Hydraulically actuatable safety valve

Abstract

There is provided a hydraulically-actuated in-line hydraulic control system (100) for controlling the supply of hydraulic fluid to a hydraulically-actuatable safety valve (12). The system (10) includes a flow control valve (20) for controlling a flow of hydraulic fluid via a hydraulic control line (14) to and / or from a safety valve (12). The flow control valve (20) includes a bi-directionally operable pressure balanced main piston (22) for opening and / or closing a fluid passage for selective passage of hydraulic fluid.

Description

[0001] HYDRAULICALLY ACTUATABLE SAFETY VALVE

[0002] TECHNICAL FIELD

[0003] The present invention relates to a method of controlling downhole equipment or devices, particularly, but not exclusively, sealing a hydraulic supply and / or control line; and associated apparatus.

[0004] BACKGROUND

[0005] Wellheads, such as for subsea oil / gas wellbores, have a number of valves for controlling flow or pressure in / from wellbores. In particular, producing wells have Xmas trees mounted at the wellhead, whereby production can be controlled and well fluids contained as desired or required. Other safety valves, such as Subsurface Safety Valves (SSVs or SSSVs) are typically located downhole of the wellhead, particularly for emergency sealing of the well below the wellhead.

[0006] A downhole safety valve (DHSV) refers to a component on an oil and gas well, which acts as a failsafe to prevent the uncontrolled release of reservoir fluids in the event of a worst-case-scenario surface disaster. It is almost always installed as a vital component on the completion.

[0007] DHSVs are commonly uni-directional flapper valves which open downwards such that the flow of wellbore fluids effectively push it shut, while pressure from the surface pushes it open. Accordingly, when closed, it will isolate the reservoir fluids from the surface.

[0008] DHSVs are typically controlled hydraulically from the surface, meaning they are opened using a hydraulic connection linked directly to a well control panel. When hydraulic pressure is applied down a control line, the hydraulic pressure forces a sleeve within the valve to slide downwards. This movement compresses a large spring and pushes the flapper downwards to open the valve. When hydraulic pressure is removed, the spring pushes the sleeve back up and causes the flapper to shut. In this way, it is failsafe and will isolate the wellbore in the event of a loss of the wellhead. Such DHSVs are often referred to as 'tubing retrievable, surface controlled, subsurface safety valves' (“TR-SCSSV”). It may be an object of one or more aspects, examples, embodiments, or claims of the present disclosure to at least mitigate or ameliorate one or more problems associated with the prior art, such as described herein or elsewhere.

[0009] SUMMARY

[0010] According to an aspect, there is provided a system for controlling operation of a hydraulically-operable safety valve (“SV”), such as a DHSV / SSV. It will be appreciated that the safety valve may comprise a DHSV, such as a TRSCSSV. The system may comprise an automatic valve closure mechanism or means, for automatically closing the SV. The system may be tripped or triggered automatically, without requiring a manual or operator input. Additionally, or alternatively, the system may be manually operable, such as controllable by an operator from surface. The system may be directly manually controllable and / or by pressure or flow manipulation (e.g. by manipulating hydraulic fluid flow).

[0011] The system may be for preventing or at least mitigating contaminant, such as gas migration. The system may be for preventing or at least mitigating contaminant, such as gas migration, along or via a hydraulic control line. The system may be operable effectively both when the SV is open and / or closed. The system may be configured to prevent or at least mitigate passage of a contaminant, such as a hydrocarbon or gas, via the hydraulic control line to surface.

[0012] The system may be configured to enable a bleeding of the hydraulic control line. The system may be configured to enable a bleeding of the SV control line below closed-in tubing head pressure (“CITHP”). The system may be configured to prevent or at least mitigate against unwelcome returns, such as returns via the hydraulic line (e.g. to surface) comprising a contaminant / s. The system may be configured to prevent or at least mitigate against gassy returns. The system may be configured to operate without requiring the pressure to drop below a SV closing pressure (e.g. the pressure drop required to normally close the DHSV). The system may be configured to prevent or at least mitigate against wells being shut in and isolated. The system may be configured to prevent contaminant / gas flow back to a hydraulic supply (e.g. a HPU / surface). For example, in an emergency scenario where the DHSV closes and control line pressure is dumped, the presently-disclosed system may be configured to provide a barrier to prevent gas flow back to the HPU. The system may be configured to operate in response to a change in flow, such as a change in flow direction. Accordingly, in at least some examples, there is provided a hydraulically-actuated inline hydraulic control valve for controlling supply of hydraulic fluid to a hydraulically- actuatable subsurface safety valve, the safety valve for (selectively) sealing a hydrocarbon flowpath; wherein the hydraulically-actuated in-line hydraulic control valve is configured to prevent or at least mitigate ingress, egress and / or migration of a hydrocarbon or other contaminant in or within the associated hydraulic control line.

[0013] According to an aspect, there is provided a method of controlling operation of a hydraulically-operable safety valve, such as a DHSV / SSV. The method may comprise automatically closing the SSV. For example, the system may be tripped or triggered automatically, without requiring a manual or operator input.

[0014] The presently-disclosed system may comprise an in-flow valve apparatus for mounting inline in the hydraulic control line between the HPU (and / or control panel) and the SV. The in-flow valve apparatus may be mounted or mountable in-line anywhere along the control line. For example, the in-flow valve apparatus may be mounted proximal the control panel. Alternatively, the in-flow valve apparatus may be mounted proximal the SV. The In-flow valve apparatus may comprise a pressure-insensitive, time-delay valve that will automatically close when the flow direction changes.

[0015] The in-flow valve apparatus may be mounted or mountable in or with a control line during installation thereof. For example, the in-flow valve apparatus may be incorporated in the control line prior to connection of the control line to the HPU, before the SV is operable for use.

[0016] It will be appreciated that the in-flow valve apparatus may be mounted or mountable in existing or pre-installed safety systems or wells. Accordingly, the present disclosure also includes a method of retrofitting the in-flow valve apparatus to existing or preinstalled safety systems or wells.

[0017] Accordingly, there is provided a hydraulic safety system, the hydraulic safety system being connected or connectable in the hydraulic control system, such as anywhere inline in the hydraulic control line, between a hydraulic supply (e.g. at surface) and a hydraulically-activatable valve, such as a SSV / DHSV. There may be provided a hydraulic safety system, the hydraulic safety system comprising the in-flow valve apparatus. In at least some examples, the hydraulic safety system comprises the hydraulically-activatable valve, such as the SSV / DHSV.

[0018] The in-flow valve apparatus may comprise a flow control valve. The flow control valve may be for and configured for controlling a flow of hydraulic fluid via the hydraulic control line to and / or from the SV.

[0019] The flow control valve may comprise a pressure-balanced valve. The flow control valve may comprise a pressure-balanced main piston for opening or closing a fluid passage for selective passage of hydraulic fluid via the flow control valve to / from the SV connected thereto. The flow control valve’s main piston may be pressure-balanced to be bidirectionally operable in response to a pressure difference across the main piston.

[0020] The flow control valve may comprise a sealed fluid chamber. The sealed fluid chamber may comprise a closed fluid chamber. The sealed fluid chamber may comprise an isolated fluid therein. The sealed fluid chamber may comprise an inert fluid therein, such as a hydraulic oil. The fluid may be segregated at all times from the hydraulic control fluid for controlling the SV. The sealed fluid chamber may comprise a damping fluid. The sealed fluid chamber may comprise a fixed amount, such as a fixed volume, of fluid therein. The sealed fluid chamber may be for and configured for providing a resistance to movement of a piston, such as the main piston or at least a member, such as a stem, associated therewith. The sealed fluid chamber may be for and configured for providing a delayed opening and / or closing of the flow control valve. Whilst the chamber piston is moving between the open and closed positions, or between the closed and open positions, the flow control valve may be at least partially opened such that hydraulic fluid can flow to and / or from the SV via the hydraulic control line. The sealed fluid chamber may provide for a same delay in opening relative and closing (e.g. a same time for the chamber piston to open and to close). Alternatively, the sealed fluid chamber may provide for a different delay in opening relative to closing. For example, the chamber piston member may encounter more resistance to movement in a first axial direction relative to a second axial direction (e.g. in a closing direction relative to an opening direction; or vice versa). The flow control valve may be adjustable to vary a time for the delayed passage of the chamber piston member. The sealed fluid chamber may comprise a chamber piston member therein. The chamber piston member may be operatively associated with the main piston. The sealed fluid chamber may comprise first and second fluid portions. The first and second fluid portions may be separated by the chamber piston member. The chamber piston may effectively dampen the main piston. The first and second fluid portions may be in fluid communication such that the sealed fluid in the sealed fluid chamber may pass between the first and second fluid portions. The sealed fluid chamber may comprise a fluid passage for the flow of the sealed fluid between the first and second fluid portions. The fluid passage may comprise a restriction, in at least one direction of flow. The restriction may define a delayed passage of fluid between the first and second fluid portions. Accordingly, the restriction may define a delayed movement of the chamber piston. The fluid passage may comprise a restrictor, such as an orifice or channel (e.g. in or through the chamber piston member). The movement of the main piston may be linked, such as directly linked, to the movement of the chamber piston. Accordingly, a delay in movement of the main piston may be associated with the delayed movement of the chamber piston. The fluid chamber is a sealed unit containing clean hydraulic oil that is used to control the closing speed of the main piston. When pressure is released, the hydraulic oil in the sealed fluid chamber must pass through the restrictor (e.g. from , controlling the speed that the Main Piston can travel back to the ‘closed’ position. The speed of closure is controlled to ensure sufficient time is given for the SV to operate. For example, the speed of closure, as determined by the delayed movement of the chamber piston, may be configured to provide sufficient time to allow a DHSV flow tube to retract and the flapper to close. The chamber piston may provide a delayed time of at least 30 seconds; optionally at least one minute; optionally at least two minutes; for the SV to close. In at least some examples, the chamber piston provides a time ranging between one minute and three minutes, preferably between two minutes and three minutes. Typically a DHSV may take from a minimum of around 15-30 seconds to a maximum of around one-two minutes to close. For safety and / or for regulatory purposes, the DHSV may comprise a designated maximum time between initiation and completion of closure, such as a maximum of two minutes. The chamber piston may be configured to provide a time delay at least as long as a maximum time required to close the SV. The chamber piston’s time for closure may be equal to or greater than the SV’s time for closure. The chamber piston’s time for closure may be greater than the SV’s maximum time for closure to ensure an extra margin of the flow control valve being open to allow bleeding from the SV, to ensure the SV is properly bled and the SV is fully closed. The flow control valve may comprise an activation piston. The Flow control valve may house a the ‘pressure balanced’ opening I closing Main Piston. The Flow control valve may comprise a sealed Fluid Chamber for a transfer fluid. The flow control valve may comprise a spring, such as a helical compression spring or the like. The spring may be an activation piston spring for biasing the activation piston. The flow control valve’s activation piston spring may apply a spring force to keeps the flow control valve in a naturally ‘closed’ position. With the flow control valve closed, the hydraulic control line to the SV is closed, preventing passage of fluid (e.g. hydraulic fluid and / or contaminant fluid) to and / or from the SV. The flow control valve may be biased closed by the activation piston spring. In the flow control valve closed position, a pressure build up in the control line is contained and cannot pass. Accordingly, fluid and / or contaminants cannot pass the Main Piston seal and escape to the returns tank when the flow control valve is closed.

[0021] The in-flow valve apparatus may comprise a flow diverter. The flow diverter may be for diverting hydraulic control fluid to and / or from the SV. The flow diverter may be a device for and configured to direct flow of applied and / or returning control line fluid. The flow diverter may provide for the selective passage of hydraulic control fluid between the control panel / HPU and the SV. The flow diverter may be for diverting hydraulic control fluid to and / or from the SV via the flow control valve. For example, the flow diverter may be configured to indirectly open and / or close the flow control valve for the selective opening or closure of the fluid control valve to control passage or blockage of flow of the hydraulic control fluid to and / or from the SV. The flow diverter may comprise an axially movable diverter piston. The diverter piston may be movable to selectively transfer a transfer fluid between the flow diverter and the flow control valve. The transfer fluid is transferable to a chamber associated with the activation piston of the flow control valve. Accordingly, the activation piston may be controllable or at least influenced by operation of the flow diverter’s diverter piston.

[0022] The flow diverter may comprise a diverter spring, such as a diverter piston compression spring. The diverter spring may be configured to bias the diverter piston to or towards the ‘closed’ position when there is no applied pressure. The flow diverter may comprise a float piston. The float piston may be configured to prevent or at least mitigate against trapped fluid from impeding or preventing full travel of the diverter piston when moving to the ‘closed’ position. The transfer fluid may be enclosed within a sealed circuit to prevent DHSV control line fluid or well fluids form interfering with the activation piston.

[0023] The in-flow valve apparatus may comprise a series of one way / check valves in a manifold. The one way I check valves may be configured to ensure that pressure applied from the control panel enters an opening port of the Flow Diverter, for moving the diverter piston from the closed position to the open position. The applied pressure moves the Diverter Piston forcing the transfer fluid from the flow diverter into the Flow control valve, via the closed fluid transfer circuit. Accordingly, the transfer fluid applies a pressure within the flow control valve. Thereby, the main piston of the flow control valve is moved from the closed to the open position, allowing flow of hydraulic control fluid via the hydraulic fluid control line down to the DHSV. It will be appreciated that the piston areas within the Flow Diverter are biased to ensure the applied pressure holds the diverter piston in the ‘open’ position; and returns pressure holds it in the ‘closed’ position (e.g. when returns pressure exceeds applied pressure, such as when pressure from the control panel is disapplied).

[0024] Accordingly, it will be appreciated that pressure can be applied, such as from the control panel, to open the SV. In response, to the applied pressure, the flow diverter’s diverter piston is activated to move axially. Accordingly, the transfer fluid is transferred via a closed fluid circuit between the flow diverter and the flow control valve. The transfer fluid circuit may comprise a closed, sealed circuit with the transfer fluid isolated fluid therein. The transfer fluid may comprise an inert fluid, such as a hydraulic oil. The transfer fluid may be segregated at all times from the hydraulic control fluid for controlling the SV. The transfer fluid may be segregated at all times from the damping fluid in the sealed fluid chamber of the flow control valve. The pressure associated with the flow of transfer fluid from the Flow Diverter to the flow control valve forces the Activation Piston to the ‘open’ position. The pressure applied via the transfer fluid acting on the activation piston overcomes the spring bias force, compressing the spring, and in turn pulls the Main Piston into the ‘open’ position allowing flow of hydraulic control fluid down to the DHSV. Accordingly, when pressure is applied to open the Flow control valve, hydraulic control fluid passes through the check valve. The activation piston is operably connected to the main piston. The activation piston is operably connected to the main piston such that axial movement of the activation piston is directly transferred to the main piston. The main piston is axially movable to selectively open and close a port / s controlling a passage of the hydraulic control fluid through the fluid control valve to and / or from the SV. When the main piston is in the open position, hydraulic control fluid can be supplied to the SV. Accordingly, the open position of the Main Piston corresponds to an open configuration of the SV (with the SV being biased to close in an absence of hydraulic control fluid supply). Seals on the Main Piston are pressure balanced. Accordingly, the main piston is balanced to close by default, such as even if pressure is still present in the line during the closing sequence.

[0025] It will be appreciated that the in-flow valve apparatus may be cyclable. For example, the in-flow valve apparatus may be endlessly cyclable between open and closed configurations. The in-flow valve apparatus may be cyclable between open and closed configurations by the selective supply of hydraulic control fluid thereto. The in-flow valve apparatus may be cyclable between open and closed configurations automatically in response to changes in hydraulic control fluid flow direction. Accordingly, the in-flow apparatus may be automatically openable and / or closeable in response to a corresponding opening and / or closing of the SV. The in-flow valve apparatus may open and / or close with a time delay relative to the SV. The in-flow valve apparatus may be configured to close and / or open at least as slowly as the SV. The inflow valve apparatus may be configured to close and / or open more slowly than the SV, such as with a predetermined time delay or buffer. The time delay or buffer may be longer than a maximum time for the SV to close. The time delay or buffer may be longer than a maximum time for the SV to open.

[0026] In at least some examples, there is provided the flow control valve in a system without the flow diverter. In such a system, the flow control valve can operate to allow a controlled, delayed bleeding of the SV, such as in response to a pressure drop (e.g. when the pressure drops below the DHSV closing pressure). Accordingly, the flow control valve may represent an improvement on an equivalent without such a flow control valve: mitigating against gas / contamination migration in / along the hydraulic line in at least some scenarios.

[0027] Accordingly, in at least one aspect, there is provided a flow control valve. The flow control valve may comprise an Ingress Isolation Valve (ii-Valve). The ii-Valve may be configured to prevent or at least mitigate against the issue of gas migration up, in or along the hydraulic control line. As with any operating panel disclosed herein, the ii- Valve c / w operating panel can be installed next to the local xmas tree well control panel. With the Il-Valve installed, the DHSV can be operated as per normal procedure. Only when the DHSV is closed and the control line pressure drops below 250psi, the Il- Valve automatically closes, therefore preventing any control line contents from migrating back to the returns tank. Any pressure build up in the control line from the closed in tubing head pressure (CITHP) does not affect the performance of the seal within the Il-Valve. To re-open the DHSV, supply pressure is applied to the DHSV as per normal operating procedures. The fully automated Il-Valve can self-equalise and open, allowing supply pressure to reach and open the DHSV. The Il-Valve may be configured to not close until the supply pressure has been bled down. For example, The Il-Valve may be configured to not close until the control line pressure is below 250psi. The Il-Valve may be configured to be activated by a closing pressure that may be below that of the DHSV closing pressure to ensure closure only occurs after DHSV is closed.

[0028] The hydraulic safety system may comprise the flow control valve. The flow control valve may be configured to mitigate against hydrocarbon migration, such as gas migration, from the hydraulically-activatable valve to the hydraulic supply via the hydraulic control line.

[0029] Accordingly, in at least some examples, there is provided a hydraulically-actuated inline hydraulic control valve apparatus for controlling supply of hydraulic fluid to a hydraulically-actuatable safety valve, the safety valve for (selectively) sealing a hydrocarbon flowpath; wherein the hydraulically-actuated in-line hydraulic control valve apparatus comprises a transitional element to facilitate a delayed opening and / or closing of the hydraulic control valve. The transitional element may comprise the sealed chamber and chamber piston therein.

[0030] With the flow control valve closed, no fluid passage to / from the SV is possible via or through the flow control valve. Accordingly, the passage of contaminants, such as hydrocarbons, gas, etc to or towards the control panel and / or HPU, etc. can be prevented or at least ameliorated.

[0031] The in-flow valve apparatus may comprise an expansion chamber. The expansion chamber may houses an expansion piston and an expansion spring (e.g. a compression spring). The expansion chamber may be configured to provide a buffer or additional volume. The expansion chamber may be configured to allow displacement of any residual fluid left in the system that might prevent the Diverter Piston from travelling fully to the ‘Open’ position. The buffer or additional volume may be in fluid communication with the hydraulic control fluid. The expansion chamber may be in fluid communication with the hydraulic control fluid via the flow diverter and / or the flow control valve.

[0032] The in-flow valve apparatus may comprise a breather vent valve. The breather vent valve may comprise a device that reduces the opening pressure of the flow diverter. The device may reduce the opening pressure of the flow diverter by preventing a vacuum from being created when the flow diverter piston strokes. The breather vent valve may be configured to ensure axial movement of the diverter piston in response to application of an opening pressure from the control panel.

[0033] Accordingly, in at least some examples, there is provided an in-flow valve apparatus comprising one or more of: a flow control valve; a flow diverter; an expansion chamber; and / or a breather vent valve. The in-flow valve apparatus may comprise each of: a flow control valve; a flow diverter; an expansion chamber; and a breather vent valve.

[0034] The presently disclosed apparatus, system and method may prevent or at least mitigate against one or more problems associated with SVs, such as one or more potential problems associated with DHSVs identified by the present inventors. By design, hydraulically controlled Down Hole Safety Valves (DHSV) incorporate an internal piston seal. When the supply pressure to the DHSV is bled off, the internal piston seal moves to the up-stop position and isolates hydrocarbon ingress from migrating into the control line. A problem with SV’s, particularly older or ageing DHSVs, recognised by the present inventor’s is the failure of the up-stop seal. As a result of this failure, gas migration is free to travel up the control line and back to the platform returns tank. The returns tank is commonly situated within the main hydraulic supply panel. The Hydraulic supply panel by design should only receive hydraulic oil returns. Gas returns could present one or more of the following concerns: where return tanks are sealed, there is the potential for over pressurisation; and / or cumulative control line returns exceeding vent limit on returns tank; and / or potential for wells to be closed in; and / or returns tank location allows for vapor cloud within non-hazardous and nonventilated areas; and / or contamination of (e.g. NAS 6 spec) control line fluid; and / or during planned or unplanned shutdown and closure of the DHSV, Operations Tech may have to manually close in the DHSV isolation block valve at the wellhead; and / or entry into potentially hazardous area during Emergency ShutDown (ESD”) scenario.

[0035] The presently-disclosed system, method and apparatus is configured to close the hydraulic control line without requiring a pressure drop in the control line. For example, the in-flow valve apparatus may be required to close without a pressure drop occurring in the control line. The in-flow valve apparatus may automatically close in response to a change in flow direction. For example, when a flow direction of hydraulic flow reverses from towards the SV to away from the SV, the in-flow valve apparatus automatically closes. The in-flow valve apparatus may automatically close with a predetermined or defined time delay. The time delay may be at least sufficient to ensure sufficient bleeding or pressure drop of hydraulic control fluid from the SV to ensure the SV is fully closed. The In-flow valve may comprise a pressure-insensitive, time-delay valve that will automatically close when the flow direction changes.

[0036] The system may comprise a bypass valve. The bypass valve is typically closed, at all times. The bypass valve may effectively be present as an auxiliary means for opening a flowpath to the hydraulically actuatable safety valve (e.g. SSV / DHSV). For example, if it is safe and desired to open or re-open the SSV / DHSV, and it is desired not so use the hydraulic supply via the (flow diverter and / or flow control valve), then the bypass valve may be opened (e.g. manually) under particular, controlled circumstances.

[0037] According to an aspect, there is provided a system comprising a controller according to an aspect, claim, embodiment or example of this disclosure, or a system arranged to perform a method according to an aspect, claim, embodiment or example of this disclosure. The controller may be configured to control an operation, such as automatically of the SV and / or in-flow valve apparatus.

[0038] According to an aspect, there is provided computer software which, when executed by a processing means, is arranged to perform a method according to aspect, claim, embodiment or example of this disclosure. The computer software may be stored on a computer readable medium. The computer software may be tangibly stored on a computer readable medium. The computer readable medium may be non-transitory.

[0039] Any controller or controllers described herein may suitably comprise a control unit or computational device having one or more electronic processors. Thus, the system may comprise a single control unit or electronic controller or alternatively different functions of the controller may be embodied in, or hosted in, different control units or controllers. As used herein the term “controller” or “control unit” will be understood to include both a single control unit or controller and a plurality of control units or controllers collectively operating to provide any stated control functionality. To configure a controller, a suitable set of instructions may be provided which, when executed, cause said control unit or computational device to implement the control techniques specified herein. The set of instructions may suitably be embedded in said one or more electronic processors. Alternatively, the set of instructions may be provided as software saved on one or more memory associated with said controller to be executed on said computational device. A first controller may be implemented in software run on one or more processors. One or more other controllers may be implemented in software run on one or more processors, optionally the same one or more processors as the first controller. Other suitable arrangements may also be used.

[0040] Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner.

[0041] The invention includes one or more corresponding aspects, embodiments or features in isolation or in various combinations whether or not specifically stated (including claimed) in that combination or in isolation. For example, it will readily be appreciated that features recited as optional with respect to the first aspect may be additionally applicable with respect to the other aspects without the need to explicitly and unnecessarily list those various combinations and permutations here (e.g. the apparatus or device of one aspect may comprise features of any other aspect). Optional features as recited in respect of a method may be additionally applicable to an apparatus or device; and vice versa.

[0042] In addition, corresponding means for performing one or more of the discussed functions are also within the present disclosure. The above summary is intended to be merely exemplary and non-limiting.

[0043] Various respective aspects and features of the present disclosure are defined in the appended claims.

[0044] It may be an aim of certain embodiments of the present disclosure to solve, mitigate or obviate, at least partly, at least one of the problems and / or disadvantages associated with the prior art. Certain embodiments may aim to provide at least one of the advantages described herein.

[0045] The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one aspect can typically be combined alone or together with other features in different aspects of the invention. Any subject matter described in this specification can be combined with any other subject matter in the specification to form a novel combination.

[0046] Various aspects of the invention will now be described in detail with reference to the accompanying figures. Still other aspects, features and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrates a number of exemplary aspects and implementations. The invention is also capable of other and different examples and aspects and its several details can be modified in various respects, all without departing from the scope of the present invention. Accordingly, each example herein should be understood to have broad application and is meant to illustrate one possible way of carrying out the invention, without intending to suggest that the scope of this disclosure, including the claims, is limited to that example. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as "including", "comprising", "having", "containing" or "involving" and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents and additional subject matter not recited and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. Thus, throughout the specification and claims unless the context requires otherwise, the word "comprise" or variations thereof such as "comprises" or "comprising" will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0047] Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention.

[0048] In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element or group of elements with transitional phrases "consisting essentially of", "consisting", "selected from the group of consisting of, "including" or "is" preceding the recitation of the composition, element or group of elements and vice versa. In this disclosure, the words "typically" or "optionally" are to be understood as being intended to indicate optional or nonessential features of the invention which are present in certain examples but which can be omitted in others without departing from the scope of the invention.

[0049] All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa. References to directional and positional descriptions such as upper and lower and directions e.g. "up", "down" etc. are to be interpreted by a skilled reader in the context of the examples described to refer to the orientation of features shown in the drawings and are not to be interpreted as limiting the invention to the literal interpretation of the term, but instead should be as understood by the skilled addressee. In particular, positional references in relation to the well such as "up" and similar terms will be interpreted to refer to a direction toward the point of entry of a borehole into the ground or the seabed and "down" and similar terms will be interpreted to refer to a direction away from the point of entry, whether the well being referred to is a conventional vertical well or a deviated well.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Elements of the present disclosure will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 shows an example of a portion of a system for controlling operation of a hydraulically-operable safety valve (“SV”), such as a DHSV / SSV, according to the present disclosure;

[0052] Figure 2 shows a first cross-sectional view of the portion of the system of Figure 1 , with the system in a closed configuration;

[0053] Figure 3 shows a second cross-sectional view of the portion of the system of Figure 1 , with the system in a closed configuration, at initiation of an opening sequence;

[0054] Figure 4 shows a third cross-sectional view of the portion of the system of Figure 1 , with the system in an open configuration;

[0055] Figure 5 shows a fourth cross-sectional view of the portion of the system of Figure 1 , with the system in a closing configuration;

[0056] Figure 6 shows a fifth cross-sectional view of the portion of the system of Figure 1 , with the system in a further closing configuration; and

[0057] Figure 7 shows a sixth cross-sectional view of the portion of the system of Figure 1 , with the system in a fully closed, bled off configuration.

[0058] DETAILED DESCRIPTION

[0059] As shown in Figure 1 , there is provided a system 10 for controlling operation of a hydraulically-operable safety valve (“SV”) 12, such as a DHSV / SSV 12. It will be appreciated that the safety valve 12 comprises a DHSV, such as a TRSCSSV 12. The system 10 comprises an automatic valve closure mechanism or means, for automatically closing the SV 12 . The system 10 is tripped or triggered automatically, without requiring a manual or operator input. Additionally, or alternatively, the system 10 is manually operable, such as controllable by an operator from surface. The system 10 is directly manually controllable and / or by pressure or flow manipulation (e.g. by manipulating hydraulic fluid flow).

[0060] The system 10 is for preventing or at least mitigating contaminant, such as gas migration, along or via a hydraulic control line 14. The system 10 is operable effectively both when the SV 12 is open and / or closed. The system 10 is configured to prevent or at least mitigate passage of a contaminant, such as a hydrocarbon or gas, via the hydraulic control line 14 to surface.

[0061] The system 10 is configured to enable a bleeding of the SV 12 control line below closed-in tubing head pressure (“CITHP”). The system 10 is configured to prevent or at least mitigate against unwelcome returns, such as returns via the hydraulic line (e.g. to surface) comprising a contaminant / s. The system 10 is configured to prevent or at least mitigate against gassy returns. The system 10 is configured to operate without requiring the pressure to drop below a SV 12 closing pressure (e.g. the pressure drop required to normally close the DHSV). The system 10 is configured to prevent or at least mitigate against wells being shut in and isolated. The system 10 is configured to prevent contaminant / gas flow back to a hydraulic supply (e.g. a HPU / surface). For example, in an emergency scenario where the DHSV 12 closes and control line pressure is dumped, the presently-disclosed system 10 is configured to provide a barrier to prevent gas flow back to the HPU. The system 10 is configured to operate in response to a change in flow, such as a change in flow direction.

[0062] As shown here, there is provided a hydraulically-actuated in-line hydraulic control valve 20 for controlling supply of hydraulic fluid to a hydraulically-actuatable subsurface safety valve 12, the safety valve 12 for (selectively) sealing a hydrocarbon flowpath (not shown); wherein the hydraulically-actuated in-line hydraulic control valve 20 is configured to prevent or at least mitigate ingress, egress and / or migration of a hydrocarbon or other contaminant in or within the associated hydraulic control line 14.

[0063] As shown here, there is provided a method of controlling operation of a hydraulically- operable safety valve, such as a DHSV / SSV 12. The method comprises automatically closing the SSV 12. For example, the system 10 is tripped or triggered automatically, without requiring a manual or operator input. The operation of the method is illustrated sequentially in Figures 2 through 7 respectively.

[0064] The presently-disclosed system 10 comprises an in-flow valve apparatus 11 for mounting inline in the hydraulic control line 14 between the HPU (and / or control panel) and the SV 12. The in-flow valve apparatus 11 is mounted or mountable in-line anywhere along the control line 14. For example, the in-flow valve apparatus 11 is mounted proximal the control panel 9not shown). Alternatively, the in-flow valve apparatus 11 is mounted proximal the SV 12. The In-flow valve apparatus 11 comprises a pressure-insensitive, time-delay valve that will automatically close when the flow direction changes. The in-flow valve apparatus 11 is mounted or mountable in or with a control line 14 during installation thereof. For example, the in-flow valve apparatus 11 is incorporated in the control line prior to connection of the control line to the HPU, before the SV 12 is operable for use. It will be appreciated that the in-flow valve apparatus 11 is also mountable in existing or pre-installed safety systems or wells. Accordingly, the present disclosure also includes a method of retrofitting the inflow valve apparatus 11 to existing or pre-installed safety systems or wells.

[0065] As shown here, there is provided a hydraulic safety system 10, the hydraulic safety system 10 being connected or connectable in the hydraulic control system 10, such as anywhere in-line in the hydraulic control line 14, between a hydraulic supply (e.g. at surface) and a hydraulically-activatable valve, such as a SSV / DHSV 12.

[0066] There is provided a hydraulic safety system 10, the hydraulic safety system 10 comprising the in-flow valve apparatus 11 . In at least some examples, the hydraulic safety system 10 comprises the hydraulically-activatable valve, such as the SSV / DHSV 12.

[0067] The in-flow valve apparatus 11 comprises a flow control valve 20. The flow control valve 20 is for and configured for controlling a flow of hydraulic fluid via the hydraulic control line 14 to and / or from the SV 12. The flow control valve 20 comprises a pressure-balanced valve with a pressure-balanced main piston 22 for opening or closing a fluid passage for selective passage of hydraulic fluid via the flow control valve 20 to / from the SV 12 connected thereto. The flow control valve 20’s main piston 22 is pressure-balanced to be bidirectionally operable in response to a pressure difference across the main piston 22.

[0068] The flow control valve 20 comprises a sealed fluid chamber 24. The sealed fluid chamber 24 comprises a closed fluid chamber 24. The sealed fluid chamber 24 comprises an isolated fluid therein. The sealed fluid chamber 24 comprises an inert fluid therein, such as a hydraulic oil. The fluid is segregated at all times from the hydraulic control fluid for controlling the SV 12. The sealed fluid chamber 24 comprises a fixed amount, such as a fixed volume, of damping fluid 25 therein. The sealed fluid chamber 24 is for and configured for providing a resistance to movement of the main piston 22 or at least a member, such as a stem, associated therewith. The sealed fluid chamber 24 is for and configured for providing a delayed opening and / or closing of the flow control valve 20. Whilst the chamber piston is moving between the open and closed positions, or between the closed and open positions, the flow control valve 20 is at least partially opened such that hydraulic fluid can flow to and / or from the SV 12 via the hydraulic control line 14. Here, the sealed fluid chamber 24 provides for a different delay in opening relative to closing, with fluid transferring across the chamber piston via only a restrictor in a first axial direction and via both a restrictor and a one-way check valve in a second, opposite axial direction. Accordingly, the chamber piston member 26 encounters more resistance to movement in the first axial direction relative to the second axial direction (e.g. in a closing direction relative to an opening direction; or vice versa). The flow control valve 20 is adjustable to vary a time for the delayed passage of the chamber piston member 26. The sealed fluid chamber 24 comprises a chamber piston member 26 therein. The chamber piston member 26 is operatively associated with the main piston 22. The sealed fluid chamber 24 comprises first and second fluid portions. The first and second fluid portions are separated by the chamber piston member 26. The chamber piston effectively dampens the main piston 22. The first and second fluid portions are in fluid communication such that the sealed fluid 25 in the sealed fluid chamber 24 can pass between the first and second fluid portions. The sealed fluid chamber 24 comprises a fluid passage for the flow of the sealed fluid between the first and second fluid portions. The fluid passage comprises a restriction, in at least one direction of flow. The restriction defines a delayed passage of fluid between the first and second fluid portions. Accordingly, the restriction defines a delayed movement of the chamber piston. The fluid passage comprises a restrictor, such as an orifice or channel (e.g. in or through the chamber piston member 26). The movement of the main piston 22 is linked, such as directly linked, to the movement of the chamber piston. Accordingly, a delay in movement of the main piston 22 is associated with the delayed movement of the chamber piston. The fluid chamber 24 is a sealed unit containing clean hydraulic oil 25 that is used to control the closing speed of the main piston 22. When pressure is released, the hydraulic oil 25 in the sealed fluid chamber 24 must pass through the restrictor (e.g. from one side of the chamber piston to the other), controlling the speed that the Main piston 22 can travel back to the ‘closed’ position. The speed of closure is controlled to ensure sufficient time is given for the SV 12 to operate. For example, the speed of closure, as determined by the delayed movement of the chamber piston, is configured to provide sufficient time to allow a DHSV 12 flow tube to retract and the flapper to close. The chamber piston provides a delayed time of at least 30 seconds; optionally at least one minute; optionally at least two minutes; for the SV 12 to close. In at least some examples, the chamber piston provides a time ranging between one minute and three minutes, preferably between two minutes and three minutes. Typically a DHSV 12 takes from a minimum of around 15-30 seconds to a maximum of around one-two minutes to close. For safety and / or for regulatory purposes, the DHSV 12 comprises a designated maximum time between initiation and completion of closure, such as a maximum of two minutes. The chamber piston is configured to provide a time delay at least as long as the maximum time required to close the SV 12. The chamber piston’s time for closure is equal to or greater than the SV’s time for closure. Here, the chamber piston’s time for closure is greater than the SV’s maximum time for closure to ensure an extra margin of the flow control valve 20 being open to allow bleeding from the SV 12, to ensure the SV 12 is properly bled and the SV 12 is fully closed.

[0069] The flow control valve 20 comprises an activation piston 28. The Flow control valve 20 houses a the ‘pressure balanced’ opening I closing Main piston 22. The Flow control valve 20 comprises a transfer fluid 32 chamber 30 for a transfer fluid 32. The flow control valve 20 comprises a spring, such as a helical compression spring or the like, being an activation piston 28 spring for biasing the activation piston 28 so as to apply a spring force to keep the flow control valve 20 in a naturally ‘closed’ position. As shown in Figure 2, with the flow control valve 20 closed, the hydraulic control line 14 to the SV 12 is closed, preventing passage of fluid (e.g. hydraulic fluid and / or contaminant fluid) to and / or from the SV 12. The flow control valve 20 is biased closed by the activation piston spring. In the flow control valve 20 closed position, a pressure build up in the control line is contained and cannot pass. Accordingly, fluid and / or contaminants cannot pass the Main piston seal and escape to the returns tank when the flow control valve 20 is closed.

[0070] The in-flow valve apparatus 11 comprises a flow diverter 40 for diverting hydraulic control fluid to and / or from the SV 12. The flow diverter 40 is a device for and configured to direct flow of applied and / or returning control line fluid. The flow diverter 40 provides for the selective passage of hydraulic control fluid between the control panel / HPU and the SV 12. The flow diverter 40 is for diverting hydraulic control fluid to and / or from the SV 12 via the flow control valve 20. For example, the flow diverter 40 is configured to indirectly open and / or close the flow control valve 20 for the selective opening or closure of the flow control valve 20 to control passage or blockage of flow of the hydraulic control fluid to and / or from the SV 12. The flow diverter 40 comprises an axially movable diverter piston 42. The diverter piston 42 is movable to selectively transfer the transfer fluid 32 between the flow diverter 40 and the flow control valve 20. The transfer fluid 32 is transferable to a chamber associated with the activation piston 28 of the flow control valve 20. Accordingly, the activation piston 28 is controllable or at least influenced by operation of the flow diverter 40’s diverter piston 42. The flow diverter 40 comprises a diverter spring, such as a diverter piston 42 compression spring. The diverter spring is configured to bias the diverter piston 42 to or towards the ‘closed’ position when there is no applied pressure. The flow diverter 40 comprises a float piston 44configured to prevent or at least mitigate against trapped fluid from impeding or preventing full travel of the diverter piston 42 when moving to the ‘closed’ position. The transfer fluid 32 is enclosed within a sealed circuit to prevent DHSV 12 control line fluid or well fluids form interfering with the activation piston 28.

[0071] The in-flow valve apparatus 11 comprises a series of one way I check valves in a manifold. The one way I check valves are configured to ensure that pressure applied from the control panel enters an opening port of the Flow diverter 40, for moving the diverter piston 42 from the closed position to the open position. As shown in Figure 3 through Figure 4, the applied pressure moves the Diverter piston 42 forcing the transfer fluid 32 from the flow diverter 40 into the Flow control valve 20, via the closed fluid transfer circuit. Accordingly, the transfer fluid 32 applies a pressure within the flow control valve 20. Thereby, the main piston 22 of the flow control valve 20 is moved from the closed to the open position, allowing flow of hydraulic control fluid via the hydraulic fluid control line down to the DHSV 12, as shown in Figure 4. It will be appreciated that the piston areas within the Flow diverter 40 are biased to ensure the applied pressure holds the diverter piston 42 in the ‘open’ position; and returns pressure holds it in the ‘closed’ position (e.g. when returns pressure exceeds applied pressure, such as when pressure from the control panel is disapplied).

[0072] As shown here, it will be appreciated that pressure can be applied, such as from the control panel, to open the SV 12. In response, to the applied pressure, the flow diverter’s diverter piston 42 is activated to move axially. Accordingly, the transfer fluid 32 is transferred via a closed fluid circuit between the flow diverter 40 and the flow control valve 20, as best seen in the transition from Figure 3 through Figure 4. The transfer fluid 32 circuit comprises a closed, sealed circuit with the transfer fluid 32 isolated fluid therein. The transfer fluid 32 comprises an inert fluid, such as a hydraulic oil. The transfer fluid 32 is segregated at all times from the hydraulic control fluid for controlling the SV 12. The transfer fluid 32 is segregated at all times from the damping fluid in the sealed fluid chamber 24 of the flow control valve 20. The pressure associated with the flow of transfer fluid 32 from the Flow diverter 40 to the flow control valve 20 forces the Activation piston 28 to the ‘open’ position. The pressure applied via the transfer fluid 32 acting on the activation piston 28 overcomes the spring bias force, compressing the spring, and in turn pulls the Main piston 22 into the ‘open’ position allowing flow of hydraulic control fluid down to the DHSV 12, as visible in Figure 4. Accordingly, when pressure is applied to open the Flow control valve 20, hydraulic control fluid passes through the check valve. The activation piston 28 is operably connected to the main piston 22. The activation piston 28 is operably connected to the main piston 22 such that axial movement of the activation piston 28 is directly transferred to the main piston 22. The main piston 22 is axially movable to selectively open and close a port / s controlling a passage of the hydraulic control fluid through the fluid control valve to and / or from the SV 12. When the main piston 22 is in the open position, hydraulic control fluid can be supplied to the SV 12. Accordingly, the open position of the Main piston 22 corresponds to an open configuration of the SV 12 (with the SV 12 being biased to close in an absence of hydraulic control fluid supply). Seals on the Main piston 22 are pressure balanced. Accordingly, the main piston 22 is balanced to close by default, such as even if pressure is still present in the line during the closing sequence.

[0073] It will be appreciated that the in-flow valve apparatus 11 is cyclable. For example, the in-flow valve apparatus 11 is endlessly cyclable between open and closed configurations. The in-flow valve apparatus 11 is cyclable between open and closed configurations by the selective supply of hydraulic control fluid thereto. As shown n the transitions from Figure 5 through Figure 6 and finally Figure 7, the in-flow valve apparatus 11 is cyclable between open and closed configurations automatically in response to changes in hydraulic control fluid flow direction. Accordingly, the in-flow apparatus is automatically openable and / or closeable in response to a corresponding opening and / or closing of the SV 12. The in-flow valve apparatus 11 closes with a time delay relative to the SV 12. The in-flow valve apparatus 11 is configured to close at least as slowly as the SV 12. Here, the in-flow valve apparatus 11 is configured to close more slowly than the SV, such as with a predetermined time delay or buffer. The time delay or buffer is longer than a maximum time for the SV 12 to close.

[0074] In other examples (not shown), there is provided the flow control valve 20 in a system 10 without the flow diverter 40. In such a system 10, the flow control valve 20 can operate to allow a controlled, delayed bleeding of the SV, such as in response to a pressure drop (e.g. when the pressure drops below the DHSV 12 closing pressure). Accordingly, the flow control valve 20 may represent an improvement on an equivalent without such a flow control valve 20: mitigating against gas / contamination migration in / along the hydraulic line in at least some scenarios.

[0075] In such examples, there is provided a flow control valve 20. The flow control valve 20 comprises an Ingress Isolation Valve (ii-Valve). The ii-Valve is configured to prevent or at least mitigate against the issue of gas migration up, in or along the hydraulic control line 14. As with any operating panel disclosed herein, the ii-Valve c / w operating panel can be installed next to the local xmas tree well control panel. With the Il-Valve installed, the DHSV 12 can be operated as per normal procedure. Only when the DHSV 12 is closed and the control line pressure drops below 250psi, the Il-Valve automatically closes, therefore preventing any control line contents from migrating back to the returns tank. Any pressure build up in the control line from the closed in tubing head pressure (CITHP) does not affect the performance of the seal within the Il-Valve. To re-open the DHSV, supply pressure is applied to the DHSV 12 as per normal operating procedures. The fully automated Il-Valve can self-equalise and open, allowing supply pressure to reach and open the DHSV 12. The Il-Valve is configured to not close until the supply pressure has been bled down. For example, The Il-Valve is configured to not close until the control line pressure is below 250psi. The Il-Valve is configured to be activated by a closing pressure that is below that of the DHSV 12 closing pressure to ensure closure only occurs after DHSV 12 is closed.

[0076] As shown in Figures 1 through 7 here, the hydraulic safety system 10 comprises the flow control valve 20. The flow control valve 20 is configured to mitigate against hydrocarbon migration, such as gas migration, from the hydraulically-activatable valve to the hydraulic supply via the hydraulic control line 14. Accordingly, here, there is provided a hydraulically-actuated in-line hydraulic control valve apparatus for controlling supply of hydraulic fluid to a hydraulically-actuatable safety valve, the safety valve for (selectively) sealing a hydrocarbon flowpath; wherein the hydraulically- actuated in-line hydraulic control valve apparatus comprises a transitional element to facilitate a delayed opening and / or closing of the hydraulic control valve. The transitional element comprises the sealed chamber and chamber piston therein.

[0077] As visible in Figure 7, with the flow control valve 20 closed, no fluid passage to / from the SV 12 is possible via or through the flow control valve 20. Accordingly, the passage of contaminants, such as hydrocarbons, gas, etc to or towards the control panel and / or HPU, etc. can be prevented or at least ameliorated. The in-flow valve apparatus 11 shown here also comprises an expansion chamber 70. The expansion chamber 70 may houses an expansion piston and an expansion spring (e.g. a compression spring). The expansion chamber 70 is configured to provide a buffer or additional volume. The expansion chamber 70 is configured to allow displacement of any residual fluid left in the system 10 that might prevent the Diverter piston 42 from travelling fully to the ‘Open’ position. The buffer or additional volume is in fluid communication with the hydraulic control fluid. The expansion chamber 70 is in fluid communication with the hydraulic control fluid via the flow diverter 40 and / or the flow control valve 20.

[0078] The in-flow valve apparatus 11 comprises a breather vent valve 80. The breather vent valve 80 comprises a device that reduces the opening pressure of the flow diverter 40. The device may reduce the opening pressure of the flow diverter 40 by preventing a vacuum from being created when the flow diverter 40 piston strokes. The breather vent valve 80 is configured to ensure axial movement of the diverter piston 42 in response to application of an opening pressure from the control panel.

[0079] As shown here, there is provided an in-flow valve apparatus 11 comprising each of: a flow control valve 20; a flow diverter 40; an expansion chamber 70; and a breather vent valve 80.

[0080] The presently disclosed apparatus, system 10 and method prevent or at least mitigate against one or more problems associated with SVs, such as one or more potential problems associated with DHSVs identified by the present inventors. By design, hydraulically controlled Down Hole Safety Valves (DHSV) incorporate an internal piston seal. When the supply pressure to the DHSV 12 is bled off, the internal piston seal moves to the up-stop position and isolates hydrocarbon ingress from migrating into the control line. A problem with SV’s, particularly older or ageing DHSVs, recognised by the present inventor’s is the failure of the up-stop seal. As a result of this failure, gas migration is free to travel up the control line and back to the platform returns tank. The returns tank is commonly situated within the main hydraulic supply panel. The Hydraulic supply panel by design should only receive hydraulic oil returns. Gas returns could present one or more of the following concerns: where return tanks are sealed, there is the potential for over pressurisation; and / or cumulative control line returns exceeding vent limit on returns tank; and / or potential for wells to be closed in; and / or returns tank location allows for vapor cloud within non-hazardous and non-ventilated areas; and / or contamination of (e.g. NAS 6 spec) control line fluid; and / or during planned or unplanned shutdown and closure of the DHSV, Operations Tech may have to manually close in the DHSV 12 isolation block valve at the wellhead; and / or entry into potentially hazardous area during Emergency ShutDown (ESD”) scenario.

[0081] The presently-disclosed system 10, method and apparatus is configured to close the hydraulic control line 14 without requiring a pressure drop in the control line. For example, the in-flow valve apparatus 11 is required to close without a pressure drop occurring in the control line. The in-flow valve apparatus 11 may automatically close in response to a change in flow direction. For example, when a flow direction of hydraulic flow reverses from towards the SV 12 to away from the SV, the in-flow valve apparatus 11 automatically closes. The in-flow valve apparatus 11 may automatically close with a predetermined or defined time delay. The time delay is at least sufficient to ensure sufficient bleeding or pressure drop of hydraulic control fluid from the SV 12 to ensure the SV 12 is fully closed. The In-flow valve comprises a pressure-insensitive, timedelay valve that will automatically close when the flow direction changes.

[0082] The system 10 comprises a bypass valve 90, which is typically closed, at all times. The bypass valve 90 may effectively be present as an auxiliary means for opening a flowpath to the hydraulically actuatable safety valve (e.g. SSV / DHSV). For example, if it is safe and desired to open or re-open the SSV / DHSV, and it is desired not so use the hydraulic supply via the (flow diverter 40 and / or flow control valve 20), then the bypass valve 90 is opened (e.g. manually) under particular, controlled circumstances.

[0083] It will be appreciated that embodiments of the present invention can be realised in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the present invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as disclosed in any aspect, example, claim or embodiment of this disclosure, and a machine-readable storage storing such a program. Still further, embodiments of the present disclosure may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same.

[0084] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The applicant indicates that aspects of the present disclosure may consist of any such individual feature or combination of features. It should be understood that the embodiments described herein are merely exemplary and that various modifications may be made thereto without departing from the scope of the disclosure. For example, it will be appreciated that although shown here with the the flow control valve, flow diverter, expansion chamber and breather vent valve, in other embodiments other configurations are provided, such as with other combinations (e.g. only the flow control valve; or flow control valve and expansion chamber, etc.).

[0085] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0086] The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

Claims

CLAIMS1 . A hydraulically-actuated in-line hydraulic control system for controlling the supply of hydraulic fluid to a hydraulically-actuatable safety valve, the system comprising: a flow control valve for controlling a flow of hydraulic fluid via a hydraulic control line to and / or from a safety valve, wherein the flow control valve comprises a bi-directionally operable pressure balanced main piston for opening and / or closing a fluid passage for selective passage of hydraulic fluid.

2. The system of claim 1 , wherein the main piston is axially moveable to selectively open and close a port controlling a passage of hydraulic fluid to and / or from a safety valve via the flow control valve.

3. The system of claim 1 or claim 2, wherein the flow control valve comprises a sealed fluid chamber having a fixed volume of damping fluid therein, wherein the damping fluid is configured to provide resistance to movement of the main piston so as to provide delayed opening and / or closing of the flow control valve.

4. The system of claim 3, wherein the fluid chamber comprises a chamber piston member therein, wherein movement of the chamber piston is directly linked to movement of the main piston.

5. The system of claim 4, wherein the fluid chamber comprises first and second fluid portions separated by the chamber piston member, wherein the chamber piston comprises a channel therethrough such that fluid may pass between the first and second portions in response to movement of the chamber piston member.

6. The system of claim 5, wherein the channel is configured such that the chamber piston member encounters more resistance in a closing direction relative to an opening direction.

7. The system of any preceding claim, wherein the flow control valve comprises an activation piston and an activation piston spring, wherein the activation piston is operably connected to the main piston such that axial movement of the activation piston is directly transferred to the main piston, and wherein the spring force is configured to keep the flow control valve in a closed position.

8. The system of claim 7, wherein the flow control valve comprises a sealed fluid chamber for a transfer fluid, wherein the fluid chamber is associated with the activation piston.

9. The system of any preceding claim, further comprising a flow diverter configured to indirectly open and / or close the flow control valve for diverting hydraulic control fluid to and / or from a safety valve via the flow control valve.

10. The system of claim 9, wherein the flow diverter comprises a diverter piston.11 . The system of claim 9, when dependent upon claim 8, wherein the diverter piston is moveable to selectively transfer the transfer fluid to the chamber associated with the activation piston of the flow control valve such that the activation piston is influenced by operation of the diverter piston.

12. The system of claim 11 , wherein the transfer fluid is enclosed within a sealed circuit.

13. The system of any of claims 9 to 12, wherein the flow diverter comprises a diverter spring configured to bias the diverter piston to or towards a closed position in the absence of applied pressure.

14. The system of any of claims 9 to 13, wherein the flow diverter comprises a float piston configured to mitigate against trapped fluid from preventing full travel of the diverter piston when moving to the closed position.

15. The system of any of claims 9 to 14, comprising check valves configured to ensure that pressure applied from a control panel enters an opening port of the flow diverter for moving the flow diverter from a closed position to an open position.

16. The system of any of claims 9 to 15, comprising an expansion chamber housing an expansion piston and an expansion spring, wherein the expansion chamber is in fluid communication with hydraulic control fluid via the flow diverter and / or flow control valve and is configured to allow displacement of residual fluid that may prevent the diverter piston from travelling to a fully open position.

17. The system according to an preceding claim, configured to operate in response to a change in flow direction and / or without requiring hydraulic control line pressure to drop below a safety valve closing pressure.

18. A flow control valve comprising the flow control valve of any of claims 1 to 8.

19. A hydraulic safety system comprising a system according to any one of claims 1 to 17 connected to a hydraulic control line and a hydraulically-activatable valve, wherein the system is configured to control the flow of hydraulic fluid via the hydraulic control line to and / or from the hydraulically-activatable valve.

20. A method of controlling the operation of a hydraulically-operable safety valve, the method comprising: applying pressure by a hydraulic control fluid from a control panel to open the safety valve; in response to the applied pressure, axially moving a diverter piston so as to displace a transfer fluid, wherein the transfer fluid is segregated from the hydraulic control fluid; applying pressure to an activation piston by the displaced transfer fluid to move the activation piston to an open position; displacing a main piston to an open position, wherein the main piston is operably connected to the activation piston and is movable to selectively open and close a port controlling a passage of hydraulic control fluid to and / or from the safety valve.

Images