Compound and Concurrent Fault Diagnosis Method for Subsea Production Systems in Offshore Oil

Abstract

The present invention belongs to the technical field of petroleum engineering, and particularly relates to a method for diagnosing compound and concurrent faults in an offshore oil underwater production system. This method for diagnosing compound and concurrent faults in an offshore oil underwater production system can accurately determine whether compound and concurrent faults have occurred in the offshore oil underwater production system, and can precisely identify the existing compound and concurrent faults, thereby providing technical support for the long-term and safe operation of the offshore oil underwater production system. The present invention provides a method for diagnosing compound and concurrent faults in an offshore oil underwater production system, and this method for diagnosing compound and concurrent faults in an offshore oil underwater production system includes the following steps: steps of fault diagnosis of the offshore oil underwater production system, judgment of compound and concurrent faults in the offshore oil underwater production system, and identification of compound and concurrent faults in the offshore oil underwater production system.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil engineering, and particularly relates to a method for diagnosing compound and concurrent faults of an underwater production system for offshore oil Background Art

[0002] As an important source of oil and gas supply in China, the underwater production system for offshore oil and gas is the core for realizing the exploitation and production of offshore oil and gas. Among them, the underwater production system is mainly used for collecting underwater oil and gas and controlling the whole process of oil and gas production; therefore, the safe and stable operation of the underwater production system for offshore oil is an important guarantee for the continuity and stability of offshore oil and gas production. Due to the long-term service of the underwater production system for offshore oil in a harsh underwater environment, the process of troubleshooting has many characteristics such as high difficulty in troubleshooting and untimely troubleshooting, so the underwater production system for offshore oil is prone to compound and concurrent faults; and such faults are difficult to diagnose and identify due to the mixing of multiple fault signals.

[0003] After further research, it is found that there is no mature product in the prior art that can be used to diagnose compound and concurrent faults of the underwater production system for offshore oil. Most of the diagnoses of such compound and concurrent faults are obtained through the manual experience judgment of on-site technicians, so it is difficult to achieve automatic fault alarm and intelligent fault location and disposal, resulting in the inability to make a timely and accurate judgment when compound and concurrent faults occur and missing the best treatment time. Therefore, it is particularly urgent and necessary to develop a method that can accurately diagnose compound and concurrent faults of the underwater production system for offshore oil. Summary of the Invention

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

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for diagnosing compound and concurrent faults of an underwater production system for offshore oil, including the following steps:

[0007] Step S101: Initialize the states of the feedback nodes of each component in the underwater production system for offshore oil;

[0008] Step S102: Obtain the data of each sensor in the underwater production system for offshore oil, and assign the state to the sensor according to the data;

[0009] Step S103: Calculate the probabilities of failures occurring in each component of the subsea production system for offshore oil.

[0010] Step S104: Determine whether a failure has occurred in each component of the subsea production system for offshore oil.

[0011] Step S201: Obtain the switch states of each component in the subsea production system for offshore oil.

[0012] Step S202: Update the failure parameters of each component in the subsea production system for offshore oil.

[0013] Step S203: Calculate the oil pressure values at the outlets of each component in the subsea production system for offshore oil.

[0014] Step S204: Calculate the error between the actual oil pressure values at the outlets of each component in the subsea production system for offshore oil and the oil pressure values at the outlets of each component in the subsea production system for offshore oil calculated in Step S203.

[0015] Step S205: When all the errors calculated in Step S204 do not exceed the preset component error threshold, determine that only a single failure has occurred in the subsea production system for offshore oil; when all the errors calculated in Step S204 exceed the preset component error threshold, set the initialized number of repetitions number = number + 1, and continue to implement Step S206.

[0016] Step S206: If the initialized number of repetitions number > n, determine that a combined and concurrent failure has occurred in the subsea production system for offshore oil.

[0017] Otherwise, sort all the errors exceeding the preset component error threshold in ascending order of their numbers, select the first error number k with the smallest number among them; and update the state of the component feedback node corresponding to the first error number k to normal, while keeping the states of the other component feedback nodes unchanged, and return to implement Step S103.

[0018] Step S301: Select the diagnostic result when the sum e of all the errors calculated in Step S204 is the smallest, and record the failed component C diagnosed by the diagnostic result b ;

[0019] Step S302: Determine the error states E1, E2,..., E corresponding to each error e1, e2,..., e when the sum e of all the errors is the smallest t ; t ;

[0020] Step S303: Based on the Bayesian network, assume each error state E1, E2,..., E t and P(C bUnder the condition of 100%, calculate the remaining components C1, C2, …, C b except for the faulty component C i 、…、C n (i≠b), and the failure probability P(C i );

[0021] Step S304: Select the component with the maximum failure probability P(C b ), which is the failure probability of the remaining components C1, C2, …, C i 、…、C n (i≠b), among the failure probabilities P(C i ). Take the faulty component C a corresponding to the failure probability P(C a ) and the faulty component C a as the diagnosis result of compound and concurrent failures in the subsea production system of offshore oil. b

[0022] Preferably, the failure probabilities of the components in the subsea production system of offshore oil in step S103 satisfy:

[0023] Equation (1);

[0024] In Equation (1), P(C i |S1(d1), S2(d2), …, S t (d t ), SC i ) represents the probability of component C t failure when the given states of S1(d1), S2(d2), …, S t (d i ) and SC i are known; P(C1, C2, …, C n ) represents the joint probability of the parent nodes; P(S m (d m ), SC i |C1, C2, …, C n ) represents the conditional probability that when the states of C1, C2, …, C n are known, the S m node is in S m (d m ), and at the same time SC i is in the given state.

[0025] Preferably, the process of determining whether each component in the subsea production system of offshore oil has failed in step S104 is specifically described as:

[0026] Select the maximum probability value among the probabilities of failures of each component in the subsea production system for offshore oil calculated in step S103;

[0027] 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.

[0028] Preferably, the oil pressure values at the outlets of the components in the subsea production system for offshore oil in S203 satisfy:

[0029] Equation (2);

[0030] 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;

[0031] Among them, each Pv i is calculated from the previous pressure Pv i-1 , and Pv1 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.

[0032] Preferably, the error between the actual oil pressure value at the outlet of each component in the subsea production system for offshore oil in step S204 and the oil pressure value at the outlet of each component in the subsea production system for offshore oil calculated in step S203 satisfies:

[0033] Equation (3);

[0034] In Equation (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 subsea production system for offshore oil and the calculated oil pressure value; PT i is the actual oil pressure value of the i-th valve component in the subsea production system for offshore oil.

[0035] The present invention provides a method for diagnosing compound and concurrent faults in a subsea production system for offshore oil, and the method for diagnosing compound and concurrent faults in the subsea production system for offshore oil includes the following steps: steps of diagnosing faults in the subsea production system for offshore oil, judging compound and concurrent faults in the subsea production system for offshore oil, and identifying compound and concurrent faults in the subsea production system for offshore oil.

[0036] A method for diagnosing compound and concurrent faults in a subsea production system for offshore oil with the above step features, compared with the prior art, at least has the following technical advantages: this method for diagnosing compound and concurrent faults in the subsea production system for offshore oil can accurately judge whether compound and concurrent faults occur in the subsea production system for offshore oil, and can accurately identify the existing compound and concurrent faults, thus providing technical support for the long-term and safe operation of the subsea production system for offshore oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and are used to explain the present invention together with the embodiments of the present invention, and do not constitute a limitation to the present invention. In the following drawings:

[0038] Figure 1 is one of the flow diagrams of a method for diagnosing compound and concurrent faults in a subsea production system for offshore oil provided by the present invention;

[0039] Figure 2 is the second flow diagram of a method for diagnosing compound and concurrent faults in a subsea production system for offshore oil provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The present invention provides a method for diagnosing compound and concurrent faults in a subsea production system for offshore oil, and this method for diagnosing compound and concurrent faults in the subsea production system for offshore oil can accurately judge whether compound and concurrent faults occur in the subsea production system for offshore oil, and can accurately identify the existing compound and concurrent faults, thus providing technical support for the long-term and safe operation of the subsea production system for offshore oil.

[0041] The present invention provides a method for diagnosing compound and concurrent faults in a subsea production system for offshore oil, as Figure 1 as Figure 2 shown, and specifically includes the following steps:

[0042] Step S101: Initialize the states of the feedback nodes of each component in the subsea production system for offshore oil.

[0043] Among them, the feedback nodes of each component are respectively represented as SC1, SC2,..., SC n。The states of all component feedback nodes after initialization are marked as unknown, i.e., SC1(N), SC2(N), …, SC n (N); the number of initialization repetitions number is marked as 0.

[0044] Step S102: Obtain the data of each sensor in the subsea production system of offshore oil and determine the state of the sensor according to the data.

[0045] Among them, each sensor is respectively represented as S1, S2, …, S t ; the states of each sensor are respectively represented as S1(d1), S2(d2), …, S t (d t )

[0046] Step S103: Calculate the probability of failure of each component in the subsea production system of offshore oil. Among them, each component is respectively represented as C1, C2, …, C n

[0047] On the basis of completing Steps S101 and S102, Step S103 is further implemented. As a relatively preferred embodiment of the present invention, the probability of failure of each component in the subsea production system of offshore oil in this Step S103 satisfies:

[0048] Equation (1);

[0049] In Equation (1), P(C i |S1(d1), S2(d2), …, S t (d t ), SC i ) represents the probability of failure of component C t given the states of S1(d1), S2(d2), …, S t (d i ) and SC i ; P(C1, C2, …, C n ) represents the joint probability of the parent nodes; P(S m (d m ), SC i |C1, C2, …, C n ) represents the conditional probability that when the states of C1, C2, …, C n are known, the S m node is in S m (d m ), and at the same time SC i is in the given state. Through the above formula (1), the probability of failure of each component in the subsea production system of offshore oil is preliminarily calculated.

[0050] Step S104: Determine whether any components in the subsea production system for offshore oil have failed.

[0051] On the basis of completing Step S103, Step S104 is further implemented. Among them, the process of determining whether any components in the subsea production system for offshore oil have failed can be specifically described as follows: Select the maximum probability value among the probabilities of failure of each component in the subsea production system for offshore oil calculated in Step S103.

[0052] 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.

[0053] For example, select the preset component failure probability threshold 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 carried out to determine whether there are compound and concurrent failures in the subsea production system for offshore oil. Otherwise, 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 subsea production system for offshore oil, and the subsequent steps of diagnosing whether there are compound and concurrent failures in the subsea production system for offshore oil do not need to be implemented.

[0054] Step S201: Obtain the switch states of each component in the subsea production system for offshore oil.

[0055] Among them, the switch states of each component in the subsea production system for offshore oil are specifically described as follows: If the state of component C x is on, mark the control parameter of the corresponding component as 1; if the state of component C x is off, mark the control parameter of the corresponding component as 0.

[0056] Step S202: Update the failure parameters of each component in the subsea production system for offshore oil.

[0057] Among them, the update method of the failure parameters of each component in the subsea production system for offshore oil is specifically described as follows: If component C x is in a failed state, update the failure parameter of the corresponding component to 0; if component C x is in a normal state, update the failure parameter of the corresponding component to 1.

[0058] Step S203: Calculate the oil pressure values at the outlets of each component in the subsea production system for offshore oil.

[0059] On the basis of completing steps S201 and S202, step S203 is further implemented. As a relatively preferred implementation manner of the present invention, the hydraulic pressure values at the outlets of the components in the subsea oil production system in step S203 satisfy:

[0060] Equation (2);

[0061] 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;

[0062] wherein each Pv i is calculated from the previous pressure Pv i-1 and Pv1 is the actual pressure of each production loop in the subsea oil production system, is the control parameter of the i-th component.

[0063] Step S204: Calculate the error between the actual hydraulic pressure value at the outlet of each component in the subsea oil production system and the hydraulic pressure value at the outlet of each component in the subsea oil production system calculated in step S203.

[0064] On the basis of completing step S203, step S204 is further implemented. As a relatively preferred implementation manner of the present invention, the error between the actual hydraulic pressure value at the outlet of each component in the subsea oil production system and the hydraulic pressure value at the outlet of each component in the subsea oil production system calculated in step S203 satisfies:

[0065] Equation (3);

[0066] In Equation (3), i = 2, 3,..., t; e i is the error between the actual hydraulic pressure value at the outlet of the i-th component in the subsea oil production system and the calculated hydraulic pressure value; PT i is the actual hydraulic pressure value of the i-th valve component in the subsea oil production system.

[0067] It should be noted that the actual hydraulic pressure value PT at the outlet of the i-th component in the subsea oil production systemi is an actual measured value directly obtained by technicians reading data through the subsea production system for offshore oil; while the oil pressure values at the outlets of each component in the subsea production system for offshore oil calculated in step S203 are calculated predicted values.

[0068] In this process, by evaluating the error between the above two types of data, it is possible to predict whether a single fault has occurred in the corresponding component; and when it is not possible to rule out the possibility of compound and concurrent faults existing in the subsea production system for offshore oil, the diagnosis of compound and concurrent faults in the subsea production system for offshore oil can be further implemented. This is also the most prominent significant technical difference between the method for diagnosing compound and concurrent faults in the subsea production system for offshore oil provided by the present invention and the prior art.

[0069] Step S205: When all the 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 subsea production system for offshore oil; when all the errors calculated in step S204 exceed the preset component error threshold, let the initialized number of repetitions number = number + 1, and continue to implement step S206.

[0070] On the basis of completing step S204, step S205 is further implemented. It should be noted that assume the preset pressure error threshold is 5%. That is to say, if the e calculated by formula (3) in step S204 i are all less than 5%, it can be determined that there are no compound and concurrent faults in the subsea production system for offshore oil, but only a single fault has occurred. Otherwise, the possibility of compound and concurrent faults existing in the subsea production system for offshore oil cannot be ruled out.

[0071] Step S206: If the initialized number of repetitions number > n, it is determined that compound and concurrent faults have occurred in the subsea production system for offshore oil;

[0072] Otherwise, sort all the errors exceeding the preset component error threshold in ascending order of their numbers, select the first error number k with the smallest number among them; and update the status of the component feedback node corresponding to the first error number k to normal: that is, SC k (Y), and the status of the remaining component feedback nodes remains unchanged, and return to step S103.

[0073] It should be noted that n is the number of times of troubleshooting for compound and concurrent failures that occur in the subsea production system of offshore oil preset by technicians. Therefore, when n satisfies the initialized repetition number number > n, it is determined that compound and concurrent failures have indeed occurred in the subsea production system of offshore oil; when n satisfies number ≤ n, it is necessary to further detect and verify whether compound and concurrent failures have occurred in the subsea production system of offshore oil.

[0074] Among them, the process of compound and concurrent failure detection can be referred to as follows: First, select the first error number k with the smallest number from all errors exceeding the preset component error threshold, and update the state of the component feedback node corresponding to it to normal; and start cycling from this, specifically judge which component has the greatest possibility of compound and concurrent failure except for the components that have been confirmed to have failed.

[0075] Step S301: Select the diagnostic result when the sum e of all errors calculated in step S204 is the smallest, and record the failed component C diagnosed by the diagnostic result b ; where the sum e of all errors satisfies: e = e1 + e2 + … + e t .

[0076] Step S302: Determine the error states E1, E2, …, E corresponding to each error e1, e2, …, e when the sum e of all errors is the smallest t t .

[0077] Step S303: Based on the Bayesian network, assuming each error state E1, E2, …, E t and P(C b ) = 100%, calculate the failure probability P(C b ) of the remaining components C1, C2, …, C i , …, C n (i ≠ b) except for the failed component C i .

[0078] Step S304: Select the maximum failure probability P(C b ) among the failure probabilities P(C i ), …, P(C n ) of the remaining components C1, C2, …, C i (i ≠ b) except for the failed component C a ), and use the failed component C corresponding to the failure probability P(C a ) and the failed component C a and the failed component C b together as the diagnostic result of compound and concurrent failures in the subsea production system of offshore oil.

[0079] On the basis of completing steps S301, S302, and S303, step S304 is further implemented. It should be noted that the faulty component C was calculated in step S204 b . Among them, the faulty component C b corresponds to the diagnostic result when the sum of all errors e is the smallest. And in the case where the faulty component C b has been diagnosed and determined, further calculate the failure probabilities of the remaining components except the faulty component C b by S302 and S303

[0080] It should be added that since the faulty component C has been diagnosed and determined in the foregoing steps b . Therefore, we choose to use the faulty component C corresponding to the maximum failure probability P(C a ) a and the faulty component C b together as the diagnostic result of the composite and concurrent faults in the subsea production system of offshore oil

[0081] So far, the method for diagnosing composite and concurrent faults in the subsea production system of offshore oil provided by the present invention not only realizes the diagnosis of composite and concurrent faults in the subsea production system of offshore oil; but also realizes the accurate identification of the components with composite and concurrent faults in the case where there are indeed composite and concurrent faults

[0082] Finally, to prove the true reliability of the detection of a method for diagnosing composite and concurrent faults in the subsea production system of offshore oil provided by the present invention. Here, the applicant provides a set of valve data in the subsea production system of offshore oil, and after diagnosing respectively based on the existing fault diagnosis method and the composite and concurrent fault diagnosis method provided by the present invention, the diagnostic results are compared and analyzed

[0083] Table 1 shows the valve data in the subsea production system of offshore oil

[0084]

[0085] After statistics, it is found that the accuracy rate of the existing fault diagnosis method for judging the normal state of the subsea production system of offshore oil can reach 98%, and the accuracy rate for judging the existence of single faults in the subsea production system of offshore oil can reach 90%; while its accuracy rate for diagnosing the existence of composite and concurrent faults in the subsea production system of offshore oil is only 85%. This is because the existing fault diagnosis method often fails to distinguish between single faults and composite faults in the subsea production system of offshore oil

[0086] In sharp contrast, the diagnostic results of the composite and concurrent fault diagnosis method provided by the present invention for the normal, single-fault, composite and concurrent-fault conditions of the subsea production system in offshore oil production can reach 99%, 93%, and 92% respectively. Thus, it is confirmed that the composite and concurrent fault diagnosis method provided by the present invention is more reliable and accurate in detection effect than the prior art.

[0087] The present invention provides a composite and concurrent fault diagnosis method for a subsea production system in offshore oil production. This composite and concurrent fault diagnosis method for a subsea production system in offshore oil production includes the following steps: steps of fault diagnosis of the subsea production system in offshore oil production, judgment of composite and concurrent faults of the subsea production system in offshore oil production, and identification of composite and concurrent faults of the subsea production system in offshore oil production.

[0088] A composite and concurrent fault diagnosis method for a subsea production system in offshore oil production with the above step features has at least the following technical advantages compared with the prior art: This composite and concurrent fault diagnosis method for a subsea production system in offshore oil production can accurately determine whether composite and concurrent faults have occurred in the subsea production system in offshore oil production, and can accurately identify the existing composite and concurrent faults, thus providing technical support for the long-term and safe operation of the subsea production system in offshore oil production.

[0089] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to 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: 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, 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 ) indicates 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 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.

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