Oil well production parameter adjusting method and system based on submergence degree of oil well pump

Abstract

The invention discloses an oil well production parameter adjusting method and system based on the submergence degree of an oil well pump, and belongs to the technical field of oil field automation control. The current oil well pump submergence degree is calculated according to the working fluid level or underground pressure data; the submergence degree of the oil well pump is compared with a preset submergence degree, and a control instruction is sent to a control module according to a comparison result so as to adjust the stroke frequency of the oil pumping unit or the running speed of a motor. According to the method, accurate adjustment of the automatic stroke frequency adjustment of the rod-pumped well is achieved, the system efficiency of the oil well is improved, and the method is not only suitable for the conditions that liquid supply is sufficient and the oil well environment is relatively stable, but also suitable for the oil well with insufficient liquid supply and large underground environment change. An automatic control system using the method is already applied to a plurality of conventional rod-pumped wells and underground oil-submerged pump wells of an oil field, the production cost of the oil well is reduced, the economic benefit of oil production of the oil field is improved, and field operation is stable and reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield automation control, and in particular relates to an oil well production parameter adjustment method and system based on the submergence degree of an oil well pump. Background Art

[0002] At present, various automatic frequency conversion speed regulation processes for oil pumps are widely used in oil fields. However, due to the complex working conditions of the oil production system and incomplete measurement information, it is difficult to determine the optimal production parameters of the oil well and the speed regulation is blind.

[0003] Generally, the indicator for measuring the best working state of the oil pump is the oil well liquid production. However, there are some shortcomings in the ground on-site liquid production measurement, such as large error with the actual oil well liquid production, complex calculation, data communication and remote calculation taking up a lot of time, and inability to make quick judgments. These have brought difficulties to the judgment of the reasonable stroke frequency of the variable frequency speed regulation oil pump.

[0004] Invention patent (publication number: CN105093930A) is a method for determining and adjusting the pumping frequency of a digital pumping unit suitable for ultra-low permeability reservoirs. It discloses a method for determining and adjusting the pumping frequency. Under the condition of ensuring the liquid production, the optimal number of strokes can be automatically found according to the size of the oil well liquid production, so that the number of strokes can be adjusted to the minimum, so that it can reach the best working state, and the number of strokes can be automatically adjusted and remote manual adjustment can be realized. The method is theoretically rigorous and feasible, but there are shortcomings in field application: 1) The implementation of this method depends on the measurement of the oil well liquid production, but the traditional measurement method cannot meet the real-time requirements. The real-time measurement equipment has too large errors for cheap ones and high prices for high precision, which limits its application in oil fields; 2) This method relies on the collected indicator diagram for data processing, but it cannot be guaranteed that each stroke can generate a power diagram on site, so the power diagram cannot respond to changes in the liquid supply status in time; 3) The error influence of the power diagram measurement cannot be eliminated; 4) In order to ensure the calculation speed, the model is overly simplified and the error is huge.

[0005] Invention patent (publication number: CN102865053A) A method for determining the best stroke frequency of an oil pumping unit, characterized in that: the relative liquid production is calculated based on the ground power diagram before and after the stroke frequency changes, and the change in the ratio is determined; the above program is continuously run until the minimum stroke frequency under the maximum daily liquid production is found, which is the best stroke frequency. Although the algorithm of this method is simple, the assumption is too ideal. In the actual production process, affected by the working conditions, the stroke frequency of the oil pumping unit may have multiple maximum points when it is continuously changed and adjusted. Therefore, this method is only a local optimal stroke frequency, not a global optimal stroke frequency.

[0006] The invention patent (publication number: 202211172860.4) is an automatic adjustment method for the pumping unit stroke frequency based on the continuous liquid production at the wellhead of the pumping unit. The characteristics are that the liquid production metering device continuously collects the liquid production data of the pumping unit at each stroke; calculates the average value of the liquid production per unit time under the current well conditions; calculates the average pump efficiency of the current liquid production conditions according to the average value of the liquid production and the theoretical displacement of the pump; compares the average pump efficiency with the preset pump efficiency to obtain a comparison result, and sends a speed control instruction to the frequency converter according to the result to adjust the pumping unit stroke frequency. The implementation of this method relies on the real-time measurement of the liquid production of each stroke of the oil well, but this measurement method has problems: 1) Measurement is difficult, especially for the case of discontinuous liquid production in low-liquid production formations, high-precision instruments must be used to accurately obtain data, which leads to excessively high equipment costs and is not conducive to field use, 2) The pumping unit production system is a complex nonlinear system, and using a simple linear model to replace the calculation will result in very large errors. Summary of the invention

[0007] In order to solve the above problems, the present invention proposes: a method for adjusting oil well production parameters based on the submergence degree of a well pump, comprising the following steps:

[0008] S1. Obtaining oil well dynamic liquid level or downhole pressure data;

[0009] S2, calculating the current submergence of the oil well pump according to the dynamic liquid level or downhole pressure data;

[0010] S3, comparing the submergence of the oil pump with a preset submergence, and sending a control instruction to a control module according to the comparison result to adjust the pumping stroke frequency or the motor running speed.

[0011] Furthermore, in step S3, the submergence value of the oil pump is compared with a preset submergence value, and a control instruction is sent to the control module according to the comparison result to adjust the pumping stroke rate or the motor running speed: if the submergence is less than the set value, a deceleration instruction is sent to the frequency converter, and the frequency converter reduces the motor speed to reduce the pumping stroke rate.

[0012] Furthermore, if the sinking degree is equal to the set value, a hold command is sent to the frequency converter, the motor maintains the current speed, and the pumping unit stroke frequency is not adjusted.

[0013] Furthermore, if the submergence is greater than a set value, a speed-up command is sent to the frequency converter, and the frequency converter increases the motor speed to increase the pumping stroke frequency.

[0014] Furthermore, different formulas are used to calculate the submergence of the oil well pump according to the different types of data obtained:

[0015] When the acquired data is the dynamic liquid level of the oil well, the calculation formula for the submergence of the oil well pump is:

[0016] H=H0-H1.

[0017] Wherein, H1 is the dynamic liquid level, H0 is the vertical depth of the current oil well pump from the ground. In vertical wells or oil wells with small well inclination angles, the pump lowering depth is directly used instead of the vertical depth of the oil well pump from the ground. In highly deviated wells or horizontal wells, relevant data is searched to obtain the vertical depth of the oil well pump.

[0018] Furthermore, when the acquired data is the downhole pressure, the calculation formula of the submergence of the oil well pump is:

[0019] H=P

[0020] ρg

[0021] Where P is the downhole pressure, ρ is the well fluid density, and g is the local gravitational acceleration.

[0022] A control system for an oil well production parameter adjustment method based on the submergence degree of an oil pump comprises a downhole data acquisition device and a motor, a transmission assembly, a submersible pump, a submersible cable, and a ground control system. The downhole data acquisition device and the motor, the transmission assembly, the submersible pump, and the oil pipe are connected in sequence from bottom to top and lowered together to the bottom of the well. The downhole data acquisition device and the motor are transmitted to the ground through the submersible cable and connected to the ground control system.

[0023] Furthermore, the ground control system includes a calculation processing module and a control output module, and the calculation processing module calculates the current submergence H of the oil pump according to the formula based on the downhole pressure data;

[0024]

[0025] Where P is the downhole pressure, ρ is the well fluid density, and g is the local gravitational acceleration. The well fluid density is calculated by the geological or production department after measurement. The calculation and processing module compares the current submergence with the preset reasonable submergence, and issues a speed control command to the control output module according to the comparison result. The control output module outputs the adjusted signal according to the command, and the electrical signal is transmitted to the downhole motor through the submersible cable, thereby changing the motor speed.

[0026] The beneficial effects of the present invention are:

[0027] The present invention provides a method for controlling an oil pump based on the submergence of an oil pump, which realizes the precise adjustment of the automatic stroke frequency of the oil pump well and improves the system efficiency of the oil well. The present invention is not only applicable to the situation where the liquid supply is sufficient and the oil well environment is relatively stable, but also applicable to the situation where the liquid supply is insufficient and the downhole environment changes greatly. The present invention does not require the judgment of the liquid production, thus avoiding the deficiency of large errors in theoretical calculation or direct measurement of the liquid production. By calculating the submergence of the oil pump to judge the size trend, the calculation amount and memory usage are greatly reduced, the judgment speed is improved, and the requirements of real-time adjustment on site are met.

[0028] The automatic control system using this method has been applied to many conventional pumping wells and submersible oil pump wells in the oil field. The results show that this method greatly reduces the production cost of oil wells, improves the economic benefits of oil production in the oil field, and the field operation is stable and reliable.

[0029] This device collects downhole pressure or dynamic liquid level data through sensors and transmits it to the ground computing control unit, which calculates the current sinking degree and compares it with the preset reasonable sinking degree value. An adjustment instruction is issued based on the comparison result and the comparison judgment result is displayed on the display module. The frequency converter or other speed regulating device changes the operating parameters of the motor or pumping system according to the instruction. Adjusting the comparison result keeps the oil production system running in the best state on the basis of giving full play to the downhole fluid supply capacity, greatly reducing the production cost of the oil well and improving the economic benefits of oil production in the oil field. The control model has a simple principle, a small amount of data, and fast calculation. It realizes the precise adjustment of the automatic adjustment of the pumping well stroke and improves the production efficiency of the oil well. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a flowchart of the process of the present invention;

[0031] Figure 2 It is a structural block diagram of an automatic control system based on the method of the present invention;

[0032] Figure 3 This is a structural diagram of a pipe string used in rodless lifting described in the second embodiment of the present invention.

[0033] Among them, the figures are marked as: 1. downhole data acquisition device and downhole motor, 2. transmission assembly, 3. submersible pump, 4. submersible cable, 5. oil pipe, 6. ground control system. DETAILED DESCRIPTION

[0034] The submergence of the oil well pump is closely related to the oil well production. If the submergence is too low, the filling degree of the oil well pump is not high, which means that the production system of the oil well pump is too large, the production efficiency is not high, and the energy consumption is wasted, and the production parameters need to be adjusted down; if the submergence is too large, it means that the current production system does not fully exert the production capacity of the well, the oil well production is too low, and the production parameters need to be increased. Therefore, a reasonable submergence plays an important role in exerting the production capacity of the oil well and obtaining the best production benefits.

[0035] The present invention provides a method and system for controlling an oil pump based on the submergence of an oil pump, which realizes accurate adjustment of the automatic stroke frequency of an oil pump well, improves the system efficiency of the oil well, and greatly reduces the production cost of the oil well.

[0036] First embodiment: application on conventional oil pumping unit

[0037] The method for automatically adjusting the stroke frequency of a pumping unit based on the dynamic liquid level of an oil well described in the first embodiment of the present invention comprises the following steps:

[0038] (1) Obtain the dynamic liquid level data of the oil well measured multiple times at the wellhead and calculate the average to obtain the current dynamic liquid level value H1;

[0039] (2) Calculate the current submergence depth H of the oil well pump;

[0040] (3) Compare the submergence of the oil pump with a preset submergence value, and send a speed control instruction to the frequency converter according to the comparison result to adjust the pump stroke frequency.

[0041] The methods for obtaining the dynamic liquid level of the oil well include but are not limited to: measuring with sound waves or other techniques at the wellhead, and converting through the ground dynamometer diagram. Since the pumping rod moves up and down during the production process of the oil well, the dynamic liquid level will fluctuate up and down, so the measured data is not completely consistent. Therefore, during the measurement period, the pumping unit runs 10 cycles, and data is collected at the same position of each movement. Finally, the average value of multiple collected data is calculated as the current dynamic liquid level value.

[0042] Calculate the submergence of the oil well pump: H=H0-H1.

[0043] Where H is the sinking degree, H1 is the dynamic liquid level, and H0 is the vertical depth of the current oil well pump from the ground. In vertical wells or oil wells with a small well inclination angle, the pump lowering depth can be directly used instead. In highly deviated wells or horizontal wells, it is necessary to find relevant information to obtain the vertical depth of the oil well pump.

[0044] As the sucker rod moves up and down, the submergence changes accordingly, and the speed regulation of the inverter will also change according to the submergence. In order to avoid too frequent speed regulation and ensure the smooth operation of the pumping unit, the reasonable submergence will be set to a range of values, such as 30-80 meters.

[0045] When the submergence of the oil pump is compared with the preset submergence value, a control instruction is sent to the frequency converter according to the comparison result to adjust the pumping stroke frequency. The specific method includes:

[0046] If the sinking degree is less than the set value (such as 30 meters), a deceleration command is sent to the inverter, and the inverter reduces the motor speed to reduce the pumping stroke frequency;

[0047] If the sinking degree is within the set value (such as 30-80 meters), a hold command is sent to the inverter, the motor maintains the current speed, and the pumping unit stroke frequency is not adjusted;

[0048] If the sinking depth is greater than the set value (such as 80 meters), a speed-up command is sent to the inverter, and the inverter increases the motor speed to increase the pumping frequency.

[0049] For speed regulation, the inverter changes the frequency by 5Hz each time, runs stably for 30 minutes after adjustment, and then determines whether to continue adjustment based on the new dynamic liquid level data.

[0050] Second embodiment: Application in rodless lifting technology

[0051] The second embodiment of the present invention describes a method and system for adjusting a submersible rodless lifting device based on wellbore fluid pressure at a wellbore pump. Figure 3 A system structure block diagram showing the method when applied on site.

[0052] The system includes: downhole data acquisition device and motor 1, transmission assembly 2, submersible pump 3, submersible cable 4, and ground control system 6. The downhole data acquisition device is lowered into the bottom of the well together with the downhole motor, transmission assembly, and submersible pump. The collected downhole pressure data is transmitted to the ground through the submersible cable. The ground control system is divided into a calculation processing module and a control output module. The calculation processing module calculates the current sinking degree H of the oil pump according to the formula based on the downhole pressure data;

[0053]

[0054] In the formula, P is the downhole pressure, ρ is the well fluid density, and g is the local gravity acceleration; the well fluid density is calculated by the geological or production department after measurement. The calculation and processing module compares the current submergence with the preset reasonable submergence, and issues a speed control instruction to the control output module based on the comparison result. The control output module outputs the adjusted signal according to the instruction, and the electrical signal is transmitted to the downhole motor through the submersible cable, thereby changing the motor speed.

[0055] In order to ensure the smooth operation of the underground motor, the reasonable submergence is set to a range of values, such as 30-80 meters. The calculation and processing module compares the current pump submergence with the preset submergence, and sends control instructions to the output control module based on the comparison results, including:

[0056] If the sinking degree is less than the set value (e.g. 30 meters), a deceleration command is sent to the output control module, and the speed of the downhole motor is reduced;

[0057] If the sinking degree is within the set value (e.g. 30-80 meters), a hold command is sent to the output control module, and the downhole motor maintains the current speed;

[0058] If the sinking depth is greater than the set value (such as 80 meters), a speed-up command is sent to the output control module, and the speed of the downhole motor is increased.

[0059] 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 dynamic liquid level data.

[0060] 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 adjusting oil well production parameters based on the submergence of a well pump, characterized in that: The steps include: S1. Obtaining oil well dynamic liquid level or downhole pressure data; S2. Calculate the current submergence of the oil well pump according to the dynamic liquid level or downhole pressure data; S3, comparing the submergence of the oil pump with a preset submergence, and sending a control instruction to a control module according to the comparison result to adjust the pumping stroke frequency or the motor running speed.

2. The oil well production parameter adjustment method based on the submergence degree of the oil well pump according to claim 1, characterized in that: In step S3, the submergence value of the oil pump is compared with a preset submergence value, and a control instruction is sent to the control module according to the comparison result to adjust the pumping stroke rate or the motor running speed: if the submergence is less than the set value, a deceleration instruction is sent to the inverter, and the inverter reduces the motor speed to reduce the pumping stroke rate.

3. The oil well production parameter adjustment method based on the submergence degree of the oil well pump according to claim 2, characterized in that: If the sinking degree is equal to the set value, a hold command is sent to the inverter, the motor maintains the current speed, and the pump stroke frequency is not adjusted.

4. The method for adjusting oil well production parameters based on the submergence degree of the oil well pump according to claim 2, characterized in that: If the sinking degree is greater than the set value, a speed-up command is sent to the inverter, and the inverter increases the motor speed to increase the pump stroke frequency.

5. The method for adjusting oil well production parameters based on the submergence degree of the oil well pump according to claim 4, characterized in that: Different formulas are used to determine the submergence of the oil well pump according to the type of data obtained: When the acquired data is the dynamic liquid level of the oil well, the calculation formula for the submergence of the oil well pump is: H=H0-H1 Wherein, H1 is the dynamic liquid level, H0 is the vertical depth of the current oil well pump from the ground. In vertical wells or oil wells with small well inclination angles, the pump lowering depth is directly used instead of the vertical depth of the oil well pump from the ground. In highly deviated wells or horizontal wells, relevant data is searched to obtain the vertical depth of the oil well pump.

6. The method for adjusting oil well production parameters based on the submergence degree of the oil well pump according to claim 5, characterized in that: When the acquired data is downhole pressure, the calculation formula for the submergence of the oil well pump is: H=P / ρg Where P is the downhole pressure, ρ is the well fluid density, and g is the local gravitational acceleration.

7. The control system of the oil well production parameter adjustment method based on the submergence degree of the oil well pump according to claim 6, characterized in that: The invention comprises a downhole data acquisition device and a motor (1), a transmission assembly (2), a submersible pump (3), a submersible cable (4), and a ground control system (6). The downhole data acquisition device and the motor (1), the transmission assembly (2), the submersible pump (3), and the oil pipe (5) are connected in sequence from bottom to top and lowered into the bottom of the well together. The downhole data acquisition device and the motor (1) are transmitted to the ground through the submersible cable (4) and connected to the ground control system (6).

8. The control system of the oil well production parameter adjustment method based on the submergence degree of the oil well pump according to claim 7, characterized in that: The ground control system (6) comprises a calculation processing module and a control output module. The calculation processing module calculates the current submergence H of the oil pump according to the formula based on the downhole pressure data; Where P is the downhole pressure, ρ is the well fluid density, and g is the local gravitational acceleration. The well fluid density is calculated by the geological or production department after measurement. The calculation and processing module compares the current submergence with the preset reasonable submergence, and issues a speed control command to the control output module according to the comparison result. The control output module outputs the adjusted signal according to the command, and the electrical signal is transmitted to the downhole motor through the submersible cable, thereby changing the motor speed.

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