Diagnosis method of minor and non-permanent faults in offshore oil subsea production system

Abstract

The present invention belongs to the field of petroleum engineering technology, and in particular, relates to a method for diagnosing minor and non-permanent faults in an underwater offshore oil production system. The method for diagnosing minor and non-permanent faults in an underwater offshore oil production system can accurately determine whether minor and non-permanent faults have occurred in an underwater offshore oil production system, and can also accurately identify existing minor and non-permanent faults, thereby providing technical support for the long-term and safe service of the underwater offshore oil production system. The present invention provides a method for diagnosing minor and non-permanent faults in an underwater offshore oil production system, and the diagnostic method includes the following steps: diagnosing an underwater offshore oil production system fault, verifying an underwater offshore oil production system fault diagnosis result, judging minor and non-permanent faults in an underwater offshore oil production system, and identifying minor and non-permanent faults in an underwater offshore oil production system.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum engineering, and in particular relates to a method for diagnosing minor and non-permanent faults of an offshore oil underwater production system. Background Art

[0002] Marine oil and gas is an important part of my country's oil and gas supply, and its underwater production system is the core to achieve this goal. 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 offshore oil underwater production system is an important guarantee for the continuity and stability of marine oil and gas production. For on-site staff, timely discovery and accurate identification of minor and non-permanent faults in the underwater production system can help on-site personnel take quick measures and make plans in advance to avoid problems from deteriorating into serious accidents. However, since the offshore oil underwater production system has been in service in harsh underwater environments for a long time, it is difficult to effectively monitor and diagnose faults, resulting in minor and non-permanent faults that are often difficult to be discovered and handled in a timely manner.

[0003] In the prior art, the monitoring method for offshore oil underwater production systems mainly relies on the status judgment of the installed pressure sensors. When the pressure at a certain point exceeds the set value, the system triggers an alarm (but will not provide specific fault location information); on-site personnel need to determine the actual location of the fault based on the specific location of the alarm sensor. Further research found that this monitoring method is difficult to quickly determine the fault location and respond in a timely manner when a fault occurs. In addition, the above technical means cannot accurately and effectively detect minor and non-permanent faults in the system, let alone achieve early warning. Therefore, it is particularly urgent and necessary to develop a method that can accurately diagnose minor and non-permanent faults in offshore oil underwater production systems. Summary of the invention

[0004] The present invention provides a method for diagnosing minor and non-permanent faults of an offshore oil underwater production system. The method for diagnosing minor and non-permanent faults of an offshore oil underwater production system can accurately determine whether minor and non-permanent faults have occurred in the offshore oil underwater production system, and can also accurately identify the existing minor and non-permanent 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:

[0006] A method for diagnosing minor and non-permanent faults in an offshore oil underwater production system includes the following steps:

[0007] Step S101: Obtain the value PT of each pressure sensor in the offshore oil underwater production system 1 , PT2 ,…,PT m ; Wherein, m is the number of the pressure sensor in the offshore oil underwater production system;

[0008] Step S102: Determine the status of each pressure sensor in the offshore oil underwater production system; wherein the status of each pressure sensor is represented by: PT 1 (S 1 )、PT 2 (S 2 )、…、PT m (S m );

[0009] Step S103: Calculating the probability of failure of each valve in the offshore oil underwater production system;

[0010] Step S104: Based on the probability of each valve in the offshore oil underwater production system failing calculated in step S103, determine whether each valve in the offshore oil underwater production system is failing: when the calculated probability of valve failure exceeds a preset valve failure probability threshold, the corresponding valve is determined to be a valve failure; otherwise, the corresponding valve is determined to be a normal valve;

[0011] Step S201: Obtain the switch status of each valve in the offshore oil underwater production system: If valve C x If the state is open, the control parameters of the corresponding valve will be Marked as 1; if valve C x If the state is closed, the control parameters of the corresponding valve Marked as 0;

[0012] Step S202: Update the fault parameters of each valve: If it is determined that valve C x If the valve is in a fault state, the corresponding valve fault parameters Update to 0; if it is determined that valve C x In normal state, the corresponding valve fault parameters Updated to 1;

[0013] Step S203: Calculating the oil pressure value at the outlet of each valve in the offshore oil underwater production system;

[0014] Step S204: Counting the actual oil pressure value of each valve outlet in the offshore oil underwater production system; calculating the error between the actual oil pressure value of each valve outlet in the offshore oil underwater production system and the oil pressure value of each valve outlet in the offshore oil underwater production system calculated in step S203;

[0015] Step S205: when all calculated errors do not exceed the preset pressure error threshold, it is determined that there are no minor and non-permanent faults in the offshore oil underwater production system; otherwise, continue to implement step S301;

[0016] Step S301: sort all errors exceeding a preset pressure error threshold in ascending order of numbers, and select the first error number k with the smallest number;

[0017] Step S302: If the first error number k corresponds to the fault parameter of the valve , then let , and re-implement steps S203 to S205 until the first error k corresponds to the fault parameter of the valve ;

[0018] If the first error k corresponds to the fault parameter of the valve , it is determined that a minor and non-permanent fault has occurred in the offshore oil underwater production system, and step S401 is continued;

[0019] Step S401: Update the fault parameters, so that the fault parameters ; And count the fault parameters in each cycle Corresponding valve number C w1 , C w2 , C w3 ,…,C wa ;

[0020] Step S402: Calculate the number of valves in the offshore oil underwater production system except valve number C w1 , C w2 , C w3 ,…,C wa , C k The probability of minor and non-permanent failure of each valve other than the above;

[0021] Step S403: When the calculated offshore oil underwater production system has valve number C w1 , C w2 , C w3 ,…,C wa When the probability of minor and non-permanent failures of valves other than the first and second valves exceeds the preset valve minor and non-permanent failure probability threshold, the corresponding valve is judged as having minor and non-permanent failures; otherwise, the corresponding valve is judged as normal.

[0022] Preferably, the probability of failure of each valve in the offshore oil underwater production system in step S103 satisfies:

[0023] Formula (1);

[0024] In formula (1), Indicates that the state of each pressure sensor in the known offshore oil underwater production system is PT 1 (S 1 )、PT 2 (S 2 )、…、PT m (S m ) under the condition of the x-th valve failure probability; Indicates that when the xth valve fails, the i-th sensor is in S i The probability of the state; represents the probability of the xth valve failing; It means that under the condition that the xth valve is normal, the i-th sensor is in S i The probability of the state; Represents the probability that the xth valve is normal.

[0025] Preferably, the oil pressure value at the outlet of each valve in the offshore oil underwater production system in step S203 satisfies:

[0026] Formula (2);

[0027] In formula (2), Pv i-1 represents the pipeline pressure before the i-th valve; represents the density of crude oil; g is the acceleration due to gravity; h is i-1 Pv represents the height of the pipeline center in front of the ith valve, with the wellhead as the reference height; i represents the pipeline pressure after the i-th valve; h i-1 It represents the height of the pipeline center after the ith valve, with the wellhead as the reference height; represents the pressure loss caused by the i-th valve; To control the parameters;

[0028] Among them, each Pv i Both are determined by the previous pressure Pv i-1 Calculated, and Pv 1 =PT 1 .

[0029] Preferably, the error between the actual oil pressure value at the outlet of each valve in the offshore oil underwater production system in step S204 and the oil pressure value at the outlet of each valve in the offshore oil underwater production system calculated in step S203 satisfies:

[0030] Formula (3);

[0031] In formula (3), i = 2, 3, …, t; e i is the error between the actual oil pressure value at the i-th valve outlet in the offshore oil underwater production system and the calculated oil pressure value; PT i is the actual oil pressure value at the outlet of the i-th valve in the offshore oil underwater production system.

[0032] Preferably, in step S402, the offshore oil underwater production system except valve number C w1 , C w2 , C w3 ,…,C wa , C k The probability of minor and non-permanent failure of each valve other than the above mentioned valves shall meet the following requirements:

[0033] Formula (4);

[0034] In formula (4), Indicates valve C x In normal state and valve C w1 , C w2 , C w3 ,…,C wa , C k Under normal conditions, valve C x The probability of minor and non-permanent failures; where x satisfies: x=1,2,…,t, and x≠C w1 , C w2 , C w3 ,…,C wa , C k ;

[0035] Indicates valve C x In fault condition and valve C w1 , C w2 , C w3 ,…,C wa , C k Under normal conditions, the sensor status is PT 1 (S 1 )、PT 2 (S 2 ),…,PT m (S m ), where represents the probability of the xth valve failing;

[0036] Indicates valve C xi In fault condition and valve C w1 , C w2 , C w3 ,…,Cwa , C k Under normal conditions, the sensor status is PT 1 (S 1 )、PT 2 (S 2 )、…、PT m (S m ), where represents the probability of the xith valve failing.

[0037] The present invention provides a method for diagnosing minor and non-permanent faults of an offshore oil underwater production system. The method comprises the following steps: diagnosing an offshore oil underwater production system fault, verifying an offshore oil underwater production system fault diagnosis result, judging minor and non-permanent faults of an offshore oil underwater production system, and identifying minor and non-permanent faults of an offshore oil underwater production system.

[0038] A method for diagnosing minor and non-permanent faults in 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 minor and non-permanent faults in an underwater offshore oil production system can accurately determine whether minor and non-permanent faults have occurred in the underwater offshore oil production system, and can also accurately identify existing minor and non-permanent faults, thereby providing technical support for the long-term and safe service of the underwater offshore oil production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] 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:

[0040] Figure 1 One of the flow charts of a method for diagnosing minor and non-permanent faults of an offshore oil underwater production system provided by the present invention;

[0041] Figure 2 The present invention provides a second flow chart of a method for diagnosing minor and non-permanent faults in an offshore oil underwater production system.

[0042] Reference numerals:

[0043] 1. Wireless charging station; 2. Transmitter; 201. Mid-end transmitting unit; 202. End transmitting unit; 3. AUV equipment group; 301. First AUV equipment; 302. Second AUV equipment; 303. Third AUV equipment. DETAILED DESCRIPTION

[0044] The present invention provides a method for diagnosing minor and non-permanent faults of an offshore oil underwater production system. The method for diagnosing minor and non-permanent faults of an offshore oil underwater production system can accurately determine whether minor and non-permanent faults have occurred in the offshore oil underwater production system, and can also accurately identify the existing minor and non-permanent faults, thereby providing technical support for the long-term and safe service of the offshore oil underwater production system.

[0045] The present invention provides a method for diagnosing minor and non-permanent faults in an offshore oil underwater production system. Figure 1 With Figure 2 As shown, it specifically includes the following steps:

[0046] Step S101: Obtain the value PT of each pressure sensor in the offshore oil underwater production system 1 PT 2 ,…,PT m ; Wherein, m is the number of the pressure sensor in the offshore oil underwater production system.

[0047] Step S102: Determine the status of each pressure sensor in the offshore oil underwater production system; wherein the status of each pressure sensor is represented by: PT 1 (S 1 )、PT 2 (S 2 )、…、PT m (S m ).

[0048] Step S103: Calculate the probability of failure of each valve in the offshore oil underwater production system.

[0049] On the basis of completing steps S101 and S102, step S103 is further implemented. It is worth noting that, as a preferred embodiment of the present invention, the probability of failure of each valve in the offshore oil underwater production system in step S103 specifically satisfies:

[0050] Formula (1).

[0051] In formula (1), Indicates that the state of each pressure sensor in the known offshore oil underwater production system is PT 1 (S 1 )、PT 2 (S 2 )、…、PT m (S m ) under the condition of the x-th valve failure probability; Indicates that when the xth valve fails, the i-th sensor is in S iThe probability of the state; represents the probability of the xth valve failing; It means that under the condition that the xth valve is normal, the i-th sensor is in S i The probability of the state; Represents the probability that the xth valve is normal.

[0052] Through the above formula (1), technicians preliminarily calculated the probability of failure of each valve in the offshore oil underwater production system.

[0053] Step S104: Based on the probability of failure of each valve in the offshore oil underwater production system calculated in step S103, determine whether each valve in the offshore oil underwater production system is faulty: when the calculated probability of valve failure exceeds a preset valve failure probability threshold, the corresponding valve is determined to be a valve failure; otherwise, the corresponding valve is determined to be a normal valve.

[0054] After completing step S103, step S104 is further implemented. For example, the preset valve failure probability threshold is selected as 0.85. That is, if the value calculated by formula (1) in step S103 is If the valve is faulty, the corresponding valve is judged to be normal.

[0055] Step S201: Obtain the switch status of each valve in the offshore oil underwater production system: If valve C x If the state is open, the control parameters of the corresponding valve will be Marked as 1; if valve C x If the state is closed, the control parameters of the corresponding valve Marked as 0.

[0056] Step S202: Update the fault parameters of each valve: If it is determined that valve C x If the valve is in a fault state, the corresponding valve fault parameters Update to 0; if it is determined that valve C x In normal state, the corresponding valve fault parameters Updated to 1.

[0057] Step S203: Calculate the oil pressure value at the outlet of each valve in the offshore oil underwater production system.

[0058] 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 valve in the offshore oil underwater production system in step S203 specifically satisfies:

[0059] Formula (2).

[0060] In formula (2), Pv i-1 represents the pipeline pressure before the i-th valve; represents the density of crude oil (obtained from well logging data); g is the acceleration of gravity; h is the gravitational acceleration; i-1 Pv represents the height of the pipeline center in front of the ith valve, with the wellhead as the reference height; i represents the pipeline pressure after the i-th valve; h i-1 It represents the height of the pipeline center after the ith valve, with the wellhead as the reference height; represents the pressure loss caused by the ith valve (which can be obtained by consulting the valve test report); is the control parameter.

[0061] Among them, each Pv i Both are determined by the previous pressure Pv i-1 Calculated, and Pv 1 =PT 1 .

[0062] Step S204: Count the actual oil pressure values ​​at the outlets of each valve in the offshore oil underwater production system; calculate the error between the actual oil pressure values ​​at the outlets of each valve in the offshore oil underwater production system and the oil pressure values ​​at the outlets of each valve in the offshore oil underwater production system calculated in step S203.

[0063] 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 valve in the offshore oil underwater production system in step S204 and the oil pressure value at the outlet of each valve in the offshore oil underwater production system calculated in step S203 specifically satisfies:

[0064] Formula (3).

[0065] In formula (3), i = 2, 3, …, t; e i is the error between the actual oil pressure value at the i-th valve outlet in the offshore oil underwater production system and the calculated oil pressure value; PT i is the actual oil pressure value at the outlet of the i-th valve in the offshore oil underwater production system.

[0066] It should be noted that step S203 calculates the oil pressure value of each valve outlet in the offshore oil underwater production system, where the oil pressure value is a calculated predicted value; while the actual oil pressure value PT of each valve outlet in the offshore oil underwater production system is iIt is obtained by technicians directly reading data from the offshore oil underwater production system and is an actual measurement value.

[0067] Step S205: When all calculated errors do not exceed the preset pressure error threshold, it is determined that there are no minor and non-permanent faults in the offshore oil underwater production system; otherwise, continue to implement step S301.

[0068] After completing step S204, step S205 is further implemented. For example, the preset pressure error threshold is selected to be 5%. That is, if the e calculated by formula (3) in step S204 is i If both are less than 5%, it is determined that there are no minor and non-permanent faults in the offshore oil underwater production system; otherwise, the possibility that there are no minor and non-permanent faults in the offshore oil underwater production system cannot be ruled out. Therefore, it is necessary to further determine whether there are minor and non-permanent faults in the offshore oil underwater production system.

[0069] Step S301: sort all errors exceeding a preset pressure error threshold in ascending order of numbers, and select the first error number k with the smallest number.

[0070] Step S302: If the first error number k corresponds to the fault parameter of the valve , then let , and re-implement steps S203 to S205 until the first error k corresponds to the fault parameter of the valve .

[0071] If the first error k corresponds to the fault parameter of the valve , it is determined that a minor and non-permanent fault has occurred in the offshore oil underwater production system, and step S401 is continued.

[0072] It should be noted that the reason why the first error number k corresponding to the valve fault parameter is accumulated is This is because repeated verification is required to determine the In this case, the corresponding valve is faulty or has a minor fault phenomenon (a minor fault is actually a lighter and smaller fault, which is essentially similar to a fault; the existing technology cannot distinguish between the minor fault and the fault during diagnosis).

[0073] Step S401: Update the fault parameters, so that the fault parameters ; And count the fault parameters in each cycle Corresponding valve number C w1 , C w2 , C w3 ,…,Cwa .

[0074] Step S402: Calculate the number of valves in the offshore oil underwater production system except valve number C w1 , C w2 , C w3 ,…,C wa , C k The probability of minor and non-permanent failure of valves other than the above.

[0075] On the basis of completing step S401, step S402 is further implemented. As a preferred embodiment of the present invention, in step S402, the offshore oil underwater production system is equipped with valve number C. w1 , C w2 , C w3 ,…,C wa , C k The probability of minor and non-permanent failure of each valve other than the above mentioned valves shall specifically meet the following requirements:

[0076] Formula (4);

[0077] In formula (4), Indicates valve C x In normal state and valve C w1 , C w2 , C w3 ,…,C wa , C k Under normal conditions, valve C x The probability of minor and non-permanent failures; where x satisfies: x=1,2,…,t, and x≠C w1 , C w2 , C w3 ,…,C wa , C k ;

[0078] Indicates valve C x In fault condition and valve C w1 , C w2 , C w3 ,…,C wa , C k Under normal conditions, the sensor status is PT 1 (S 1 )、PT 2 (S 2 ),…,PT m (S m ), where represents the probability of the xth valve failing;

[0079] Indicates valve C xi In fault condition and valve C w1 , C w2 , C w3 ,…,C wa , C k Under normal conditions, the sensor status is PT 1 (S 1 )、PT 2 (S 2 ),…,PT m (S m ), where represents the probability of the xith valve failing.

[0080] Step S403: When the calculated offshore oil underwater production system has valve number C w1 , C w2 , C w3 ,…,C wa When the probability of minor and non-permanent failures of valves other than the first and second valves exceeds the preset valve minor and non-permanent failure probability threshold, the corresponding valve is judged as having minor and non-permanent failures; otherwise, the corresponding valve is judged as normal.

[0081] Thus, the method for diagnosing minor and non-permanent faults in an offshore oil underwater production system provided by the present invention realizes the diagnosis of minor and non-permanent faults in an offshore oil underwater production system; and in the case where minor and non-permanent faults do exist, it realizes the accurate identification of valves having minor and non-permanent faults.

[0082] The present invention provides a method for diagnosing minor and non-permanent faults of an offshore oil underwater production system. The method comprises the following steps: diagnosing an offshore oil underwater production system fault, verifying an offshore oil underwater production system fault diagnosis result, judging minor and non-permanent faults of an offshore oil underwater production system, and identifying minor and non-permanent faults of an offshore oil underwater production system.

[0083] A method for diagnosing minor and non-permanent faults in 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 minor and non-permanent faults in an underwater offshore oil production system can accurately determine whether minor and non-permanent faults have occurred in the underwater offshore oil production system, and can also accurately identify existing minor and non-permanent faults, thereby providing technical support for the long-term and safe service of the underwater offshore oil production system.

[0084] 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 method for diagnosing minor and non-permanent faults in an offshore oil underwater production system, characterized in that: The steps include: Step S101: Obtain the values ​​PT1, PT2, ..., PT of each pressure sensor in the offshore oil underwater production system m ; Wherein, m is the number of the pressure sensor in the offshore oil underwater production system; Step S102: Determine the status of each pressure sensor in the offshore oil underwater production system; wherein the status of each pressure sensor is represented as: PT1 (S1), PT2 (S2), ..., PT m (S m ); Step S103: Calculating the probability of failure of each valve in the offshore oil underwater production system; Step S104: Based on the probability of each valve in the offshore oil underwater production system failing calculated in step S103, determine whether each valve in the offshore oil underwater production system is failing: when the calculated probability of valve failure exceeds a preset valve failure probability threshold, the corresponding valve is determined to be a valve failure; otherwise, the corresponding valve is determined to be a normal valve; Step S201: Obtain the switch status of each valve in the offshore oil underwater production system: If valve C x If the state is open, the control parameters of the corresponding valve will be Marked as 1; if valve C x If the state is closed, the control parameters of the corresponding valve Marked as 0; Step S202: Update the fault parameters of each valve: If it is determined that valve C x If the valve is in a fault state, the corresponding valve fault parameters Update to 0; if it is determined that valve C x In normal state, the corresponding valve fault parameters Updated to 1; Step S203: Calculating the oil pressure value at the outlet of each valve in the offshore oil underwater production system; Step S204: Counting the actual oil pressure value of each valve outlet in the offshore oil underwater production system; calculating the error between the actual oil pressure value of each valve outlet in the offshore oil underwater production system and the oil pressure value of each valve outlet in the offshore oil underwater production system calculated in step S203; Step S205: when all calculated errors do not exceed the preset pressure error threshold, it is determined that there are no minor and non-permanent faults in the offshore oil underwater production system; otherwise, continue to implement step S301; Step S301: sort all errors exceeding a preset pressure error threshold in ascending order of numbers, and select the first error number k with the smallest number; Step S302: If the first error number k corresponds to the fault parameter of the valve , then let , and re-implement steps S203 to S205 until the first error k corresponds to the fault parameter of the valve ; If the first error k corresponds to the fault parameter of the valve , it is determined that a minor and non-permanent fault has occurred in the offshore oil underwater production system, and step S401 is continued; Step S401: Update the fault parameters, so that the fault parameters ; And count the fault parameters in each cycle Corresponding valve number C w1 , C w2 , C w3 ,…,C wa ; Step S402: Calculate the number of valves in the offshore oil underwater production system except valve number C w1 , C w2 , C w3 ,…,C wa , C k The probability of minor and non-permanent failure of each valve other than the above; Step S403: When the calculated offshore oil underwater production system has valve number C w1 , C w2 , C w3 ,…,C wa When the probability of minor and non-permanent failures of valves other than the first and second valves exceeds the preset valve minor and non-permanent failure probability threshold, the corresponding valve is judged as having minor and non-permanent failures; otherwise, the corresponding valve is judged as normal.

2. The method for diagnosing minor and non-permanent faults of an offshore oil underwater production system according to claim 1 is characterized in that: The probability of failure of each valve in the offshore oil underwater production system in step S103 satisfies: Formula (1); In formula (1), Indicates that the status of each pressure sensor in the known offshore oil underwater production system is PT1 (S1), PT2 (S2), ..., PT m (S m ) under the condition of the x-th valve failure probability; Indicates that when the xth valve fails, the i-th sensor is in S i The probability of the state; represents the probability of the xth valve failing; It means that under the condition that the xth valve is normal, the i-th sensor is in S i The probability of the state; Represents the probability that the xth valve is normal.

3. The method for diagnosing minor and non-permanent faults of an offshore oil underwater production system according to claim 1, characterized in that: The oil pressure values ​​at the outlets of the valves in the offshore oil underwater production system in step S203 satisfy: Formula (2); In formula (2), Pv i-1 represents the pipeline pressure before the i-th valve; represents the density of crude oil; g is the acceleration due to gravity; h is i-1 Pv represents the height of the pipeline center in front of the ith valve, with the wellhead as the reference height; i represents the pipeline pressure after the i-th valve; h i-1 It represents the height of the pipeline center after the ith valve, with the wellhead as the reference height; represents the pressure loss caused by the i-th valve; To control the parameters; Among them, each Pv i Both are determined by the previous pressure Pv i-1 Calculated, and Pv1=PT1.

4. The method for diagnosing minor and non-permanent faults 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 valve in the offshore oil underwater production system in step S204 and the oil pressure value at the outlet of each valve 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 i-th valve outlet in the offshore oil underwater production system and the calculated oil pressure value; PT i is the actual oil pressure value at the outlet of the i-th valve in the offshore oil underwater production system.

5. The method for diagnosing minor and non-permanent faults of an offshore oil underwater production system according to claim 1, characterized in that: In step S402, in the offshore oil underwater production system, the valve number C is removed. w1 , C w2 , C w3 ,…,C wa , C k The probability of minor and non-permanent failure of each valve other than the above mentioned valves shall meet the following requirements: Formula (4); In formula (4), Indicates valve C x In normal state and valve C w1 , C w2 , C w3 ,…,C wa , C k Under normal conditions, valve C x The probability of minor and non-permanent failures; where x satisfies: x=1,2,…,t, and x≠C w1 , C w2 , C w3 ,…,C wa , C k ; Indicates valve C x In fault condition and valve C w1 , C w2 , C w3 ,…,C wa , C k Under normal conditions, the sensor status is PT1 (S1), PT2 (S2), ..., PT m (S m ), where represents the probability of the xth valve failing; Indicates valve C xi In fault condition and valve C w1 , C w2 , C w3 ,…,C wa , C k Under normal conditions, the sensor status is PT1 (S1), PT2 (S2), ..., PT m (S m ), where represents the probability of the xith valve failing.

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