KR102475015B1 - Subsea bop hydraulic fluid flow monitoring - Google Patents

Abstract

A method and system for accurately measuring and monitoring the accumulated volume of operating fluid in a blowout preventer (BOP) system (200) of a function of particular interest is disclosed. The method includes: initializing a state machine algorithm (600) responsive to activation of a BOP function of interest; measuring an initial hydraulic flow rate reference value and an initial pressure reference value to generate hydraulic impedance variables used in the state machine algorithm; monitoring the total flow rate and pressure of the working fluid of the BOP system over time; applying the hydraulic impedance variable to negate BOP system hydraulic flow rates that are unrelated to the BOP function of interest; and applying the state machine algorithm (600) to determine when the BOP function of interest is complete in response to the total cumulative volume of working fluid.

Description

Subsea BOP fluid flow monitoring {SUBSEA BOP HYDRAULIC FLUID FLOW MONITORING}

related application

This application is a PCT application claiming priority to U.S. Provisional Application Serial No. 62/078,236, filed on November 11, 2014, which is hereby incorporated by reference in its entirety. U.S. Application Serial No. 14/884,563 was filed on October 15, 2015, and claims priority to U.S. Provisional Application No. 62/065,431, filed on October 17, 2014, the disclosures of which are incorporated herein by reference in their entirety. included

field of invention

This disclosure relates generally to oil and gas equipment, and more particularly to methods of measuring flow to determine whether hydraulic control has been performed to perform a particular function. In particular, the present disclosure provides systems and methods for monitoring aggregated flow rates and pressures within a hydraulic control system to realize information about specific loads of interest.

A blowout preventer (BOP) system is a hydraulically controlled system used to prevent blowout from subsea oil and gas wells. Subsea BOP equipment typically includes a set of two or more redundant control systems with separate hydraulic pathways that operate designated BOP functions in the BOP stack. Redundant control systems are commonly referred to as blue and yellow control pods. In known systems, communication and power cables transmit information and power to actuators with specific addresses. The actuator then controls a portion of the BOP by moving a hydraulic valve to open a fluid path leading to a series of other valves/piping.

One disadvantage of current BOP systems is that the communication of the working fluid from the sea is through a pair of redundant conduits, and the fluid is supplied from a single source with limited measuring means, usually a single flow meter. In the case where there are multiple separate control systems at sea that use a common hydraulic supply to convey subsea components, the multiple separate control systems at sea can be used to control other control systems on the basis of a common measuring instrument such as a common flow meter or a common pressure gauge. It may not be accurately recognized that the function has been performed by For example, a primary offshore control system used to energize subsea components to execute a function may not accurately communicate that execution function to a backup safety system if that system has a common flowmeter.

In known systems, it is difficult to meter the fluid to a specific load when the system has two or more independent control systems using one hydraulic source. Adding additional flow and pressure gauges complicates the system and can lead to other drawbacks.

Embodiments of the systems and methods of the present disclosure allow monitoring of flow meters in systems having multiple control systems and blocking of flow to specific loads. Embodiments of the method enable synchronization of the initial activation of the load and the initial readout signal. Monitoring of the flow meter is used to isolate the flow meter's noise signal and filter the flow going to the intended load in a system having multiple control systems.

The systems and methods of the present disclosure enable the use of a common hydraulic system and flow meter for multiple control systems. The systems and methods of the present disclosure substantially enhance the analytical capabilities of BOP systems and allow for improved diagnostics and safety with minimal sensor additions.

The present invention discloses a method for accurately measuring and monitoring the accumulated volume of working fluid in a blowout preventer (BOP) system. The method involves initializing a state machine algorithm responsive to activation of the BOP function of interest and measuring an initial hydraulic flow baseline and initial pressure baseline to generate hydraulic impedance variables used in the state machine algorithm. It includes steps to In some embodiments, the method further comprises monitoring the total hydraulic flow rate and pressure of the BOP system over time and applying a hydraulic impedance variable to negate BOP system hydraulic flow unrelated to the BOP function of interest. In some embodiments, the method further comprises applying a state machine algorithm to determine when the BOP function of interest is complete according to the total cumulative volume of working fluid.

Also disclosed herein is a system for accurately measuring and monitoring the accumulated volume of working fluid in a blowout preventer (BOP) function of interest. The system is a marine hydraulic component comprising a hydraulic power unit (HPU) and at least two control systems fluidly coupled to the HPU and independently operable to cause a flow of hydraulic fluid from the HPU; A subsea BOP component comprising a BOP stack having a BOP stack function operable to be performed by a subsea BOP component disposed on a rigid conduit between the HPU and the BOP stack to measure the total flow of hydraulic fluid from the HPU to the BOP stack. and a fluid flow meter operable to

In some embodiments, the system includes: a manometer disposed on or near the HPU supplying hydraulic fluid to a rigid conduit and operable to measure the line pressure of the total flow of hydraulic fluid from the HPU to the BOP stack; and a processing unit comprising a processor operable to receive total fluid flow data from the manometer and line pressure data from the manometer. The processing unit includes a tangible, non-transitory memory medium in communication with the processor having a stored set of instructions, the stored set of instructions executable by the processor, and the BOP of interest initiating a state machine algorithm responsive to activation of the function; applying a measured initial hydraulic flow rate reference value and an initial pressure reference value to generate a hydraulic impedance variable used in the state machine algorithm; monitoring the line pressure of the total flow of working fluid from the HPU to the BOP stack and the total flow of working fluid from the HPU to the BOP stack over time; applying a hydraulic impedance variable to negate BOP system hydraulic flow unrelated to the BOP function of interest; and applying the state machine algorithm to determine when the BOP function of interest is complete according to the total cumulative volume of working fluid.

The further disclosed apparatus includes a tangible, non-transitory memory medium storing a set of instructions, which when executed by an appropriate processing unit cause the processing unit to perform a method comprising the steps of: The steps may include: initializing a state machine algorithm responsive to activation of the BOP function of interest; applying a measured initial hydraulic flow rate reference value and an initial pressure reference value to generate a hydraulic impedance variable used in the state machine algorithm; monitoring the line pressure of the total flow of working fluid from the HPU to the BOP stack and the total flow of working fluid from the HPU to the BOP stack over time; applying the hydraulic impedance variable to negate BOP system hydraulic flow unrelated to the BOP function of interest; and applying the state machine algorithm to determine when the BOP function of interest is complete according to the total cumulative volume of working fluid.

1 is a representative system overview of a BOP stack.
2 is a representative system diagram of a BOP system.
3 is a flow diagram illustrating one embodiment of a top-level system diagram for the systems and methods of the present disclosure.
4 is a flowchart illustrating an embodiment of a marine hydraulic system simulation.
5 is a flowchart illustrating one embodiment of subsea hydraulic system simulation.
Figure 6 is a flow chart for simulation of the system described in Figures 3-5 using a state machine algorithm, also referred to as a state machine system.
7 is a graph showing a flow compensator function (S ₂ ) that varies S (maximum flow rate allowed by the system) over time.
FIG. 8 is a graph showing a repetitive sequence block in the subsea hydraulic system described in FIG. 5 .
9 is a graph illustrating a flow according to one embodiment of a simulation of the systems and methods of the present disclosure.
10 is a graph showing pressure recorded at sea through one embodiment of a simulation of the systems and methods of the present disclosure.
11 is a graph illustrating flow recorded at sea through one embodiment of a simulation of the systems and methods of the present disclosure.
12 is a graph showing gallons per minute (GPM) and total gallons flowing over time in one embodiment of a simulation of the systems and methods of the present disclosure.
13 is a graph illustrating the results of using the systems and methods of the present disclosure to remove flow from a second BOP function and leakage flows from the total flow to obtain an accurate reading of the flow used to perform the first BOP function. .
14 is a graph showing the results of using the systems and methods of the present disclosure to remove flow from a second BOP function and leakage flows from the total flow to obtain an accurate reading of the flow used to perform the first BOP function. to be.
15 is a graph illustrating the use of a flow compensator function with the systems and methods of the present disclosure.
16 shows a graph of the results of a modeled failure function in a system of the present disclosure.
17 provides one embodiment of a decision tree representing program logic for the systems and methods of the present disclosure.

The described methods and systems are used with components of a subsea BOP system, where a basic process control system (BPCS) can operate loads on and off asynchronously from the same hydraulic source. SIL) rated load or flow to the BPCS function (function of interest). The systems and methods of the present disclosure eliminate flow noise caused by state switching and switching transients phenomena of the BPCS as well as flow noise due to leakage within the system.

Another use for the methods and systems disclosed herein is in BPCS, such as, for example, drilling control systems where it is necessary to measure flow from a function while ignoring flow from any leaks present in the system. Systems and methods can derive functional signals from fundamental noise due to leakage.

A more common use of the methods disclosed herein also involves measuring flow from one control system in a facility where several independent control systems operate functions from a common hydraulic pressure source. The systems and methods may use a logic tree and specific algorithms to identify signals of interest while ignoring other independent control systems.

Referring first to Figure 1, a representative system overview of a BOP stack is illustrated. 1 shows a BOP stack 100 comprising a lower marine riser package (LMRP) 102 and a lower stack 104 . LMRP 102 includes an annular 106 , a blue control pod 108 and a yellow control pod 110 . Hot line 112, blue conduit 114 and yellow conduit 120 run from riser 122 into LMRP 102 and down through conduit manifold 124 to control pods 108, 110. Blue power and communication lines 116 and yellow power under communication lines 118 go to control pods 108 and 110, respectively. LMRP connector 126 connects LMRP 102 to lower stack 104 . Hydraulically actuated wedges 128 and 130 are arranged to suspend a connectable hose or pipe 132 that can be connected to a shuttle panel, such as shuttle panel 134.

The lower stack 104 may include a blind shear ram BOP 136, a casing shear ram BOP 138, a first pipe ram 140 and a second pipe ram 142, as well as a shuttle panel 134. . The BOP stack 100 is disposed above the well head connection 144 . The lower stack 104 may further include an optional stack-mounted accumulator 146 that receives an amount of hydraulic fluid required to activate certain functions within the BOP stack 100 .

Referring now to FIG. 2, a representative system diagram for a BOP system is shown. The BOP system 200 includes a BOP stack 100 having a marine unit 202 and a riser 122 also shown in FIG. 1 . Marine unit 202 includes a separate independent control system 204 , 206 , 208 in communication with a hydraulic power unit (HPU) 210 . When any one of these independent control systems is operating, that is to say, to cause the HPU 210 to supply hydraulic fluid (e.g., from a hydraulic reservoir (not shown)) and/or current to the BOP stack 100. When commanded, working fluid and/or current is provided to the BOP stack 100 using the common conduit 212 . The flow rate of the working fluid is measured by the flow meter 214. BOP system 200 may also include a common pressure sensor 216 . These meters 214 and 216 are located near the sea and near the HPU 210 .

In one example of BOP system 200, blind shear ram BOP 136 and casing shear ram BOP 138 may need to be activated. The independent control system 204 may provide an operating fluid to close the blind shear ram BOP 136 . However, some of this working fluid may leak. Also, the independent control system 204 may not provide enough fluid to perform both functions and may not activate the casing front ram BOP 138. In this case, the casing front end ram BOP 138 may need to be activated by the independent control system 206 or 208. In this case, the independent control system 206 or 208 needs to know the amount of fluid or load first delivered by the independent control system 204 in order to perform either or both functions.

Without the systems and methods of the present disclosure, meter 214 cannot provide independent control systems 206 and 208 with accurate measurements of the functions performed by independent control system 204 . The total flow reading is not enough to know how much fluid has been supplied to perform the individual functions of the subsea in the BOP stack.

In the described systems and methods, when a function of interest, such as a ram, is actuated or activated, a state machine, such as state machine system 600 (also referred to herein as a state machine algorithm), executes all internal variables and flags. Remove and read the initial flow rate reference value and initial pressure reference value. This reading creates a “hydraulic impedance” or head loss variable that is used to negate any flow due to leakage and/or other functions that run before the function of interest. This variable is referred to herein as K, where K is P/F. F represents the working fluid flow and P represents the pressure. The state machine uses a total flow meter, such as meter 214 of FIG. 2, and integrates the flow rate by volume. Within the state machine, a condition is monitored that detects a change in flow rate, also referred to herein as dF/dt.

If dF/dt is detected as a large value and the function of interest is not yet complete, the system is baselined using the total flow, or in other words, the flow for the function of interest and the updated pressure value. In a BOP system, a situation where dF/dt is detected as a large value and the function is not yet complete is, in some embodiments, a second function is requested to be activated before the first function is completed (area B in FIG. 13 ). ~C) or a hydraulic connection failure, such as a broken hose. The logic loop continues until the function is completed or an error condition is determined. Error conditions may include situations where a given function is not completed or there is too much fluid present for a given function. For example, an error condition may be (1) when the function's elapsed time is longer than expected, such as 45 seconds, (2) the volume is greater than or equal to the required function volume, or (3) the function of interest is inactive. may occur in case of

Referring now to FIG. 3 , a flow diagram illustrating one embodiment of a top-level system diagram is provided. Although the experiments and simulations of the present disclosure were programmed, run, and verified using MATLAB® computer programs, those skilled in the art will understand that the systems and methods disclosed herein may be implemented using other software and/or hardware, such as, for example, Siemens® programmable logic controllers. and can be programmed and executed.

Referring now to FIG. 3 , a flow diagram illustrating one embodiment of a top-level system diagram is provided. In system 300, at step 302, a complete subsystem model of surface hydraulics (see, eg, independent control systems 204, 206, 208 in FIG. 2) is provided. Step 302 is further described below with respect to FIG. 4 . At step 304, a subsystem model is provided that models the hydraulic leak, the function of interest, and the unexpected function performed during the expected function (ie, the function of interest). Step 304 is further described below with respect to FIG. 5 .

In step 306, hardware timers and signals, essential components of the state machine, are defined. In some embodiments, step 306 includes defining an internal computer and/or programmable logic controller component and/or a stand-alone timing mechanism. At step 308, a state machine is implemented. In step 310, the maximum allowable dF/dt in system 300 is defined. The maximum allowable dF/dt can be dynamically adjusted to accommodate the exponentially increasing flow caused by the long pipe (rigid conduit) between the offshore hydraulic system and the subsea hydraulic system (see 212 in FIG. 2 ). Those skilled in the art will appreciate that additional steps may be applied for validation in a simulator, such as, for example, the simulator for system 300.

Referring now to FIG. 4 , a flow diagram illustrating one embodiment of an offshore hydraulics simulation is provided. System 400 further defines step 302 described with reference to FIG. 3 . At step 402, a functional model of the HPU is provided using a simple repository as an equivalent circuit, such as HPU 210 of FIG. 2, for example. At step 404, a hydraulic fluid sensor is optionally provided that measures the flow of GPM. At step 406, the total flow rate, optionally GPM, from the HPU skid model is calculated. Steps 404 and 406 represent flow meters. One physical embodiment of steps 404 and 406 is a fluid flow meter.

At step 408, a hydraulic pressure sensor is provided. At step 410, the pressure gauge of system 400 between the tubing from the HPU and the rigid conduit is used to create a "pressure transducer". Steps 408 and 410 together represent a pressure transmitter. Once again, step 402 represents the HPU. At step 412, a model of a rigid conduit, such as conduit 212 of FIG. 2, is provided. In some embodiments, up to 2 miles of rigid conduit may be used between offshore and subsea components of the BOP system, and any potential length of conduit may be accurately modeled. Those skilled in the art will appreciate that additional steps may be applied for verification in a simulator, such as for example the simulator for system 400.

Referring now to FIG. 5 , a flow diagram illustrating one embodiment of a subsea hydraulic system simulation is provided. System 500 further defines step 304 discussed with reference to FIG. 4 . At step 502 , hydraulic fluid from the offshore hydraulics simulation shown in FIG. 4 is provided to system 500 . Blocks 504, 506, and 508 represent a BPCS function, safety integrity level (SIL) function, and leakage flow, respectively. These blocks represent similar functions, but in block 504 the BPCS sync signal is unique, and in block 508 representing leakage flow, a lower flow rate is used to indicate leakage rather than the desired function.

In step 510, a signal representative of the repeating sequence is simulated and opens and closes the gate valve shown in step 512. The gate valve shown at step 512 is the valve that supplies operating fluid to the function of interest in the BOP stack. At step 514, a sync signal for the BPCS is calculated, which is only applicable to block 504 and not to blocks 506 and 508. Step 516 represents the pipe setting the flow rate approximately equal to that required for the BOP stack function. Those skilled in the art will appreciate that additional steps may be used for verification in a simulator, such as for example a simulator for system 500.

Referring now to FIG. 6, a flow chart for simulation of the system described in FIGS. 3-5 is provided. 6 provides one embodiment of functions that may be implemented in the state machine algorithm of the present disclosure. In the figures and examples described herein, the following abbreviations are applicable: A refers to the accumulated hydraulic fluid volume in gallons; F represents the working fluid flow; P stands for pressure; FM refers to flow meter readings from offshore hydraulics; PM refers to pressure gauge readings from offshore hydraulics; K stands for “hydraulic impedance” or head loss parameter (P/F); T represents time in seconds; error refers to a flag indicating whether an error was detected; S represents the maximum flow rate allowed by the system; S ₂ refers to a compensator that changes S (the maximum flow rate allowed by the system) over time. S ₂ may be adjusted if the product is used for extremely short piping or electronic products that do not contain capacitors.

A predefined subscript number indicates a temporary storage location for the indicated variable. For example, t ₂ is a temporary location used for processing time when the loop is running, or F ₄ is a location to store a temporary flow rate. The term "SilFnct" is a local representation of the BPCS synchronization variable described with respect to FIG. 5 .

In step 602 of Figure 6, state machine system 600 does not monitor the flow. At step 604, flow monitoring is initialized with the following functions: input: A = 0; Input: F ₁ = FM; Input: P ₁ = PM; Output: K = P ₁ /F ₁ ; input: flags = 0; input: dt = 0; input: t ₂ = 0; Input: t = 0; input: error = 0; Input: S ₂ = 5*S; Input: F ₄ = 0; and output: K2 = P ₁ /F ₁ . Step 604 is an initialization state that sets the starting value of the variable before the synchronization signal. At step 606, flow monitoring continues with the following functions: Input: F ₂ = FM; P ₂ = PM; Input: t = t+1; Input: dt = tt ₂ ; output: t ₂ = t; Output: A = A + ((FM-(PM/K))*dt/60); and output: S ₂ = S*(1+5^exp(-t/2)). Step 606 for flow monitoring is the main condition. During the monitoring state, flow meters and pressure meters are monitored, and time variables are updated in response to hardware clocks, such as hardware timers and signals, in step 306 of FIG. 3 . Also, a totalizer integrates the flow meter and an S ₂ corrector is calculated over time. At step 608, a store function is performed with input: F _i -F ₁ -(P ₁ /K) and output: flag = 1. When the first time is applied to the monitoring step 606, the step 608 to the storage function is executed. Step 608 captures an initial flow rate that may be attributable to leaks or other functions.

At step 610, the update function is performed with the following functions: input t = t+1; Input: K ₃ = PM/(FM-F ₄ ); and output: K =(K ₂ *K ₃ )/(K ₂ +K ₃ ). At step 612, the save primary S function is performed by: Input: F ₄ = F ₂ ; P ₄ = P ₂ ; and input: t = t-1. At step 614, a loop check is performed with output: dF = FM-F ₂ and input: t = t+1. Step 614 calculates the dF/dt used by the loop. If dF/dt is less than GPM, S ₂ , and the function is not complete, the system returns to monitoring step 606 . If dF/dt is too large, the process resets the baseline by calculating a new hydraulic impedance variable (K) in steps 610 and 612. Step 616 is a dummy state.

A dummy state is a transient state in which a loop executes two time cycles without updating a variable, providing synchronization between the loop and the physical device in the system.

Step 618 is an error condition of input: error=1. Step 618 is the point at which state machine system 600 determines that the function has failed. For example, an error condition may exist if A>75, i.e. the accumulated volume is greater than 75 gallons and the function of interest has not been completed. Otherwise, an error condition may exist, for example, if t>45 and A<67, i.e. elapsed time greater than 45 seconds and accumulated volume still less than 67 gallons after executing the function of interest. This is important because 45 seconds is the American Petroleum Institute (API) required BOP closure time and 67 gallons is the volume required for shear ram BOP closure. Those skilled in the art will appreciate that additional steps may be used for verification in a simulator, such as, for example, a simulator for system 600.

Referring now to FIG. 7 , a graph is provided showing compensator S ₂ varying S (maximum flow rate allowed by the system) over time. As mentioned in relation to FIG. 6, S refers to the maximum flow rate allowed by the system, and S ₂ refers to a compensator that changes S (the maximum flow rate allowed by the system) over time. It may be necessary to adjust S ₂ if the product is used for extremely short piping or electronic devices that do not contain capacitors. S ₂ compensates for the initial flow rate. Line 700 represents S, the maximum gallons per minute allowed by the system. The S ₂ compensator compensates for the transient response of the hydraulic system by adjusting the maximum allowable flow rate over time.

Referring now to FIG. 8 , a graph representing the repeating sequence blocks of the subsea hydraulic system described in FIG. 5 is provided. Line 802 represents “leakage” modeled in system 500, which is always modeled as active. Line 804 indicates that the BPCS (function of interest) is activated 25 seconds after the simulation begins. Line 806 indicates that the SIL is activated 50 seconds after the simulation begins. Line 808 indicates that the BPCS is disabled with an off state. Line 810 indicates that the SIL is disabled with an off state.

9 is a graph illustrating a flow according to one embodiment of a simulation of the systems and methods of the present disclosure. In a BOP stack, such as BOP stack 100 shown in FIG. 1 , there will be some amount of fluid leakage when the BOP stack receives fluid from a common conduit, such as common conduit 212 in FIG. 2 . In FIG. 9 , leakage is indicated by a constant amount by line 902 . The amount of leakage selected is a decision made during simulation. During validation, several different levels can be tested to ensure that the algorithm is stable against different errors in the system.

At 25 seconds, the BPCS function, represented by line 904, is activated for hydraulic supply to perform the function of the BOP stack. Initially, the flow rate increases rapidly to about 600 GPM and then decreases stepwise back to 0 GPM at about 74 seconds. At 50 seconds, the SIL function indicated by line 906 is activated, which requires additional hydraulic load from the sea. As can be seen, the SIL flow rate initially increases rapidly to about 500 GPM and then decreases to 0 GPM in about 100 seconds.

Still referring to FIG. 9 , line 908 represents the total flow rate measured from the sea to the BOP stack. Line 908 represents the sum of the flow of line 902 (leak), line 904 (function of interest) and line 906 (SIL function). In a BOP system, such as BOP system 200, the total flow recorded at sea, e.g., by meter 214 (represented by line 908 in FIG. ) and the SIL function indicated by line 906 (function of interest). As illustrated, line 908 is reduced and returns to leak flow only at about 104 seconds after both the BPCS function flow and the SIL function flow have ended.

10 is a graph showing pressure recorded at sea according to one embodiment of a simulation of the systems and methods of the present disclosure. Line 1002 represents the decrease in line pressure for the embodiment of the simulation shown in FIG. 9 . As total flow increases, line pressure decreases. These changes in line pressure and flow rate may be measured in some embodiments by a meter, such as meters 214 and 216 illustrated in the embodiment of FIG. 2 .

11 is a graph showing flow rates recorded at sea in accordance with one embodiment of a simulation of the systems and methods of the present disclosure. Line 908 represents an increase in flow rate for the embodiment of the simulation illustrated in FIG. 9 . As the total flow rate increases, the line pressure decreases (illustrated in FIG. 10 ). These changes in line pressure and flow rate may be measured in some embodiments by a meter, such as meters 214 and 216 illustrated in the embodiment of FIG. 2 . In some embodiments, a combination of aggregated pressure and flow measurements are used together to accurately measure hydraulic fluid flow rates to components of a BOP stack within a BOP system. Again, embodiments of the systems and methods simulated herein are simulated by MATLAB®, but other commercially available software may be used in combination with hardware to implement the systems and methods. Referring to Figures 10 and 11, since the pressure and flow curves are inverted shapes, the hydraulic impedance (P/F) is constant for a given situation.

12 is a graph showing GPM and total gallons flowing over time in one embodiment of a simulation of the systems and methods of the present disclosure. Line 908 represents the total flow rate in units of GPM from the example of the simulation described in FIG. 9 . An integration function may be provided within the simulation. Line 1202 represents the total number of gallons flowed into the BOP stack over time, which is calculated by integrating the total flow rate over time.

FIG. 13 shows results of using the systems and methods of the present disclosure to remove leaky and secondary functional flows from the total flow to obtain a fluid flow to a function of interest, also referred to as a BPCS function. As discussed with respect to FIG. 9 , line 908 represents the overall flow from sea to BOP stack. Line 908 represents the sum of the flow of line 902 (leak), line 904 (function of interest) and line 906 (SIL function). In a BOP system, such as BOP system 200, the total flow recorded at sea by meter 214 (represented by line 908 in FIG. 9) is the leakage represented by line 902, the leakage represented by line 904. It contains the sum of the function of interest (BPCS) and the SIL indicated by line 906. Line 1202 represents the total number of gallons flowed over time for the BOP stack, which is calculated by integrating the total flow rate over time.

Still referring to FIG. 13 , stepped line 1302 represents a state machine algorithm similar to that described in FIG. 6 , which compensates for flows that need to be ignored. For example, in the embodiment of FIG. 13 , the value of interest is (1) flow in GPM into the BPCS (function of interest) and/or (2) flow in gallons over time into the function of interest (BPCS). may be the total flow. In region A of FIG. 13, before 25 seconds, line 908 represents leakage in units of GPM. Line 1202 in this area represents the total leak in gallons at a given time as a function of integration. As the leakage accumulates in the integral function (line 1202), the state machine algorithm ignores the accumulated leakage amount, as shown by line 1302 branching from line 1202 while remaining at 0 GPM. In other words, a BOP system such as the BOP system 200 of FIG. 2 should not include a leakage amount on the side of the total amount of working fluid required to perform a given function.

In area B of FIG. 13 , between 25 and 50 seconds, line 908 for the total flow rate measured in the system includes leakage and flow from the BPCS function. The BPCS function is activated at 25 seconds. In this region, the line 1202 for the integrated total flow rate and the line 1302 for the state machine algorithm are offset by the leak amount, but have about the same slope. At 50 seconds, the SIL function, referred to as the second function, is activated. Thus, in region C, between about 50 seconds and about 76 seconds, line 908 represents the sum of the total leakage in the system plus the flow for the BPCS function and the flow for the SIL function. While line 1202 continues counting the total flow in area C, line 1302 shows that the state machine function algorithm is ignoring the flow from the second SIL function. The state machine algorithm calculates the flow rate going to the BPCS function by eliminating leaks and the flow rate from the SIL function by using the measurements provided by the flow meter and pressure gauge as described with respect to variable K in FIG. 6 .

For example, at 70 seconds of region C, line 1302 to the state machine algorithm indicates that the total flow rate that went through the BPCS function is about 68 gallons. State machine algorithms do not count leaks in the system and flows from the SIL function. At 70 seconds of section C of line 1202, the total flow collector indicates that the total flow is about 95 gallons. This includes the flow due to leakage, the flow from the first BPCS function and the flow from the second SIL function. Thus, line 1302 to the state machine algorithm provides an accurate reading of the total flow going to the function of interest, excluding leaks or sources of flow other than the secondary function.

As applicable, the value of interest includes when the BOP function is performed, or in other words when a sufficient amount of working fluid is provided to perform the function. For example, line 1304 shows that line 1302 for the state machine algorithm reaches about 73 gallons in about 76 seconds. However, based on line 1202 for integration of the total flow rate, it reaches about 76 gallons in about 62 seconds. Thus, the state machine algorithm provides an accurate measure of the achievement of a function by providing an accurate measure of the total fluid flow rate related to the function of interest.

14 is a graph depicting the results of using the systems and methods of the present disclosure to remove leakage flows and flows from a second BOP function from an aggregate flow to obtain an accurate reading of flows used to perform a first BOP function. . At 25 seconds, the state machine algorithm represented by line 1302 starts calculating the total volume of accumulated flow when the BPCS function is activated. Lines with similar labels indicate the same lines in the previous figures.

15 is a graph showing the results of using the systems and methods of the present disclosure to remove flow from a second BOP function and leakage flows from an aggregate flow to obtain an accurate reading of the flow used to perform the first BOP function. to be. In FIG. 15 , line 1502 represents a flow compensator function, such as the flow compensator function S ₂ described above with respect to FIGS. 6 and 7 . At 50 seconds when the second function, SIL, is activated, the rise time of line 908 representing the system's flow meter measuring total flow is slowed due to the length of a rigid conduit, such as conduit 212 illustrated in system 200. That is, there is a delay between the activation of the second function and the reading at the flow meter. Adding a flow compensator function, such as flow compensator function S ₂ , provides a straight line transition represented by line 1504, which is advantageous for performing state transitions.

16 shows a graph of the results of a modeled failure function in a system of the present disclosure. Figure 16 shows an experimental simulation where the BPCS timing driver is modified to deactivate the valve at the wrong time. Graphs are normalized to show all results. Line 1602 represents the faulty function, line 1604 represents the total flow rate, and line 1606 represents the error signal. Experimentation shows that in some embodiments, a minimum allowable flow rate needs to be added during the time the function is active. Additionally, in some embodiments, a maximum flow rate is added for certain functions to catch false positives caused by high flow rates, for example, when a hose is removed from a fixture.

17 provides one embodiment of a decision tree representing program logic for the systems and methods of the present disclosure. In a BOP system, such as BOP system 200, only one aggregate flow meter and one aggregate pressure gauge are provided. In Figure 17, S is the allowable flow rate step change, t is time, K is "hydraulic resistance", P is pressure, F is flow rate, and A is cumulative volume. At the start, at step 1702 A=0. In step 1704, a first flow rate F ₁ is measured and a first pressure P ₁ is measured. In step 1706, a value for K is calculated, where K=P ₁ /F ₁ . At step 1708, the BOP function is activated. In step 1710, a second flow rate measurement F ₂ is measured and a second pressure measurement P ₂ is measured. At step 1712, the logic checks whether A=0. If yes, at step 1714, the initial flow rate F _i is stored, F _i =F ₂ -(P ₂ /K). After step 1714, the process proceeds to step 1716.

If A is non-zero in step 1712, then in step 1716 the following is calculated: A = A +(F ₂ -P ₂ /K)*t. In step 1718, a third flow rate F ₃ is measured. In step 1720, ΔF is calculated for the change in flow rate as follows: ΔF=F ₃ -F ₂ . At step 1722, |ΔF| > S then the decision tree proceeds to step 1724. If |ΔF| is not greater than S, the decision tree proceeds to step 1710. In step 1724, when A is complete, or in other words the accumulated volume reaches the desired accumulated volume, the decision tree is completed in step 1726. If the accumulated volume does not reach the desired accumulated volume or if A is not complete, the decision tree transitions to step 1728 reading the first flow rate value (F ₄ ) and the fourth pressure value (P ₄ ). do. At step 1730, K is calculated once again according to K = P ₄ /(F ₄ -F _i ). After step 1730, the decision tree returns to step 1710 and the logic is performed until A is complete or the desired accumulated volume is achieved.

In various embodiments of the described disclosure, those skilled in the art will appreciate various types of memory, such as memory described in connection with various computers and servers, such as computers, computer servers, web servers, or other computers in embodiments of the present disclosure. It will be appreciated that is readable by a computer.

The unspecified singular form and the designated singular form include the plural unless the context clearly dictates otherwise.

Examples of computer-readable media include, but are not limited to: read-only memory (ROM), one or more non-volatile hard-coded media such as CD-ROMs and DVD-ROMs, or removable, electrically programmable read-only memory (EEPROM). ); recordable media such as floppy disks, hard disk drives, CD-R/RW, DVD-RAM, DVD-R/RW, DVD+R/RW, flash drives, memory sticks and other modern types of memory; and transmission-type media such as digital and analog communication links. For example, such media may contain operational instructions as well as instructions relating to the previously described system and method steps and operable on a computer. Those skilled in the art will understand that such media may be located in other locations instead of or in addition to the locations described for storing computer program products, including, for example, software. Those skilled in the art can understand that various previously described software modules or electronic components may be implemented and maintained by electronic hardware, software, or a combination of both, and that such embodiments may be considered by embodiments of the present disclosure. will understand

In the drawings and specifications, embodiments of a non-transitory computer-readable medium storing a method, system, and computer program of the present disclosure are disclosed, and specific terms are used, but the terms are used only for descriptive purposes and not for limiting purposes. it was used Embodiments of methods, systems, and non-transitory computer-readable media storing computer programs of the present disclosure have been described in great detail with particular reference to these illustrated embodiments. However, it is clear that various modifications and changes may be made within the spirit and scope of the embodiments of the method, system, and non-transitory computer-readable medium storing the computer program of the present disclosure described in the foregoing specification, and such modification and modifications are to be considered equivalents and parts of this disclosure.

Claims (20)

A method for accurately measuring and monitoring the accumulated volume of working fluid in a blowout preventer (BOP) system (200), the method comprising:
initializing a state machine algorithm (600) responsive to activation of the BOP function of interest;
measuring an initial hydraulic flow baseline and an initial pressure baseline to generate hydraulic impedance variables used in the state machine algorithm (600);
monitoring the total hydraulic flow rate and pressure of the BOP system 200 over time;
applying the hydraulic impedance variable to negate BOP system hydraulic flow unrelated to the BOP function of interest;
applying the state machine algorithm (600) to determine when the BOP function of interest is complete in response to the total accumulated volume of working fluid.
A method comprising a. 2. The method of claim 1, further comprising operating the state machine algorithm (600) to integrate the total hydraulic flow rate over time to obtain a total cumulative flow volume. The method of claim 1 further comprising modeling surface hydraulics of the BOP system (200), the surface hydraulics comprising: a hydraulic power unit (HPU) (210); rigid conduit 212; hydraulic reservoir; and a pressure gauge disposed proximate said HPU (216). The method of claim 1 further comprising modeling a subsea hydraulic system of the BOP system (200), wherein the subsea hydraulic system comprises: a valve supplying hydraulic fluid to the BOP function of interest; a signal to open and close the operating fluid supply valve for modeling purposes; a synchronization signal for the BOP function of interest; and a supply of hydraulic fluid from a marine hydraulic system. The method of claim 1 further comprising setting a maximum allowable change in hydraulic flow per unit time in the BOP system. 2. The method of claim 1, wherein the BOP system hydraulic flow unrelated to the BOP function of interest is selected from the group consisting of hydraulic flow from a leak in the BOP system and hydraulic flow associated with an auxiliary BOP function. 2. The method of claim 1, further comprising operating the state machine algorithm (600) to determine a fault state, the fault state being responsive to an elapsed time from activation of the BOP function of interest. and responding to a failure to operate a BOP function of interest. 2. The method of claim 1, further comprising applying a flow compensator function to effect state transitions. The method of claim 1 , further comprising applying a minimum allowable flow rate and a maximum allowable flow rate while the BOP function of interest is active. 2. The method of claim 1, wherein the BOP function of interest is a Basic process control system function, and the BOP system hydraulic flow independent of the BOP function of interest is a Safety integrity level function and a BOP system function. characterized in that it is a hydraulic leak. A system for accurately measuring and monitoring the accumulated volume of working fluid in a blowout preventer (BOP) function of interest, the system comprising:
A marine hydraulic system component comprising a hydraulic power unit (HPU) (210) and at least two control systems (204, 206), said at least two control systems (204, 206) being fluidly coupled to said HPU (210). A marine hydraulic system component that is fluidly coupled and independently operable so that the hydraulic fluid flows from the HPU 210;
A subsea BOP component comprising a BOP stack (100), wherein the BOP stack (100) includes BOP stack functions operable to be performed by the flow of hydraulic fluid from the HPU (210). (100, 122);
A fluid flow meter disposed near a rigid conduit 212 between the HPU 210 and the BOP stack 100 and operable to measure the total flow of working fluid from the HPU 210 to the BOP stack 100. (214);
A manometer disposed near the HPU 210 supplying the working fluid to the rigid conduit 212 and operable to measure the line pressure of the total flow of the working fluid from the HPU 210 to the BOP stack 100 ( 216);
A processing unit operable to perform a method comprising the steps of:
Including, the steps are:
initializing a state machine algorithm (600) responsive to activation of the BOP function of interest;
applying a measured initial hydraulic flow rate reference value and an initial pressure reference value to create a hydraulic impedance variable used in the state machine algorithm (600);
Monitoring the total flow of working fluid from the HPU 210 to the BOP stack 100 and the line pressure of the total flow of the working fluid from the HPU 210 to the BOP stack 100 over time;
applying the hydraulic impedance variable to negate BOP system hydraulic flow unrelated to the BOP function of interest; and
applying the state machine algorithm (600) to determine when the BOP function of interest is complete in response to the total accumulated volume of working fluid.
A system comprising a. 12. The method of claim 11, wherein the method operates the state machine algorithm (600) to integrate over time the total flow of working fluid from the HPU (210) to the BOP stack (100) to obtain a total cumulative flow volume. The system further comprising the step of doing. 12. The method of claim 11, further comprising modeling an offshore hydraulic system of the BOP system, the offshore hydraulic system comprising: a hydraulic power unit (HPU) (210); rigid conduit 212; hydraulic reservoir; pressure gauge 216; and a fluid flow meter (214). 12. The method of claim 11 further comprising modeling a subsea hydraulic system of the BOP system, the subsea hydraulic system comprising: a valve that supplies hydraulic fluid to the BOP function of interest; a signal to open and close the operating fluid supply valve for modeling purposes; a synchronization signal for the BOP function of interest; and a flow of working fluid from the HPU. 12. The system of claim 11, wherein the method further comprises setting a maximum allowable change in hydraulic flow per unit time in the BOP system. 12. The system of claim 11, wherein the BOP system hydraulic flow unrelated to the BOP function of interest is selected from the group consisting of hydraulic flow from a leak in the BOP system and hydraulic flow associated with an auxiliary BOP function. 12. The method of claim 11, further comprising operating the state machine algorithm (600) to determine a fault condition, the fault condition being responsive to an elapsed time from activation of the BOP function of interest. A system characterized in that it responds to the failure of the operation of the target BOP function. 12. The system of claim 11, wherein the method further comprises applying a flow compensator function to effect a state transition. 12. The system of claim 11, wherein the method further comprises applying a minimum allowable flow rate and a maximum allowable flow rate while the BOP function of interest is active. A tangible non-transitory memory medium that stores a set of instructions, wherein the set of instructions when executed by a processing unit causes the processing unit to perform a method comprising the steps of: As a device characterized in that,
These steps are:
initializing a state machine algorithm (600) responsive to activation of the BOP function of interest;
applying a measured initial hydraulic flow rate reference value and an initial pressure reference value to create a hydraulic impedance variable used in the state machine algorithm (600);
Monitoring the total flow of the working fluid from the HPU 210 to the BOP stack 100 and the line pressure of the total flow of the working fluid from the HPU 210 to the BOP stack 100 over time;
applying the hydraulic impedance variable to negate BOP system hydraulic flow unrelated to the BOP function of interest; and
applying the state machine algorithm (600) to determine when the BOP function of interest is complete in response to the total accumulated volume of working fluid.
A device comprising a.

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