Methods for assessing the reliability of hydraulically-actuated devices and related systems

This disclosure includes methods for testing hydraulically-actuated devices and related systems. Some hydraulically-actuated devices have a housing defining an interior volume and a piston disposed within the interior volume and dividing the interior volume into a first chamber and a second chamber, where the piston is movable relative to the housing between a maximum first position and a maximum second position in response to pressure differentials between the first and second chambers. Some methods include: (1) moving the piston to the first position by varying pressure within at least one of the first and second chambers such that pressure within the second chamber is higher than pressure within the first chamber; and (2) while the piston remains in the first position: (a) reducing pressure within the second chamber and/or increasing pressure within the first chamber; and (b) increasing pressure within the second chamber and/or decreasing pressure within the first chamber.

BACKGROUND

1. Field of Invention

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.

2. Description of Related Art

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.

SUMMARY

Some embodiments of the present disclosure can provide for testing of a system that includes a hydraulically-actuated device having a piston movable between maximum first and second positions, in some instances, without requiring full actuation of the hydraulically-actuated device (e.g., movement of the piston to each of the first and second positions), via, for example, being configured for and/or including moving the piston to the first position and, while the piston remains in the first position: (1) reducing a force that acts to urge the piston toward the first position; and (2) increasing a force that acts to urge the piston toward the first position. Such testing may be performed automatically and/or manually to decrease a PFD of a system.

Some embodiments of the present systems are configured as a safety and/or back-up blowout prevention system having increased availability, reliability, fault-tolerance, retrofitability, and/or the like, via, for example, including a hydraulically-actuated device and a (e.g., dedicated) hydraulic pressure source for actuating the hydraulically-actuated device, a (e.g., dedicated) processor, communications channel, and/or the like for controlling the hydraulically-actuated device, and/or the like (e.g., such that the system is independent of other blowout prevention system(s), integration, and thus fault transfer, between the system and other blowout prevention system(s) is minimized, and/or the like).

Some embodiments of the present systems comprise: 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, and a processor configured to control the pressure source to, while the piston is in the first position: (a) decrease pressure within the second chamber and/or increase pressure within the first chamber; and (b) increase pressure within the second chamber and/or decrease pressure within the first chamber. In some systems, the processor is configured to control the pressure source to move the piston to the first position. In some systems, the processor is configured to control the pressure source to move the piston to the second position. In some systems, the hydraulically-actuated device comprises a blowout preventer (BOP).

In some systems, the pressure source comprises a pump. In some systems, the pump 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 motor coupled to the pump and configured to actuate the pump. In some systems, the motor comprises an electric motor. Some systems comprise a battery coupled to the motor and configured to supply electrical power to the motor. Some systems comprise an electric motor speed controller coupled to the motor and configured to control the motor.

Some systems comprise one or more sensors configured to capture data indicative of: a pressure of hydraulic fluid within the system; a flowrate of hydraulic fluid within the system; a temperature of hydraulic fluid within the system; and/or a position of the piston relative to the housing. Some systems comprise one or more sensors configured to capture data indicative of a speed of the pump. Some systems comprise one or more sensors configured to capture data indicative of: a speed of the motor; a torque output by the motor; and/or and a power output by the motor. Some systems comprise one or more sensors configured to capture data indicative of a voltage supplied to the motor and/or a current supplied to the motor.

Some systems comprise one or more sensors configured to capture data indicative of one or more parameter values, including a pressure of hydraulic fluid within the system, a flowrate of hydraulic fluid within the system, a temperature of hydraulic fluid within the system, and/or a position of the piston relative to the housing. In some systems, the one or more parameter values includes a speed of the pump. In some systems, the one or more parameter values includes a speed of the motor; a torque output by the motor; and/or a power output by the motor. In some systems, the one or more parameter values includes a voltage supplied to the motor and/or a current supplied to the motor.

In some systems, the processor is configured to compare at least one of the one or more parameter values indicated in data captured by the one or more sensors to an expected parameter value. In some systems, the processor is configured to determine if a difference between the parameter value indicated in data captured by the one or more sensors and the expected parameter value exceeds a threshold.

Some systems comprise a reservoir in fluid communication with the pressure source. Some systems comprise a remotely-operated underwater vehicle (ROV) interface in fluid communication with the hydraulically-actuated device.

Some embodiments of the present methods comprise coupling an embodiment of the present systems to a BOP stack.

Some embodiments of the present methods 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: (1) 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; and (2) while the piston remains in the first position: (a) reducing pressure within the second chamber and/or increasing pressure within the first chamber; and (b) increasing pressure within the second chamber and/or decreasing pressure within the first chamber. In some methods, steps (1) and (2) are performed using a bidirectional hydraulic pump. In some methods, the hydraulically-actuated device is coupled to a BOP stack.

Some methods comprise repeating step (2). Some methods comprise: (3) 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 (1) and (2).

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

In some methods, varying, increasing, and/or reducing pressure within the first chamber and/or varying, increasing, and/or reducing pressure within the second chamber is performed by actuating a pump. In some methods, actuating the pump comprises actuating a motor that is coupled to the pump. In some methods, the motor comprises an electric motor.

In some methods, the one or more parameter values includes a speed of the pump. In some methods, the one or more parameter values includes: 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 at least one of the one or more parameter values indicated in data captured by the one or more sensors to an expected parameter value. Some methods comprise determining if a difference between the parameter value indicated in data captured by the one or more sensors and the expected parameter value exceeds a threshold.

In some methods, the hydraulically-actuated device contains a hydraulic fluid. 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.

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

DETAILED DESCRIPTION

Referring now to the drawings, and more particularly toFIG. 1, shown therein and designated by the reference numeral10is one embodiment of the present systems. In the embodiment shown, system10includes a hydraulically-actuatable device14. In this embodiment, hydraulically-actuatable device14is a component of a BOP18(e.g., a ram- or annular-type BOP). In other embodiments, a hydraulically-actuatable device (e.g.,14) 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 device14comprises a housing22defining an interior volume26. As shown, hydraulically-actuatable device14includes a piston30disposed within interior volume26such that the piston divides the interior volume into a first chamber34and a second chamber38. In this embodiment, piston30, in response to pressures within first chamber34and second chamber38, is movable relative to housing22between a maximum first position (e.g., shown with phantom lines30a) and a maximum second position (e.g., shown with phantom lines30b). For example, in the depicted embodiment, piston30may be moved toward the first position in response to pressure within second chamber38being greater than pressure within first chamber34, 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.,30) may be in a maximum position relative to a housing (e.g.,22) 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 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10% of the total stroke of the piston of the end-of-stroke position). In some embodiments (e.g.,10), a piston (e.g.,30) of a hydraulically-actuated device (e.g.,14) may be coupled to one or more rams of a BOP (e.g.,18) 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, system10includes a pressure source42(examples of which are provided below) configured to vary pressure within at least one of first chamber34and second chamber38. To illustrate, in this embodiment, pressure source42is in fluid communication with first chamber34via a first communication path46and in fluid communication with second chamber38via a second communication path50. Such communication path(s) (e.g.,46,50, and/or the like) may include rigid and/or flexible conduit(s), which may be coupled to a pressure source (e.g.,42) and/or a hydraulically-actuated device (e.g.,14) 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, system10includes one or more interfaces54, each of which may include a valve60, configured to provide control of and/or access to hydraulic fluid within system10from outside of the system (e.g., control of fluid communication through a communication path46,50, 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.,54) may be operable by a remotely-operated underwater vehicle. Such valve(s) (e.g.,60), whether or not a component of an interface (e.g.,54), may be used direct hydraulic fluid out of system10to, for example, decrease pressure within first chamber34and/or second chamber38.

In the embodiment shown, system10comprises a fluid reservoir64(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.,64) to decrease a pressure within a first chamber (e.g.,34) and/or a second chamber (e.g.,38) of a hydraulically-actuated device (e.g.,14). In some embodiments, a fluid reservoir (e.g.,64) 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.,64) may comprise an accumulator, which may facilitate a reduction in hydraulic fluid flow rate and/or pressure spikes within a system (e.g.,10) and/or provide pressurized hydraulic fluid in addition to or in lieu of pressurized hydraulic fluid provided by a pressure source (e.g.,42).

In this embodiment, pressure source42comprises a pump68(which may include one or more pumps) configured to provide hydraulic fluid to hydraulically-actuated device14to actuate the hydraulically-actuated device. Some hydraulically-actuated devices (e.g.,14) may, for effective and/or desirable operation, require hydraulic fluid at a flow rate of between 3 gallons per minute (gpm) and 130 gpm and at a pressure of between 500 pounds per square inch gauge (psig) and 5,000 psig. In embodiments (e.g.,10) including such a hydraulically-actuated device, a pump (e.g.,68) 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.,68) of the present systems (e.g.,10) 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, pump68is configured to actuate hydraulically-actuated device14by selectively pressurizing first chamber34and second chamber38of the hydraulically-actuated device. For example, in the embodiment shown, pump68comprises a bi-directional pump. To illustrate, pump68may include a first port72in fluid communication with first chamber34and a second port76in fluid communication with second chamber38. When pump68is used to pressurize first chamber34, first port72may be characterized as an outlet and second port76may be characterized as an inlet. Conversely, when pump68is used to pressurize second chamber38, first port72may be characterized as an inlet and second port76may be characterized as an outlet.

More particularly, in this embodiment, pump68is configured such that rotation of the pump in a first direction urges fluid toward first chamber34, thereby increasing pressure within the first chamber, and/or urges fluid away from (e.g., out of) second chamber38, thereby decreasing pressure within the second chamber (e.g., causing piston30to be moved toward or maintained in the second position). Similarly, in the depicted embodiment, pump68is configured such that rotation of the pump in a second direction urges fluid toward second chamber38, thereby increasing pressure within the second chamber, and/or urges fluid away from (e.g., out of) first chamber34, thereby decreasing pressure within the first chamber (e.g., causing piston30to be moved toward or maintained in the first position). Some embodiments of the present systems in which a pump (e.g.,68) is not bi-directional may nevertheless be configured such that the pump can selectively pressurize a first chamber (e.g.,34) and a second chamber (e.g.,38) of a hydraulically-actuated device (e.g., via valve(s) disposed between the pump and the hydraulically-actuated device).

In the embodiment shown, system10comprises a motor82(which may include one or more motors) configured to actuate pump68(e.g., rotate the pump in the first and second directions). In the embodiment shown, motor82is electrically actuated; however, in other embodiments, a motor (e.g.,82) may be hydraulically-actuated. In embodiments (e.g.,10) comprising an electric motor (e.g.,82), 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, system10comprises a controller102(which may include one or more controllers) configured to be coupled to motor82and 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, controller102comprises an electric motor speed controller, such as, for example, a variable speed drive; however, in other embodiments, a controller (e.g.,102) may comprise any suitable controller that is capable of controlling a motor.

In the embodiment shown, system10comprises a battery86(which may include one or more batteries). In this embodiment, battery86is configured to provide electrical power to motor82. In some embodiments (e.g.,10), a battery (e.g.,86) may be configured to provide electrical power to a motor (e.g.,82) sufficient to actuate a hydraulically-actuated device (e.g.,14) using a pump (e.g.,68) coupled to the motor, without requiring electrical power from an above-sea power source. A battery (e.g.,86) of the present systems (e.g.,10) 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.,86) may be less susceptible to effectiveness losses at increased pressures than other energy storage devices (e.g., accumulators). A battery (e.g.,86) 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, system10includes one or more sensors92. Sensor(s) (e.g.,92) of the present systems (e.g.,10) 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)92may be configured to capture data indicative of parameters such as pressure, flow rate, temperature, and/or the like of hydraulic fluid within system10(e.g., within pump68, hydraulically-actuated device14, first communication path46, second communication path50, fluid reservoir64, and/or the like), a position, velocity, and/or acceleration of piston30relative to housing22, a (e.g., rotational) speed of motor82and/or the pump, a torque output by the motor, a voltage supplied to the motor (e.g., by battery86), a current supplied to the motor (e.g., by the battery), and/or the like. Data captured by sensor(s)92may be transmitted to controller102, processor106, an above-sea interface, and/or the like. In some embodiments, a system (e.g.,10) may include a memory configured to store data captured by sensor(s) (e.g.,92).

In this embodiment, system10includes a processor106configured to control pump68to move piston30relative to housing22. For example, in the depicted embodiment, processor106may transmit commands to controller102to actuate motor82to rotate pump68(e.g., in the first direction), thereby increasing pressure within first chamber34and/or decreasing pressure within second chamber38and causing piston30to move toward or be maintained in the second position. Similarly, processor106may transmit commands to controller102to actuate motor82to rotate pump68(e.g., in the second direction), thereby increasing pressure within second chamber38and/or decreasing pressure within first chamber34and causing piston30to move toward or be maintained in the first position. In the depicted embodiment, control of pump68by processor106may be facilitated by data captured by sensor(s)92. For example, processor106may receive data captured by sensor(s)92and adjust a speed and/or direction of pump68until a speed and/or direction of the pump, a hydraulic fluid flow rate and/or pressure within system10, a position of piston30relative to housing22, and/or the like, as indicated in data captured by the sensor(s), meets a target value. In some embodiments, a processor (e.g.,106) 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.,106) may be performed by a controller (e.g.,102) and/or function(s) described herein for a controller (e.g.,102) may be performed by a processor (e.g.,106). In some embodiments, a processor (e.g.,106) and a controller (e.g.,102) may be the same component. As used herein, “processor” encompasses a programmable logic controller.

In a system (e.g.,10) where a hydraulically-actuated device (e.g.,14) is a component of a BOP (e.g.,18), the system may be configured to function as a safety and/or back-up blowout prevention system. For example, a processor (e.g.,106) 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.,92) 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 toFIG. 2, shown is an embodiment120of the present methods for assessing the reliability of a hydraulically-actuated device (e.g.,14). In the embodiment shown, at step124, a piston (e.g.,30) of a hydraulically-actuated device (e.g.,14) can be moved to a maximum first position (e.g.,30a). If the piston is already in the first position prior to step124, step124may be omitted. To illustrate, in system10, pump68can be actuated to increase pressure within second chamber38and/or decrease pressure within first chamber34, thereby moving piston30to the first position.

At step126, 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 system10, to illustrate, pump68can be actuated to decrease pressure within second chamber38and/or increase pressure within first chamber34(e.g., thereby reducing a pressure differential between the first and second chambers). In the depicted embodiment, at step128, 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 position30btoward the first position). To illustrate, in system10, pump68can be actuated to increase pressure within second chamber38and/or decrease pressure within first chamber34(e.g., thereby increasing a pressure differential between the first and second chambers).

Step128may be performed such that a pressure within the hydraulically-actuated device (e.g., within second chamber38) meets a threshold or target pressure, such as, for example, a maximum operating pressure of the hydraulically-actuated device (e.g., 3,000, 4,000, 5,000, or more psig for many ram-type BOPs). During step128, 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., pump68), 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)92), as in, for example, a maintained pressure test. Step128may be performed for a (e.g., pre-determined) period of time, such as, for example, 15, 30, 45, or more seconds, 1, 2, 5, 10, 15, 20, 25, 30, 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.,10) associated therewith, which may be determined considering, for example, system components (e.g., a resolution of sensor(s)92, controller102, and/or the like), a hydraulic analysis of the system, and/or the like.

In the embodiment shown, steps132,136, and/or140may be performed concurrently with step128. At step132, in this embodiment, system (e.g.,10) parameter value(s) can be sensed (e.g., using sensor(s)92). Such parameter(s) can be any suitable parameter(s), including any one or more of those described above with respect to sensor(s)92. In the depicted embodiment, at steps136and140, the sensed parameter value(s) can be compared to expected parameter value(s) to detect and/or identify fault(s). In method120, such fault(s) may be communicated (e.g., by processor106) to an above-sea interface.

For example, and particularly when implementing a pressure-decay test, processor106may compare a sensed pressure within system10(e.g., within pump68, hydraulically-actuated device14, first communication path46, second communication path50, fluid reservoir64, 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, processor106may compare a sensed speed of motor82and/or pump68to 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, processor106may be configured to compare a sensed voltage and/or current supplied by battery86to 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, steps126-140can be repeated any suitable number of times, and such repetition can occur at any suitable interval (e.g., 2, 4, 6, 8, 10, 12, or more hours, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more days, and/or the like). In these ways and others, method120, and particularly steps126-140, may provide for testing of a system (e.g.,10), without requiring full actuation of a hydraulically-actuated device (e.g.,14) (e.g., movement of a piston30to each of a maximum first position30aand a maximum second position30b). For example, in a system (e.g.,10) where a hydraulically-actuated device (e.g.,14) is a component of a BOP (e.g.,18), method120, and particularly steps126-140, may provide for testing of the system without requiring closing of the BOP.

At step142, 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 system10, pump68can be actuated to increase pressure within first chamber34and/or decrease pressure within second chamber38, thereby moving piston30to the second position. During step142, 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 steps132,136, and140. In this embodiment, method120can be repeated any suitable number of times, and such repetition can occur at any suitable interval (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, or more days, and/or the like). Method120may be performed manually (e.g., via commands from an above-sea interface) and/or automatically (e.g., implemented via processor106). For example, in some embodiments, steps126-140may be performed automatically, and step142may be performed manually.

FIG. 3is a graphical representation of PFD versus time for a system (e.g.,10), with and without implementing embodiments (e.g.,120) of the present methods. Curve180represents PFD of system10without implementing embodiments (e.g.,120) of the present methods. As shown, the PFD increases over time due to, for example, growing uncertainty regarding the operability of system10. Curve184represents PFD of system10with implementing embodiments (e.g.,120) of the present methods. Reductions in the PFD at times T1, T2, T3can be attributed, at least in part, to steps126-140of method120, and the reduction in the PFD at time T4can be attributed, at least in part, to step142.

As shown inFIGS. 4 and 5, system10may be integrated with an existing BOP stack188, in some instances, without affecting the operation of other systems of the BOP stack. Provided for illustrative purposes,FIG. 4depicts such a configuration in which system10replaces an existing BOP of BOP stack188, andFIG. 5depicts a configuration in which system10is coupled to a wellhead end of BOP stack188.