Composite and concurrent fault diagnosis method for offshore oil underwater production system

Abstract

The invention belongs to the technical field of petroleum engineering, and particularly relates to a composite and concurrent fault diagnosis method for an offshore oil underwater production system. According to the composite and concurrent fault diagnosis method for the offshore oil underwater production system, whether composite and concurrent faults occur in the offshore oil underwater production system can be accurately judged, and the existing composite and concurrent faults can be accurately identified; therefore, technical support is provided for long-term and safe service of the offshore oil underwater production system. The invention provides a composite and concurrent fault diagnosis method for an offshore oil underwater production system. The offshore oil underwater production system compounding and concurrent fault diagnosis method comprises the following steps of offshore oil underwater production system fault diagnosis, offshore oil underwater production system compounding and concurrent fault judgment, and offshore oil underwater production system compounding and concurrent fault identification.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum engineering, and in particular relates to a composite and concurrent fault diagnosis method for an offshore oil underwater production system. Background Art

[0002] Marine oil and gas is an important source of oil and gas supply in my country, and its underwater production system is the core of marine oil and gas exploitation and production. Among them, the underwater production system is mainly used to collect underwater oil and gas and control the entire process of oil and gas production; therefore, the safe and stable operation of the marine oil underwater production system is an important guarantee for the continuity and stability of marine oil and gas production. Since the marine oil underwater production system has been serving in harsh underwater environments for a long time, its troubleshooting process has many characteristics such as high troubleshooting difficulty and untimely troubleshooting, which makes the marine oil underwater production system prone to complex and concurrent faults; and this type of fault is difficult to diagnose and identify due to the mixture of multiple fault signals.

[0003] After further research, it was found that there is no mature product in the existing technology that can be used to diagnose composite and concurrent faults in offshore oil underwater production systems. The composite and concurrent fault diagnosis is mostly obtained through manual experience judgment of on-site technicians, making it difficult to achieve automatic fault alarm and intelligent fault location and disposal, resulting in the inability to make timely and accurate judgments when composite and concurrent faults occur, and missing the best processing time. Therefore, it is particularly urgent and necessary to develop a method that can accurately diagnose composite and concurrent faults in offshore oil underwater production systems. Summary of the invention

[0004] The present invention provides a method for diagnosing composite and concurrent faults of an offshore oil underwater production system. The method can accurately determine whether composite and concurrent faults have occurred in the offshore oil underwater production system, and can accurately identify the existing composite and concurrent faults, thereby providing technical support for the long-term and safe service of the offshore oil underwater production system.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: The present invention provides a method for diagnosing composite and concurrent faults of an offshore oil underwater production system, comprising the following steps: Step S101: Initializing the status of each component feedback node in the offshore oil underwater production system; Step S102: acquiring data of each sensor in the offshore oil underwater production system, and determining the status of the sensor according to the data; Step S103: Calculating the probability of failure of each component in the offshore oil underwater production system; Step S104: determining whether any component in the offshore oil underwater production system has failed; Step S201: obtaining the switch status of each component in the offshore oil underwater production system; Step S202: updating the fault parameters of each component in the offshore oil underwater production system; Step S203: Calculating the oil pressure value at the outlet of each component in the offshore oil underwater production system; Step S204: Calculate the error between the actual oil pressure value at the outlet of each component in the offshore oil underwater production system and the oil pressure value at the outlet of each component in the offshore oil underwater production system calculated in step S203; Step S205: when all errors calculated in step S204 do not exceed the preset component error threshold, it is determined that only a single fault has occurred in the offshore oil underwater production system; when all errors calculated in step S204 exceed the preset component error threshold, the number of repetitions of initialization number=number+1, and step S206 is continued; Step S206: if the number of repetitions of the initialization number>n, it is determined that a composite and concurrent fault has occurred in the offshore oil underwater production system; Otherwise, all errors exceeding the preset component error threshold are sorted in ascending order of numbers, and the first error number k with the smallest number is selected; and the state of the component feedback node corresponding to the first error number k is updated to normal, and the states of the other component feedback nodes remain unchanged, and the process returns to step S103; Step S301: Select the diagnosis result that minimizes the sum of all errors e calculated in step S204, and record the faulty component C diagnosed in the diagnosis result. b ; Step S302: When the sum of all errors e is determined to be the smallest, each error e 1 、e 2 ,…,e t The corresponding error state E 1 、E 2 ,…,E t ; Step S303: Based on the Bayesian network, assume that each error state E 1 、E 2 ,…,E t and P(C b ) = 100%, calculate the fault component C b Other components C 1 , C 2 ,…,C i ,…,C n (i≠b) failure probability P(C i ); Step S304: Select faulty component C b Other components C 1 , C 2 ,…,C i ,…,C n (i≠b) failure probability P(C i ) has the largest failure probability P(C a ), the failure probability P (C a ) corresponds to the faulty component C a and the faulty component C b Together they serve as the diagnostic results for complex and concurrent faults in offshore oil underwater production systems.

[0006] Preferably, the probability of failure of each component in the offshore oil underwater production system in step S103 satisfies: Formula (1); In formula (1), P(C i |S 1 (d 1 ), S 2 (d 2 ),…,S t (d t ), SC i ) means that when S is known 1 (d 1 )、S 2 (d 2 ),…,S t (d t ) and SC i In a given state, component C i Probability of failure; P(C 1 ,C 2 ,…,C n ) represents the joint probability of the parent node; P(S m (d m ),SC i |C 1 ,C 2 ,…,C n ) indicates that C 1 , C 2 ,…,C n When in state, S m The node is at S m (d m ), while SC i The conditional probability of being in a given state.

[0007] Preferably, the process of determining whether a failure occurs in each component of the offshore oil underwater production system in step S104 is specifically described as follows: Select the maximum probability value among the probabilities of failures occurring in each component of the subsea production system for offshore oil calculated in step S103; If the maximum probability value exceeds the preset component failure probability threshold, it is determined that the component corresponding to the maximum probability value has failed; otherwise, it is determined that no failure has occurred in the subsea production system for offshore oil.

[0008] Preferably, the hydraulic pressure values of the oil at the outlets of the components in the subsea production system for offshore oil in S203 satisfy: Equation (2); In Equation (2), i = 1, 2,..., t; Pv i-1 represents the pipeline pressure before the i-th component; represents the crude oil density; g is the acceleration due to gravity; h i-1 represents the height of the center of the pipeline before the i-th component, with the wellhead as the reference height; Pv i represents the pipeline pressure after the i-th component; h i-1 represents the height of the center of the pipeline after the i-th component, with the wellhead as the reference height; represents the pressure loss caused by the i-th component; wherein each Pv i is calculated from the previous pressure Pv i-1 and Pv 1 is the actual pressure of each production loop in the subsea production system for offshore oil, is the control parameter of the i-th component.

[0009] Preferably, the error between the actual hydraulic pressure value of the oil at the outlet of each component in the subsea production system for offshore oil in step S204 and the hydraulic pressure value of the oil at the outlet of each component in the subsea production system for offshore oil calculated in step S203 satisfies: Equation (3); In Equation (3), i = 2, 3,..., t; e i is the error between the actual hydraulic pressure value of the oil at the outlet of the i-th component in the subsea production system for offshore oil and the calculated hydraulic pressure value; PT i is the actual hydraulic pressure value of the oil at the i-th valve component in the subsea production system for offshore oil.

[0010] The present invention provides a method for diagnosing compound and concurrent failures of a subsea production system for offshore oil. The method for diagnosing compound and concurrent failures of the subsea production system for offshore oil includes the following steps: steps of diagnosing failures of the subsea production system for offshore oil, judging compound and concurrent failures of the subsea production system for offshore oil, and identifying compound and concurrent failures of the subsea production system for offshore oil.

[0011] A method for diagnosing complex and concurrent faults of an underwater offshore oil production system having the above-mentioned step characteristics has at least the following technical advantages compared to the prior art: the method for diagnosing complex and concurrent faults of an underwater offshore oil production system can accurately determine whether complex and concurrent faults have occurred in the underwater offshore oil production system, and can accurately identify existing complex and concurrent faults, thereby providing technical support for the long-term and safe service of the underwater offshore oil production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the following drawings: Figure 1 One of the flow charts of a composite and concurrent fault diagnosis method for an offshore oil underwater production system provided by the present invention; Figure 2 The present invention provides a second flow chart of a method for diagnosing composite and concurrent faults in an offshore oil underwater production system. DETAILED DESCRIPTION

[0013] The present invention provides a method for diagnosing composite and concurrent faults of an offshore oil underwater production system. The method can accurately determine whether composite and concurrent faults have occurred in the offshore oil underwater production system, and can accurately identify the existing composite and concurrent faults, thereby providing technical support for the long-term and safe service of the offshore oil underwater production system.

[0014] The present invention provides a method for diagnosing composite and concurrent faults in an offshore oil underwater production system. Figure 1 With Figure 2 As shown, it specifically includes the following steps: Step S101: Initialize the status of each component feedback node in the offshore oil underwater production system.

[0015] Among them, each component feedback node is represented by SC 1 , SC 2 ,…,SC n The initial status of each component feedback node is marked as unknown, that is, SC 1 (N), SC 2 (N),…,SC n (N); The initialized number of repetitions is marked as 0.

[0016] Step S102: Acquire data of each sensor in the offshore oil underwater production system, and determine the status of the sensor according to the data.

[0017] Among them, each sensor is represented by S 1 , S 2 ,…,S t ; The state of each sensor is represented by S 1 (d 1 )、S 2 (d 2 ),…,S t (d t ).

[0018] Step S103: Calculate the probability of failure of each component in the offshore oil underwater production system. 1 , C 2 ,…,C n .

[0019] On the basis of completing steps S101 and S102, step S103 is further implemented. As a preferred embodiment of the present invention, the probability of failure of each component in the offshore oil underwater production system in step S103 satisfies: Formula (1); In formula (1), P(C i |S 1 (d 1 ), S 2 (d 2 ),…,S t (d t ), SC i ) means that when S is known 1 (d 1 )、S 2 (d 2 ),…,S t (d t ) and SC i In a given state, component C i Probability of failure; P(C 1 ,C 2 ,…,C n ) represents the joint probability of the parent node; P(S m (d m ),SC i |C 1 ,C 2 ,…,C n ) indicates that C 1 , C 2 ,…,C n When in state, S mThe node is at S m (d m ), while SC i Conditional probability under a given state. Through the above formula (1), the probability of failure of each component in the offshore oil underwater production system is preliminarily calculated.

[0020] Step S104: Determine whether any component in the offshore oil underwater production system has failed.

[0021] After completing step S103, step S104 is further implemented. The process of determining whether each component in the offshore oil underwater production system has failed can be specifically described as: selecting the maximum probability value of the failure probability of each component in the offshore oil underwater production system calculated in step S103.

[0022] If the maximum probability value exceeds the preset component failure probability threshold, it is determined that the component corresponding to the maximum probability value has failed; otherwise, it is determined that no failure has occurred in the offshore oil underwater production system.

[0023] For example, the preset component failure probability threshold is selected to be 0.85. If at this time, the maximum probability value exceeds the preset component failure probability threshold of 0.85, it can be determined that the component corresponding to the maximum probability value has failed, and further detection and diagnosis can be performed to determine whether a composite and concurrent failure has occurred in the offshore oil underwater production system. On the contrary, when the maximum probability value does not exceed the preset component failure probability threshold of 0.85, it means that no failure has occurred in the offshore oil underwater production system, and there is no need to implement the following steps to diagnose whether a composite and concurrent failure has occurred in the offshore oil underwater production system.

[0024] Step S201: Obtain the switch status of each component in the offshore oil underwater production system.

[0025] The switch states of each component in the offshore oil underwater production system are described as follows: x If the status is on, the control parameters of the corresponding component Marked as 1; if component C x If the status is closed, the control parameters of the corresponding component Marked as 0.

[0026] Step S202: updating the fault parameters of each component in the offshore oil underwater production system.

[0027] The updating method of the fault parameters of each component in the offshore oil underwater production system is specifically described as follows: If component C x In a fault state, the fault parameters of the corresponding component Update to 0; if component Cx In normal state, the fault parameters of the corresponding components Updated to 1.

[0028] Step S203: Calculate the oil pressure value at the outlet of each component in the offshore oil underwater production system.

[0029] On the basis of completing steps S201 and S202, step S203 is further implemented. As a preferred embodiment of the present invention, the oil pressure value at the outlet of each component in the offshore oil underwater production system in step S203 satisfies: Formula (2); In formula (2), i=1, 2, …, t; Pv i-1 represents the pipeline pressure before the i-th component; represents the density of crude oil; g is the acceleration due to gravity; h is i-1 Pv represents the height of the center of the pipeline in front of the i-th component, with the wellhead as the reference height; i represents the pipeline pressure after the i-th component; h i-1 represents the height of the pipeline center after the i-th component, with the wellhead as the reference height; represents the pressure loss caused by the i-th component; Among them, each Pv i Both are determined by the previous pressure Pv i-1 Calculated, and Pv 1 is the actual pressure of each production circuit in the offshore oil underwater production system, is the control parameter of the i-th component.

[0030] Step S204: Calculate the error between the actual oil pressure value at the outlet of each component in the offshore oil underwater production system and the oil pressure value at the outlet of each component in the offshore oil underwater production system calculated in step S203.

[0031] On the basis of completing step S203, step S204 is further implemented. As a preferred embodiment of the present invention, the error between the actual oil pressure value at the outlet of each component in the offshore oil underwater production system in step S204 and the oil pressure value at the outlet of each component in the offshore oil underwater production system calculated in step S203 satisfies: Formula (3); In formula (3), i = 2, 3, …, t; e i is the error between the actual oil pressure value at the outlet of the i-th component in the offshore oil underwater production system and the calculated oil pressure value; PT i is the actual oil pressure value of the i-th valve component in the offshore oil underwater production system.

[0032] It should be noted that the actual oil pressure value PT at the outlet of the i-th component in the offshore oil underwater production system is i It is an actual measurement value, which is obtained by technicians directly reading data from the offshore oil underwater production system; and the oil pressure value of each component outlet in the offshore oil underwater production system calculated in step S203 is a calculated predicted value.

[0033] In this process, by evaluating the error between the above two data, it is possible to predict whether a single fault has occurred in the corresponding component; and when the possibility of compound and concurrent faults in the offshore oil underwater production system cannot be ruled out, the diagnosis of compound and concurrent faults in the offshore oil underwater production system can be further implemented. This is also the most prominent and significant technical difference between the offshore oil underwater production system compound and concurrent fault diagnosis method provided by the present invention and the prior art.

[0034] Step S205: When all errors calculated in step S204 do not exceed the preset component error threshold, it is determined that only a single fault has occurred in the offshore oil underwater production system; when all errors calculated in step S204 exceed the preset component error threshold, the number of initialization repetitions number=number+1, and continue to implement step S206.

[0035] After completing step S204, step S205 is further implemented. It is worth noting that, assuming that the preset pressure error threshold is 5%. That is, if the e calculated by formula (3) in step S204 is i If both are less than 5%, it can be determined that there are no compound and concurrent faults in the offshore oil underwater production system, but only a single fault occurs. Otherwise, the possibility of compound and concurrent faults in the offshore oil underwater production system cannot be ruled out.

[0036] Step S206: if the number of repetitions of the initialization number>n, it is determined that a composite and concurrent fault has occurred in the offshore oil underwater production system; Otherwise, all errors exceeding the preset component error threshold are sorted in ascending order, and the first error number k with the smallest number is selected; and the state of the component feedback node corresponding to the first error number k is updated to normal: that is, SC k (Y), the states of the other component feedback nodes remain unchanged, and the process returns to step S103.

[0037] It is worth noting that n is the number of times the technicians preset the elimination of compound and concurrent faults in the offshore oil underwater production system. Therefore, when n satisfies the initialization repetition number number>n, it is determined that compound and concurrent faults have indeed occurred in the offshore oil underwater production system; and when n satisfies number≤n, it is necessary to further detect and verify whether compound and concurrent faults have occurred in the offshore oil underwater production system.

[0038] The process of compound and concurrent fault detection can be referred to as follows: first, the first error number k with the smallest number is selected from all errors that exceed the preset component error threshold, and the status of the component feedback node corresponding to it is updated to normal; and the cycle is started from this point to specifically determine which component, except for the component that has been confirmed to have a fault, is most likely to have a compound and concurrent fault.

[0039] Step S301: Select the diagnosis result that minimizes the sum of all errors e calculated in step S204, and record the faulty component C diagnosed in the diagnosis result. b ; where the sum of all errors, e, satisfies: e=e 1 +e 2 +…+e t .

[0040] Step S302: When the sum of all errors e is determined to be the smallest, each error e 1 、e 2 ,…,e t The corresponding error state E 1 、E 2 ,…,E t .

[0041] Step S303: Based on the Bayesian network, assume that each error state E 1 、E 2 ,…,E t and P(C b ) = 100%, calculate the fault component C b Other components C 1 , C 2 ,…,C i ,…,C n (i≠b) failure probability P(C i ).

[0042] Step S304: Select faulty component C b Other components C 1 , C 2 ,…,C i ,…,C n (i≠b) failure probability P(C i) has the largest failure probability P(C a ), the failure probability P (C a ) corresponds to the faulty component C a and the faulty component C b Together they serve as the diagnostic results for complex and concurrent faults in offshore oil underwater production systems.

[0043] After completing steps S301, S302, and S303, step S304 is further implemented. It is worth noting that step S204 calculates the fault component C b Among them, the faulty component C b The corresponding diagnosis result is when the sum of all errors e is the smallest. b If the diagnosis is confirmed, the faulty component C is further removed by S302 and S303. b The failure probability of the remaining components is calculated.

[0044] It should be noted that the faulty component C has been diagnosed and identified in the previous steps. b Therefore, we choose the one that will have the largest failure probability P(C a ) corresponds to the faulty component C a and the faulty component C b Together they serve as the diagnostic results for complex and concurrent faults in offshore oil underwater production systems.

[0045] Thus, the method for diagnosing composite and concurrent faults of an offshore oil underwater production system provided by the present invention not only realizes the diagnosis of composite and concurrent faults of an offshore oil underwater production system, but also realizes the accurate identification of components where composite and concurrent faults occur when composite and concurrent faults do exist.

[0046] Finally, in order to prove the authenticity and reliability of the detection of a composite and concurrent fault diagnosis method for an offshore oil underwater production system provided by the present invention, the applicant provides a set of valve data in an offshore oil underwater production system, and performs comparative analysis on the diagnosis results based on the existing fault diagnosis method and the composite and concurrent fault diagnosis method provided by the present invention.

[0047] Table 1 shows the valve data in the offshore oil underwater production system.

[0048]

[0049] After statistics, it is found that the existing fault diagnosis methods have an accuracy rate of 98% in judging the normal state of offshore oil underwater production systems, and an accuracy rate of 90% in judging the existence of a single fault in offshore oil underwater production systems; while the accuracy rate for judging the existence of compound and concurrent faults in offshore oil underwater production systems is only 85%. This is because the existing fault diagnosis methods often cannot distinguish between single faults and compound faults in offshore oil underwater production systems.

[0050] In sharp contrast, the composite and concurrent fault diagnosis method provided by the present invention can diagnose 99%, 93%, and 92% of the offshore oil underwater production system when it is normal, has a single fault, and has composite and concurrent faults, respectively. This proves that the composite and concurrent fault diagnosis method provided by the present invention is more reliable and accurate than the prior art.

[0051] The present invention provides a method for diagnosing composite and concurrent faults of an offshore oil underwater production system. The method comprises the following steps: diagnosing an offshore oil underwater production system fault, judging a composite and concurrent fault of an offshore oil underwater production system, and identifying a composite and concurrent fault of an offshore oil underwater production system.

[0052] A method for diagnosing complex and concurrent faults of an underwater offshore oil production system having the above-mentioned step characteristics has at least the following technical advantages compared to the prior art: the method for diagnosing complex and concurrent faults of an underwater offshore oil production system can accurately determine whether complex and concurrent faults have occurred in the underwater offshore oil production system, and can accurately identify existing complex and concurrent faults, thereby providing technical support for the long-term and safe service of the underwater offshore oil production system.

[0053] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A composite and concurrent fault diagnosis method for an offshore oil underwater production system, characterized in that: The steps include: Step S101: Initialize the status of each component feedback node in the offshore oil underwater production system; Step S102: acquiring data of each sensor in the offshore oil underwater production system, and determining the status of the sensor according to the data; Step S103: Calculating the probability of failure of each component in the offshore oil underwater production system; Step S104: determining whether any component in the offshore oil underwater production system has failed; Step S201: obtaining the switch status of each component in the offshore oil underwater production system; Step S202: updating the fault parameters of each component in the offshore oil underwater production system; Step S203: Calculating the oil pressure value at the outlet of each component in the offshore oil underwater production system; Step S204: Calculate the error between the actual oil pressure value at the outlet of each component in the offshore oil underwater production system and the oil pressure value at the outlet of each component in the offshore oil underwater production system calculated in step S203; Step S205: when all errors calculated in step S204 do not exceed the preset component error threshold, it is determined that only a single fault has occurred in the offshore oil underwater production system; when all errors calculated in step S204 exceed the preset component error threshold, the number of repetitions of initialization number=number+1, and step S206 is continued; Step S206: if the number of repetitions of the initialization number>n, it is determined that a composite and concurrent fault has occurred in the offshore oil underwater production system; Otherwise, all errors exceeding the preset component error threshold are sorted in ascending order of numbers, and the first error number k with the smallest number is selected; and the state of the component feedback node corresponding to the first error number k is updated to normal, and the states of the other component feedback nodes remain unchanged, and the process returns to step S103; Step S301: Select the diagnosis result that minimizes the sum of all errors e calculated in step S204, and record the faulty component C diagnosed in the diagnosis result. b ; Step S302: When the sum of all errors e is determined to be the smallest, the errors e1, e2, ..., e t The corresponding error states E1, E2, ..., E t ; Step S303: Based on the Bayesian network, assume that each error state E1, E2, ..., E t and P(C b ) = 100%, calculate the fault component C b In addition, the remaining components C1, C2, ..., C i ,…,C n The failure probability P (C i ), where i≠b; Step S304: Select faulty component C b In addition, the remaining components C1, C2, ..., C i ,…,C n The failure probability P (C i ) has the largest failure probability P(C a ), where i≠b; the failure probability P(C a ) corresponds to the faulty component C a and the faulty component C b Together they serve as the diagnostic results for complex and concurrent faults in offshore oil underwater production systems.

2. The method for composite and concurrent fault diagnosis of an offshore oil underwater production system according to claim 1, characterized in that: The probability of failure of each component in the offshore oil underwater production system in step S103 satisfies: Formula (1); In formula (1), P(C i |S1(d1),S2(d2),…,S t (d t ), SC i ) means that when S1(d1), S2(d2), …, S t (d t ) and SC i In a given state, component C i The probability of failure; P(C1,C2,…,C n ) represents the joint probability of the parent node; P(S m (d m ),SC i |C1,C2,…,C n ) means that C1, C2, …, C n When in state, S m The node is at S m (d m ), while SC i The conditional probability of being in a given state.

3. The method for composite and concurrent fault diagnosis of an offshore oil underwater production system according to claim 1, characterized in that: The process of determining whether a failure has occurred in each component of the offshore oil underwater production system in step S104 is specifically described as follows: Selecting the maximum probability value among the probabilities of failure of each component in the offshore oil underwater production system calculated in step S103; If the maximum probability value exceeds the preset component failure probability threshold, it is determined that the component corresponding to the maximum probability value has failed; otherwise, it is determined that no failure has occurred in the offshore oil underwater production system.

4. The method for composite and concurrent fault diagnosis of an offshore oil underwater production system according to claim 1, characterized in that: The oil pressure values ​​at the outlets of each component in the offshore oil underwater production system in S203 satisfy: Formula (2); In formula (2), i=1, 2, …, t; Pv i-1 represents the pipeline pressure before the i-th component; represents the density of crude oil; g is the acceleration due to gravity; h is i-1 Pv represents the height of the center of the pipeline in front of the i-th component, with the wellhead as the reference height; i represents the pipeline pressure after the i-th component; h i-1 represents the height of the pipeline center after the i-th component, with the wellhead as the reference height; represents the pressure loss caused by the i-th component; Among them, each Pv i Both are determined by the previous pressure Pv i-1 Calculated, and Pv1 is the actual pressure of each production circuit in the offshore oil underwater production system, is the control parameter of the i-th component.

5. The method for composite and concurrent fault diagnosis of an offshore oil underwater production system according to claim 1, characterized in that: The error between the actual oil pressure value at the outlet of each component in the offshore oil underwater production system in step S204 and the oil pressure value at the outlet of each component in the offshore oil underwater production system calculated in step S203 satisfies: Formula (3); In formula (3), i = 2, 3, …, t; e i is the error between the actual oil pressure value at the outlet of the i-th component in the offshore oil underwater production system and the calculated oil pressure value; PT i is the actual oil pressure value of the i-th valve component in the offshore oil underwater production system.

Images