Calculation method and design device for running stroke frequency of pumping unit in constant power mode

Abstract

The invention provides a method for calculating the running stroke frequency of a pumping unit in a constant power mode and a method and device for controlling the pumping unit. The method comprises the following steps: acquiring production data of a sucker-rod pump producing well and basic parameters of a pumping unit; identifying that the working condition of the sucker-rod pump oil extraction system is normal according to the production indicator diagram; drawing a net torque curve in combination with basic parameters of the oil pumping unit; the average output power of the oil pumping unit in one swabbing period of the oil well pump is calculated based on the stroke frequency and the net torque curve; and the stroke frequency corresponding to each crank rotation angle in one swabbing period of the oil well pump is calculated based on the average output power of the oil pumping unit and the net torque curve. According to the invention, real-time dynamic optimization is carried out on the production working condition of the pumping unit, and constant power mode operation of the pumping unit is realized.

Description

Technical Field

[0001] The present invention relates to a method for calculating the number of strokes in a constant power mode of an oil pump, a method and device for controlling an oil pump, and in particular to a technology for determining the number of strokes in a constant power mode of a conventional beam pump, and belongs to the field of rod pump oil production technology. Background Art

[0002] Rod pumping is one of the most important mechanical oil production methods in onshore oil fields. More than 90% of my country's onshore oil wells use rod pumping. The power consumption of the pumping unit exceeds 50% of the entire oil field, and the energy saving problem is becoming more and more prominent. At present, domestic oil fields such as Xifeng Oilfield and Tuha Oilfield are trying to carry out variable frequency control of rod pumping systems, and have achieved certain energy-saving effects. Therefore, calculating the constant power simulation operation strokes of conventional beam pumping units is the key to variable frequency control of rod pumping systems.

[0003] At present, the frequency conversion method used to calculate the stroke frequency of the constant power model is: by measuring the dynamometer diagram of each cycle, calculating the liquid production, adjusting the stroke frequency, and selecting the stroke frequency with the optimal liquid production. In this process, the dynamometer diagram needs to be continuously measured, the steps are cumbersome and time-consuming, and the parameter setting of one well cannot be applied to other wells. Therefore, it is necessary to propose a calculation method for the constant power mode operation stroke frequency suitable for conventional walking beam pumping units. Summary of the invention

[0004] In view of the technical defects and technical drawbacks in the prior art, the present invention provides a method for calculating the net torque according to the indicator diagram, and then calculating the stroke number of constant power mode operation, and a pumping unit control method and device.

[0005] An embodiment of the present invention provides a method for calculating the number of strokes of a pumping unit in a constant power mode, which includes:

[0006] Obtain production data of rod pump oil wells and basic parameters of pumping units;

[0007] According to the production dynamometer diagram, it is identified that the working condition of the rod pump oil production system is normal;

[0008] Drawing a net torque curve based on the basic parameters of the oil pumping unit;

[0009] Calculating the average output power of the oil pump in one pumping cycle of the oil pump based on the stroke frequency and net torque curve;

[0010] The number of strokes corresponding to each crank angle in one pumping cycle of the oil pump is calculated based on the average output power and net torque curve of the oil pump.

[0011] Another aspect of an embodiment of the present invention provides a control method for an oil pump, which includes: selecting a corresponding stroke frequency based on a crank angle value of the oil pump in a next pumping cycle according to a calculation result obtained by the above calculation method.

[0012] Another aspect of the embodiments of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the program implements the above method when executed by a processor.

[0013] Another aspect of an embodiment of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above method when executing the program.

[0014] Another aspect of the embodiment of the present invention provides a design device for the stroke frequency of a pumping unit in a constant power mode, comprising:

[0015] An acquisition module is used to acquire production data of a rod pump oil well and basic parameters of the pumping unit;

[0016] An identification module, used to identify that the working condition of the rod pump oil production system is normal according to the production dynamometer diagram;

[0017] A drawing module, used for drawing a net torque curve based on the basic parameters of the oil pumping unit;

[0018] The calculation module calculates the strokes corresponding to each crank angle in one pumping cycle of the oil pump based on the average output power and net torque curve of the oil pump.

[0019] The embodiment of the present invention performs real-time dynamic optimization of the production conditions of the oil pumping unit to achieve constant power mode operation of the oil pumping unit.

[0020] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structure described in the written description, claims, and drawings.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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 accompanying drawings:

[0023] Figure 1 It is a dimensionless dynamometer diagram for identifying the normal working condition of the rod pump oil production system;

[0024] Figure 2 It is the calculation result of the stroke frequency of the conventional beam pumping unit in constant power mode;

[0025] Figure 3 It is a flow chart of a method for calculating the number of strokes of a pumping unit in a constant power mode according to an embodiment of the present invention;

[0026] Figure 4 This is a structural diagram of a device for calculating the number of strokes of a pumping unit in constant power mode according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0028] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0029] This embodiment provides a method for calculating the stroke frequency of a pumping unit in a constant power mode, wherein the pumping unit is, for example, a conventional beam pumping unit, such as Figure 3 As shown, the calculation method may include the following steps:

[0030] Step 100, obtaining production data of a rod pump oil well and basic parameters of a pumping unit.

[0031] The production data of the sucker rod pump oil well includes: sucker rod string combination, stroke times, stroke, production dynamometer diagram, etc.

[0032] The basic parameters of the oil pump include: geometric parameters and balance parameters of the oil pump.

[0033] Step 200: Identify, based on the production dynamometer diagram, that the operating condition of the rod pumping system is normal.

[0034] The term "normal" means that, as shown on the dynamometer diagram, the oil well has normal operation of the pumping rod, and there is no abnormal operating condition such as leakage, gas influence, insufficient fluid supply, etc.

[0035] The specific identification process may include: normalizing the production performance diagram of the target well to be identified; comparing the normalized production performance diagram with the normal well performance diagram sample; and when the image overlap is higher than a predetermined value, determining that the operating condition of the rod pump oil production system of the target well is normal. Figure 1 shown.

[0036] from Figure 1 It can be seen from the figure that the degree of overlap between the indicator diagram of the identification well and the indicator diagram of the normal well is used as the basis for whether this method can be used for frequency conversion. The line marked with dots represents the dimensionless indicator diagram under normal working conditions, and the line marked with boxes represents the dimensionless indicator diagram of the identification well. The horizontal axis S represents the dimensionless displacement of the bare rod, as shown in formula (1); the vertical axis W represents the dimensionless load of the suspension point, as shown in formula (2).

[0037]

[0038]

[0039] Where W is the dimensionless load; W i is the load for producing the dynamometer diagram, kN; W max , W min is the maximum load and minimum load for producing the dynamometer diagram, kN; s is the dimensionless displacement; s i is the displacement of the dynamometer diagram, m; s max is the stroke of the pumping unit, m.

[0040] Step 300: draw a net torque curve based on the basic parameters of the oil pumping unit.

[0041] The specific drawing process includes: converting the production indicator diagram under normal working conditions into a relationship curve between load and crank angle; obtaining the net torque value corresponding to each crank angle based on the relationship curve and the geometric parameters and balance parameters obtained in the basic parameters of the pumping unit; and drawing the net torque curve based on the net torque value.

[0042] Among them, the calculation formula of the net torque curve is shown in formula (3):

[0043]

[0044] Where, W(θ) is the suspension point load, kN; B is the unbalance value of the pumping unit structure, kN; is the torque factor of the pumping unit, m; W cb is the crank balance weight, kN; R c is the crank balance radius, m; W c is the crank weight, kN; R c is the radius of the crank center of gravity, m.

[0045] Step 400: obtaining an average output power of the oil pump based on the net torque curve.

[0046] Specifically, the instantaneous output power of the reduction box of the oil pumping unit can be obtained according to the net torque curve and the stroke frequency of the oil pumping unit; the instantaneous output power is integrated by the trapezoidal area method to obtain the average output power as the frequency conversion reference.

[0047] The expression of average output power is shown in formula (4):

[0048]

[0049] Where P(θ) is the instantaneous output power of the reduction gearbox, kW; ω(θ) is the angular velocity of the crank, rad / s.

[0050] Step 500, calculating the number of strokes corresponding to each crank angle in a pumping cycle of the oil pump based on the average output power and net torque curve of the oil pumping unit.

[0051] Specifically, the following processes may be included:

[0052] Step 510: based on the basic parameters of the oil pump, the stroke loss corresponding to the upstroke loading and downstroke unloading is obtained, and the stroke number corresponding to each crank angle when the oil pump is upstroke loading and downstroke unloading is obtained by interpolation.

[0053] Among them, the calculation method of stroke loss λ under static load is shown in formula (5).

[0054]

[0055] In the formula, λ r is the elongation of the rod column due to the increase in load, m; λ t L is the shortening of the column due to load reduction, m; p is the length of the sucker rod string (i.e., pump depth), m; h is the submergence, m; E is the elastic modulus of the material, kPa; A t is the metal cross-sectional area of ​​the oil pipe, m 2 ; A r is the cross-sectional area of ​​the sucker rod, m 2 ρ L is the liquid density t / m 3 ; g is the acceleration due to gravity, m / s 2 ; A p is the cross-sectional area of ​​the plunger, m 2 .

[0056] Step 520 , based on the average output power and the net torque curve, the number of strokes corresponding to each crank angle after the upward loading and downward unloading of the oil pump are completed is obtained.

[0057] Specifically, the crank rotation angular velocity corresponding to the crank angle is obtained based on the average output power and net torque curve obtained previously, and then converted into the number of strokes.

[0058] The calculation formula for the stroke frequency of a conventional beam pumping unit in constant power mode is shown in formula (6).

[0059]

[0060]

[0061] Among them, θ1 is the crank rotation angle corresponding to the end of the upstroke loading; θ2 is the maximum crank angle of the pumping unit in the constant power mode during the upstroke; θ x1 is the crank angle corresponding to the negative power during the upward process. θ3 is the crank angle corresponding to the end of the downstroke unloading; θ4 is the maximum crank angle of the pumping unit in constant power mode; θ x3 is the crank angle corresponding to the negative power during the downward process. max is the maximum stroke frequency that can be adjusted by the pumping unit, min -1 , n min is the minimum stroke frequency that can be adjusted by the pumping unit, min -1 .

[0062] The calculation method described in this embodiment is to perform real-time dynamic optimization of the production conditions of the oil pumping unit to achieve constant power mode operation of the oil pumping unit.

[0063] For example, the calculation result obtained by the above calculation method is applied to the control of the oil pump, and the corresponding stroke is selected based on the crank angle value of the oil pump in the next pumping cycle. Specifically, the instantaneous crank angle corresponding to the negative work power operation of the oil pump can be calculated first, and then the instantaneous crank angle corresponding to the occurrence of negative work power can be obtained according to the net torque curve obtained previously. In order to reduce the negative work power, the minimum stroke is selected; when the conversion stroke exceeds the maximum adjustable stroke, the maximum stroke is selected; when it is less than the minimum stroke, the minimum stroke is selected.

[0064] The following are examples:

[0065] A rod pump well uses a conventional pumping unit CYJ8-3-48B, with a stroke of 3m and a stroke of 9min. -1 Production below, D = 56mm, L p =1200m,ρ L =0.95t / m 3 , L f =100m,2 7 / 8 The lower end of the in tubing is not anchored, and the sucker rod is 22×19mm (rod length ratio 1:3).

[0066] First, the stroke loss λ=0.539m is obtained, and the corresponding angle is 44.7°. The stroke loss in the downstroke is also 0.539m, the suspension point displacement is 2.461m, and the corresponding crank angle is 240.1°. It can be calculated that the crank angle value that first appears negative in the upstroke is 160°, and the crank angle value that first appears negative at the end of the downstroke is 315°. Therefore, the stroke calculation results are attached. Figure 2 shown.

[0067] Among them, 0-44.7° is the loading stage of the oil well pump, and the minimum stroke rate is selected to ensure the stable starting of the motor; 44.7°-120° is the constant power frequency conversion stage, 120°-160° is exceeding the maximum stroke rate, and the maximum stroke rate is selected; 160°-180° is negative power, and the minimum stroke rate is selected; 180°-240.1° is the unloading process of the oil well pump, and the lowest stroke rate is selected; 240.1°-310° is constant power frequency conversion; 310°-315° is exceeding the maximum stroke rate, and the maximum stroke rate is selected; 315°-360° is to reduce the negative power and the minimum stroke rate is selected.

[0068] The method described in this embodiment aims at the problem that constant power frequency conversion of oil pumps lacks theoretical basis and the frequency conversion effect is not very good, conducts theoretical analysis, establishes a constant power frequency conversion mathematical model, and provides a method for calculating the stroke frequency of a conventional walking beam oil pump in constant power mode. After obtaining the indicator diagram after the oil pump has run for a cycle, the stroke frequency of the oil pump is adjusted to realize the transformation of the "constant speed, variable power" operation of the traditional oil pump into the "variable speed, constant power" operation, thereby ensuring the smooth operation of the oil pump and reducing the output power of the motor at the same time, achieving better production and energy-saving effects.

[0069] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects:

[0070] (1) The required parameters can be obtained from on-site production data, which is convenient and quick to use;

[0071] (2) The calculation method of the stroke frequency of the conventional beam pumping unit in constant power mode can determine the stroke frequency of the pumping unit in the next cycle and better guide the variable stroke frequency work;

[0072] (3) Calculate the number of strokes separately for the upper and lower strokes, and calculate separately for different situations.

[0073] Another embodiment of the present invention provides a design device for the stroke frequency of a pumping unit in a constant power mode, such as Figure 4 As shown, it includes: an acquisition module 10, a recognition module 20, a drawing module 30 and a calculation module 40, and its working principle is as follows:

[0074] The acquisition module 10 acquires the production data of the rod pump oil well and the basic parameters of the pumping unit; the identification module 20 identifies that the operating condition of the rod pump oil production system is normal according to the production dynamometer diagram; the drawing module 30 draws the net torque curve based on the basic parameters of the pumping unit; the calculation module 40 calculates the strokes corresponding to each crank angle in one pumping cycle of the pumping unit based on the average output power of the pumping unit and the net torque curve.

[0075] For other technical details and related technical effects of this embodiment, please refer to the relevant contents of the above method embodiment, which will not be repeated here.

[0076] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, 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 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 and optical storage, etc.) containing computer-usable program code.

[0077] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0078] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0079] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1The steps for the functions specified in one or more boxes.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the number of strokes of a pumping unit in constant power mode, characterized in that: include: Obtain production data of rod pump oil wells and basic parameters of pumping units; According to the production dynamometer diagram, it is identified that the working condition of the rod pump oil production system is normal; Drawing a net torque curve based on the basic parameters of the oil pumping unit; Calculating the average output power of the oil pump in one pumping cycle of the oil pump based on the stroke frequency and net torque curve; The number of strokes corresponding to each crank angle in one pumping cycle of the oil pump is calculated based on the average output power and net torque curve of the oil pump.

2. The method according to claim 1, characterized in that The production data of the sucker rod pump oil well includes: sucker rod string combination, stroke frequency, stroke, and production dynamometer diagram; the basic parameters of the pumping unit include: geometric parameters and balance parameters of the pumping unit.

3. The method according to claim 1, characterized in that The process of identifying that the working condition of the rod pump oil production system is normal includes: Normalize the production performance diagram of the target well to be identified; The normalized production performance diagram is compared with the normal well performance diagram sample; When the image overlap is higher than a predetermined value, it is determined that the operating condition of the rod pump production system of the target well is normal.

4. The method according to claim 2, characterized in that: The process of drawing the net torque curve includes: Converting the normal production dynamometer diagram into a curve of load versus crank angle; Obtaining a net torque value corresponding to each crank angle based on the relationship curve, the geometric parameter, and the balance parameter; The net torque curve is plotted based on the net torque value.

5. The method according to claim 1, characterized in that The process of obtaining the average output power of the oil pumping unit includes: Obtaining the instantaneous output power of the reduction box of the pumping unit according to the net torque curve and the stroke frequency; The instantaneous output power is integrated by the trapezoidal area method to obtain the average output power.

6. The method according to claim 2, characterized in that The process of obtaining the number of strokes corresponding to each crank angle in a pumping cycle of the oil pump includes: Based on the basic parameters of the oil pump, the stroke loss corresponding to the upstroke loading and downstroke unloading is obtained, and the stroke number corresponding to each crank angle when the oil pump is loaded upward and unloaded downward is obtained by interpolation; Based on the average output power and the net torque curve, the number of strokes corresponding to each crank angle after the upward loading and downward unloading of the oil pump are completed is obtained.

7. A method for controlling an oil pump, characterized in that: include: According to the calculation result obtained by the calculation method described in any one of claims 1 to 6, the corresponding stroke number is selected based on the crank angle value of the pumping unit in the next pumping cycle.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the method according to any one of claims 1 to 7 is implemented.

10. A design device for the stroke frequency of a pumping unit in constant power mode, characterized in that: include: An acquisition module is used to acquire production data of a rod pump oil well and basic parameters of the pumping unit; An identification module, used to identify that the working condition of the rod pump oil production system is normal according to the production dynamometer diagram; A drawing module, used for drawing a net torque curve based on the basic parameters of the oil pumping unit; The calculation module calculates the strokes corresponding to each crank angle in one pumping cycle of the oil pump based on the average output power and net torque curve of the oil pump.

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