Oil well downhole flow control valve fault monitoring method, device, equipment and medium

Abstract

The embodiment of the present invention provides a method, device, equipment and medium for monitoring the fault of a flow control valve in a downhole oil well. By driving the valve column of the flow control valve to perform a switch movement; recording the curve of the relationship between the excitation current and time during the movement of the valve column; calculating the square area under the curve, the square area under the curve is used to characterize the cumulative energy change of the system during the movement of the valve column; when the cumulative energy change of the system exceeds a threshold, confirming that the flow control valve has a fault, the intelligent monitoring of the fault of the downhole flow control valve of the oil well is realized, which can effectively improve the reliability and working efficiency of the control valve and ensure the operation status of the oil well to a certain extent.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development, and in particular to a method, device, equipment and medium for monitoring faults of a downhole flow control valve of an oil well. Background Art

[0002] Oil wells are the core facilities for oil and gas exploration and production. They transport underground oil and gas resources to the surface through complex systems. The operating status of oil wells is directly related to the stability of energy supply and economic benefits. In actual operations, the status of the oil well downhole flow control valve is often the key factor affecting the operation of the oil well.

[0003] Common faults of oil well downhole flow control valves during operation include solenoid valve component failure, valve body blockage, seal aging, circuit failure, etc. Among them, the main sources of solenoid valve (SVs) failures are circuit short circuits and open circuits in the valve coil, as well as contamination by external impurities. Further, solenoid valve failures can be divided into intermittent and permanent. Intermittent failures can cause temporary failure of valve components until they are restored to full operating standards. Permanent failures can cause permanent failure of components until they are replaced. Solenoid valve failures can also be further classified into sudden or gradual failures based on their suddenness. Sudden failures, such as stick-slip effects, structural collapse, and spring breakage, are almost impossible to predict through previous tests. Gradual failures can be evaluated through previous inspections, such as coil burnout deterioration and valve seat leakage.

[0004] In order to deal with these common faults, intelligent fault monitoring methods are needed to improve the reliability and working efficiency of control valves. Summary of the invention

[0005] In view of the above problems, a method, device, equipment and medium for monitoring faults of downhole flow control valves in oil wells is proposed to overcome the above problems or at least partially solve the above problems, including:

[0006] Drive the flow control valve spool to perform on-off movement;

[0007] Record the relationship curve between the excitation current and time during the movement of the valve stem;

[0008] Calculate the area under the square of the curve, which is used to characterize the cumulative energy change of the system during the movement of the valve stem;

[0009] In the event that the accumulated energy change of the system exceeds a threshold value, a flow control valve failure is confirmed.

[0010] Preferably, driving the valve column of the flow control valve to perform a switching movement includes:

[0011] The driving coil circuit is used to drive the valve column of the flow control valve to perform a switching movement. The driving coil circuit includes a solenoid coil and an inductor connected in series.

[0012] Preferably, the excitation current and time relationship curve includes several significant points of the excitation current, and the significant points include an excitation current peak point, an excitation current valley point, and an excitation current steady-state point;

[0013] Record the amplitude of the excitation current peak point and the time when the excitation current peak point is reached;

[0014] Record the amplitude of the excitation current valley point and the time to reach the excitation current valley point;

[0015] Record the amplitude of the excitation current steady-state point and the time to reach the excitation current steady-state point.

[0016] Preferably, the formula for the area under the square of the curve is:

[0017]

[0018] Among them, E 12 is the cumulative energy change of the system during the valve stem movement, t1 is the time when the excitation current reaches the peak point, t2 is the time when the excitation current reaches the valley point, R is the equivalent resistance of the solenoid coil, and i is the current flowing through the solenoid coil.

[0019] Preferably, when the curve is not fully recorded, the area formula is:

[0020]

[0021] Where I1 is the amplitude of the excitation current reaching the peak point, I2 is the amplitude of the excitation current reaching the valley point, and E 12 is the cumulative energy change of the system during the valve stem movement, t1 is the time when the excitation current reaches the peak point, and t2 is the time when the excitation current reaches the valley point.

[0022] Preferably, the method for monitoring faults of a downhole flow control valve in an oil well further comprises:

[0023] Durability tests were performed on several flow control valves to verify the validity of the cumulative energy variation.

[0024] Preferably, the flow control valve comprises a prototype of an industrial DC solenoid valve.

[0025] A downhole flow control valve fault monitoring device for an oil well, comprising:

[0026] A drive module, used for driving the valve column of the flow control valve to perform on-off movement;

[0027] A recording module, used for recording a curve of the relationship between the excitation current and time during the movement of the valve stem;

[0028] A calculation module, used for calculating the area under the square of the curve, where the area under the square of the curve is used to characterize the cumulative energy change of the system during the movement of the valve stem;

[0029] The confirmation module is used to confirm that the flow control valve fails when the accumulated energy change of the system exceeds a threshold value.

[0030] An electronic device includes a processor, a memory, and a computer program stored in the memory and capable of running on the processor. When the computer program is executed by the processor, the above method for monitoring faults of a downhole flow control valve in an oil well is implemented.

[0031] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above method for monitoring faults of a downhole flow control valve in an oil well is implemented.

[0032] The embodiment of the present invention drives the valve column of the flow control valve to perform a switching movement; records the relationship curve between the excitation current and time during the movement of the valve column; calculates the square area under the curve, and the square area under the curve is used to characterize the cumulative energy change of the system during the movement of the valve column; when the cumulative energy change of the system exceeds a threshold, it is confirmed that the flow control valve has a fault, thereby realizing intelligent monitoring of downhole flow control valve faults in oil wells, which can effectively improve the reliability and working efficiency of the control valve and ensure the operating status of the oil well to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0034] Figure 1 It is a flowchart of the steps of a method for monitoring a downhole flow control valve fault in an oil well provided by an embodiment of the present invention;

[0035] Figure 2 is a schematic diagram of a driving coil circuit provided by an embodiment of the present invention;

[0036] Figure 3 is a schematic diagram of a curve showing the relationship between an excitation current and time provided by an embodiment of the present invention;

[0037] Figure 4 It is a schematic diagram of performing durability test on several flow control valves provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Reference Figure 1 , shows a flow chart of the steps of a method for monitoring a downhole flow control valve fault in an oil well provided by an embodiment of the present invention, which may specifically include the following steps:

[0040] Step 101, driving the valve stem of the flow control valve to perform an on-off movement.

[0041] In some embodiments of the present invention, a driving coil circuit can be used to drive the valve column of the flow control valve to perform a switching movement, such as Figure 2 As shown, the equivalent model of the drive coil circuit may include a series connection of a solenoid coil and an inductor.

[0042] According to electromagnetic dynamics, by Figure 2 Applying Kirchhoff's voltage law to the drive coil circuit shown, the following formula can be obtained:

[0043]

[0044] Where V(t) represents the excitation voltage, i(t) represents the current through the solenoid coil, R represents the equivalent resistance of the solenoid coil, and φ B (t) represents the magnetic flux of the solenoid coil. Specifically, the first term on the right side of the formula, i.e., Ri(t), represents the resistive voltage drop, and the second term on the right side of the formula represents the induced voltage.

[0045] The inductance L and the magnetic flux φ B The constitutive relation of (t) is:

[0046] φ B (t) = L i (t) (2)

[0047] Therefore, combining the above formula (1) and formula (2), the equivalent model of the drive coil circuit can be obtained as follows:

[0048]

[0049]

[0050] Wherein, Vbemf(t) represents the back electromotive force, which is caused by the change of magnetic resistance or magnetic permeability when the valve stem performs the switching movement.

[0051] It can be understood that in actual operation, when the solenoid coil is energized, the valve column will perform a switch movement. Due to the movement of the valve column, the air gap distance x (the air gap distance is equivalent to the relative position of the moving valve column) will also change, such as Figure 2 As shown, because the distance of the air gap is changing, the geometry of the valve core will also change, that is, the geometry of the valve core will change due to the movement of the valve stem. This changing magnetic resistance or permeability phenomenon can be expressed by a changing inductance L(x, t, i) that depends on the current i(t) through the solenoid coil and the air gap distance x(t):

[0052] L(x;t)≡L(x;t,i)(5)

[0053] It is understandable that in electronic circuits, due to the physical structure and the characteristics of some materials themselves, some non-ideal effects, namely parasitic effects, will inevitably occur. These effects can exist in any part of the circuit, such as resistors, inductors and other components, and even in the wires. The above equation (5) not only reflects that the valve stem will produce non-constant magnetic permeability or magnetic flux during the switching movement, but the dependence in equation (5) also reflects the existence of parasitic effects such as magnetic flux leakage, hysteresis and eddy current loss.

[0054] Furthermore, in an embodiment of the present invention, the above equation (5) can be further optimized: the simplified model of the variable inductance L(x, t, i) can be expressed by, for example, the relationship between the non-constant magnetic permeability through inductance and the equivalent magnetic permeability Pm(x; t) of the magnetic circuit. The expressed equation can be approximated as the magnetic permeability Pgap(x; t) of the air gap, thereby obtaining the following equation (6):

[0055]

[0056] Among them, N turn Represents the number of turns in the solenoid. From the above derivation, it can be seen that the air gap distance x(t) will change when the valve stem performs a switching movement. Therefore, the magnetic permeability of the above air gap can be expressed as:

[0057]

[0058] Where A represents the cross-sectional area of ​​the air gap, and μ gap Represents the magnetic permeability of the medium in the air gap.

[0059] It can be understood that when the air gap is closed, that is, when the air gap distance is infinitely small, the magnetic permeability between the gaps will be infinite, usually manifesting as a magnetic short circuit.

[0060] Furthermore, combining the above equations (6) and (7), it can be deduced that:

[0061]

[0062] Then, the time parameter of equation (8), t, is derived to obtain the following equation:

[0063]

[0064] In an embodiment of the present invention, the above equation (9) is substituted into the above-obtained equation (3) and equation (4), and the following equation can be obtained:

[0065]

[0066]

[0067] From the above equation, it is not difficult to see that the back electromotive force V bemf (t) and the dependence of the valve stem motion x(t).

[0068] Step 102, recording a curve of the relationship between the excitation current and time during the movement of the valve stem.

[0069] like Figure 3 As shown ( Figure 3 The left half of the middle part records the variation curve of the excitation current and time during the switching process of the healthy valve, and the right half records the variation curve of the excitation current and time during the switching process of the faulty valve). In some embodiments of the present invention, the variation curve of the excitation current I (mA) and time t (ms) during the movement of the valve stem can be recorded. Among them, the relationship curve between the excitation current and time includes 3 significant points of the excitation current.

[0070] Specifically, the significant points include the excitation current peak point P1, the excitation current valley point P2, and the excitation current steady-state point P3;

[0071] according to Figure 3 It is not difficult to see that due to the obstruction of the switching movement of the flow control valve spool, the current range between P1 and P2 is significantly reduced.

[0072] Record the amplitude I1 of the excitation current peak point and the time t1 when the excitation current reaches the peak point; record the amplitude I2 of the excitation current valley point and the time t2 when the excitation current reaches the valley point; record the amplitude I3 of the excitation current steady-state point and the time t3 when the excitation current reaches the steady-state point.

[0073] In some embodiments of the present invention, the “peak-to-valley distance” may also be derived based on a linear or nonlinear combination of the above-mentioned salient point information:

[0074] I 12 =I1-I2(1 2)

[0075] It is understandable that in practical applications, if the flow control valve spool does not complete the switch motion, the amplitude I2 of the excitation current valley point will be very high, making the peak-to-valley distance I 12 The value of is reduced. Figure 3 However, in this case, since the valves still actuate at approximately the same time, the change in t2 will be small.

[0076] Additionally, a damaged spring inside the flow control valve can cause the valve to close more quickly, resulting in a smaller t2.

[0077] Step 103, calculating the area under the square of the curve, where the area under the square of the curve is used to characterize the cumulative energy change of the system during the movement of the valve stem.

[0078] In some embodiments of the present invention, the area under the square of the valve excitation current versus time curve may be calculated using the following formula:

[0079]

[0080] Among them, E 12 is the cumulative energy change of the system during the valve stem movement, t1 is the time when the excitation current reaches the peak point, t2 is the time when the excitation current reaches the valley point, R is the equivalent resistance of the solenoid coil, and i is the current flowing through the solenoid coil.

[0081] However, in practical applications, it takes some time to obtain the excitation current vs. time curve. When the excitation current vs. time curve is not completely obtained, that is, when only point measurement data is available, the above formula (13) can be approximated as the area of ​​the triangle (the baseline value is equal to ):

[0082]

[0083] It can be understood that formula (14) is an approximation of formula (13). When the excitation current and time relationship curve can be completely obtained, formula (13) can be used to completely replace formula (14).

[0084] Step 104: When the accumulated energy change of the system exceeds a threshold, it is confirmed that the flow control valve is faulty.

[0085] In the embodiment of the present invention, whether the flow control valve fails can be further determined by determining whether the accumulated energy variation amplitude of the system is abnormal.

[0086] Specifically, an energy change threshold can be set in advance. This threshold can be determined based on historical data, experimental results or industry standards. The embodiments of the present invention do not limit this. However, it should be noted that the setting of the threshold should take into account the energy change range under normal operating conditions to distinguish it from the significant changes when a fault occurs.

[0087] In the embodiment of the present invention, the calculated cumulative energy change E 12 Compared with the set threshold, if the calculated cumulative energy change E 12 If the preset threshold is exceeded, the flow control valve is considered to be faulty.

[0088] In some embodiments of the present invention, after determining that the flow control valve has a fault, a pre-trained fault identification algorithm can be used to diagnose the flow control valve and determine the specific fault type, so that relevant personnel can take targeted measures to address the fault.

[0089] The embodiment of the present invention drives the valve column of the flow control valve to perform a switching movement; records the relationship curve between the excitation current and time during the movement of the valve column; calculates the square area under the curve, and the square area under the curve is used to characterize the cumulative energy change of the system during the movement of the valve column; when the cumulative energy change of the system exceeds a threshold, it is confirmed that the flow control valve has a fault, thereby realizing intelligent monitoring of downhole flow control valve faults in oil wells, which can effectively improve the reliability and working efficiency of the control valve and ensure the operating status of the oil well to a certain extent.

[0090] In order to verify the validity of the above-mentioned indicator of cumulative energy change of the system, the embodiment of the present invention also conducts large-scale durability tests on several flow control valves.

[0091] In an embodiment of the present invention, the flow control valve may be an industrial direct current solenoid valve (DC SVs).

[0092] Specifically, you can set N valves = 12 industrial DC solenoid valves, tested until three of them were considered damaged, where these industrial DC solenoid valves were equipped with dedicated data acquisition equipment.

[0093] Durability testing can include a degradation phase as well as an acquisition phase, e.g. Figure 4As shown. The purpose of the degradation phase is to stress test the solenoid valves, while the collection phase is used to collect relevant data of the solenoid valves. In the degradation phase, solenoid valves No. 1 to No. 6 are set to switch at a frequency of 20 Hz, while solenoid valves No. 7 to No. 12 are set to switch at a frequency of 50 Hz. Each degradation phase performs approximately 10,000 continuous cycles. In each cycle, whether or not it is collected, it includes the complete start-up and release action of the valve.

[0094] Between the two degradation phases, there is a collection phase for generating collection blocks. In the collection phase, the valve switches at a frequency of 3 Hz and measures data at a frequency of 1.5 Hz. Therefore, for every two start-up cycles, that is, the valve switches twice, the data acquisition device measures one cycle of data, such as Figure 4 As shown in FIG. 1 , each acquisition phase has about 1000 startup cycles, so in one acquisition phase, there are about 500 measurements. The measurement data includes the values ​​of t1, t2, I1, I2, and I3, and these measurement data constitute an acquisition block.

[0095] After collecting the above measurement data, the health of the valve can be evaluated regularly.

[0096] Specifically, dedicated quality inspection procedures can be used: resistance and impedance estimation, minimum excitation voltage estimation, mechanical deformation and time response evaluation.

[0097] Among others, resistance and impedance estimation can include:

[0098] Resistance measurement: Use a multimeter or a special resistance measuring instrument to regularly measure the resistance value of the solenoid valve coil. Under normal circumstances, the resistance value should be stable within a certain range. Significant changes in resistance value may indicate that the coil is aging or damaged.

[0099] Impedance measurement: Use an impedance analyzer to measure the impedance value of the solenoid valve coil. Changes in the impedance value can reflect changes in the electrical performance of the coil, such as short circuits or open circuits between coil turns.

[0100] The minimum excitation voltage estimate can include:

[0101] Voltage test: gradually reduce the excitation voltage and record the minimum voltage value at which the solenoid valve starts to move. Under normal circumstances, the minimum excitation voltage should be stable within a certain range. Significant changes in voltage values ​​may indicate that the valve stem movement is blocked or the coil performance is degraded.

[0102] Current test: Measure the starting current of the solenoid valve at different voltages and analyze the current change trend. Abnormal changes in current may indicate abnormal valve stem movement or decreased coil performance.

[0103] Mechanical deformation assessments may include:

[0104] Visual inspection: Disassemble the solenoid valve regularly and conduct a visual inspection to observe whether the valve stem, valve body and seals are worn, cracked or deformed.

[0105] Dimension measurement: Use precision measuring tools (such as micrometers, calipers, etc.) to measure the key dimensions of the valve stem and valve body, compare them with standard values, and evaluate mechanical deformation.

[0106] Vibration analysis: Use vibration sensors to monitor the vibration of the solenoid valve in operation, analyze the vibration spectrum, and identify potential mechanical failures.

[0107] Time response assessments may include:

[0108] Time measurement: Under different excitation voltages, measure the time from solenoid valve start to full action. Under normal circumstances, the response time should be stable within a certain range. Significant changes in response time may indicate that the valve stem movement is blocked or the control system performance is degraded.

[0109] Frequency response test: Test the solenoid valve on and off at different frequencies (such as 3Hz, 5Hz, 20Hz, 50Hz, etc.), and record the response time and stability. Abnormal changes in frequency response may indicate abnormal valve spool movement or degraded control system performance.

[0110] It is understandable that the above quality inspection procedures are only exemplary, and those skilled in the art can freely choose according to actual conditions, and the present invention does not limit this.

[0111] In the embodiment of the present invention, after the above measurement data is collected, since the valve temperature will affect the valve current curve, the embodiment of the present invention can also clean the above measurement data, for example, manually clear the time points where there are temperature transient effects.

[0112] At the same time, considering the scale of the collected measurement data, the embodiment of the present invention can also aggregate information by taking an average value to reduce the complexity and computational workload of subsequent analysis:

[0113]

[0114] v=1,...N valves

[0115] b=1,...,B [v] (1 5)

[0116] Among them, N [v] (b) represents the number of measurements of the vth valve in the bth acquisition block, B [v] Indicates the number of acquisition blocks for the vth valve.

[0117] For all other data I1, I2, I3, t1, t2 and I calculated by formula (12) 12 All perform the same operation.

[0118] In the embodiment of the present invention, considering the index calculated in formula (15), data normalization is also required to compare the values ​​from different SVs. is normalized relative to its first value (i.e. the value of the first acquisition block), as follows:

[0119]

[0120] in, It can be regarded as a reference value before degradation occurs. It is normalized by calculating its percentage increase as follows:

[0121]

[0122] Formula (17) is able to binary classify the healthy state and fault state of the valve, while the CI in formula (16) shows a gradually increasing trend pattern, which is suitable for quantifying the degree of degradation during the SV operation stage.

[0123] It should be noted that, for the sake of simplicity, the method embodiments are described as a series of action combinations, but those skilled in the art should be aware that the embodiments of the present invention are not limited by the order of the actions described, because according to the embodiments of the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present invention.

[0124] An embodiment of the present invention further provides a downhole flow control valve fault monitoring device for an oil well, which may specifically include the following modules:

[0125] A drive module, used for driving the valve column of the flow control valve to perform on-off movement;

[0126] A recording module, used for recording a curve of the relationship between the excitation current and time during the movement of the valve stem;

[0127] A calculation module, used for calculating the area under the square of the curve, where the area under the square of the curve is used to characterize the cumulative energy change of the system during the movement of the valve stem;

[0128] The confirmation module is used to confirm that the flow control valve fails when the accumulated energy change of the system exceeds a threshold value.

[0129] Optionally, the driver module includes:

[0130] The driving submodule is used to drive the valve column of the flow control valve to perform switching movement by using a driving coil circuit, wherein the driving coil circuit includes a solenoid coil and an inductor connected in series.

[0131] Optionally, the recording module includes:

[0132] The recording submodule is used to record the amplitude of the excitation current peak point and the time when the excitation current peak point is reached; record the amplitude of the excitation current valley point and the time when the excitation current valley point is reached; record the amplitude of the excitation current steady-state point and the time when the excitation current steady-state point is reached.

[0133] Optionally, the formula for the area under the square of the curve is:

[0134]

[0135] Among them, E 12 is the cumulative energy change of the system during the valve stem movement, t1 is the time when the excitation current reaches the peak point, t2 is the time when the excitation current reaches the valley point, R is the equivalent resistance of the solenoid coil, and i is the current flowing through the solenoid coil.

[0136] Optionally, when the curve is not fully recorded, the area formula is:

[0137]

[0138] Where I1 is the amplitude of the excitation current reaching the peak point, I2 is the amplitude of the excitation current reaching the valley point, and E 12 is the cumulative energy change of the system during the valve stem movement, t1 is the time when the excitation current reaches the peak point, and t2 is the time when the excitation current reaches the valley point.

[0139] Optionally, the validity of the cumulative energy variation is verified by performing durability tests on several flow control valves.

[0140] Optionally, the flow control valve includes a prototype of an industrial DC solenoid valve.

[0141] An embodiment of the present invention further provides an electronic device, which may include a processor, a memory, and a computer program stored in the memory and capable of running on the processor. When the computer program is executed by the processor, the above-mentioned method for monitoring faults of a downhole flow control valve in an oil well is implemented.

[0142] An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the above method for monitoring faults of a downhole flow control valve in an oil well is implemented.

[0143] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0144] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0145] Those skilled in the art will appreciate that the embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the embodiments of the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the embodiments of the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0146] The above is a detailed introduction to the provided oil well downhole flow control valve fault monitoring method, device, equipment and medium. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for monitoring faults of a downhole flow control valve in an oil well, characterized in that: The method comprises: Drive the flow control valve spool to perform on-off movement; Recording a curve of the relationship between the excitation current and time during the movement of the valve stem; Calculating the area under the square of the curve, where the area under the square of the curve is used to characterize the cumulative energy change of the system during the movement of the valve stem; In the event that the accumulated energy change of the system exceeds a threshold value, a failure of the flow control valve is determined.

2. The method according to claim 1, characterized in that The method of driving the flow control valve spool to perform a switching motion comprises: The flow control valve stem is driven by a driving coil circuit to perform a switching movement. The driving coil circuit includes a solenoid coil and an inductor connected in series.

3. The method according to claim 2, characterized in that The excitation current and time relationship curve includes several significant points of the excitation current, and the significant points include the excitation current peak point, the excitation current valley point and the excitation current steady-state point; Recording the amplitude of the excitation current peak point and the time when the excitation current peak point is reached; Recording the amplitude of the excitation current valley point and the time when the excitation current valley point is reached; The amplitude of the excitation current steady-state point and the time to reach the excitation current steady-state point are recorded.

4. The method according to claim 3, characterized in that The formula for the area under the square of the curve is: Among them, E 12 is the cumulative energy change of the system during the movement of the valve stem, t1 is the time when the excitation current reaches the peak point, t2 is the time when the excitation current reaches the valley point, R is the equivalent resistance of the solenoid coil, and i is the current flowing through the solenoid coil.

5. The method according to claim 4, characterized in that When the curve is not fully recorded, the area formula is: Where I1 is the amplitude of the excitation current reaching the peak point, I2 is the amplitude of the excitation current reaching the valley point, E 12 is the cumulative energy change of the system during the movement of the valve stem, t1 is the time when the excitation current reaches the peak point, and t2 is the time when the excitation current reaches the valley point.

6. The method according to claim 1, characterized in that The method further comprises: The effectiveness of the accumulated energy variation is verified by performing durability tests on a number of the flow control valves.

7. The method according to claim 6, characterized in that The flow control valve comprises a prototype of an industrial DC solenoid valve.

8. A downhole flow control valve fault monitoring device for an oil well, characterized in that: The device comprises: A drive module, used for driving the valve column of the flow control valve to perform on-off movement; A recording module, used for recording a curve of the relationship between the excitation current and time during the movement of the valve stem; A calculation module, used for calculating the area under the square of the curve, wherein the area under the square of the curve is used for characterizing the cumulative energy change of the system during the movement of the valve stem; The confirmation module is used to confirm that the flow control valve fails when the accumulated energy change of the system exceeds a threshold value.

9. An electronic device, characterized in that: The method comprises a processor, a memory and a computer program stored in the memory and capable of running on the processor, wherein when the computer program is executed by the processor, the method for monitoring faults of a downhole flow control valve in an oil well as described in any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for monitoring faults of a downhole flow control valve in an oil well according to any one of claims 1 to 7 is implemented.

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