Patent Description:
Relief valves are used for processes involving flow to ensure that excessive system pressures will not cause major failures in the system. Typical relief valve control systems are used to control the relief valves associated with mud pumps on drilling rigs. These pumps are high powered and deliver fluids at high flow rates and delivery pressures.

Starting a pump against a closed valve or a plugged line may result in major damage to the system unless the system contains a pressure relief valve that can operate to avoid the over pressurization.

Hydraulic power units ("HPUs") are often designed so that a pressure relief valve ("PRV") is opened when fluid pressure at a particular point in the system exceeds a predetermined set point, and may be closed when the aforesaid fluid pressure drops to a predetermined set point. Some prior art HPUs are designed to operate a PRV to protect drilling equipment (e.g., a mud pump) from overpressure. In such instances, an HPU may be configured to assume a "Fail Open" configuration when there is loss of power supply or loss of solenoid signal. An example of such a system is described in <CIT>. In certain circumstances, a loss in pressure may affect a drilling operation and may cause a potentially dangerous situation. Hence, there is a need for an HPU system that can readily configured to accommodate a plurality of different failure modes without significant modifications.

Some prior art HPUs may also be configured to operate hydraulically actuated non-proportional valves having two states: an open state or a closed state. This may be accomplished by means of an HPU that includes components such as a pump, relief valves, directional valves, ball valves, a reservoir, an accumulator, etc. The HPU pump may be configured to build hydraulic pressure by drawing oil from a reservoir and then using a directional valve to divert oil flow to open or close the non- proportional valve. Many prior art HPUs, however, are relatively complex, using a plurality of control valves and accumulators which in turn creates a plurality of failure points within the HPU. In addition, many prior art HPUs do not use a return filter for hydraulic fluid going into reservoir, which can lead to oil contamination and pump damage over time. Still further, many prior art HPUs utilize a single pump. If a suction filter disposed between the reservoir and the pump gets clogged, the suction filter will prevent fluid from reaching the pump thereby causing the pump to stall.

What is needed is an HPU system having fewer potential HPU failure point, and one that is readily configured to accommodate a plurality of different well failure modes without significant modifications.

The invention relates to a hydraulic power unit system according to the appended claims.

According to the present disclosure a hydraulic power unit system is provided that includes a pressure relief valve (PRV) and a hydraulic power unit (HPU. The PRV has an open port and a close port. The HPU includes a pneumatic primary pump, a hydraulic fluid reservoir, an accumulator, and a first two position solenoid directional valve (TPSDV). The hydraulic fluid reservoir is in fluid communication with the primary pump. The first TPSDV is in communication with the primary pump, the reservoir, the accumulator. The first TPSDV is configured for fluid communication with the PRV. The HPU may be configurable in both a PRV fail open configuration and a PRV fail close configuration.

In the PRV fail CLOSE configuration, the HPU may be configured to provide hydraulic fluid at an elevated pressure to the close port of the PRV, which elevated pressure is adequate to maintain the PRV in a closed configuration.

In the PRV fail OPEN configuration, the HPU may be configured to provide hydraulic fluid at an elevated pressure to the open port of the PRV, which elevated pressure is adequate to maintain the PRV in an open configuration.

The HPU may further comprise at least one valve in fluid communication with the at least one second fluid line. The at least one valve is configured so that fluid flow from the open port of the PRV is restricted.

The HPU may include at least one valve in fluid communication with the at least one second fluid line. The at least one valve is configured to permit fluid flow at an elevated pressure to pass through the at least one valve to the open port of the PRV.

The at least one valve may include at least one fluid flow restriction valve and at least one fluid flow valve disposed in parallel with one another, and the fluid flow valve has an open configuration and a closed configuration, and in the closed configuration fluid flow from the PRV passes through the at least one fluid flow restriction valve.

The HPU may be further configurable in a pressure relief valve PRV fail as-is configuration.

The HPU further may include a controller. The controller includes at least one processor in communication with the second TPSDV and a memory storing instructions, which instructions when executed cause the processor to selectively operate the second TPSDV in a first configuration or a second configuration. In the first configuration, the at least one first fluid line provides fluid communication between the first TPSDV and the close port of the PRV, and the at least one second fluid line provides fluid communication between the first TPSDV and the open port of the PRV. In the second configuration the at least one first fluid line provides fluid communication between the first TPSDV and the open port of the PRV, and the at least one second fluid line provides fluid communication between the first TPSDV and the close port of the PRV.

The HPU may include a controller that includes at least one processor in communication with a first fluid flow valve and a second fluid flow valve, and a memory storing instructions. The instructions when executed may cause the processor to selectively operate the first fluid flow valve in a first open configuration or a first close configuration, and to selectively operate the second fluid flow valve in a second open configuration or a second close configuration.

The hydraulic fluid reservoir may include at least one of a float switch or a sight glass.

The HPU may include a pneumatic secondary pump in fluid communication with the TPSDV.

The foregoing has outlined rather broadly several aspects of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter.

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings.

The configurations shown in <FIG> do not fall within the scope of the invention, they rather show configurations and examples useful for understanding the invention. Referring to <FIG>, aspects of the present disclosure include a system <NUM> that includes a pressure relief valve ("PRV") <NUM>, and a hydraulic power unit <NUM> ("HPU <NUM>") configured to operate a PRV <NUM>. The HPU <NUM> may be configured to receive pressurized air from a pressurized air source <NUM>, and includes a primary pump <NUM>, a reservoir <NUM>, an accumulator <NUM>, and a two position solenoid directional valve (4w/2p) <NUM>. As will be described below, the HPU <NUM> may be configured to provide three different failure modes relating to loss of power supply/ loss of solenoid signal scenarios; e.g., a PRV "fail CLOSE" configuration, a PRV "fail OPEN" configuration, and a PRV "fail AS-IS" configuration. The HPU <NUM> may be used for, but is not limited to use within, hydrocarbon well drilling applications; e.g., protection of hydrocarbon well drilling equipment (such as mud pumps) protection applications.

Referring to <FIG>, the PRV <NUM> includes a hydraulic actuator <NUM> (e.g., a cylinder) that is operable to actuate a valve <NUM> in communication with a fluid system such as a mud pump system on a well drilling rig. The PRV <NUM> includes an OPEN port <NUM> and a CLOSE port <NUM>. The PRV <NUM> is configured so that hydraulic fluid at or above a predetermined pressure provided to the OPEN port <NUM> will cause the PRV <NUM> to open. Similarly, the PRV <NUM> is configured so that hydraulic fluid at or above a predetermined pressure provided to the CLOSE port <NUM> will cause the PRV <NUM> to close. The present disclosure may be used with a variety of different types of PRVs, and therefore is not limited to use with any particular type PRV. A non-limiting example of an acceptable PRV is disclosed in <CIT>. The PRV <NUM> may include a well fluid pressure sensor <NUM> that is in communication with the controller <NUM>.

Referring to <FIG>, the primary pump <NUM> may be a pneumatically powered pump sized to produce hydraulic fluid pressure within the HPU <NUM> in a range that is adequate to operate the PRV <NUM>. The primary pump <NUM> is in fluid communication with the pressurized air source <NUM> via line <NUM>. The line <NUM> may include a pressurized air source pressure sensor <NUM> (that may be in communication with the controller <NUM>). The term "line" as used herein is defined as a conduit (e.g., a tube, a pipe, a hose, etc.) through which a fluid at a pressure above ambient can be passed. The primary pump <NUM> is in selective fluid communication with the PRV <NUM> via lines <NUM>-<NUM>, and in fluid communication with a hydraulic fluid suction line <NUM> that extends back to the reservoir <NUM>. A dump valve <NUM> may be in communication with pressure side line <NUM> (which is in communication with the primary pump <NUM>), and in communication with the reservoir <NUM> via return line <NUM>. The primary hydraulic pump <NUM> may be controlled via a valve <NUM> disposed in line <NUM> that is configured to regulate the flow of pneumatic air to the pump <NUM> from the pressurized air source <NUM>, which valve <NUM> may be in communication with the controller <NUM>.

In some embodiments, the HPU <NUM> may include a secondary pump <NUM>. The secondary pump <NUM> may also be pneumatically powered, and is sized to operate the PRV <NUM> in the event of a primary pump <NUM> failure. The secondary pump <NUM> is in fluid communication with the pressurized air source <NUM> via lines <NUM>, <NUM>, with a valve <NUM> (e.g., a ball valve) disposed in the line <NUM> connecting the secondary valve to the pressurized air source <NUM> via line <NUM>. When the valve <NUM> is open, pressurized air is fed to the secondary pump <NUM> so that the secondary pump <NUM> may build up an amount of hydraulic pressure that is adequate to keep the HPU <NUM> and PRV <NUM> operational; e.g., so the PRV <NUM> can be switched between an OPEN configuration and a CLOSE configuration. The secondary pump <NUM> is in fluid communication with hydraulic fluid suction line <NUM> that extends back to the reservoir <NUM>. The secondary pump <NUM> may provide a back up to the primary pump <NUM> to ensure that the criticality of the PRV <NUM> operation is not affected if the primary pump <NUM> is not available. The secondary hydraulic pump <NUM> may be controlled via a valve <NUM> disposed in line <NUM> that is configured to regulate the flow of pneumatic air to the pump <NUM> from the pressurized air source <NUM>, which valve <NUM> may be in communication with the controller <NUM>.

In some embodiments, a filter <NUM> may be disposed in line <NUM> between the pressurized air source <NUM> and the primary pump <NUM> (and secondary pump <NUM> as applicable).

In some embodiments, a filter regulator lubricator <NUM> ("FRL") may be disposed in line <NUM> between the pressurized air source <NUM> and the pump to provide conditioned air to the primary pump <NUM> (and the secondary pump <NUM> in some instances) as required.

A single two position solenoid directional valve <NUM> ("TPSDV"; <NUM> way / <NUM> position) is disposed downstream of the primary pump <NUM> (and secondary pump <NUM> in some embodiments) via lines <NUM>-<NUM> and upstream of the PRV <NUM> via lines <NUM>, <NUM>. The TPSDV <NUM> is in fluid communication with the reservoir <NUM> via lines <NUM>-<NUM>. The TPSDV <NUM> is, therefore, in fluid communication with primary pump <NUM> (and the secondary pump <NUM> in some embodiments), the PRV <NUM>, and the reservoir <NUM>. The configuration of the TPSDV <NUM> itself, and its position within the HPU <NUM> enables configurable PRV <NUM> operation without the need for multiple directional valves. As a result, the number of components within the HPU <NUM> and the potential for failure of each component is reduced.

In some embodiments, the TPSDV <NUM> has a spring return solenoid <NUM>. The TPSDV <NUM> is configured to fail default to one of the two positions. For example, an HPU <NUM> that is configurable in a PRV fail OPEN mode or an HPU <NUM> that is configurable in a PRV fail CLOSE mode, may use a TPSDV <NUM> that has a spring return solenoid <NUM>. In some embodiments, the TPSDV <NUM> may be detented instead of having a spring return, and may include a pair of solenoids <NUM>, 74A (See <FIG>). The detented TPSDV <NUM> coupled with the PRV <NUM> results in the TPSDV <NUM> having a fail default in its current position. As a result, the PRV <NUM> also remains in its current state OPEN or CLOSE configuration upon loss of power / loss of solenoid signal; i.e., this HPU configuration may be described as a PRV fail AS-IS configuration. For example, if the PRV <NUM> is in an OPEN configuration and there is loss of power / loss of solenoid signal, the TPSDV <NUM> would be remain in its current position which in turn would cause the PRV <NUM> to also remain in an OPEN configuration. Conversely, if the PRV <NUM> is in a CLOSED configuration and there is loss of power / loss of solenoid signal, the TPSDV <NUM> would be remain in its current position which in turn would cause the PRV <NUM> to also remain in a CLOSED configuration.

In some embodiments, the TPSDV <NUM> may have a manual push button override feature <NUM> which can be used if the TPSDV solenoid <NUM> (or solenoid 74A) is stuck and unable to be activated via a solenoid signal.

In some embodiments, one of the lines <NUM>, <NUM> connecting the TPSDV <NUM> to the PRV <NUM> may include a valve configuration that facilitates operation of the PRV <NUM>. For example, the valve configuration may be such that during normal operation of the PRV <NUM>, fluid flow is selectively allowed to either the PRV OPEN port <NUM> or the PRV CLOSE port <NUM> in a substantially unimpeded manner. However, when it is desirable to change the position of the PRV <NUM> (e.g., from a closed configuration to an open configuration, or vice versa), the valve configuration permits the PRV <NUM> to open quickly, and to close in a controlled manner; e.g., to prevent damage to the PRV <NUM>. Non-limited examples of such a valve configuration can be seen in <FIG> and <FIG>. In <FIG>, a PRV fail CLOSE configuration is shown wherein a throttle valve <NUM> (e.g., an orifice) and a check valve <NUM> are disposed in parallel within line <NUM> that connects the TPSDV <NUM> to the PRV <NUM>. In this configuration, hydraulic fluid may be passed to the OPEN port <NUM> of the PRV <NUM> from the TPSDV <NUM> in a substantially unimpeded manner; e.g., the directional check valve <NUM> allows fluid flow to the PRV OPEN port <NUM>. In this configuration, if the HPU <NUM> is operated to change from an OPEN configuration to a CLOSE configuration, hydraulic fluid exiting the PRV OPEN port <NUM> is not permitted to pass through the directional check valve <NUM>, but rather must pass through the throttle valve <NUM>. The throttle valve <NUM> impedes the flow of the exiting hydraulic fluid and thereby prevents PRV <NUM> closure in a manner that may damage the PRV <NUM>; i.e., the throttle valve <NUM> creates a cushioning effect when the PRV <NUM> closes, and avoids the potential for ramming the PRV <NUM> which can be detrimental to the trims within the PRV <NUM>. In <FIG>, a PRV fail OPEN configuration is shown wherein a throttle valve <NUM> (e.g., an orifice) and a check valve <NUM> are disposed in parallel within line <NUM> that connects the TPSDV <NUM> to the PRV <NUM>. The functionality of the valve configuration is the similar to that described above with respect to <FIG>. In this configuration, if the HPU <NUM> is operated to change from an OPEN configuration to a CLOSE configuration, hydraulic fluid exiting the PRV OPEN port <NUM> is not permitted to pass through the directional check valve <NUM>, but rather must pass through the throttle valve <NUM>. The throttle valve <NUM> impedes the flow of the exiting hydraulic fluid and thereby prevents PRV <NUM> closure in a manner that may damage the PRV <NUM>. The exemplary valve configuration (i.e., a check valve <NUM> and a throttle valve <NUM>) described is an example of a valve configuration, and the present disclosure is not limited thereto. Alternative valve configurations may include the use of a single valve configuration that provides the functionality of a directional valve and a flow restriction valve, an adjustable orifice valve (manual or solenoid operated), a two position flow valve (manual or solenoid operated), etc. Solenoid or other electromechanical valves may be configured for control by the controller <NUM>.

In some embodiments (see <FIG>), a valve configuration functionally equivalent to that described above may be disposed within both of the lines <NUM>, <NUM> connecting the TPSDV <NUM> to the PRV <NUM>. For example, a throttle valve <NUM> and a check valve <NUM> disposed in parallel may be disposed within both of the lines <NUM>, <NUM> connecting the TPSDV <NUM> to the PRV <NUM>. The parallel throttle valve <NUM> and check valve <NUM> are configured in each line <NUM>, <NUM> so that fluid flow to the PRV <NUM> through one of the lines <NUM>, <NUM> passes principally through the directional check valve <NUM> (i.e., path of least resistance) with minimal impedance, and fluid exiting the PRV <NUM> through the other line <NUM>, <NUM> cannot pass through the check valve <NUM> but must instead pass through the throttle valve <NUM>. Embodiments that include a throttle valve <NUM> and a check valve <NUM> disposed in parallel within both of the lines <NUM>, <NUM> connecting the TPSDV <NUM> to the PRV <NUM> facilitate converting the HPU <NUM> from a fail OPEN configuration to a fail CLOSE configuration (and vice versa); e.g., there is no need to remove the throttle valve <NUM> / check valve <NUM> from one line (e.g., line <NUM> or line <NUM>) to the other (e.g., line <NUM> or line <NUM>) to change from one configuration to the other. Hence, the HPU <NUM> can accommodate multiple failure operational modes in a single HPU <NUM> design. In those embodiments wherein a throttle valve <NUM> (or other flow restriction device) is used, an adjustable orifice throttle valve (e.g., solenoid operated that may be controlled by the controller <NUM>) may be used to minimize or remove the fluid flow restriction that would otherwise be caused by the valve in situations where it is desired to open the PRV as quickly as possible.

As will be explained below and shown in <FIG>, in some embodiments a two position directional valve <NUM> (4way/ 2pos) having a pair of solenoids <NUM>, 174A may be in communication with the lines <NUM>, <NUM> extending between the TPSDV <NUM> and the PRV <NUM>. The two position directional valve <NUM> may actuated via instructions from the controller <NUM> to change the fluid communication paths between the lines <NUM>, <NUM> and the OPEN and CLOSE ports <NUM>, <NUM> of the PRV; e.g., the controller may include instructions (e.g., operated via user input) that when implemented cause the two position directional valve <NUM> to switch positions, thereby changing the HPU from a fail OPEN configuration (e.g., see <FIG>) to a fail CLOSE configuration (e.g., see <FIG>), or vice versa. The two position directional valve <NUM> may be operated to switch positions for purposes other than changing the HPU <NUM> configuration.

Referring to <FIG>, in some embodiments a valve <NUM> (e.g., a ball valve) may be in communication with one of the lines <NUM>, <NUM> connecting the TPSDV <NUM> to the PRV <NUM>, configured to permit fluid to bypass the valve configuration (e.g., throttle valve <NUM> and a check valve <NUM>) disposed in parallel. In some embodiments, a first valve <NUM> (e.g., a ball valve) may be in communication with one of the lines <NUM> connecting the TPSDV <NUM> to the PRV <NUM>, and a second valve 80A may be in communication with the other line <NUM> connecting the TPSDV <NUM> to the PRV <NUM>, with both the first and second valves <NUM>, 80A configured to permit fluid to bypass the respective valve configuration (e.g., throttle valve <NUM> and a check valve <NUM>). Each valve <NUM>, 80A may be manually operated between a closed configuration and an open configuration. Alternatively, each valve <NUM>, 80A may be configured for automated operation; e.g., solenoid operated valves <NUM>, 80A. The automated valves <NUM>, 80A may actuated via instructions from the controller <NUM> to change from an open configuration to a closed configuration, or vice versa. The HPU <NUM> configuration shown in <FIG> utilizes both the two position directional valve <NUM> and the valves <NUM>, 80A for increased operational versatility.

In some embodiments (e.g., see <FIG>), a manual two position directional valve <NUM> (4way/ 2pos) may be in communication with the lines <NUM>, <NUM> extending between the TPSDV <NUM> and the PRV <NUM>. During a fail OPEN configuration or a fail CLOSE configuration, the manual lever detent valve <NUM> located downstream of the TPSDV <NUM> can be used to manually open and close PRV <NUM> using pump flow passing though the defaulted fail position of the TPSDV <NUM>.

The accumulator <NUM> is in fluid communication with the TPSDV <NUM> via lines <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. An isolation valve <NUM> may be disposed in the hydraulic fluid line <NUM> between the primary pump <NUM> and the accumulator <NUM>. A dump valve <NUM> may be in communication with hydraulic fluid line <NUM> between the reservoir <NUM> and the accumulator <NUM>, and in communication with the reservoir <NUM> via line <NUM>. The accumulator <NUM> may be configured to provide increased pump fluid flow and/or to act as fluid pressure source when the pump is not operating or is functioning adequately to power the PRV <NUM>.

In some embodiments, the HPU <NUM> may include a float switch <NUM> disposed with the reservoir <NUM> and/or a reservoir sight glass <NUM>. The float switch <NUM> may be installed on the reservoir <NUM> at a location deemed as the minimum acceptable level of hydraulic fluid in reservoir <NUM>. When the oil level falls below the float switch <NUM> location, the float switch <NUM> sends a signal (e.g., a digital signal) to a controller <NUM> to indicate low reservoir level (e.g., an alarm message) and the signal may also be sent to alarm devices such as beacons / audible devices to alert the user of the low hydraulic fluid condition. The signal from the float switch <NUM> sent to the controller <NUM> may also be used to control the valve <NUM> disposed in line <NUM> that is configured to regulate the flow of pneumatic air to the pump <NUM>, <NUM> from the pressurized air source <NUM>; e.g., if a low hydraulic fluid condition is sensed, the pump <NUM>, <NUM> may be shut down by closing the air source to prevent damage within pump <NUM>, <NUM>. The float switch <NUM> provides redundancy in reservoir <NUM> level monitoring that ensures that the user is alerted so that the pump <NUM>, <NUM> can be prevented from a potentially damaging run dry condition. The avoidance of a pump "run dry" condition is significant also because a pump "run dry" condition can negatively affect the operation of the PRV <NUM>.

In some embodiments, the HPU <NUM> may include a return filter <NUM> configured to filter hydraulic fluid returning to the reservoir <NUM>. The hydraulic fluid passing through the HPU hydraulic system <NUM> (e.g., through the pumps <NUM>, <NUM>, the hydraulic lines, the valves, other HPU fluid components, and through PRV <NUM>) may pick up contaminants before returning to the reservoir <NUM>. Hydraulic pumps, in particular, can over time be susceptible to damage caused by contaminated hydraulic fluid. The return filter <NUM> removes contaminates from the hydraulic fluid before the fluid reaches the reservoir <NUM> and is subsequently drawn into the HPU hydraulic system <NUM> via the pump. <FIG> illustrates a non-limiting example wherein the return filter <NUM> is disposed within a hydraulic fluid suction line <NUM> in communication with the reservoir <NUM>. In the embodiment shown in <FIG>, a bypass valve <NUM> is included configured to allow hydraulic fluid bypass; e.g., the bypass valve <NUM> may be a pressure threshold check valve that opens upon exposure to a predetermined fluid pressure such as may happen if the return filter <NUM> becomes clogged. The aforesaid embodiment also includes a pressure gauge <NUM> configured to detect and show a differential pressure across the return filter <NUM>; e.g., to enable a user to evaluate the performance of the return filter <NUM> / fluid flow impediment across the return filter <NUM>.

The HPU <NUM> may include other components that facilitate the operation of the HPU <NUM>, and/or facilitate safe operation of the HPU <NUM>. For example, the HPU <NUM> configuration shown in <FIG> includes a pressure relief valve <NUM> in fluid communication with the pump pressurized hydraulic line <NUM> and with a line <NUM> extending to the reservoir <NUM>. The pressure relief valve <NUM> may be configured to open and dump hydraulic fluid back to the reservoir <NUM> if fluid pressure within the pump pressurized hydraulic line <NUM> exceeds predetermined limit, which excessive pressure may otherwise damage PRV externals. In addition, the HPU <NUM> may include pressure gauges, pressure transmitters, etc..

The HPU <NUM> may include a controller <NUM> in communication with various different components. For example, the controller <NUM> may be in communication with a variety of HPU components, including valving associated with the pumps <NUM>, <NUM>, an HPU pressure transmitter, a PRV pressure transmitter, pressure sensors, the reservoir float switch <NUM>, the TPSDV <NUM>, a two position directional valve, etc. The controller <NUM> may include any type of computing device, computational circuit, or any type of process or processing circuit capable of executing a series of instructions that are stored in memory. The controller <NUM> may include multiple processors and/or multicore CPUs and may include any type of processor, such as a microprocessor, digital signal processor, co-processors, a micro-controller, a microcomputer, a central processing unit, a field programmable gate array, a programmable logic device, a state machine, logic circuitry, analog circuitry, digital circuitry, etc., and any combination thereof. The instructions stored in memory may represent one or more algorithms for controlling the HPU <NUM> / PRV <NUM>, and the stored instructions are not limited to any particular form (e.g., program files, system data, buffers, drivers, utilities, system programs, etc.) provided they can be executed by the controller. The memory may be a non-transitory computer readable storage medium configured to store instructions that when executed by one or more processors, cause the one or more processors to perform or cause the performance of certain functions. The memory may be a single memory device or a plurality of memory devices. A memory device may include a storage area network, network attached storage, as well a disk drive, a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. The HPU <NUM> may also include input (e.g., a keyboard, a touch screen, etc.) and output devices (a monitor, sensor readouts, data ports, etc.) that enable the operator to input instructions, receive data, etc..

The HPU <NUM> is configurable in at least three different modes of operation (sometimes referred to as "failure modes") in the event of a loss of electrical power to the controller <NUM> / HPU <NUM>, and/or the loss of signal communication to the TPSDV <NUM>: a PRV fail OPEN configuration, a PRV fail CLOSE configuration, and a PRV fail AS-IS configuration.

PRVs are often used for well drilling processes involving flow to ensure that excessive system pressures will not cause major failures in the well drilling system. For example, it is known to use a PRV with mud pump systems on well drilling rigs. The mud pump systems are typically high powered and deliver fluids at high flow rates and delivery pressures. Starting a mud pump against a closed valve or a plugged line will very likely result in major damage to the mud pump system unless the PRV for the mud system opens rapidly to relieve the excessive pressure.

Referring to <FIG>, in the PRV fail OPEN configuration, embodiments of the present disclosure HPU <NUM> are configured to switch the PRV <NUM> to an OPEN configuration in the event of a loss of electrical power to the controller <NUM> / HPU <NUM>, and/or the loss of signal communication to the TPSDV <NUM>. In the OPEN configuration, the PRV <NUM> provides a pressure relief that prevents the formation of a potentially damaging pressure level within the mud pump system. For example, and as shown diagrammatically in <FIG>, an embodiment of the present HPU <NUM> may include a TPSDV <NUM> with a spring return solenoid that is configured to default to a fail OPEN configuration upon the loss of electrical power to the HPU <NUM>, and/or the loss of signal communication to the TPSDV <NUM>. In this configuration, the TPSDV <NUM> defaults to a position wherein pressurized fluid within the HPU <NUM> (which may include pressurized fluid from the accumulator <NUM>) is fed to the OPEN port <NUM> of the PRV <NUM> to cause the PRV <NUM> to be maintained in an OPEN configuration.

In the PRV fail OPEN configurations that include a throttle valve <NUM> and a check valve <NUM> disposed in parallel (e.g., see <FIG>), the parallel throttle valve <NUM> / check valve <NUM> are in communication with the line <NUM> extending to the OPEN port <NUM> of the PRV <NUM>. Hence, the directional check valve <NUM> is configured to allow pressurized fluid to pass through to the PRV <NUM> and thereby bypass the throttle valve <NUM>. As stated above, the parallel throttle valve <NUM> and check valve <NUM> are non-limiting examples of a valve configuration that may be used.

In the PRV fail CLOSE configuration, embodiments of the present disclosure HPU <NUM> are configured to switch the PRV <NUM> to a CLOSE configuration in the event of a loss of electrical power to the controller <NUM> / HPU <NUM>, and/or the loss of signal communication to the TPSDV <NUM>. In the CLOSE configuration, the PRV <NUM> does not provide a pressure relief, but rather helps to maintain existing well pressure during drilling; e.g., maintain well pressure during drilling within a mud pump system. For example, and as shown diagrammatically in <FIG>, an embodiment of the present HPU <NUM> may include a TPSDV <NUM> with a spring return solenoid <NUM> that is configured to default to a fail CLOSE configuration upon the loss of electrical power to the controller <NUM> / HPU <NUM>, and/or the loss of signal communication to the TPSDV <NUM>. In this configuration, the TPSDV <NUM> defaults to a position wherein pressurized hydraulic fluid (which may include pressurized fluid from the accumulator <NUM>) is fed to the CLOSE port <NUM> of the PRV <NUM> to cause the PRV <NUM> to move to, and be maintained in, a PRV fail CLOSE configuration.

In the PRV fail CLOSE configurations that include a throttle valve <NUM> and a check valve <NUM> disposed in parallel (e.g., see <FIG>), the parallel throttle valve <NUM> / check valve <NUM> are in communication with the line <NUM> extending to the OPEN port <NUM> of the PRV <NUM>. Hence, the directional check valve <NUM> is configured to not allow fluid flow exiting the PRV <NUM> to pass through the check valve <NUM>, thereby forcing the fluid exiting the PRV <NUM> to pass through the throttle valve <NUM>. As stated above, the parallel throttle valve <NUM> and check valve <NUM> are non-limiting examples of a valve configuration that may be used.

As stated above, in some embodiments a valve configuration (e.g., a throttle valve <NUM> and a check valve <NUM> and/or a fluid control valve <NUM>, 80A) may be disposed within both of the lines <NUM>, <NUM> connecting the TPSDV <NUM> to the PRV <NUM>. Using the throttle valve <NUM> and a check valve embodiment to illustrate, the parallel throttle valve <NUM> and check valve <NUM> are configured in each line so that fluid flow to the PRV <NUM> through one of the lines <NUM>, <NUM> passes principally through the directional check valve <NUM> (i.e., path of least resistance) with minimal impedance, and fluid exiting the PRV <NUM> through the other line <NUM>, <NUM> cannot pass through the check valve <NUM> but must instead pass through the throttle valve <NUM>. <FIG> shows an HPU <NUM> in a PRV fail CLOSE configuration and <FIG> shows an HPU <NUM> in a PRV fail OPEN configuration. Embodiments that include a valve configuration (e.g., throttle valve <NUM> and a check valve <NUM> disposed in parallel) within both of the lines <NUM>, <NUM> connecting the TPSDV <NUM> to the PRV <NUM> facilitate converting the HPU <NUM> from a fail OPEN configuration to a fail CLOSE configuration (and vice versa); e.g., there is no need to remove the throttle valve <NUM> / check valve <NUM> from one line to the other to change from one configuration to the other. With the HPU <NUM> configurations shown in <FIG>, the change from a fail OPEN configuration (e.g., <FIG>) to a fail CLOSE configuration (e.g., <FIG>) may be accomplished by changing the positions of the lines <NUM>, <NUM> relative to the ports <NUM>, <NUM> of the PRV <NUM>; e.g., line <NUM> connected to PRV OPEN port <NUM> (as shown in <FIG>), can be switched to PRV CLOSE port <NUM> (as shown in <FIG>) and vice versa for line <NUM>. Hence, the HPU <NUM> can accommodate multiple failure operational modes in a single HPU <NUM> design. As stated above, in those embodiments wherein a throttle valve <NUM> (or other flow restriction device) is used, an adjustable orifice throttle valve (e.g., solenoid operated that may be controlled by the controller <NUM>) may be used to minimize or remove the fluid flow restriction that would otherwise be caused by the valve in situations where it is desired to open the PRV as quickly as possible.

Alternatively, as explained below and shown in <FIG>, the HPU <NUM> may include an automated two position directional valve <NUM> (4way/ 2pos) in communication with the lines <NUM>, <NUM>. The two position directional valve <NUM> may actuated via instructions from the controller <NUM> to change the fluid communication paths between the lines <NUM>, <NUM> and the OPEN and CLOSE ports <NUM>, <NUM> of the PRV; e.g., the controller may include instructions (e.g., operated via user input) that when implemented cause the two position directional valve <NUM> to switch positions, thereby changing the HPU from a fail CLOSE configuration (e.g., see <FIG>) to a fail OPEN configuration (e.g., see <FIG>).

In those HPU <NUM> embodiments that include a valve <NUM>, 80A (e.g., a ball valve) positioned parallel to each line connecting the TPSDV <NUM> to the PRV <NUM> (e.g., see <FIG>), the HPU <NUM> is configured so that the valve <NUM> in communication with the line <NUM> extending to the CLOSE port <NUM> of the PRV <NUM> is closed in the PRV fail OPEN configuration, and the valve 80A in communication with the line <NUM> extending to the OPEN port <NUM> of the PRV <NUM> is open in the PRV fail OPEN configuration (see <FIG>), and conversely the valve 80A in communication with the line <NUM> extending to the CLOSE port <NUM> of the PRV <NUM> is open in the PRV fail CLOSED configuration, and the valve <NUM> in communication with the line <NUM> extending to the OPEN port <NUM> of the PRV <NUM> is closed in the PRV fail CLOSED configuration. As stated above, each valve <NUM>, 80A may be manually operated between a closed configuration and an open configuration. Alternatively, each valve <NUM>, 80A may be configured for automated operation; e.g., solenoid operated valves <NUM>, 80A. The automated valves <NUM>, 80A may actuated via instructions from the controller <NUM> to change from an open configuration to a closed configuration, or vice versa. In these embodiments, the valves <NUM>, 80A may be utilized with the check valves <NUM> as shown in <FIG>, <FIG>, or may be utilized without the check valves <NUM>.

In some embodiments where mud pump protection (e.g., protection from excessive pressure) is desired during a PRV fail CLOSE configuration, the controller can be adapted to provide instructions to the mud pumps modify the performance of the mud pumps (e.g., instructions that cause the mud pumps to decrease their strokes per minute -SPM) and thereby decrease the potential for over pressurization of the mud pumps that may otherwise potentially lead to damage.

In the PRV fail AS-IS configuration, embodiments of the present disclosure HPU <NUM> are configured to maintain the current state of the PRV <NUM> in the event of a loss of electrical power to the controller <NUM> / HPU <NUM>, and/or the loss of signal communication to the TPSDV <NUM>. Maintaining the PRV <NUM> in its current state in the event of a loss of electrical power to the HPU <NUM>, and/or the loss of signal communication to the TPSDV <NUM>, will prevent any unintentional movement of the PRV <NUM> in a safety critical operation.

For example, and as shown diagrammatically in <FIG>, an embodiment of the present HPU <NUM> may include a TPSDV <NUM> that is detented. The detented TPSDV <NUM> coupled with the PRV <NUM> results in the TPSDV <NUM> having a fail default in its current position. As a result, the PRV <NUM> also remains in its current state OPEN or CLOSE configuration upon loss of power / loss of solenoid signal.

Initial testing suggests that embodiments of the above described HPU <NUM> are able to provide an increased acceleration of PRV <NUM> opening / closing times with less number of components/tubing (e.g., <NUM> cycle time). Since the potential for over pressurization and damage attributable to over pressurization increase with PRV <NUM> operation lag, the decreased PRV <NUM> response is believed to provide a benefit to the user.

In those embodiments that include a return filter <NUM>, the return filter <NUM> is useful in reducing the contaminant level within the hydraulic oil, which is understood to increase the longevity of the pump <NUM>, <NUM> and thus keeping the HPU <NUM> operational to function the PRVs.

In those embodiments that include a reservoir float level switch <NUM> in addition to a sight glass <NUM>, it is believed that the redundancy will facilitate reservoir <NUM> fluid level monitoring to prevent pump <NUM>, <NUM> from running dry and get damaged.

In those embodiments that include a secondary pump <NUM>, it is believed that the redundancy of the pumps will decrease or avoid down time that may be caused by a primary pump <NUM> malfunction.

Claim 1:
A hydraulic power unit system (<NUM>) comprising:
a hydraulic power unit, HPU, (<NUM>) and a pressure relief valve, PRV, (<NUM>);
the PRV having an open port (<NUM>) and a close port (<NUM>);
the HPU including:
a pneumatic primary pump (<NUM>);
a hydraulic fluid reservoir (<NUM>) in fluid communication with the primary pump (<NUM>);
an accumulator (<NUM>);
a first two position solenoid directional valve, TPSDV, (<NUM>) in communication with the primary pump (<NUM>), the reservoir (<NUM>), and the accumulator (<NUM>), and the first TPSDV (<NUM>) provides fluid communication with the PRV;
a second TPSDV (<NUM>, <NUM>);
at least one first fluid line (<NUM>); and
at least one second fluid line (<NUM>);
wherein in a first configuration of the second TPSDV (<NUM>, <NUM>), the at least one first fluid line (<NUM>) provides fluid communication between the first TPSDV (<NUM>) and the close port (<NUM>) of the PRV, and the at least one second fluid line (<NUM>) provides fluid communication between the first TPSDV (<NUM>) and the open port (<NUM>) of the PRV;
wherein in a second configuration of the second TPSDV (<NUM>, <NUM>), the at least one first fluid line (<NUM>) provides fluid communication between the first TPSDV (<NUM>) and the open port (<NUM>) of the PRV, and the at least one second fluid line (<NUM>) provides fluid communication between the first TPSDV (<NUM>) and the close port (<NUM>) of the PRV; and
wherein the HPU (<NUM>) is configurable in a PRV fail open configuration and a PRV fail close configuration.