Patent Grant
10590726
This disclosure relates in general to oil and gas equipment, and to a subsea electronics module (SEM) for use in oil and gas equipment. In particular, the disclosure provides systems and methods for a select mode to activate or deactivate one of available SEMs in a control pod, separately from its redundant counterpart in another control pod, to enable use of the control POD with components of a lower marine riser package (LMRP) in a blowout preventer (BOP).
Blow-out preventer (BOP) systems are hydraulically-controlled systems used to prevent blowouts from subsea oil and gas wells. Subsea BOP equipment typically includes a set of two or more redundant control systems with separate hydraulic pathways to operate a specified BOP function on a BOP lower stack. The redundant control systems are commonly referred to as blue and yellow control PODs. The control PODs are interchangeably referred to herein as PODs. A communications and power cable sends information and electrical power to an actuator with a specific address. The actuator in turn moves a hydraulic valve, thereby opening a fluid path to a series of other valves/piping to control a portion of the BOP. The actuator and hydraulic valve action may be performed by a solenoid valve that receives an electronic input and that reacts by opening or closing the valve associated with a fluid flow. As such, a solenoid and valve or an actuator and valve combination may be referred to as a solenoid valve or a hydraulic valve unless otherwise stated. The opening or closing of the valve as a result of a signal is generally referred to herein as activating or deactivating of the combined valve.
Power and communications connections have been centralized on the control PODs subsea. Each control POD may include one or more subsea electronics modules (SEM(s)) with included electronic modules attached to the SEM for handing power requirements of the solenoids and various other components of a lower marine riser package (LMRP). However, when control has to be switched to a redundant counterpart, such as a different SEM, in a different control pod, the process is time consuming and technically challenging as it may require many deactivations—electrical and/or hydraulic—to complete. Then the different control POD is subject to counterpart processes to activate the connections. Fluid is required to be shut off to or for the deactivated pod, while required to be turned on to the activated pod. Moreover, the SEM of the deactivated POD still actively receives signals meant for the active pod, and continues to activate and deactivate the solenoid or the hydraulic valves in the deactivated pod. As the deactivated POD has no fluid flowing through it, there is no action by the deactivated POD on components requiring fluid control in the BOP. This, however, reduces the life of the solenoid or the hydraulic valves.
Embodiments of the present disclosure resolve the above identified issues of the SEM and BOP assembly using a novel configuration of the SEM. In an example, a blow-out preventer (BOP) is disclosed as having a BOP lower stack and a lower marine riser package (LMRP). The LMRP includes at least a first subsea electronics module (SEM) and a second SEM in a first pod. The LMRP further includes at least a third SEM and a fourth SEM in a second pod. Particularly, the third SEM is redundant with the first SEM and the fourth SEM is redundant with the second SEM. This redundancy is a safety feature to bring the redundant SEM to active state if the active SEM displays signs of trouble. Further, at least one selector circuit is included for transmitting an SEM select signal that electrically activates or electrically deactivates the first SEM separately from the third SEM. The electrical activation or the electrical deactivation of the first SEM that occurs separately from the third SEM controls fluid for use in BOP components.
In another example, a configuration of multiple PODs for a lower marine riser package (LMRP) is disclosed. The configuration includes at least a first subsea electronics module (SEM) and a second SEM in a first pod, and at least a third SEM and a fourth SEM in a second pod. The third SEM is redundant with the first SEM, while the fourth SEM is redundant with the second SEM. At least one selector circuit transmits an SEM select signal that electrically activates or electrically deactivates the first SEM separately from the third SEM.
In yet another example, a method of operation of PODs for a lower marine riser package (LMRP) is disclosed. The method includes providing at least a first subsea electronics module (SEM) and a second SEM in a first pod, and providing at least a third SEM and a fourth SEM in a second pod. The third SEM is redundant with the first SEM, and the fourth SEM is redundant with the second SEM. A further part of the method includes providing at least one selector circuit with electrical paths to the first SEM, the second SEM, the third SEM, and the fourth SEM. The method includes transmitting an SEM select signal that electrically activates or electrically deactivates the first SEM separately from the third SEM.
These and other features, aspects, and advantages of the present disclosure will become better understood with regard to the following descriptions, claims, and accompanying drawings. It is to be noted, however, that the drawings illustrate only several embodiments of the disclosure and are therefore not to be considered limiting of the disclosure's scope as it can admit to other equally effective embodiments.
So that the manner in which the features and advantages of the embodiments for select mode SEMs and PODs, and their associated methods of operation, as well as others, which will become apparent, may be understood in more detail, a more particular description of the embodiments of the present disclosure briefly summarized previously may be had by reference to the embodiments thereof, which are illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only various embodiments of the disclosure and are therefore not to be considered limiting of the present disclosure's scope, as it may include other effective embodiments as well.
Lower stack 104 can include shuttle panel 134, as well as a blind shear ram BOP 136, a casing shear ram BOP 138, a first pipe ram 140, and a second pipe ram 142. BOP lower stack 100 is disposed above a wellhead connection 144. Lower stack 104 can further include optional stack-mounted accumulators 146 containing a necessary amount of hydraulic fluid to operate certain functions within BOP lower stack 100. The blue and yellow control PODs 110, 108 is a subsea component that may include two or more SEMs, a subsea transformer, solenoids, and subsea hydraulic control valves and regulators. Each of the SEMs and the subsea hydraulic control valves and regulators are considered major subsystems of the blue and yellow control PODs 106, 108. The SEMs, apart from providing power, also support collection and transmission of data (e.g., pressure, temperature, flow rate, and ram position) to the surface control subsystem, as well as the electric actuation of subsea hydraulic control valves (also referred to herein as pilot valves) through the solenoids. The two SEMs, within each POD, may be two partly redundant SEM units. Further, each SEM within each of the control PODs (e.g., control POD 110) may be fully redundant with another SEM in a different control POD (e.g., control POD 108). As such, each SEM in POD 110 has a redundant counterpart in POD 108. In addition, subsea hydraulic control valves and regulators can include shuttle valves, lines, SPM valves, and accumulator bottles. The accumulator bottles provide the hydraulic fluid/pressure necessary to actuate a BOP in the event of disconnection from the surface supply. The redundancy, as used herein, in one aspect, is to functions performed or instructions provided by the SEMs to control components within the POD or throughout the BOP.
The blue and yellow PODs may both have active SEMs sending identical signals to solenoids at all times. Only one pod, however, has the hydraulic pressure on its subplate mounted valves (SPMs). As such, one SEM is active by virtue of drying switching, where a lack of underlying fluid implies that no control is offered from the POD hosting such an SEM. However, the inlet or “POD Select Valve” controls which POD is active even though the SEM select signal, from the user input, is sent to both SEMs. As such, a single point failure in possible via the POD Select Valve and as all solenoids/SPM pistons in both PODs are always firing together, there is high wear and tear in both PODs, when only one POD is truly active. Furthermore, straight through functions require special shuttle valves for interflow from both PODs as a result of this configuration.
According to some embodiments, the BOP lower stack 104 may include a frame that can have a two-point lifting capability, which allows the frame to be split into two parts. In some embodiments, the entire stack 102, 104 can be retrievable from either a horizontal or vertical position, and the frame can have a wellhead connector position indicator to provide easy viewing of the connector operations.
In some embodiments, the BOP lower stack 104 has a three-piece frame design, including a one-piece LMRP 102 and a two-piece lower stack including upper and lower portions. Various BOPs 136-142 are attachable to individual rather than multiple levels of the frame, allowing the BOP lower stack 104 to be split without removing all the BOPs. Additionally, hydraulic manifolds are provided at each level of the frame; this allows sections of piping to be readily attached to the manifolds when the frame is assembled, simplifying installation and maintenance operations. The three-piece design also facilitates transportation of the BOP lower stack 104 components from the site of manufacture to the drill ship or platform.
In some embodiments, the BOP lower stack 104 is configurable as a 6, 7, or 8 cavity stack. When desired by the user, the configuration can be modified in the field after initial deployment. The BOP lower stack 104 may include modular components which allow double BOPs to be exchanged with single BOPs and vice versa, depending on the needs of the user. Configurability of the stack 102, 104 enables a user to add or subtract BOPs based upon the needs of each wellsite, such as for reasons related to weight, the specific subsea wellhead being used (e.g., 15 ksi or 20 ksi), etc. Because the stack is modular and includes strategically placed connections, in order to replace a damaged or worn BOP, a user can swap a portion of the stack, rather than pulling apart the entire stack, thus reducing down time.
A remotely operated vehicle (ROV) may interface with the LMRP systems via an ROV intervention panel is designed to allow the ROV to perform multiple functions on the LMRP 102. A person of ordinary skill would recognize that the present illustration of
In operation, the subsea BOP rams of BOPs 136-142 are hydraulically controlled by the first or second POD 108, 110. For example, hydraulic lines 132 run from each of the first and second control PODs 108, 110 to individual rams 136-142 of the BOP lower stack 104. One of the two control PODs 108, 110 may be responsible to hydraulically control the rams through its respective hydraulic lines, while the other control POD remains idle. The idle configuration includes shutting off fluid flow to the control pod, which in turn ensures that there is no fluid exiting the control POD for hydraulic control of components connected to the control pod. This configuration may maintain the signaling to the active and the inactive (redundant) control POD concurrently, but as the inactive (redundant) control POD does not have fluid passing through, any hydraulic or solenoid valve activates or deactivates without any actual effect of control.
When required, the inactive (redundant) control POD may be activated by providing the fluid flow and by stopping fluid flow for the counterpart active control pod, which then deactivates it. As such, redundancy is built into the system because, when the control POD actually controlling components of the BOP, such as the rams, becomes incapacitated for whatever reason, or otherwise requires maintenance or replacement, the inactive (redundant) control POD can be activated to continue operation of the rams. However, it is understood to a person of ordinary skill that the activating and deactivating of the hydraulic or solenoid valve in the inactive (redundant) control POD without fluid flow reduces the life expectancy of the hydraulic or solenoid valve, and/or also subjects the hydraulic or solenoid valves to wear and tear. In addition, maintenance is required for the valves of the inactive POD that are functioning without fluid for control. As such, there is a high likelihood of that a valve may fail for the inactive POD resulting in unprepared rig downtime. Further, swapping the POD is also a time consuming process and could result in unexpected outcomes.
In an embodiment, receivers in the BOP lower stack 104 can be constructed of, for example, galling and corrosion resistant stainless steels. The BOP receivers can be spring-loaded and can be bolted to a welded companion flange on the bottom of the BOP plate. The receiver can also provide function ports for the BOP hydraulic components.
In
In an aspect, the user input may be control input in the form of electrical signals from a surface control subsystem that is manually or automatically operated. The user input activates or deactivates an SEM to provide the signals to its associated solenoid or hydraulic valves in its associated pod. As such, activation or deactivation is used in many ways in this disclosure—at least to indicate which components are turned on and turned off or at least to indicate which components provide an output for an associated input. For example, even though solenoid or hydraulic valves of POD 302B are activated, there is no fluid control from this pod. As such, POD 302B is inactive, but its solenoid or hydraulic valves are active and its SEM A 306 A is also active by virtue of receiving the user input 308 and providing signals to activate the solenoid or hydraulic valves of POD 302B. SEM B 306B of POD 302B, as in the case of SEM A 306A, provides redundant support for SEM B 304B of POD 302A.
In a further aspect, input control valves 410A, 410B in the first POD and in the second POD may be in the hydraulically active state so that fluid, from the external source, is present at all the solenoid or hydraulic values, including—at first hydraulic valves associated with the first SEM, at second hydraulic valves associated with the second SEM, at third hydraulic valves associated with the third SEM, and at fourth hydraulic valves associated with the fourth SEM. Separately, a single shared outlet and a single shared inlet may be provided for the SEMs in each POD. As such, a fluid path is via the activated valves of the activated SEM while the inactive or standby state of an SEM does not allow fluid flow through the shared outlet or inlet valves. This allows for redundant electrical control over singular fluid paths.
In an aspect, computer 424 provides a SEM select signal to activate a SEM of SEMs 404A, 404B, 406A, and 406B. The activated SEM, e.g., SEM A 404A in
Flow paths 412A and 412B may also be connected such that activation of SEM A 404A causes fluid to flow to the same BOP component supported by SEM B 404B. As such, activation of SEM A 404A would accomplish the same as activation of SEM B 404B, under one redundancy aspect of the present disclosure. This supports a feature in the present disclosure to operate fluid via flow path 412B by activation of either SEM B or SEM A, independent of each other. The flow path connection within sub-PODs 404A and 404B or 406A and 406B may be inside or outside of the control POD 402A. Similarly, flow path 412A may be connected to flow path 412B, and separately, flow path 412C may be connected with flow path 412D. All these connections may be internal or external to each control POD 402A and 402B. Such a configuration supports individual activation of either one of SEMs A, B, C, and D to accomplish all the required BOP functions through use of a hydraulic shuttle valve arrangement, for instance. As such, the electrically redundant interface of the present configuration using SEMs A, B, C, and D support either an overall single valve for either or both of the inlet and the outlet for and from SEMs A and B, and separately, either a second overall single valve for either or both of the inlet and the outlet for and from SEMs C and D.
As illustrated in
Sub-process 506 provides at least one selector circuit with electrical or signal lines or paths to the first SEM, the second SEM, the third SEM, and the fourth SEM. Further, sub-process 508 determines if an SEM select signal is provided for one of the electrical paths. Alternatively, in another aspect, instead of such a determination, sub-process 508 may determine if an SEM select signal is provided for one of the SEMs. When a determination is that no SEM select signal is received, the select circuit may be monitored continuously. When an SEM select signal is provided so that the determination in sub-process 508 is confirmed—that an SEM select signal is provided for an SEM or for an electrical path, then sub-process 510 transmits the SEM select signal to the specific SEM, such as the first SEM and the SEM select signal electrically activates or electrically deactivates the first SEM separately from the third SEM. This ensures that the SEMs may be activated independently and that they do not continuously remain in an active mode. Indeed, as the inlet valves for fluid is in an always ON state, the present aspect requires the use of the SEM select signal to active an intended SEM without other SEMs changing state, so that fluid flow for control of BOP components come from the POD associated with the solenoids or hydraulic valves of the active SEM.
In a further operative aspect, the method in flowchart 500 further supports providing fluid from an external source to first hydraulic valves and to second hydraulic valves in the first POD and to third hydraulic valves and fourth hydraulic valves in the second pod. Sub-process 510, then supports activating the first SEM by the SEM select signal to open a fluid path through the first hydraulic valves for the fluid to traverse the first POD and to exit the first POD via an output valve. In this implementation the third SEM is maintained in a deactivated status so that the fluid is unable to flow through the third hydraulic valves. In the event of maintenance or other requirements to switch the PODs, the system and method herein supports deactivating the first POD to switch operations to the second pod. This may be by shutting off or switching the selector circuit so that the SEM select signal does not reach the first POD or so that the SEM select signal is now directed to an SEM of the second pod. At the same time, fluid from the external source is maintained to first hydraulic valves and second hydraulic valves in the first POD and to third hydraulic valves and fourth hydraulic valves in the second pod. As such, the second POD may be activated by the provided SEM select signal to activate the redundant SEM—i.e., the above-referenced third SEM in the second pod. The SEM select signal then opens a fluid path through the third hydraulic valves for the fluid to traverse the second POD and to exit the second POD via an output valve. At the same time, the first POD is maintained in a deactivated status so that the fluid is unable to flow out of the second pod, even though it is available in the POD by virtue of the FLOW IN or inlet valve 410A, 410B remaining open, for instance.
An advantage of the present disclosure is that a higher level of redundancy is achieved by the use of the SEM select signal and selector circuit to select individual SEMs, and reduce the burden on the unselected, but fully available redundant SEM. This process takes full reliability advantage of dual coils by removing single point failure of a “POD select valve” which may be by toggling the FLOW IN or inlet valve 410A, 410B. In addition, the advance of the present system and method is also seen in a reduction of power consumption by firing only one solenoid at a time; a reduction of total solenoid valve cycle count by 50%, which supports that the solenoid now lasts twice as long; and a reduction in SPM cycles by 50% as only one SPM in each POD is ever fired, so that each SPM valve seal now lasts twice as long. Further, advantages are also seen in lesser software interlocks from a previously complicated function, as the interface now may only need to fire in 1 SEM all the time or functionally fire in all SEMs all the time (as regulators, for example).
A person of ordinary skill would recognize that the present system increases spares by a function of 1 and increases safety, so that when a function fails, there is no time lost on POD swap. As such, instead of a POD swap of all functions, a single function could be swapped either between SEMs in the currently activated POD or by activating of the function in a redundant POD, along with the redundant POD. Circuits with readbacks can automatically be fired from the associated POD when the first circuit fails and results in each POD always being able to be used for the functions that work inside of it. For example, 80% of function may be fired on SEM A (
In an example, data from the field may be used to build predictive models on usage of components in the POD and/or the BOP, and of expected life under conditions being experienced. This data can be used to secure full redundancy, to its maximum potential, of the present system before maintenance is required. This data can also be utilized to indicate when maintenance will be required. Generation and analysis of a reliability block diagram of the present system may be used to indicate increases in “probability of failure on demand” of components as they wear. When redundant components are switched the failure rate of the system is maintained at the minimum failure rate allowed given the wear on components.
For instance each SEM in
Table 1 provides an example usage of duty cycle switching SEMs so to decrease failure rates and extend maintenance intervals. X indicates function number that is activated by an SEM select signal to the corresponding SEM.
Table 2 provides of an example usage of duty cycle taking into consideration changes in function assignment to reduce failure rate.
The interface discussed in
As the industry and users of the present method and system most times require certified components and systems, the ability to secure the above-referenced SIL rating provides advantages in the present system. In an example, all functions in the BOP control POD may not need to have automatic switching and duty cycling. Users may request to have a small subset of functions monitored for failures and duty cycle with the added requirement that separate IEC-standards rated hardware monitor the surface and subsea communications. Users may also requests the use of sensors and access to commands for fire (e.g., trigger or select) functions from any SEM or a completely separate POD on surface or subsea when certain criteria are met. The present system may be of a higher fidelity and more practical to implement.
In the various embodiments of the disclosure described, a person having ordinary skill in the art will recognize that alternative arrangements of components, units, conduits, and fibers could be conceived and applied to the present invention.
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