isolated and replaced.

Accordingly, there remains a need in the art for devices and methods for managing unanticipated excessive pressurizations of subsea environment. Such devices and methods would be particularly well received if the pressure setting at which the pressure relief device operates could be easily adjusted. Further, it would be advantageous if the pressure relief device could act passively, not requiring operator monitoring and actuation or the input of any hydraulic, electrical, or acoustic signal for actuation. Still further, it would be advantageous if the pressure relief device could be retrieved and replaced with relative ease.

BRIEF

SUMMARY

OF THE DISCLOSURE

These and other needs in the art are addressed in one embodiment by a device for relieving pressure in a subsea component. In an embodiment, the device comprises a housing including an inner cavity, an open end in fluid communication with the inner cavity, and a through bore extending from the inner cavity to an outer surface of the housing. In addition, the device comprises a connector coupled to the open end. The connector is configured to releasably engage a mating connector coupled to the subsea component. Further, the device comprises a burst disc assembly mounted to the housing within the through bore. The burst disc assembly is configured to rupture at a predetermined differential pressure between the inner cavity and the environment outside the housing.

These and other needs in the art are addressed in another embodiment by a method for relieving pressure within a subsea conduit. In an embodiment, the method comprises (a) deploying a pressure relief device subsea. The pressure relief device includes a housing having an inner cavity and a through bore extending from the inner cavity to an outer surface of the housing, and a burst disc assembly mounted to the housing within the through bore. In addition, the method comprises (b) coupling the pressure relief device to the subsea conduit. Further, the method comprises (c) transferring fluid pressure from the subsea conduit to the inner cavity.

These and other needs in the art are addressed in another embodiment by a device for relieving pressure in a subsea fluid conduit. In an embodiment, the device comprises a manifold including an inlet end and a plurality of outlet ends. In addition, the device comprises a connector coupled to the inlet end of the manifold. The connector is configured to releasably engage a mating connector coupled to the fluid conduit. Further, the device comprises a plurality of valve spools. Each valve spool is coupled to one of the outlet ends of the manifold. Each valve spool includes a valve configure to control a flow of fluids through the corresponding valve spool. Still further, the device comprises a plurality of burst disc assemblies. One burst disc assembly is disposed in a through bore in each valve spool. Each burst disc assembly is configured to rupture at a predetermined differential pressure between the inner cavity and the environment outside the housing.

Embodiments described herein comprise a combination of features and advantages intended to address various shortcomings associated with certain prior devices, systems, and methods. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the apparatus, systems and methods disclosed herein, reference will now be made to the accompanying drawings in which:

FIG. 1 is a schematic view of an offshore hydrocarbon production system;

FIG. 2 is an isometric view of the containment and disposal manifold assembly of FIG. 1 including an embodiment of a pressure relief device in accordance with the principles described herein;

FIG. 3 is a side view of the containment and disposal manifold assembly of FIG. 2;

FIG. 4 is an isometric view of the pressure relief device of FIG. 2;

FIG. 5 is a side view of the pressure relief device of FIG. 4;

FIG. 6 is a cross-sectional view of the pressure relief device of FIG. 4;

FIG. 7A is a cross-sectional view of one of the burst disc assemblies of FIG. 4;

FIG. 7B is a top view of one of the burst disc assemblies of FIG. 4;

FIG. 8 is a schematic view of the upper riser assembly and lower riser assembly of the free standing riser of FIG. 1;

FIG. 9 is an isometric view of the pressure relief device coupled to the lower riser assembly of FIG. 8;

FIG. 10 is a side view of the pressure relief device of FIG. 9;

FIG. 11 is a cross-sectional view of the pressure relief device of FIG. 9;

FIG. 12 is a schematic cross-sectional view of the pressure relief device coupled to the upper riser assembly of FIG. 8; and

FIG. 13 is a schematic view of an embodiment of a pressure relief device in accordance with the principles described herein.

DETAILED DESCRIPTION

OF THE EMBODIMENTS

The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis.

A subsea pressure relief or control system for subsea applications is disclosed herein. Embodiments described herein may be employed in various subsea applications; however, it has particular application as a device to relieve excessive fluid pressures that may develop in subsea flow lines, manifolds, tanks, vessels and reservoirs containing and/or transporting hydrocarbons from the sea floor or between subsea containment systems.

Referring now to FIG. 1, an overview of an offshore hydrocarbon production system 100 is shown. In this embodiment, system 100 comprises a blowout preventer (BOP) 130 mounted to a subsea wellhead, a choke/kill manifold assembly 140 disposed on the sea floor 120, a plurality of processing vessels 170 and collecting vessels 180 disposed at the sea surface 110, a containment and disposal manifold assembly 200 disposed on sea floor 120, and a plurality of subsea free standing risers (FSRs) 600.

Each FSR 600 is vertically oriented and has a first or upper end 600a and a second or lower end 600b. In this embodiment, each FSR 600 includes a buoyancy can 166 at upper end 600a, an upper riser assembly (URA) 610 coupled to can 166, a foundation 168 at lower end 600b, and a lower riser assembly (LRA) 620 coupled to foundation 168. Foundations 168 secure FSRs 600 to the sea floor 120, and buoyancy cans 166 place FSRs 600 in tension. URAs 610 of each FSR 600 are disposed below the wave zone proximal the sea surface 110, thereby minimizing lateral and radial loads applied to FSRs 600. As will be described in more detail below, an embodiment of a subsea pressure relief device in accordance with principles described herein is included in LRA 620 and URA 610 of each FSR 600 to protect such components from over pressurization.

Processing vessels 170 are coupled to URAs 610 of each FSR 600 by a plurality of flexible jumpers 104. In addition, a fluid conduit 108 couples each vessel 170 to a corresponding vessel 180.

In this embodiment, a capping stack 131 is coupled to BOP 130. Examples of capping stacks are disclosed in U.S. provisional patent application Ser. No. 61/475,032 filed Apr. 13, 2011, and entitled “Systems and Methods for Capping a Subsea Well,” which is hereby incorporated here in reference in its entirety. Choke/kill manifold assembly 140 is coupled to BOP 130, and a drill string 106 and containment and disposal manifold assembly 200 are coupled to choke/kill manifold assembly 140 by subsea conduits 102. As will be described in more detail below, containment and disposal manifold assembly 200 provides additional protection during an over pressurization. As will be described in more detail below, an embodiment of a subsea pressure relief device in accordance with principles described herein is included in containment and disposal manifold assembly 200.

The offshore hydrocarbon production system 100 may be further explained in provisional application Nos. 61/392,443 and 61/392,899. Provisional application No. 61/392,443 and provisional application No. 61/392,899 are incorporated by reference in their entirety, for all purposes.

Referring now to FIGS. 2 and 3, containment and disposal manifold assembly 200 is shown. Manifold assembly 200 includes a base 210, a support frame 220, a manifold 230, an ROV panel 260, and a pressure relief device 400. Base 210 distributes the weight of manifold assembly 200 along the sea floor 120, thereby restricting and/or preventing manifold assembly 200 from sinking into the sea floor 120. In addition, base 210 covers and shields the sea floor 120 from turbulence induced by ROV thrusters, thereby reducing visibility loss due to disturbed mud during installation and operation. Accordingly, base 210 effectively functions as a mud mat.

Support frame 220 sits atop base 210 and provides support for manifold 230. Manifold 230 includes an arrangement of interconnected fluid conduits 238, a plurality of valves 232, and a plurality of vertical connection conduits 234. Valves 232 are configured to control the flow of fluids through conduits 238, 234. For example, each valve 232 has an open position allowing fluid flow therethrough and a closed position restricting and/or preventing fluid flow therethrough. One valve 232 is associated with each conduit 234, thereby controlling fluid communication between that particular conduit 234 and the remaining conduits 238 of manifold 230. ROV panel 260 enables a subsea ROV to selectively and independently control valves 232. The upper end of each conduit 234 includes a connector or hub 236 configured to mate and releasably engage a mating connector. In this embodiment, pressure relief device 400 is releasably coupled to one hub 236.

Referring now to FIGS. 4-6, pressure relief device 400 has a central or longitudinal axis 405, a first or upper end 400a, and a second or lower end 400b. In this embodiment, assembly 400 includes a connector 420 at lower end 400b and a tubular housing 410 coupled to connector 420.

As best shown in FIG. 6, tubular housing 410 is coaxially aligned with axis 405, and has a first or upper end 410a coincident with end 400a, a second or lower end 410b connected to connector 420, a radially inner surface 418, and a radially outer surface 419 Inner surface 418 defines an inner cavity 416 extending axially between ends 410a, b. Tubular housing 410 also includes a plurality of axially spaced radial bores 417 extending radially between surfaces 418, 419. One burst disc assembly 500 is mounted within each bore 417. In this embodiment, a plurality of lugs or lift eyes 414 extend from outer surface 419 and are used to lift and deploy assembly 400.

A cap 430 is mounted to upper end 410a of tubular housing 410, thereby generally closing upper end 410a. Cap 430 includes a through bore 432 in fluid communication with cavity 416 of tubular housing 410. The upper end of bore 432 includes a receptacle 435 coupled to a conduit 448 that extends to a hot stab receptacle 442 in an ROV panel 446 mounted to tubular housing 410. A valve 444 in panel 446 controls fluid communication between conduit 448 and receptacle 442. Namely, valve 444 has an open position allowing fluid communication between conduit 448 and receptacle 442, and a closed position restricting and/or preventing fluid communication between conduit 448 and receptacle 442.

During subsea operations, receptacle 442 and conduit 448 can be used to either inject chemicals into tubular housing 410 or to receive hydrocarbons from housing 410. For example, a subsea ROV may insert a hot stab connector into receptacle 442, open valve 444, and inject a hydrate inhibitor (e.g., methanol) into tubular housing 410. Receptacle 442 and conduit 448 may also be used to inject dispersant into tubular housing 410 through conduit 448 in the event of the rupturing of burst disk assemblies 500. Further, samples of fluid within tubular housing 410 may be taken by flowing fluid from housing 410 through conduit 448 and into a hot stab connector coupled to receptacle 442. Receptacle 442 and conduit 448 may also be used to displace fluid within tubular housing 410 and manifold 230. For instance, a relatively less dense fluid, such as methanol, may be injected into manifold 230 through conduit 448 and tubular housing 410 in order to displace hydrocarbons out of housing 410 and manifold 230. Alternatively, a relatively high density fluid, such as glycol, may be inputted into tubular member 410 from manifold 230, displacing hydrocarbons from within member 410 through conduit 448 and into a hot stab connector coupled to receptacle 442.

Connector 420 is coaxially aligned with tubular housing 410 and includes a female receptacle 428 at lower end 400b and an internal passage 425 extending axially from receptacle 428 to cavity 416 of tubular housing 410. Thus, passage 425 and cavity 416 are in fluid communication. Connector 420 is configured to releasably connect with manifold hub 236 previously described. In particular, hub 236 is received, seated, and releasably locked within female receptacle 428 of connector 420, thereby providing fluid communication between passages 425, 416 and conduit 234 of manifold 230. Connector 420 also includes a plurality of circumferentially spaced vertical indicator pins 422 as are known in the art. Indicator pins 422 provide a visual indication of the configuration of connector 420. Namely, when pins 422 are axially extended from connector 420 as shown in FIGS. 4-6, connector 420 is in an unlocked position (e.g., connector 420 is not locked onto mating hub 236; however, when pins 422 are retracted into connector 420, connector 420 is in a locked position (e.g., connector 420 is locked onto mating hub 236). In this embodiment, connector 420 is a hydraulically actuated collet connector, such as a 3″ mini CVC connector, made by Cameron International Corporation of Houston, Texas. In other embodiments, connector 420 may be an Optima™ subsea connector made by Vector Technology Group of Drammen, Norway, or other connectors of the like known in the art.

As best seen in FIGS. 4 and 5, ROV panel 450 is coupled to connector 420 and enables a subsea ROV to actuate connector 420 between the locked and unlocked positions. In this embodiment, panel 450 includes a hot stab receptacle 452 and a valve 454 that controls the flow of fluids from receptacle 452 to connector 420. For example, an ROV can actuate connector 420 by opening a valve 454 and inputting hydraulic power to connector 420 via a hot stab receptacle 454.

Referring now to FIGS. 7A and 7B, one burst disc assembly 500 is shown. Burst disc assembly 500 has a central axis 560 and includes a radially outer annular body or housing 510 sized to fit within a corresponding bore 417 in tubular housing 410, and an annular burst disc 540 disposed within housing 510. Disc 540 has a concave outer surface 542 facing the ambient environment surrounding assembly 400, and a convex inner surface 544 facing cavity 416. Disc 540 is configured to be forcibly pushed axially out of housing 510 at a predetermined differential pressure thereacross. Thus, when one or more burst disc assembly 500 ruptures, cavity 416 of tubular housing 410 is placed in fluid communication with the surrounding environment, thereby relieving pressure within assembly 400 as well as other components in fluid communication with assembly 400. In this embodiment, each of the plurality of burst disc assemblies 500 in assembly 400 is configured to rupture at the same differential pressure between cavity 416 and the outside environment. In general, burst disc assemblies 500 may comprise any suitable passive device designed to rupture at a predetermined pressure differential. Examples of suitable burst discs are burst discs manufactured by the Fike Corporation of Blue Springs, Mo.

Referring now to FIGS. 2, 5 and 6, in the event of an over pressurization of manifold 230, the high fluid pressure seen by manifold 230 is transmitted through vertical connection conduit 234 and connector 420 into cavity 416 of tubular housing 410. The increased fluid pressure within cavity 416 results in a larger differential pressure across burst disc assemblies 500 (i.e., a larger pressure differential between cavity 416 and the outside ambient environment). Upon the reaching of a predetermined pressure differential, one or more discs 540 are forced radially outward from the corresponding housing(s) 510, thereby placing cavity 416 and manifold 230 into fluid communication with the ambient environment and relieving pressure therewithin.

Once discs 540 have been expelled and hydrostatic pressure has sufficiently decreased within manifold 230 (i.e., to a level at which damage from over pressurization is no longer of concern), valve 232 can be actuated into its closed position via an ROV, thereby restricting and/or preventing further flow of fluids from manifold 230 to vertical connection conduit 234 and assembly 400. At this point, assembly 400 may be disconnected from manifold 230 at connector 420 and lifted to the surface via a cable attached to lift eyes 414. With assembly 400 removed, a new assembly 400, including intact burst disc assemblies 500, is coupled to manifold 230 at connector 420, thereby replacing the previous assembly 400. Upon coupling new assembly 400 and manifold 230, valve 232 is actuated into its open position, establishing fluid communication between new assembly 400 and manifold 230.

Referring now to FIG. 8, a schematic view of FSR 600, including URA 610 and LRA 620, is shown. In this embodiment, a pressure relief device 700 is removably coupled to LRA 620 and a pressure relief device 800 is removably coupled to URA 610. In particular, fluid conduits 602, 604 are coupled to LRA 620 and URA 610, respectively. Conduit 602 is in fluid communication with LRA 620 and has an inlet end 602a connected to LRA 620, an outlet end 602b releasably coupled to pressure relief device 700, and a valve 622 disposed between ends 602a, b. Pressure relief device 700 is removably coupled to end 602b. In particular, end 602b comprises a connector configured to mate and releasably engage a mating connector 710 of pressure relief device 700. Valve 622 controls the flow of fluids between ends 602a, b. Namely, valve 622 has an open position allowing fluid communication between ends 602a, b and a closed position restricting and/or preventing fluid communication between ends 602a, b.

Conduit 604 is in fluid communication with URA 610 and has an inlet end 604a connected to URA 610, an outlet end 604b releasably coupled to pressure relief device 800, and a pair of valves 612 disposed between ends 604a, b. Pressure relief device 800 is removably coupled to end 604b. In particular, end 604b comprises a hot stab receptacle 810 configured to mate and releasably engage a mating hot stab 810 of pressure relief device 800. Valves 612 control the flow of fluids between ends 604a, b. Namely, each valve 612 has an open position allowing fluid communication therethrough and a closed position restricting and/or preventing fluid communication therethrough. Thus, if one or both valves 612 are closed, fluid communication between ends 604a, b is restricted and/or prevented.

Referring now to FIGS. 9-11, pressure relief device 700 has a central or longitudinal axis 705, a first or upper end 700a, and a second or lower end 700b. In this embodiment, assembly 700 includes connector 710 at end 700b, a tubular member 720, a burst disc housing 730 at end 700a, and a plurality of burst disc assemblies 500 as previously described mounted to housing 730. As best shown in FIG. 11, connector 710 has a radially outer surface including an annular flange 714 and a radially inner surface defining a through bore 712. In this embodiment, connector 710 is the female end of a vice connector, such as an Optima Subsea Connector, made by Vector Technology Group of Drammen, Norway. Tubular member 720 extends axially between connector 710 and housing 730 and includes an inner through bore 724 in fluid communication with bore 712 of connector 710.

Housing 730 is disposed at upper end 700a and includes an inner cavity 735 in fluid communication with bore 724 and a plurality of bores 732 extending radially through housing 730 from cavity 735 to the outer surface of housing 730. Each bore 732 includes an inner annular shoulder 736. One burst disc assembly 500 is coaxially disposed within each bore 732 and seated against the corresponding shoulder 736. A tubular retention member 742 is threaded into each bore 732 following installation of the corresponding burst disc assembly 500 to maintain the position of burst disc assembly 500 seated against shoulder 736. Retention member 742 engages housing 510 of burst disc assembly 500, but does not engage disc 540. In particular, retention member 742 has an inner diameter greater than the diameter of disc 540, and thus, disc 540 can be forced radially outward through retention member 742. As previously described, disc 540 is configured to be forcibly pushed axially out of housing 510 at a predetermined differential pressure thereacross. Thus, at a predetermined differential pressure between cavity 735 and the outside ambient environment, disc 540 is forced radially outward from housing 510 through retention member 742, thereby relieving fluid pressure within assembly 700. As best seen in FIGS. 9 and 10, a lug or lifting ring 733 and an ROV handle 731 are coupled to housing 730 and facilitate the subsea installation and removal of assembly 700.

Referring now to FIGS. 8 and 11, in the event of an over pressurization of LRA 620, the relatively high hydrostatic pressure seen by LRA 620 is transmitted through conduit 602, valve 622, and connector 710 into assembly 700. The increased hydrostatic pressure within cavity 735 results in a larger differential pressure across burst disc assemblies 500. At a predetermined differential pressure, disc 540 is forcibly compelled radially from housing 510 through retention member 742, thereby placing cavity 735 and LRA 620 in fluid communication with the surrounding ambient environment and relieving fluid pressure therein.

Once disc 540 has been expelled and pressure has decreased within LRA 620, valve 622 may be actuated into its closed position via an ROV, thereby restricting and/or preventing fluid flow from LRA 620 to connector 710. At this point assembly 700 is disconnected from LRA 620 at connector 710 and lifted to the surface via a cable attached to lifting ring 733. Once assembly 700 has been removed, another assembly 700 is coupled to LRA 620 at connector 710. Valve 622 is then opened, establishing fluid communication between new assembly 700 and LRA 620.

Referring now to FIGS. 8 and 12, pressure relief device 800 has a central or longitudinal axis 805, a first end 800a, and a second end 800b opposite end 800a. In this embodiment, assembly 800 comprises a stabbing member 820 extending axially from end 800a, a burst disc housing 830 coupled to stabbing member 820, and a burst disc assembly 500 mounted to housing 830 at end 800b. Stabbing member 820 is coaxially aligned with housing 830 and has a first end 820a coincident with end 800a and a second end 820b opposite end 820a. End 820a is configured to be inserted and axially advanced into receptacle 810, and end 820b comprises an internally threaded receptacle 824 that receives housing 830. An inner axial flow passage 821 extends through stabbing member 820 from proximal end 820a to receptacle 824, and a port 822 extends radially from passage 821 to the outer surface of member 820.

Member 820 is configured to be coaxially inserted into and removably seated within mating receptacle 810. A plurality of annular seal assemblies 828 are disposed about stabbing member 820 to seal between member 820 and receptacle 810. In this embodiment, each seal assembly 828 includes an annular recess or seal gland in the outer surface of stabbing member 820 and an annular seal member (e.g., O-ring seal) seated in the gland. In general, stabbing member 820 may comprise any suitable member configured to be inserted into and releasably engaged with receptacle 810. In this embodiment, stabbing member 820 is a 2″ Subsea Stab, produced by NLI Asker Subsea of Lier, Norway. With stabbing member 820 seated in receptacle 810, port 822 is aligned with a mating port 813 in receptacle 810, thereby placing flow passage 821 in fluid communication with conduit 604, which is in selective fluid communication with URA 610 of FSR 600. A handle 826 is attached to stabbing member 820 and is configured to allow a subsea ROV to position and manipulate assembly 800.

Referring still to FIG. 12, housing 830 has a first end 830a, a second end 830b opposite end 830a, an inner cavity 834 at end 830b, and a flow bore 833 extending axially from end 830a to cavity 834. In addition, housing 830 includes a cylindrical connection portion 831 extending axially from end 830a and a burst disc mounting portion 832 extending axially from portion 831 to end 830b. Passage 833 extends through connection portion 831 and cavity 834 is disposed within mounting portion 832. Connection portion 831 is threaded into mating receptacle 824. With housing 830 coupled to stabbing member 820, cavity 834 and bore 833 are in fluid communication with passage 821 of stabbing member 820. An annular seal assembly 837 is disposed about connection portion 831 to seal between housing 830 and stabbing member 820. In this embodiment, seal assembly 837 includes an annular recess or seal gland in the outer surface of connection portion 831 and an annular seal member (e.g., O-ring seal) seated in the gland.

A burst disc assembly 500 as previously described is coaxially mounted in an aperture 835 in portion 832 at end 830b. As previously described, disc 540 is configured to be forcibly pushed axially out of housing 510 at a predetermined differential pressure thereacross. Thus, at a predetermined differential pressure between cavity 834 and the outside ambient environment, disc 540 is forced radially outward from housing 510, thereby relieving fluid pressure within assembly 800.

In the event of an overpressurization of URA 610 of FSR 600, the relatively high fluid pressure within URA 610 is transmitted through conduit 604, valves 612, port 813, and passages 822, 833 into cavity 834. At a predetermined differential pressure, disc 540 is forcibly compelled radially from housing 510, thereby placing cavity 834 and URA 610 in fluid communication with the surrounding ambient environment and relieving fluid pressure therein.

Once disc 540 has been expelled and pressure has decreased within URA 610, valves 612 may be actuated into their closed positions via an ROV, thereby restricting and/or preventing fluid flow from URA 610 to receptacle 810. At this point assembly 800 is disconnected from URA 610 and lifted to the surface. Once assembly 800 has been removed, another assembly 800 is coupled to URA 610 at receptacle 810. Valves 612 are then opened, establishing fluid communication between new assembly 800 and URA 610.

Now referring to FIG. 13, another embodiment of a burst disc assembly 900 is schematically shown. Assembly 900 includes a connector 910, a main conduit 920 coupled to connector 910, a manifold 924 coupled to conduit 920, and a plurality of valve spools 926 coupled to manifold 924. Conduit 920 has a central or longitudinal axis 925, a first or upper end 920a, and a second or lower end 920b. Connector 910 is coupled to end 920b and manifold 924 is coupled to end 920a. Connector 910 is configured to couple assembly 900 to a subsea component such as containment and disposal manifold assembly 200, URA 610 or LRA 620 of FSR 600, or other locations within hydrocarbon production system 100 of FIG. 1. In general, connector 910 may comprise any suitable connector or device for coupling assembly 900 to a subsea component such as a Cameron CVC connector, as described above, or a Vector Optima™ connector, also described above.

Manifold 924 includes an inlet 924a in fluid communication with conduit 920 and a plurality of outlets 924b, each outlet 924 in fluid communication with one valve spool 926. Thus, manifold 924 supplies fluid from conduit 920 to valve spools 926.

Each valve spool 926 includes a valve 928 that controls the flow of fluids therethrough, a plurality of circumferentially spaced radial through bores 417, and a plurality of burst disc assemblies 500 as previously described, one burst disc assembly 500 being mounted in each bore 417. Each valve 928 has an open position that allows fluid communication between manifold 924 and the corresponding burst disc assemblies 500, and a closed position restricting and/or preventing fluid communication between manifold 924 and the corresponding burst disc assemblies 500.

A cap 430 as previously described is mounted to the upper end of each spool 926 distal manifold 924. Receptacle 435 in each cap 430 is coupled to a conduit 448 connected to a hot stab receptacle 442 in an ROV panel 446 mounted to conduit 920. A valve 444 is provided in panel 446 for each conduit 448, each valve controlling fluid communication between conduit 448 and receptacle 442. During subsea operations, receptacle 442 and conduit 448 may be used to inject chemicals into the corresponding valve spool 926 or receive fluids from within valve spool 926 in the manner previously described above.

As previously described, each burst disc assembly 500 is configured to rupture at a predetermined pressure differential. One or more burst disc assemblies 500 may be configured to rupture at the same or different predetermined pressure differentials. For example, within each valve spool 926, burst disc assemblies 500 may be configured to rupture at the same predetermined pressure differential, but between different valves spools 926, burst disc assemblies 500 may be configured to rupture at different predetermined pressures. Thus, for example, one spool 926 may include burst disc assemblies 500 configured to burst at a lower or higher differential pressure than the burst disc assemblies 500 of the other spools 926. In this example, the burst disc assemblies 500 configured to rupture at the lowest predetermined pressure differential will rupture first, thereby partially relieving pressure within assembly 900. Additional burst disc assemblies 500 may rupture until the pressure is sufficiently relieved. Any one or more valve spools 926 including a ruptured burst disc assembly 500 may be isolated from manifold 924 by the actuation of its respective valve 928 into the closed position. Spools 926 including burst disc assemblies 500 that have not ruptured can be kept open to protect against future over pressurizations.

In the manner described herein, embodiments of devices and methods described herein provide passive protection against unanticipated over pressurization of subsea components. Although embodiments described herein Such embodiments may be tailored to provide pressure relief at a particular predetermined pressure differential between the fluid within the subsea component and the ambient environment outside the component, thereby enabling control over the pressure differential at which pressure relief is triggered. In addition, embodiments described herein enable control over the location at which pressure relief occurs, effectively sacrificing an easily replaced relatively low cost device (e.g., burst disc assembly) to reduce the potential for undesirably damaging one or more other subsea components that may be more difficult to repair and/or replace. In general, embodiments of pressure relief devices, systems, and methods described herein may be used in conjunction with subsea fluid conduits, subsea containment vessels or devices, or any other subsea component that flows or contains fluid.

Although embodiments of pressure relief devices (e.g., burst disc assemblies) are shown and described in connection with upper riser assemblies, lower riser assemblies, and subsea manifolds, it should be appreciated that embodiments described herein can be used as pressure control devices on a variety of other subsea conduits and components. For example, a pressure relief device can be connected to a capping stack, BOP, fluid conduit, etc. Further, it should be appreciated that embodiments described herein may be used in conjunction with other subsea pressure relief systems and devices. Examples of other pressure relief devices are described in U.S. provisional patent application Nos. 61/481,976, 61/479,693, and 61/479,671, each of which is hereby incorporated herein by reference in its entirety for all purposes.

While specific embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the invention. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.



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stats Patent Info
Application #
US 20120305262 A1
Publish Date
12/06/2012
Document #
13470793
File Date
05/14/2012
USPTO Class
166363
Other USPTO Classes
International Class
21B33/00
Drawings
14


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