Patent Description:
The present invention relates generally to hydraulically-actuated devices, such as hydraulically-actuated devices of blowout preventers, and more specifically, but not by way of limitation, to methods for assessing the reliability of such hydraulically-actuated devices and related systems.

A blowout preventer (BOP) is a mechanical device, usually installed redundantly in a stack, used to seal, control, and/or monitor an oil and gas well. A BOP typically includes or is associated with a number of components, such as, for example, rams, annulars, accumulators, test valves, kill and/or choke lines and/or valves, riser connectors, hydraulic connectors, and/or the like, many of which may be hydraulically-actuated.

Due at least in part to the magnitude of harm that may result from failure to actuate a BOP, safety or back-up systems are often implemented, such as, for example, deadman and autoshear systems. However, such systems are typically integrated with an existing BOP such that, if the BOP fails, the systems may be unavailable.

Probability of failure on demand (PFD), which typically increases over time, is a measure of the probability that a given system will fail when it is desired to function that system. Testing is an effective way to reduce PFD; however testing of existing BOPs and/or safety or back-up systems may be difficult. For example, to traditionally test an existing BOP and/or safety or back-up system, full functioning of the BOP and/or safety or back-up system may be required, in some instances, necessitating time- and cost-intensive measures, such as the removal of any objects, such as drill pipe, disposed within the wellbore, the disconnection of the lower marine riser package, and/or the like.

Examples of safety or back-up blowout prevention systems are disclosed in (<NUM>) <CIT> and <CIT><CIT>. <CIT> discloses an actuator predictive system with a piston-cylinder arrangement which includes a piston that is movable with respect to a cylinder. <CIT> also discloses flow paths in fluid communication with the piston-cylinder arrangement, and a control system which is operable to fluidly connect a first flow path to a source of high-pressure fluid and to connect a second flow path to a drain to move the piston in a first direction. A pressure sensor is fluidly connected to the first flow path and is operable to measure sufficient pressure data during the movement of the piston to generate a pressure versus time curve. The control system is operable to compare the generated pressure versus time curve to a known standard pressure versus time curve stored in the control system to determine the condition of the piston-cylinder arrangement. <CIT> does not disclose measurements of threshold target pressure during a pre-determined period of time selected based on a calculated or approximated period of time necessary to detect a leak within the hydraulically-actuated device, or a system associated therewith. <CIT> discloses a method of detecting hydraulic valve failure in a hydraulic system.

According to a first aspect of the present invention, there is provided a method for testing a hydraulically-actuated device having a housing defining an interior volume and a piston disposed within the interior volume such that the piston divides the interior volume into a first chamber and a second chamber, where the piston is movable relative to the housing to a maximum first position in response to pressure within the second chamber being higher than pressure within the first chamber and to a maximum second position in response to pressure within the first chamber being higher than pressure within the second chamber, comprise: (<NUM>) moving the piston to the first position by varying pressure within at least one of the first chamber and the second chamber such that pressure within the second chamber is higher than pressure within the first chamber; (<NUM>) while the piston remains in the first position, varying pressure to reduce the force(s) acting on the piston; and (<NUM>) measuring if the pressure within the first or second chamber meets a threshold or target pressure during a predetermined period of time selected based on a calculated or approximated period of time necessary to detect a leak within the hydraulically-actuated device or a system associated therewith.

Some methods comprise: (<NUM>) moving the piston to the second position by varying pressure within at least one of the first chamber and the second chamber such that pressure within the first chamber is higher than pressure within the second chamber. Some methods comprise repeating steps (<NUM>), (<NUM>) and (<NUM>).

Some methods comprise a hydraulic fluid within the hydraulically-actuated device and comprises capturing, with one or more sensors, data indicative of one or more parameter values, including: a pressure of the hydraulic fluid within the hydraulically-actuated device, a flowrate of the hydraulic fluid within the hydraulically-actuated device, and/or a temperature of the hydraulic fluid within the hydraulically-actuated device.

In some methods, moving the piston is performed by actuating a hydraulic pressure source. In some methods, the motor comprises an electric motor.

In some methods, the one or more parameter values includes a speed of the hydraulic pressure source, a speed of the motor; a torque output by the motor; and/or a power output by the motor. In some methods, the one or more parameter values includes a voltage supplied to the motor and/or a current supplied to the motor.

Some methods comprise comparing one or more parameter values to an expected parameter value. Some methods comprise determining if a difference between the one or more of parameter and the expected parameter value exceeds a threshold.

In some methods, the hydraulically-actuated device contains a hydraulic fluid and an access port fluidically coupled to a remotely-operated underwater vehicle (ROV). In some methods, the hydraulic fluid comprises an oil-based fluid, sea water, desalinated water, treated water, and/or water-glycol. In some methods, the hydraulic fluid comprises water-glycol. In some methods, the hydraulically-actuated device is a component of a blowout preventer (BOP).

Some methods comprise calculating a probability of failure (PFD) versus time for the hydraulically-actuated device or the system associated therewith. In some methods, the maximum pressure in the first or the second chamber is selected to be at a target pressure. The target pressure may be about a maximum operating pressure of the hydraulically-actuated device, potentially <NUM>, <NUM> or5000 psig (<NUM>, <NUM>, or <NUM> MPa). Some methods comprise isolating the hydraulically-actuated device from a pressure source once the maximum operating pressure is met.

According to a second aspect of the present invention, there is provided a system comprising: a hydraulically-actuated device including a housing defining an interior volume and a piston disposed within the interior volume such that the piston divides the interior volume into a first chamber and a second chamber, where the piston is movable relative to the housing to a maximum first position in response to pressure within the second chamber being greater than pressure within the first chamber and to a maximum second position in response to pressure within the first chamber being greater than pressure within the second chamber, a hydraulic pressure source configured to vary pressure within at least one of the first chamber and the second chamber, a processor configured to control the hydraulic pressure source, while the piston is moving from the maximum first position in response to pressure within the second chamber being smaller than pressure within the first chamber, and wherein the system is further configured to measure if the pressure within the hydraulically-actuated device meets a threshold or target pressure during a pre-determined period of time selected based on a calculated or approximated period of time necessary to detect a leak within the hydraulically-actuated device or a system associated therewith.

In some systems, the pressure source comprises a bidirectional pump, and the system is configured such that: rotation of the pump in a first direction decreases pressure within the second chamber and/or increases pressure within the first chamber; and rotation of the pump in a second direction that is opposite the first direction increases pressure within the second chamber and/or decreases pressure within the first chamber.

Some systems comprise a reservoir in fluid communication with the hydraulic pressure source. Some systems comprise a remotely-operated underwater vehicle (ROV) interface in fluid communication with the hydraulically-actuated device. In some embodiments, the reservoir comprises an accumulator disposed between the bidirectional hydraulic pressure source and the hydraulically-actuated device, the accumulator being configured to provide pressurized hydraulic fluid to the hydraulically-actuated device to vary pressure within at least one of the first chamber or the second chamber.

Some details associated with the embodiments described above and others are described below.

The following drawings illustrate by way of example and not limitation. For the sake of brevity and clarity, every feature of a given structure is not always labeled in every figure in which that structure appears. Identical reference numbers do not necessarily indicate an identical structure. Rather, the same reference number may be used to indicate a similar feature or a feature with similar functionality, as may non-identical reference numbers.

Referring now to the drawings, and more particularly to <FIG>, shown therein and designated by the reference numeral <NUM> is one embodiment of the present systems. In the embodiment shown, system <NUM> includes a hydraulically-actuatable device <NUM>. In this embodiment, hydraulically-actuatable device <NUM> is a component of a BOP <NUM> (e.g., a ram- or annular-type BOP). In other embodiments, a hydraulically-actuatable device (e.g., <NUM>) may be a component of any suitable device, such as, for example, an accumulator, test valve, failsafe valve, kill and/or choke line and/or valve, riser joint, hydraulic connector, and/or the like.

In the depicted embodiment, hydraulically-actuatable device <NUM> comprises a housing <NUM> defining an interior volume <NUM>. As shown, hydraulically-actuatable device <NUM> includes a piston <NUM> disposed within interior volume <NUM> such that the piston divides the interior volume into a first chamber <NUM> and a second chamber <NUM>. In this embodiment, piston <NUM>, in response to pressures within first chamber <NUM> and second chamber <NUM>, is movable relative to housing <NUM> between a maximum first position (e.g., shown with phantom lines 30a) and a maximum second position (e.g., shown with phantom lines 30b). For example, in the depicted embodiment, piston <NUM> may be moved toward the first position in response to pressure within second chamber <NUM> being greater than pressure within first chamber <NUM>, and the piston may be moved toward the second position in response to pressure within the first chamber being greater than pressure within the second chamber. A piston (e.g., <NUM>) may be in a maximum position relative to a housing (e.g., <NUM>) when the piston is at an end-of-stroke position beyond which the piston cannot move relative to the housing (e.g., due to physical interference between the piston and the housing) or at any one of a range of positions that are proximate to the end-of-stroke position (e.g., including positions that are within <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>% of the total stroke of the piston of the end-of-stroke position). In some embodiments (e.g., <NUM>), a piston (e.g., <NUM>) of a hydraulically-actuated device (e.g., <NUM>) may be coupled to one or more rams of a BOP (e.g., <NUM>) such that, for example, when the piston is in one of a maximum first position (e.g., 30a) and a maximum second position (e.g., 30b), the one or more rams are in an open position, and, when the piston is in the other of the first position and the second position, the one or more rams are in a closed position (e.g., some embodiments of the present systems may be used to close and seal a wellbore).

In the embodiment shown, system <NUM> includes a pressure source <NUM> (examples of which are provided below) configured to vary pressure within at least one of first chamber <NUM> and second chamber <NUM>. To illustrate, in this embodiment, pressure source <NUM> is in fluid communication with first chamber <NUM> via a first communication path <NUM> and in fluid communication with second chamber <NUM> via a second communication path <NUM>. Such communication path(s) (e.g., <NUM>, <NUM>, and/or the like) may include rigid and/or flexible conduit(s), which may be coupled to a pressure source (e.g., <NUM>) and/or a hydraulically-actuated device (e.g., <NUM>) in any suitable fashion, such as, for example, via stab(s), port(s), and/or the like. Hydraulic fluid for use in the present systems can comprise any suitable hydraulic fluid, such as, for example: an oil-based fluid, sea water, desalinated water, treated water, water-glycol, and/or the like.

In the depicted embodiment, system <NUM> includes one or more interfaces <NUM>, each of which may include a valve <NUM>, configured to provide control of and/or access to hydraulic fluid within system <NUM> from outside of the system (e.g., control of fluid communication through a communication path <NUM>, <NUM>, and/or the like, access to provide and/or remove hydraulic fluid to and/or from the system, and/or the like). Such interface(s) (e.g., <NUM>) may be operable by a remotely-operated underwater vehicle. Such valve(s) (e.g., <NUM>), whether or not a component of an interface (e.g., <NUM>), may be used direct hydraulic fluid out of system <NUM> to, for example, decrease pressure within first chamber <NUM> and/or second chamber <NUM>.

In the embodiment shown, system <NUM> comprises a fluid reservoir <NUM> (which may include one or more fluid reservoirs) configured to store and/or receive hydraulic fluid such that, for example, the fluid reservoir may facilitate the system in compensating for a loss of hydraulic fluid (e.g., due to leaks), an excess of hydraulic fluid, and/or the like. In some embodiments, hydraulic fluid may be directed (e.g., using one or more valves) to a fluid reservoir (e.g., <NUM>) to decrease a pressure within a first chamber (e.g., <NUM>) and/or a second chamber (e.g., <NUM>) of a hydraulically-actuated device (e.g., <NUM>). In some embodiments, a fluid reservoir (e.g., <NUM>) may be configured to receive hydraulic fluid from an above-sea fluid source (e.g., via a rigid conduit and/or hot line). In some embodiments, a fluid reservoir (e.g., <NUM>) may comprise an accumulator, which may facilitate a reduction in hydraulic fluid flow rate and/or pressure spikes within a system (e.g., <NUM>) and/or provide pressurized hydraulic fluid in addition to or in lieu of pressurized hydraulic fluid provided by a pressure source (e.g., <NUM>).

In this embodiment, pressure source <NUM> comprises a pump <NUM> (which may include one or more pumps) configured to provide hydraulic fluid to hydraulically-actuated device <NUM> to actuate the hydraulically-actuated device. Some hydraulically-actuated devices (e.g., <NUM>) may, for effective and/or desirable operation, require hydraulic fluid at a flow rate of between <NUM> gallons per minute (gpm) (<NUM> dm<NUM>/s) and <NUM> gpm (<NUM> dm<NUM>/s) and at a pressure of between <NUM> pounds per square inch gauge (psig) (<NUM> MPa) and <NUM>,<NUM> psig (<NUM> MPa). In embodiments (e.g., <NUM>) including such a hydraulically-actuated device, a pump (e.g., <NUM>) may be configured to output hydraulic fluid at such flow rates and pressures (e.g., the pump alone may be capable of providing hydraulic fluid at a sufficient flow rate and pressure to effectively and/or desirably operate the hydraulically-actuated device). A pump (e.g., <NUM>) of the present systems (e.g., <NUM>) may comprise any suitable pump, such as, for example, a positive displacement pump (e.g., a piston pump, such as, for example, an axial piston pump, radial piston pump, duplex, triplex, quintuplex, or the like piston/plunger pump, diaphragm pump, gear pump, vane pump, screw pump, gerotor pump, and/or the like), velocity pump (e.g., a centrifugal pump, and/or the like), over-center pump, switched-mode pump, unidirectional pump, bi-directional pump, and/or the like.

In the depicted embodiment, pump <NUM> is configured to actuate hydraulically-actuated device <NUM> by selectively pressurizing first chamber <NUM> and second chamber <NUM> of the hydraulically-actuated device. For example, in the embodiment shown, pump <NUM> comprises a bi-directional pump. To illustrate, pump <NUM> may include a first port <NUM> in fluid communication with first chamber <NUM> and a second port <NUM> in fluid communication with second chamber <NUM>. When pump <NUM> is used to pressurize first chamber <NUM>, first port <NUM> may be characterized as an outlet and second port <NUM> may be characterized as an inlet. Conversely, when pump <NUM> is used to pressurize second chamber <NUM>, first port <NUM> may be characterized as an inlet and second port <NUM> may be characterized as an outlet.

More particularly, in this embodiment, pump <NUM> is configured such that rotation of the pump in a first direction urges fluid toward first chamber <NUM>, thereby increasing pressure within the first chamber, and/or urges fluid away from (e.g., out of) second chamber <NUM>, thereby decreasing pressure within the second chamber (e.g., causing piston <NUM> to be moved toward or maintained in the second position). Similarly, in the depicted embodiment, pump <NUM> is configured such that rotation of the pump in a second direction urges fluid toward second chamber <NUM>, thereby increasing pressure within the second chamber, and/or urges fluid away from (e.g., out of) first chamber <NUM>, thereby decreasing pressure within the first chamber (e.g., causing piston <NUM> to be moved toward or maintained in the first position). Some embodiments of the present systems in which a pump (e.g., <NUM>) is not bi-directional may nevertheless be configured such that the pump can selectively pressurize a first chamber (e.g., <NUM>) and a second chamber (e.g., <NUM>) of a hydraulically-actuated device (e.g., via valve(s) disposed between the pump and the hydraulically-actuated device).

In the embodiment shown, system <NUM> comprises a motor <NUM> (which may include one or more motors) configured to actuate pump <NUM> (e.g., rotate the pump in the first and second directions). In the embodiment shown, motor <NUM> is electrically actuated; however, in other embodiments, a motor (e.g., <NUM>) may be hydraulically-actuated. In embodiments (e.g., <NUM>) comprising an electric motor (e.g., <NUM>), the motor may comprise any suitable electric motor, such as, for example, a synchronous alternating current (AC) motor, asynchronous AC motor, brushed direct current (DC) motor, brushless DC motor, permanent magnet DC motor, and/or the like.

In this embodiment, system <NUM> comprises a controller <NUM> (which may include one or more controllers) configured to be coupled to motor <NUM> and to control (e.g., activate, deactivate, change or set a rotational speed of, change or set of a direction of, and/or the like) the motor. In the depicted embodiment, controller <NUM> comprises an electric motor speed controller, such as, for example, a variable speed drive; however, in other embodiments, a controller (e.g., <NUM>) may comprise any suitable controller that is capable of controlling a motor.

In the embodiment shown, system <NUM> comprises a battery <NUM> (which may include one or more batteries). In this embodiment, battery <NUM> is configured to provide electrical power to motor <NUM>. In some embodiments (e.g., <NUM>), a battery (e.g., <NUM>) may be configured to provide electrical power to a motor (e.g., <NUM>) sufficient to actuate a hydraulically-actuated device (e.g., <NUM>) using a pump (e.g., <NUM>) coupled to the motor, without requiring electrical power from an above-sea power source. A battery (e.g., <NUM>) of the present systems (e.g., <NUM>) can comprise any suitable battery, such as, for example, a lithium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, and/or the like. A battery (e.g., <NUM>) may be less susceptible to effectiveness losses at increased pressures than other energy storage devices (e.g., accumulators). A battery (e.g., <NUM>) may also occupy a smaller volume and/or have a lower weight than other energy storage devices (e.g., accumulators). Thus, batteries may be efficiently adapted to provide at least a portion of an energy necessary to, for example, perform emergency functions associated with a BOP (e.g., autoshear functions, deadman functions, and/or the like).

In the depicted embodiment, system <NUM> includes one or more sensors <NUM>. Sensor(s) (e.g., <NUM>) of the present systems (e.g., <NUM>) can comprise any suitable sensor, such as, for example, a pressure sensor (e.g., a piezoelectric pressure sensor, strain gauge, and/or the like), flow sensor (e.g., a turbine, ultrasonic, Coriolis, and/or the like flow sensor, a flow sensor configured to determine or approximate a flow rate based, at least in part, on data indicative of pressure, and/or the like), temperature sensor (e.g., a thermocouple, resistance temperature detector, and/or the like), position sensor (e.g., a Hall effect sensor, potentiometer, and/or the like), proximity sensor, acoustic sensor, and/or the like. By way of example, in the embodiment shown, sensor(s) <NUM> may be configured to capture data indicative of parameters such as pressure, flow rate, temperature, and/or the like of hydraulic fluid within system <NUM> (e.g., within pump <NUM>, hydraulically-actuated device <NUM>, first communication path <NUM>, second communication path <NUM>, fluid reservoir <NUM>, and/or the like), a position, velocity, and/or acceleration of piston <NUM> relative to housing <NUM>, a (e.g., rotational) speed of motor <NUM> and/or the pump, a torque output by the motor, a voltage supplied to the motor (e.g., by battery <NUM>), a current supplied to the motor (e.g., by the battery), and/or the like. Data captured by sensor(s) <NUM> may be transmitted to controller <NUM>, processor <NUM>, an above-sea interface, and/or the like. In some embodiments, a system (e.g., <NUM>) may include a memory configured to store data captured by sensor(s) (e.g., <NUM>).

In this embodiment, system <NUM> includes a processor <NUM> configured to control pump <NUM> to move piston <NUM> relative to housing <NUM>. For example, in the depicted embodiment, processor <NUM> may transmit commands to controller <NUM> to actuate motor <NUM> to rotate pump <NUM> (e.g., in the first direction), thereby increasing pressure within first chamber <NUM> and/or decreasing pressure within second chamber <NUM> and causing piston <NUM> to move toward or be maintained in the second position. Similarly, processor <NUM> may transmit commands to controller <NUM> to actuate motor <NUM> to rotate pump <NUM> (e.g., in the second direction), thereby increasing pressure within second chamber <NUM> and/or decreasing pressure within first chamber <NUM> and causing piston <NUM> to move toward or be maintained in the first position. In the depicted embodiment, control of pump <NUM> by processor <NUM> may be facilitated by data captured by sensor(s) <NUM>. For example, processor <NUM> may receive data captured by sensor(s) <NUM> and adjust a speed and/or direction of pump <NUM> until a speed and/or direction of the pump, a hydraulic fluid flow rate and/or pressure within system <NUM>, a position of piston <NUM> relative to housing <NUM>, and/or the like, as indicated in data captured by the sensor(s), meets a target value. In some embodiments, a processor (e.g., <NUM>) may be configured to communicate with an above-sea interface, to, for example, send and/or receive data, commands, signals, and/or the like. In some embodiments, function(s) described herein for a processor (e.g., <NUM>) may be performed by a controller (e.g., <NUM>) and/or function(s) described herein for a controller (e.g., <NUM>) may be performed by a processor (e.g., <NUM>). In some embodiments, a processor (e.g., <NUM>) and a controller (e.g., <NUM>) may be the same component. As used herein, "processor" encompasses a programmable logic controller.

In a system (e.g., <NUM>) where a hydraulically-actuated device (e.g., <NUM>) is a component of a BOP (e.g., <NUM>), the system may be configured to function as a safety and/or back-up blowout prevention system. For example, a processor (e.g., <NUM>) of the system may be configured to actuate the hydraulically-actuated device to close the wellbore in response to a command received from an above-sea interface (e.g., via a dedicated communication channel, acoustic interface, and/or the like), a signal from a traditional autoshear, deadman, and/or the like system, and/or the like. For further example, the system may have sensor(s) (e.g., <NUM>) including a sensor (e.g., a proximity sensor, such as, for example, an electromagnetic-, light-, or sound-based proximity sensor) configured to detect disconnection of the lower marine riser package from the BOP stack, and the processor, based at least in part on data captured by the sensor, may actuate the hydraulically-actuated device to close the wellbore. For yet further example, the processor may be configured to detect a loss of communication with the surface, upon which the processor may actuate the hydraulically-actuated device to close the wellbore.

Referring now to <FIG>, shown is an embodiment <NUM> of the present methods for assessing the reliability of a hydraulically-actuated device (e.g., <NUM>). In the embodiment shown, at step <NUM>, a piston (e.g., <NUM>) of a hydraulically-actuated device (e.g., <NUM>) can be moved to a maximum first position (e.g., 30a). If the piston is already in the first position prior to step <NUM>, step <NUM> may be omitted. To illustrate, in system <NUM>, pump <NUM> can be actuated to increase pressure within second chamber <NUM> and/or decrease pressure within first chamber <NUM>, thereby moving piston <NUM> to the first position.

At step <NUM>, in this embodiment, while the piston remains in the first position, pressure(s) within the hydraulically-actuated device can be varied to reduce force(s) acting on the piston. In system <NUM>, to illustrate, pump <NUM> can be actuated to decrease pressure within second chamber <NUM> and/or increase pressure within first chamber <NUM> (e.g., thereby reducing a pressure differential between the first and second chambers). In the depicted embodiment, at step <NUM>, while the piston remains in the first position, pressure(s) within the hydraulically-actuated device can be varied to urge, but not necessarily move, the piston toward the first position (e.g., the pressure(s) can be varied to generate or increase a force exerted on the piston in a direction from a maximum second position 30b toward the first position). To illustrate, in system <NUM>, pump <NUM> can be actuated to increase pressure within second chamber <NUM> and/or decrease pressure within first chamber <NUM> (e.g., thereby increasing a pressure differential between the first and second chambers).

Step <NUM> may be performed such that a pressure within the hydraulically-actuated device (e.g., within second chamber <NUM>) meets a threshold or target pressure, such as, for example, a maximum operating pressure of the hydraulically-actuated device (e.g., <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, or more psig (<NUM>, <NUM>, <NUM> or more MPa) for many ram-type BOPs). During step <NUM>, once a pressure within the hydraulically-actuated device meets the threshold or target pressure, the hydraulically-actuated device may be isolated from a pressure source (e.g., pump <NUM>), as in, for example, a pressure decay test, and/or the pressure source may be actuated to maintain the pressure within the hydraulically-actuated device at or proximate to the threshold or target pressure (e.g., using feedback from sensor(s) <NUM>), as in, for example, a maintained pressure test. Step <NUM> may be performed for a (e.g., pre-determined) period of time, such as, for example, <NUM>, <NUM>, <NUM>, or more seconds, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more minutes, and/or the like. Such a period of time may be selected based on, for example, a calculated or approximated period of time necessary to detect a (e.g., maximum acceptable) leak within the hydraulically-actuated device or a system (e.g., <NUM>) associated therewith, which may be determined considering, for example, system components (e.g., a resolution of sensor(s) <NUM>, controller <NUM>, and/or the like), a hydraulic analysis of the system, and/or the like.

In the embodiment shown, steps <NUM>, <NUM>, and/or <NUM> may be performed concurrently with step <NUM>. At step <NUM>, in this embodiment, system (e.g., <NUM>) parameter value(s) can be sensed (e.g., using sensor(s) <NUM>). Such parameter(s) can be any suitable parameter(s), including any one or more of those described above with respect to sensor(s) <NUM>. In the depicted embodiment, at steps <NUM> and <NUM>, the sensed parameter value(s) can be compared to expected parameter value(s) to detect and/or identify fault(s). In method <NUM>, such fault(s) may be communicated (e.g., by processor <NUM>) to an above-sea interface.

To illustrate, in system <NUM>, processor <NUM> may compare sensed parameter value(s) to corresponding expected parameter value(s), such as for example, a known, minimum, maximum, calculated, commanded, and/or historical pressure, flow rate, temperature, and/or the like of hydraulic fluid within system <NUM>, position, velocity, and/or acceleration of piston <NUM> relative to housing <NUM>, speed of motor <NUM> and/or pump <NUM>, torque output by the motor, voltage and/or current supplied to the motor, and/or the like. Processor <NUM> may be configured to detect and/or identify a fault if, for example, difference(s) between sensed and expected parameter value(s) exceed a threshold (e.g., the sensed and expected parameter value(s) differ by <NUM>, <NUM>, <NUM>, <NUM>, <NUM>% or more), a time rate of change of a sensed parameter value is below or exceeds a threshold, a sensed parameter value is below a minimum expected parameter value or exceeds a maximum expected parameter value, and/or the like.

For example, and particularly when implementing a pressure-decay test, processor <NUM> may compare a sensed pressure within system <NUM> (e.g., within pump <NUM>, hydraulically-actuated device <NUM>, first communication path <NUM>, second communication path <NUM>, fluid reservoir <NUM>, and/or the like) to an expected pressure within the system, and/or the like, and, if difference(s) between the sensed value(s) and the expected value(s) exceed a threshold, a fault, such as a leak within the system, may be detected and/or identified. For further example, and particularly when implementing a maintained pressure test, processor <NUM> may compare a sensed speed of motor <NUM> and/or pump <NUM> to an expected speed of the motor and/or pump, a sensed voltage and/or current supplied to the motor to an expected voltage and/or current supplied to the motor, and/or the like, and, if difference(s) between the sensed value(s) and the expected value(s) exceed a threshold, a fault, such a leak within the system, may be detected or identified. For yet further example, processor <NUM> may be configured to compare a sensed voltage and/or current supplied by battery <NUM> to an expected voltage and/or current supplied by the battery, and, if difference(s) between the sensed value(s) and the expected value(s) exceed a threshold, a fault, such as a fault associated with the battery, may be detected or identified (e.g., as in a battery load test).

In the depicted embodiment, steps <NUM>-<NUM> can be repeated any suitable number of times, and such repetition can occur at any suitable interval (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more hours, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more days, and/or the like). In these ways and others, method <NUM>, and particularly steps <NUM>-<NUM>, may provide for testing of a system (e.g., <NUM>), without requiring full actuation of a hydraulically-actuated device (e.g., <NUM>) (e.g., movement of a piston <NUM> to each of a maximum first position 30a and a maximum second position 30b). For example, in a system (e.g., <NUM>) where a hydraulically-actuated device (e.g., <NUM>) is a component of a BOP (e.g., <NUM>), method <NUM>, and particularly steps <NUM>-<NUM>, may provide for testing of the system without requiring closing of the BOP.

At step <NUM>, in the embodiment shown, the piston of the hydraulically-actuated device can be moved to a maximum second position (e.g., 30b). To illustrate, in system <NUM>, pump <NUM> can be actuated to increase pressure within first chamber <NUM> and/or decrease pressure within second chamber <NUM>, thereby moving piston <NUM> to the second position. During step <NUM>, system parameter value(s) can be sensed, compared to expected system parameter value(s), and fault(s) can be identified and/or detected in a same or substantially similar fashion to as described above for steps <NUM>, <NUM>, and <NUM>. In this embodiment, method <NUM> can be repeated any suitable number of times, and such repetition can occur at any suitable interval (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more days, and/or the like). Method <NUM> may be performed manually (e.g., via commands from an above-sea interface) and/or automatically (e.g., implemented via processor <NUM>). For example, in some embodiments, steps <NUM>-<NUM> may be performed automatically, and step <NUM> may be performed manually.

<FIG> is a graphical representation of PFD versus time for a system (e.g., <NUM>), with and without implementing embodiments (e.g., <NUM>) of the present methods. Curve <NUM> represents PFD of system <NUM> without implementing embodiments (e.g., <NUM>) of the present methods. As shown, the PFD increases over time due to, for example, growing uncertainty regarding the operability of system <NUM>. Curve <NUM> represents PFD of system <NUM> with implementing embodiments (e.g., <NUM>) of the present methods. Reductions in the PFD at times T1, T2, T3 can be attributed, at least in part, to steps <NUM>-<NUM> of method <NUM>, and the reduction in the PFD at time T4 can be attributed, at least in part, to step <NUM>.

As shown in <FIG>, system <NUM> may be integrated with an existing BOP stack <NUM>, in some instances, without affecting the operation of other systems of the BOP stack. Provided for illustrative purposes, <FIG> depicts such a configuration in which system <NUM> replaces an existing BOP of BOP stack <NUM>, and <FIG> depicts a configuration in which system <NUM> is coupled to a wellhead end of BOP stack <NUM>.

Claim 1:
A method for testing a hydraulically-actuated device (<NUM>) having a housing (<NUM>) defining an interior volume (<NUM>) and a piston (<NUM>) disposed within the interior volume (<NUM>) such that the piston (<NUM>) divides the interior volume (<NUM>) into a first chamber (<NUM>) and a second chamber (<NUM>), where the piston (<NUM>) is movable relative to the housing (<NUM>) to a maximum first position (30a) in response to pressure within the second chamber (<NUM>) being higher than pressure within the first chamber (<NUM>) and to a maximum second position (30b) in response to pressure within the first chamber (<NUM>) being higher than pressure within the second chamber (<NUM>), characterised by:
(<NUM>) moving the piston (<NUM>) to the first position (30a) by varying pressure within at least one of the first chamber (<NUM>) and the second chamber (<NUM>) such that pressure within the second chamber (<NUM>) is higher than pressure within the first chamber (<NUM>); and
(<NUM>) while the piston remains in the first position (30a), varying pressure to reduce the force(s) acting on the piston (<NUM>); and
(<NUM>) measuring if the pressure within the first (<NUM>) or second chamber (<NUM>) meets a threshold or target pressure during a pre-determined period of time selected based on a calculated or approximated period of time necessary to detect a leak (<NUM>) within the hydraulically-actuated device (<NUM>) or a system associated therewith.