Systems and Methods for Fluid Pressure Control

This application is a national stage application, filed under 35 U.S.C. § 371, of International Patent Application No. PCT/US2023/021768, filed on May 10, 2023, which claims the benefit of U.S. Provisional Patent Application Nos. 63/342,075, filed May 14, 2022, and 63/402,348, filed Aug. 30, 2022, all of which are incorporated by reference herein in their entirety.

The present disclosure relates generally to the field of fluid pressure controls. More particularly, the present disclosure relates to fluid pressure controls applied to systems that undergo repeated fluid pressurization for qualification or testing purposes.

Many conventional systems in various fields of operation are operated or function via subjection to fluid under pressure. Some of these systems require routine testing to ensure the integrity of the system to sustain or maintain the required fluid pressure for normal operation. One such system used in the oil and gas industry is a blowout preventer (BOP). BOPS are used to prevent potentially catastrophic events known as blowouts, where high pressures and uncontrolled flow from a well reservoir can blow tubing, tools, and drilling fluid out of a wellbore. Blowouts present a serious safety hazard and can be extremely costly to remediate.

Conventional BOPs comprise one or more sets of reversibly operable “ram-type” pressure control elements, for example “blind rams” and “shear rams”, along with sealing elements. Blind rams fully close an interior bore of the BOP housing to hydraulically isolate the well below the BOP housing. Shear rams may be provided to enable cutting through conduit and/or drilling tools disposed within the interior bore in the BOP housing and subsequently closing to hydraulically isolate the well below the shear rams. Annular seals may be used where it is desired to hydraulically isolate the well while enabling a conduit such as drill pipe, or other drilling tools to pass through the interior bore of the BOP housing.

Each of the foregoing ram-type pressure control elements may be disposed in opposed pairs on the BOP housing and may be hydraulically pushed across the wellbore to close off the wellbore. Hydraulic fluid pressure to operate the various ram-type elements and/or the annular seals may be controlled by a hydraulic fluid line extending from a control valve manifold to the drilling platform, and by providing a plurality of accumulators each having hydraulic fluid and gas (e.g., nitrogen) under pressure to supply a relatively large volume of fluid rapidly in the event it becomes necessary to close any one or more of the ram elements in the BOP. A plurality of ram elements may be connected to each other to form a BOP “stack” assembly (i.e., arranged one atop the other).

Per industry standards and government regulations BOP pressure tests are periodically conducted (e.g., at 12-14-day intervals) to corroborate the integrity of the unit and the equipment, to verify that the BOP has the capacity to withstand the reservoir fluids and pressure in case of a blowout. To test the integrity of the rams, a plug is typically inserted within the BOP to provide a barrier for a column of hydraulic fluid pumped in under pressure to expose the equipment to a fluid pressure effect. Generally, all rams on a BOP should be tested, which entails systematic isolation and pumping of fluids to each of the rams in the unit. Conventional pressure testing of BOPs typically entails the conveyance of hydraulic fluid via one or more lines from a separate pressurized hydraulic fluid supply, which often results in significant down time for well operations.

A need remains for improved techniques to provide fluid pressure control effectively and efficiently for equipment, tools, and systems entailing fluids under pressure during operation.

According to an aspect of the invention, a fluid pressurization unit includes an enclosure configured to link to a vessel having an internal fluid passage. The enclosure has a moveable member therein, wherein the moveable member is configured for selective insertion within and/or withdrawal from the vessel internal passage to respectively increase and/or decrease the pressure of fluid in the vessel internal fluid passage when the enclosure is linked to the vessel.

According to another aspect of the invention, a method for controlling a fluid pressure in a vessel includes linking an enclosure to a vessel having an internal fluid passage, wherein the enclosure is configured with a moveable member therein; and selectively actuating the moveable member for insertion within and/or withdrawal from the vessel internal passage to respectively increase and/or decrease the pressure of fluid in the vessel internal fluid passage.

The foregoing description of the figures is provided for the convenience of the reader. It should be understood, however, that the embodiments are not limited to the precise arrangements and configurations shown in the figures. Also, the figures are not necessarily drawn to scale, and certain features may be shown exaggerated in scale or in generalized or schematic form, in the interest of clarity and conciseness. Figures of the disclosed embodiments may not show all the conduits (e.g., tubing, piping, electrical wiring, etc.) interconnected between the described components for clarity of the illustration. Nevertheless, it will be understood by those skilled in the art how the components are linked together to operate as disclosed herein.

While various embodiments are disclosed herein, in the interest of clarity all features of an actual implementation may not be described in this specification. In the development of any such actual embodiment, numerous implementation-specific decisions may need to be made to achieve the design-specific goals, which may vary from one implementation to another. It will be appreciated that such a development effort, while possibly complex and time-consuming, would nevertheless be a routine undertaking for persons of ordinary skill in the art having the benefit of this disclosure. The following detailed description of exemplary embodiments, read in conjunction with the accompanying drawings, is merely illustrative and is not to be taken as limiting the scope of the invention.

shows an embodiment of a fluid pressurization unitaccording to this disclosure. The cross section ofshows the fluid pressurization unitlinked to a vesselhaving an internal passageconfigured to sustain a fluid under pressure. As used herein for purposes of this disclosure, the word “vessel” is not to be limited to any structure or device; it is meant to encompass any apparatus configured with one or more internal passages to sustain and/or contain a fluid under pressure as described herein (e.g., BOP, Frac Stack, gate valves, conventional valves, etc.). The fluid pressurization unithas an enclosurehousing a pistonwith a large surface areaat one end compared to a smaller surface areaat an opposing end. As shown in, the fluid pressurization unitis affixed to the vesselsuch that the pistonend with the smaller surface areais directly exposed to the internal passage. The pistonincludes seals,(e.g., O-rings) to restrict fluid passage within the enclosure. The enclosureincludes a fluid portto accept fluid under pressure to push the pistoninto the internal passage. Fluid pressurization unitembodiments of this disclosure may be implemented to receive several types of fluids to move the piston, including via pneumatic actuation.

shows the fluid pressurization unitofafter the pistonhas been actuated via fluid pressure through the fluid port. Prior to actuation of the fluid pressurization unit, the internal passagein the vesselhas been filled with fluid (e.g., hydraulic fluid) and the passage has been isolated from fluid communication with other passages or ports in the vessel. As fluid is introduced into the enclosureto push the large surface areaof the piston, a pressure intensification occurs as the smaller surface areais in direct fluid communication with the fluid in the passage. As the pistonend travels into the internal passage, the fluid pressure in the passage increases and internal vesselpressurization is achieved to test the integrity of the internal passage (including associated seals and elastomers).

Embodiments of the fluid pressurization unitsmay also be implemented with a second fluid porton the enclosureto accept fluid under pressure to push the pistonback to the retracted or passive position when de-pressurization of the internal passageis desired, such as when pressure testing is concluded. It will be appreciated by those skilled in the art that the fluid ports,may be implemented using conventional components permitting permanent or temporary coupling of a fluid supply source.

shows a BOP assemblyintegrated with fluid pressurization unitembodiments. The BOP assemblyincludes stacked conventional BOP units, which as previously described, are generally configured with ramsthat are actuated by hydraulic fluid under pressure typically provided by accumulator tanks (seein). The fluid pressurization unitsare shown linked to a vessel, in this case a BOP assembly. The fluid pressurization unitsare linked to the ramsin the stack. Each fluid pressurization unitis linked to the BOP assemblysuch that the piston (see) is introduced into the internal rampassage to increase the pressure of the fluid contained in the passage when the unit is actuated. The internal rampassages may be isolated and filled with fluid (e.g., hydraulic fluid) as known in the art. For example, the fluid to fill the internal passages may be conveyed to the vessel via one or more conduitscoupled to the BOP assemblyto a separate fluid supply.

The embodiment ofis also equipped with a unitary moduleconsisting of a variable displacement pump, a subsea motor, and variable frequency drive (VFD). These components may be provided separately and individually linked to the vessel or coupled together to provide a compact unit as shown in the unitary module. The variable displacement pump in the moduleis fluidly coupled to a hydraulic fluid reservoirmounted on the assembly. A controller bottleis also linked to the unitary moduleto house local electronics and processors for operational control of the system. One or more batteries may be housed in the controller bottleor mounted independently as desired.

Once pressure testing is completed on the particular internal passage of the vessel, the obstruction used to isolate the passage is removed. For example, for the BOP assemblyonce the plug or ram(s) are moved to open the internal passage to allow normal fluid transfer, the pistonsin the fluid pressurization unitscan be returned to the retracted or passive position in different ways. For example, the pump in the unitary modulemay be actuated to provide fluid under pressure to the second portin the fluid pressurization unitvia a fluid conduit, while fluid conveyance to the first portis simultaneously ceased. Fluid evacuating from the enclosurevia the first portas the pistonis retracted can return to the reservoir. Another embodiment can be implemented to include a sealed container or tankfluidly connected into the system to provide a vacuum or low-pressure reservoir. By fluidly connecting the tankinto the lines supplying the fluid to the pistonsvia the ports, a differential pressure assist can be obtained to retract the pistons to the passive position until the next pressurization operation. When testing is completed and the internal passage is allowed to return to a normal state, the low-pressure tankcan be activated (e.g., by opening a valve in the line) to enable differential pressure assisted movement of the pistonto its retracted or passive position. Once the tankis full of fluid, valves in the lines may be activated to close the first line between the tank and the pistonand to open a second line from the tank to another pumpfluidly connected to the tank. Once the second line is opened, the second pumpcan be activated to evacuate the fluid from the tankto reinstate or re-charge the vacuum in the tank. The evacuated fluid may be pumped into the reservoir. In this manner, a vacuum reservoir may be maintained in the tankfor use in the system as desired. While the embodiment ofis described in terms of vacuum being maintained in the tank, in principle it is only necessary to maintain a lower pressure in the tank than the hydrostatic pressure of fluid in the internal passage of the pistonto be retracted. Other embodiments may be implemented with other configurations to return the pistonto the passive position in the enclosure(e.g., via mechanical means, electromagnets, etc.).

It will be appreciated that the fluid pressure control systems of this disclosure may be used in offshore applications where the vesselis deployed underwater. The embodiment ofis suitable for such deployment. In such applications, embodiments may be implemented with the fluid portson the fluid pressurization unitsconfigured for engagement with a Remotely Operated Vehicle (ROV)suspended from the surface via an umbilicalas known in the art. In the event the local components (e.g., the unitary moduleor controller) fail to operate to actuate the fluid pressurization units, the ROVmay be deployed to disconnect the fluid conduits coupled to the fluid ports() and to couple to the ports to provide the fluid pressure (from a pressurized tank within the ROV) needed to actuate the unitsand carry out the internal passage pressurization.

shows another embodiment of this disclosure. In this embodiment, a BOP assemblyis configured with a frame structureincluding a front paneland interconnected guide rails. The guide railsare linked together in a planar configuration, defining a plane to provide a platform for two-dimensional linear movement within the plane defined by the rails. One such plane or front panelis shown inas extending in the x, y directions. The frame structureis implemented with a movable railmovably disposed between the vertical guide rails. The movable railmay move up or down along the guide rails. The movable railis implemented with a fluid pressurization unitmounted thereon. In this embodiment, the fluid pressurization unitconsists of a fluid injection module configured to move back and forth along the length of the movable rail(e.g., horizontally, from side-to-side in the embodiment of). Some embodiments may also comprise an articulated armcoupled to the frame structureand configured with a manipulation device.

The movable railmay be moved up and down along the guide railsby a linear actuator (not shown separately) which may comprise any suitable device known in the art for linear motion, including, without limitation, a linear electric motor, hydraulic cylinder and ram, gear and rack combination, worm gear and ball nut combination and sheave and cable system. A corresponding linear actuator (not shown) may be provided to move the fluid pressurization unitalong the movable rail. In combination, the linear actuator for the movable railand corresponding linear actuator for the fluid pressurization unitenables the fluid pressurization unit to be positioned at any chosen location within the plane of the front panel.

Behind the control panelare situated the rams (seein) of the BOP assembly. The control panelis configured with openingsaligned with fluid portson the ram housings for the internal ram passages of the BOP assembly. The fluid pressurization unitmay be coupled to a hydraulic fluid line that is linked to a fluid reservoir, unitary module, and controller(like the embodiment of). In operation, the fluid injection module of the pressurization unitis moved vertically and horizontally (via the rails,) to the desired ram fluid port. The injection module is then actuated to couple with the selected portto permit injection of hydraulic fluid from the reservoir, under pressure from the pump in the unitary module, to pressurize the internal passage of the vessel(the BOP assemblyin this embodiment). When the pressure test is completed, the fluid injection module of the pressurization unitis decoupled from the fluid portand the internal ram passage is allowed to depressurize. The BOP assemblyofis shown equipped with accumulator bottles, a local power supply(e.g., batteries), and a multiplex (MUX) cable(e.g., for underwater communication and data transfer to and from the surface). Other frame structures and linear actuation configurations that may be used to implement the embodiments of this disclosure are further described in Published PCT Patent Application No. WO 2022/066896, assigned to the present assignee, and entirely incorporated herein by reference.

shows another fluid pressurization unitembodiment of this disclosure. The cross section ofshows a high-pressure enclosurehousing a moveable memberwhich is configured as a piston with a large surface areaat one end compared to a smaller surface areaat an opposing end of a shaft. As previously mentioned, this configuration provides an intensified hydraulic actuator when hydraulic fluid pressure is supplied to the enclosureas described herein. As shown in, the moveable memberdivides the enclosureinto a first chamber Cand a second chamber C. The moveable memberincludes a seal(e.g., O-ring) to restrict fluid passage between chambers Cand C, and seals(e.g., annular packer seals) to restrict fluid passage along the enclosurebore containing the shaft. Some embodiments may also be implemented with a removable test plugsealing an orifice leading to an annulus formed between the sealsto facilitate pressure testing of the seals as known in the art.

The fluid pressurization unitis shown linked to a vesselhaving an internal passageconfigured to sustain a fluid under pressure. The fluid pressurization unitmay be affixed to the vesselwith conventional fasteners(e.g., bolts). As shown in the cross section of, the shaftend of the moveable memberpartially resides within the internal passageof the vessel when the moveable member is in the retracted or passive position.

Some embodiments may also incorporate an integral spring(e.g., 350-psi (2413165.05 Pa) spring) disposed in the enclosurechamber C. Such embodiments allow for precise low-pressure testing of the vesselinternal passage. For example, enclosurechamber Ccan be filled with hydraulic fluid via fluid inlet/outlet portto push the movable memberto compress the springuntil the movable member is in the passive position, as shown in. When low-pressure testing of the vesselinternal passageis desired, fluid portis opened to allow evacuation the hydraulic fluid from chamber Cas the springpushes the movable memberto the actuated position as shown in, thereby providing precise and gradual low pressurization of the internal passage.

Some embodiments may also be implemented with a fluid inlet/outlet portleading to enclosurechamber C. Such embodiments permit injection of hydraulic fluid via portto further actuate the movable memberto a fully actuated position to provide full-pressure testing of the vesselinternal passage, as shown in. Such hydraulic fluid injection via portalso permits the movable memberto be held at a selected position within the enclosureto provide the desired pressure testing of the vesselinternal passagefor a sustained period. It will be appreciated by those skilled in the art that the hydraulic fluid supply/evacuation conduits for the fluid ports,may be implemented via suitable conventional means. As shown in, a temperature and pressure sensormay also be integrated into the enclosureto provide testing data of the internal passagefluid via channel.

In the case where the vesselconsists of a BOP, when a pressure test is desired, the BOP is filled with fluid and a test plug is set. As each ram is closed, the movable memberis actuated into the side outlet of the internal fluid passage, displacing the wellbore fluid and increasing wellbore pressure against the seal being tested. Once the BOP seal to be tested is closed, the fluid pressurization unitis actuated and the springpushes the shaftinto the wellbore achieving a stable low-pressure test. Once the low-pressure test is completed, hydraulic pressure may be applied to chamber Cas described herein to achieve a high-hold pressure test.

shows another fluid pressurization unitembodiment of this disclosure. The cross section ofshows a high-pressure enclosurehousing a moveable memberwhich is configured as a test rodwith a conventional internal screwand lead nut. The internal screwis coupled to a planetary torque converterwhich is coupled to an electric motor. In some embodiments, the electric motorincludes an encoder. Some embodiments may also be implemented with redundant annular packer seals, seal test plugs, and a pressure transmitterto detect packer sealfailure via channel. A temperature and pressure sensormay also be integrated into the enclosureto provide testing data of the internal passagefluid. A variable frequency drivelinked to the electric motoris also housed in the enclosure.

Power for the electric motormay be provided by a local power source (e.g., batteries in the enclosure). For underwater applications, electric power may be provided by an ROVequipped with batteries and a programmable logic controller (PLC). An ROVequipped with a Wet Mate connectorcan be deployed to couple to a connectorintegrated in the enclosureto provide power for the motorand internal electronics. Some embodiments may also be configured with a pressure balanced oil-filled enclosure. For such embodiments, a conventional pressure compensatormay be integrated into the enclosureto provide balanced oil pressure compensation to the enclosurefor underwater applications.

When pressure testing of the vesselinternal fluid passageis desired, the electric motoris actuated to rotate the internal screw, thereby extending the test rodinto the internal passage to provide the desired pressure to the passage.shows the fluid pressurization unitwith the test rodfully extended into the internal fluid passageto allow for full pressure testing.also shows an embodiment configured with a combination MUX/power cableto provide control signals and electric power to actuate the motorand moveable memberas desired in underwater applications.

shows another fluid pressurization unitembodiment of this disclosure. The cross section ofshows a high-pressure enclosurehousing a moveable memberwhich is configured as a shaftwith an externally threaded section. The shaftis coupled to a planetary torque converterwhich is coupled to an electric motor. In this embodiment, the torque converterincludes an extended tubewith an engaging ringthat engages the exterior of the shaft(e.g., via grooves in the shaftouter surface). When the electric motoris actuated, the torque converterrotates the extended tubeand engaging ring, which rotates the shaft. The externally threaded sectionof the shaftmates with an internally threaded sectionalong the enclosurebore, which guides the shaft into and out of the vesselinternal passageto provide the desired pressure as described herein.

As shown in, some embodiments may be implemented with a pressure sensordisposed within an internal channelrunning along the full length of the shaftto provide test data of the vesselinternal passage. Some embodiments may be implemented with a pressure transfer pistonmounted at the distal end of the shaft. In such embodiments, the internal channelmay be filled with a grease compound to isolate the pressure sensorand convey the wellbore pressure transferred via the piston. An orificeat the tip of the shaftallows for such real time pressure sensing.also shows the enclosurehousing a VFD, power supply, batteries, a PLC, and a connectorto receive external communication signals/power as described herein.shows the fluid pressurization unitwith the shaftfully extended into the internal fluid passageto allow for full pressure testing. As shown in, an extendable/rotatable electrical connectoris coupled to the pressure sensorto communicate the data to a processor/memory for local storage in the enclosureor conveyance externally as known in the art.

shows another fluid pressurization unitembodiment of this disclosure. This embodiment is similar to the embodiment of. However, this embodiment is configured to receive power via an ROVequipped with batteries and a PLC. A Wet Mate connectorextends from the ROVto couple to the connectoron the enclosure. Some embodiments may also be implemented with the combination MUX/power cableto provide control signals and electric power to actuate the motorand moveable memberas desired in underwater applications.shows the fluid pressurization unitwith the shaftfully extended into the internal fluid passageto allow for full pressure testing.

Advantages of the disclosed fluid pressurization unitembodiments include the ability to provide fluid pressurization selectively and repeatedly in an efficient manner without having to run additional fluid supply lines and interrupt normal operation of the vesselfor an extended period. Embodiments implemented with controllers and processors programmed to perform the pressurization operations can be activated remotely and/or configured to perform autonomous operations at selected intervals. When implemented with BOP assemblies, the fluid pressurization unitscan be configured to provide for sequential seal/ram testing by selectively closing the rams to isolate the desired internal chambers or passages for pressurization in an ordered manner. Implementations using the fluid pressurization unitsallow for greater control of applied fluid pressure, which provides for more controlled testing to account for specific vessel parameters (e.g., metal expansion, gas compression, elastomer movement, etc.). Incorporating pressure sensors into the disclosed systems also aids in monitoring the pressurization of the desired vessel passages and components.

In light of the principles and example embodiments described and illustrated herein, it will be recognized that the example embodiments can be modified in arrangement and detail without departing from such principles. It will be appreciated by those skilled in the art that conventional hardware, electronics, software, controllers, components, as well as conventional frame structures, tubing, and housings using suitable materials, may be used to implement the embodiments according to this disclosure. It will also be appreciated that the valves, controls, and components of embodiments of this disclosure may be remotely operated (e.g., via ROV, linked signal/communication channels, etc.).

It will also be appreciated that embodiments of this disclosure may be implemented for use at surface and in underwater applications and operations, in the oil and gas industry, and in other fields of endeavor. For purposes of defining the scope of this disclosure, any embodiment referenced herein is freely combinable with any one or more of the other embodiments referenced herein, and any number of features of different embodiments are combinable with one another, unless expressly stated otherwise. It will also be appreciated that embodiments may be implemented using conventional processors and memory in applied computer systems. What is claimed as the invention, therefore, are all implementations that come within the scope of the following claims, and all equivalents to such implementations.