Underground fault judgment method and system based on automatic parameter adjustment technology of oil pumping unit

Abstract

The invention discloses an underground fault judgment method and system based on an automatic parameter adjustment technology of a pumping unit, and belongs to the technical field of oil field automation control, and the method comprises the following steps: when an automatic speed adjustment system of the pumping unit sends an adjustment instruction, a timer T and a counter C are started at the same time, and after the set time length of the timer T is the adjustment instruction, the counter C is started; when the oil pumping unit completes the action, the control system obtains more than two times of the feedback time, and the counter C assigns 0; the reading control system is used for judging whether the current value A0 of the index is adjusted or not, and after the timer reaches the set time, the current value A1 is read; comparing the values of A0 and A1 to judge whether reasonable and obvious changes exist or not, if yes, entering the step 2, continuing to adjust until an adjusting target is reached, and if no obvious change exists, adding 1 to the value C; when Cgt; and when n is equal to n, the system sends a fault signal and exits the adjustment program. The applicability and service life of the control system are improved, and safe and stable production of an oil field is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield automation control, and in particular relates to a method and system for determining downhole faults based on automatic parameter adjustment technology for oil pumping units. Background Art

[0002] At present, various methods of automatic variable frequency speed regulation of oil pumps are widely used in oil fields. However, the control systems designed according to various theoretical inventions often shut down due to various unexpected failures when applied on site. Therefore, the control system needs to accurately judge various failures in the oil field and take measures. Among them, the judgment of downhole failure risks is the most difficult. Because people can only infer the downhole conditions through various ground equipment and parameter performances. If the downhole fault cannot be judged in time and accurately, there is often a situation where the ground system issues a variable frequency speed regulation command-downhole fault, and the downhole parameters do not change after the speed regulation-the system continues to regulate the speed because the parameters have not changed-the parameters have not changed-the speed is adjusted again until the pump stops due to the mechanical limit, and even causes equipment damage in severe cases. Therefore, a simple and intuitive method for judging downhole faults in oil wells is needed to improve the automatic speed regulation technology and system of oil pumps.

[0003] The invention patent (publication number: CN109255134A) discloses a method for obtaining the fault condition of a pumping well. The method includes: establishing a time series model of power, load and current of the pumping well according to the automation data of multiple pumping wells, thereby determining the standard dynamometer diagram of the normal state of the pumping well; establishing a normal / faulty binary classification model of the pumping well according to the standard dynamometer diagram and the measured dynamometer diagram of the pumping well at the abnormal time point; and using the classification model to judge the fault type of the pumping well with fault. The method is theoretically feasible and has a high degree of automation. However, there are still some shortcomings: (1) The premise of the application of this method is to obtain the standard dynamometer diagram of the normal working state of the pumping unit, but there are many factors that affect the operation of the pumping unit, and it may not be possible to obtain the standard dynamometer diagram with all indicators in the ideal state on site; (2) The method adopts the dynamometer diagram method to judge the fault, which requires the installation of a dynamometer diagram acquisition device, and cannot be applied to the pumping system without the dynamometer diagram; (3) The method takes too long to obtain accurate data. The training time of the embodiment is as long as 3 years, which is obviously difficult to promote and apply quickly.

[0004] The utility model (application number: 201821599388.1) discloses a pumping unit control device with fault diagnosis function. Its basic principle is: to obtain the simulated dynamometer diagram of the pumping unit through calculation of various sensor data on site; on this basis, to complete detailed fault diagnosis through dimensionless processing of the dynamometer diagram and pattern recognition, and to confirm special faults through historical data to complete the final comprehensive fault analysis. The device has a simple principle and can identify many types of faults. However, there are obvious shortcomings: (1) The accuracy of fault identification depends on the generation of the dynamometer diagram of the pumping unit. The accuracy of the dynamometer diagram is restricted by the system computing power and theoretical model. The model is over-simplified and the result is not accurate. The use of a more accurate model requires a large amount of computing and a high cost of the computing module; (2) The device needs to install more sensors on the oil well, which invisibly increases the system cost and affects the promotion and application of the system.

[0005] Other patents for oil well fault judgment (a method for predicting downhole faults of a rod pump oil well based on a multivariate grey model, publication number: CN111520114A, a method for diagnosing oil well faults based on a pump performance diagram, publication number: CN106321078B, and a system-level method for intelligent analysis and decision-making of oil well faults, publication number: CN106761668B) all have a shortcoming: all kinds of invention methods need to collect data to generate an oil well performance diagram, and then analyze and judge based on the performance diagram. This cannot be applied to oil wells that are not equipped with performance diagram data sensors. This virtually restricts the promotion of automated control systems. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes: a downhole fault judgment method based on the automatic parameter adjustment technology of the oil pump, comprising the following steps:

[0007] Step 1: When the automatic speed control system of the oil pumping unit issues an adjustment command, a timer T and a counter C are started at the same time. The setting time of the timer T should be more than twice the time it takes for the oil pumping unit to complete the action and the control system to get feedback after the adjustment command. The counter C is set to 0;

[0008] Step 2: Read the current value A0 of the indicator used by the control system to determine whether to make adjustments. After the timer reaches the set time, read the current value A1 again;

[0009] Step 3: Compare A0 and A1 values ​​to see if there is a reasonable and obvious change. If there is a change, go to step 1 and continue to adjust until the adjustment target is reached. If there is no obvious change, add 1 to the C value, issue an adjustment command again, and go to step 2.

[0010] Step 4: When C>=n, the system sends out a fault signal and exits the adjustment procedure. n is the number of judgment values, which can be set in advance.

[0011] A control system for a downhole fault judgment method based on automatic parameter adjustment technology of an oil pump, the system comprises: a production liquid metering device, a computing and processing module, a frequency converter and an oil pump system, the frequency converter and the computing and processing module, the display module and the computing and processing module are all connected via RS485, and the display module adopts a touch screen to display the current pump efficiency and stroke times in real time.

[0012] Furthermore, the liquid production metering device is used to continuously collect the liquid production data of the pumping unit at each stroke, and transmit the liquid production data to the calculation and processing module; the calculation and processing module has the functions of external signal reception and transmission, data calculation, analysis and storage. After receiving the liquid production data, the calculation and processing module calculates the pump efficiency value under the current well conditions through data processing, compares the pump efficiency value with the preset pump efficiency value, and sends an adjustment instruction to the frequency converter according to the comparison result.

[0013] Furthermore, when the liquid production value obtained by the system is low and it is decided to perform frequency conversion speed regulation, a counter C is set and the value of C is assigned to 0.

[0014] Further, the system issues an adjustment instruction, the system calculates the current pump efficiency value A0, and starts a timer in the system.

[0015] Furthermore, the inverter output frequency is increased by 5 Hz, and the pumping unit stroke speed is increased. When the timer reaches the set duration, the system calculates the current pump efficiency A1 and determines whether A1-A0>5% is established.

[0016] Furthermore, if the above formula holds true, indicating that the speed regulation is effective, the system continues to regulate the speed until the pump efficiency reaches the set target.

[0017] Furthermore, if the above formula is not true, it means that the oil well system is faulty, resulting in unsuccessful speed regulation. At this time, the counter value is C+1, and the following steps are repeated to continue speed regulation:

[0018] When the system obtains a low liquid production value and decides to perform variable frequency speed regulation, a counter C is set and the value of C is assigned to 0; the system issues an adjustment instruction, the system calculates the current pump efficiency value A0, and starts a timer in the system;

[0019] When C>3, the system issues a fault alarm and exits the adjustment procedure.

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides a process method for quickly and simply judging downhole faults. The method has a simple principle, a fast system judgment speed, and can improve the original system function without adding any hardware equipment. It can meet the needs of oil wells using automatic variable frequency speed regulation technology for pumping units, extend the life of the equipment, and ensure safe and stable production of oil wells.

[0022] The present invention provides a method for quickly judging downhole faults. By regularly observing and comparing the changes in index values, it is determined whether the speed regulation is successful. This is a beneficial supplement and improvement to the automatic parameter adjustment control technology of the oil pumping unit. The system does not need to add any hardware equipment, and only needs to write a program in the speed control system.

[0023] The program of this method has been written into the automatic parameter adjustment control system of many conventional pumping wells and submersible oil pump wells. The results show that this method greatly reduces the development and upgrading cost of the automatic variable frequency speed regulation system of the pumping unit. The principle is simple, the program judgment speed is fast, and the applicability and life of the control system are improved, ensuring the safe and stable production of the oil field. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flowchart of the process of the present invention;

[0025] Figure 2 This is a system structure block diagram when the present invention is applied to an automatic parameter adjustment system for an oil pumping unit;

[0026] Figure 3 This is a structural diagram of the pipe column in the rodless lifting process control system of the present invention.

[0027] Among them, the accompanying drawings are marked as: 1. downhole pressure gauge, 2. submersible motor, 3. submersible pump, 4. submersible cable, 5. ground control system. DETAILED DESCRIPTION

[0028] A method for determining downhole faults based on automatic parameter adjustment technology of oil pumping units, such as Figure 1 The steps shown include:

[0029] Step 1: When the automatic speed control system of the oil pumping unit issues an adjustment command, a timer T and a counter C are started at the same time. The setting time of the timer T should be more than twice the time it takes for the oil pumping unit to complete the action and the control system to get feedback after the adjustment command. The counter C is set to 0;

[0030] Step 2: Read the current value A0 of the indicator used by the control system to determine whether to make adjustments. After the timer reaches the set time, read the current value A1 again;

[0031] Step 3: Compare A0 and A1 values ​​to see if there is a reasonable and obvious change. If there is a change, go to step 1 and continue to adjust until the adjustment target is reached. If there is no obvious change, add 1 to the C value, issue an adjustment command again, and go to step 2.

[0032] Step 4: When C>=n, the system sends out a fault signal and exits the adjustment procedure. n is the number of judgment values, which can be set in advance.

[0033] First embodiment: application on conventional oil pumping unit

[0034] The present invention provides a method for determining downhole faults based on the automatic parameter adjustment technology of the oil pump. Since the walking beam pump is the most commonly used oil production equipment in oil fields, and under current technical conditions, the parameter adjustment of this type of oil pump is limited to adjusting the motor speed through the frequency conversion method and then changing the pump stroke rate. Therefore, this embodiment is an automatic control system combined with an oil well production liquid continuous monitoring and adjustment device, and the system includes: a production liquid metering device, a calculation and processing module, a frequency converter and an oil pump system. The frequency converter and the calculation and processing module, and the display module and the calculation and processing module are all connected via RS485. The display module uses a touch screen, which can display the current pump efficiency and stroke rate in real time, such as Figure 2 .

[0035] The method comprises the following steps:

[0036] The liquid production metering device is used to continuously collect the liquid production data of the pumping unit at each stroke, and transmit the liquid production data to the calculation and processing module; the calculation and processing module can be in various forms such as a single-chip microcomputer, PLC, RTU, etc., and has functions such as external signal reception and transmission, data calculation and analysis storage, etc. After receiving the liquid production data, the calculation and processing module calculates the pump efficiency value under the current well conditions through data processing, compares the pump efficiency value with the preset pump efficiency value, and sends an adjustment instruction to the frequency converter according to the comparison result.

[0037] When the liquid production value obtained by the system is low and it is decided to perform frequency conversion speed regulation, a counter C is set and the value of C is assigned to 0.

[0038] (3) The system issues an adjustment command, calculates the current pump efficiency value A0, and starts a timer in the system. If the system does not support it, an external hardware timer can also be used. Considering that the pump efficiency can be improved in about 5 minutes after the adjustment, the timer is set to 10 minutes.

[0039] (3) The inverter output frequency is increased by 5 Hz, and the pumping speed is increased. When the timer reaches the set duration, the system calculates the current pump efficiency A1 and determines whether A1-A0>5% is true.

[0040] (4) If the above equation is true, it means that the speed regulation is effective, and the system continues to regulate the speed until the pump efficiency reaches the set target.

[0041] (5) If the above equation is not true, it means that the oil well system is faulty, resulting in unsuccessful speed regulation. At this time, the counter value is C+1, and steps (2)-(3) are repeated to continue speed regulation. When C>3, the system issues a fault alarm and exits the adjustment program.

[0042] In December 2020, an oil well on site started an automatic parameter adjustment program due to low pump efficiency (13%), with the aim of increasing the pump efficiency to 40%. Three hours later, the pump efficiency hovered around 15%, and the system issued a fault alarm and exited the parameter adjustment program. No other faults were found during the on-site inspection. The downhole tubing was pulled out and it was confirmed that the downhole pump was leaking, resulting in the inability to improve the pump efficiency, thus successfully avoiding the ineffective operation of the system.

[0043] Second embodiment: Application in rodless lifting process control system

[0044] The second embodiment of the present invention is applied to the submersible rodless lifting automatic control system, such as Figure 3 . The system includes: a downhole pressure gauge (1), a submersible motor (2), a submersible pump (3), a submersible cable (4), and a ground control system (5). The data collected by the downhole pressure gauge is transmitted to the ground through the submersible cable. The ground control system determines whether the motor speed is reasonable and whether it needs to be adjusted based on the downhole pressure data. To ensure the smooth operation of the downhole motor, the judgment value is set to the downhole pressure, and the downhole pressure adjustment range is set to 1.5-4.0MPa. The duration T = 30 minutes, and the number of judgments is set to n = 5. The process of the method is as follows:

[0045] (1) When the downhole pressure is greater than 4.0 MPa, it is determined that the pressure is too high and the submergence is too large. The ground control program issues an instruction to set a counter C and assign C to 0, recording the current pressure value P0;

[0046] (2) The motor speed is increased by 10 rpm and the motor is operated for 30 minutes. The current downhole pressure is P1. It is determined whether P0-P1>0.1 MPa is established.

[0047] If the above formula is established, it proves that the adjustment is effective. Repeat step (2) and continue to adjust until the adjustment target is reached.

[0048] If the above formula is not true, it means that the rodless lifting system is faulty and the adjustment is unsuccessful, then the C value is increased by 1 and steps (2) to (3) are repeated until C>n, at which point the system issues a fault alarm and exits the adjustment procedure.

[0049] For each speed adjustment, the downhole motor speed is changed by 10 rpm each time. After adjustment, it runs stably for 30 minutes, and then determines whether to continue adjustment based on the new downhole pressure data.

[0050] In February 2023, an on-site rodless lift oil field started the automatic parameter adjustment program due to excessive downhole pressure, with the aim of reducing the downhole pressure to 1.5MPa. After 10 hours, the pressure remained unchanged, and the system issued a fault alarm and exited the parameter adjustment. No other faults were found during the on-site inspection. After the equipment was pulled out of the operation, it was confirmed that the rubber of the submersible screw pump was aged and the seal failed, causing well fluid leakage, successfully avoiding the ineffective operation of the system.

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for determining downhole faults based on automatic parameter adjustment technology of a pumping unit, characterized in that: The steps include: Step 1: When the automatic speed control system of the oil pumping unit issues an adjustment command, a timer T and a counter C are started at the same time. The setting time of the timer T should be more than twice the time it takes for the oil pumping unit to complete the action and the control system to get feedback after the adjustment command. The counter C is set to 0; Step 2: Read the current value A0 of the indicator used by the control system to determine whether to make adjustments. After the timer reaches the set time, read the current value A1 again; Step 3: Compare A0 and A1 values ​​to see if there is a reasonable and obvious change. If there is a change, go to step 1 and continue to adjust until the adjustment target is reached. If there is no obvious change, add 1 to the C value, issue an adjustment command again, and go to step 2. Step 4: When C>=n, the system sends out a fault signal and exits the adjustment procedure. n is the number of judgment values, which can be set in advance.

2. The control system of the downhole fault judgment method based on the automatic parameter adjustment technology of the oil pumping unit according to claim 1 is characterized in that: The system includes: liquid production metering device, computing and processing module, frequency converter and pumping unit system. The frequency converter and computing and processing module, display module and computing and processing module are connected through RS485. The display module adopts touch screen to display the current pump efficiency and stroke times in real time.

3. The control system of the downhole fault judgment method based on the automatic parameter adjustment technology of the oil pumping unit according to claim 2 is characterized in that: The liquid production metering device is used to continuously collect the liquid production data of the pumping unit at each stroke, and transmit the liquid production data to the calculation and processing module; The calculation and processing module has the functions of receiving and sending external signals, calculating, analyzing and storing data. After receiving the liquid production data, the calculation and processing module calculates the pump efficiency value under the current well conditions through data processing, compares the pump efficiency value with the preset pump efficiency value, and sends an adjustment instruction to the frequency converter according to the comparison result.

4. The control system of the downhole fault judgment method based on the automatic parameter adjustment technology of the oil pumping unit as claimed in claim 3 is characterized in that: When the liquid production value obtained by the system is low and it is decided to perform frequency conversion speed regulation, a counter C is set and the value of C is assigned to 0.

5. The control system of the downhole fault judgment method based on the automatic parameter adjustment technology of the oil pumping unit according to claim 4 is characterized in that: The system issues an adjustment instruction, calculates the current pump efficiency value A0, and starts a timer in the system.

6. The control system of the downhole fault judgment method based on the automatic parameter adjustment technology of the oil pumping unit according to claim 5 is characterized in that: The inverter output frequency increases by 5Hz, and the pumping unit speeds up. When the timer reaches the set duration, the system calculates the current pump efficiency A1 and determines whether A1-A0>5% is true.

7. The control system of the downhole fault judgment method based on the automatic parameter adjustment technology of the oil pumping unit according to claim 6 is characterized in that: If the above formula is true, it means that the speed regulation is effective, and the system will continue to regulate the speed until the pump efficiency reaches the set target.

8. The control system of the downhole fault judgment method based on the automatic parameter adjustment technology of the oil pumping unit according to claim 7 is characterized in that: If the above formula is not true, it means that the oil well system is faulty, resulting in unsuccessful speed regulation. At this time, the counter value is C+1, and the following steps are repeated to continue speed regulation: When the system obtains a low liquid production value and decides to perform variable frequency speed regulation, a counter C is set and the value of C is assigned to 0; the system issues an adjustment instruction, the system calculates the current pump efficiency value A0, and starts a timer in the system; When C>3, the system issues a fault alarm and exits the adjustment procedure.

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