Rod pumped well fullness coefficient calculation method based on electrical parameter curve

Abstract

A rod pumped well fullness coefficient calculation method based on an electrical parameter curve belongs to the technical field of rod pumped well deep well pump fullness coefficient calculation, and comprises the following steps: S1, curve understanding: actually measuring an operation electrical parameter curve of a pumping unit motor; s2, determining a unit appearing in a reciprocating manner in the actual measurement curve as a cycle of the oil pumping unit, and marking the abscissa of the horsehead running to the uppermost end as C and the abscissa of the horsehead running to the lowermost end as A in the cycle curve; s3, finding out an abscissa D of a pumping unit polish rod suspension center load sudden change point from the point C to the point A; s4, the ratio beta'of the unloading stroke time to the polish rod stroke time is calculated; and S5, converting the time ratio into a displacement ratio by using a pumping unit simple harmonic motion model formula. According to the method, only an electrical parameter curve is adopted, synchronous testing of a dynamometer is not needed, influences of balance adjustment, parameter adjustment, belt replacement and the like are avoided, and influences of mechanical vibration are avoided. The calculation formula is converted by a pumping unit simple harmonic motion model, and the calculation result of the fullness coefficient is more accurate.

Description

Technical Field

[0001] This invention belongs to the technical field of deep well pump filling coefficient calculation for oil pumping units, specifically relating to a method for calculating the filling coefficient of oil pumping units based on electrical parameter curves. Background Technology

[0002] The well fill factor of a deep well pump is a crucial indicator for evaluating the rationality of the pumping system's operating regime. Current methods for calculating the well fill factor rely solely on dynamometer data from the dynamometer. This involves measuring the length of the filled portion (the downstroke curve) from the load change curve of the pump plunger at different stroke positions, and then calculating the ratio of this length to the length of the polished rod stroke. While the dynamometer identifies polished rod deformation or load based on sensor installation locations, the dynamometer data is severely interfered with by external factors such as mechanical vibration and sucker rod deformation, resulting in a non-regular curve and affecting the accurate calculation of the well fill factor. Applying IoT technology to analyze and calculate the well fill factor by real-time acquisition of pumping unit electrical parameters is a key research direction in oilfield management. However, accurately and stably calculating the pump fill factor using electrical parameter curves remains a challenge for its further application. Currently, there is no method for calculating the pump fill factor using electrical parameters. Finding the stroke length and unloading stroke length of the polished rod in the electrical parameters, and converting the time length of the electrical parameters into the displacement length of the indicator diagram, have become urgent technical challenges.

[0003] Existing technology CN109611064B discloses a method and apparatus for determining the power consumption of an oil pumping unit, which can save energy consumption and costs required for determining the power consumption of the oil pumping unit. This patent studies the method for calculating the power consumption of the oil pumping unit, wherein the filling coefficient is obtained by on-site testing of the patented device, based on the acquisition of data from a traditional dynamometer. However, the existing patent does not solve the problem of automatically obtaining the filling coefficient from electrical parameters, and still relies on on-site testing of the dynamometer to obtain the dynamometer diagram and thus obtain the filling coefficient. This does not avoid the disadvantages of unstable parameter acquisition and high equipment failure rate caused by vibration of the oil pumping unit equipment.

[0004] The existing technology CN113404483B discloses a method for measuring oil well production using the electrical parameters of a beam pumping unit motor. However, it has the following drawbacks: First, obtaining the filling coefficient still requires three sensors to simultaneously measure the polished rod load, motor output speed, and crank balance block placement cycle starting position. Second, the method for establishing the connection between electrical parameters and dynamometer diagram data relies solely on simple constant calculations. When electrical parameters change due to balancing, parameter adjustments, or belt replacements of the pumping unit, the equipment needs to be re-tested. Third, the calculation of the filling coefficient is based on time, failing to consider that the pumping unit does not move at a constant speed, thus affecting the accuracy of the filling coefficient calculation. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a method for calculating the fill factor of a pumping unit well based on electrical parameter curves, comprising the following steps:

[0006] S1. Curve Understanding: Measured operating electrical parameter curves of the pumping unit motor;

[0007] S2. Determine that one reciprocating unit in the measured curve is one cycle of the pumping unit. Mark the horizontal coordinate of the donkey head running to the top of the cycle curve with the letter C, and mark the horizontal coordinate of the donkey head running to the bottom of the cycle curve with the letter A. The trajectory from the top C of the donkey head to the bottom A of the donkey head is the downstroke of the pumping unit.

[0008] S3. By monitoring the operating electrical parameters, find the point of sudden change in load at the suspension point of the oil pumping unit between point C and point A within one cycle of the oil pumping unit. The horizontal axis is represented by the letter D.

[0009] S4. Calculate the ratio β' of the unloading stroke time to the polished rod stroke time;

[0010] S5. Based on the calculation method of the filling coefficient of the indicator diagram, the ratio of the unloading stroke displacement to the polished rod stroke displacement is adopted. Considering that the pumping unit is a non-uniform motion, the time ratio is converted into a displacement ratio by applying the formula of the simple harmonic motion model of the pumping unit.

[0011] Furthermore, in step S1, the operating electrical parameter curve of the pumping unit motor is measured, with the horizontal axis representing the sampling point and the vertical axis representing the power.

[0012] Furthermore, in step S2, the time used for the downstroke is the polished rod stroke time, calculated as AC = (AC) * 120 milliseconds.

[0013] Furthermore, in step S3, the time from point D to the adjacent point A is the unloading stroke time, calculated as AD = (AD) * 120 milliseconds.

[0014] Furthermore, in step S4, the ratio of the unloading stroke time to the polished rod stroke time is β', and the calculation formula is β' = AD / AC.

[0015] Furthermore, in step S5, the motion of the pumping unit is simplified into a simple harmonic motion model.

[0016] Furthermore, the displacement of suspension point A' is s. A’ a is the distance from the head of the walking beam pumping unit to the fulcrum, b is the distance from the fulcrum to the tail of the walking beam, ωt is the crank angle, ω is the crank rotational angular velocity, t is time, and r is the crank radius.

[0017]

[0018] Furthermore, C represents the position of the balance block corresponding to the top of the donkey head, A represents the position of the balance block corresponding to the bottom of the donkey head, and D represents the position of the balance block corresponding to the start of unloading during the downward movement. Through the formula of the simple harmonic motion model of the pumping unit well, the curve is calculated to change from uniform motion to simple harmonic motion.

[0019] Furthermore, the relationship between the motion of the balance block and the motion of the suspension point:

[0020] (2r-m) / 2r=n / S=S AD / S AC .

[0021] Where S AD S represents the displacement between AD. AC This represents the displacement between AC.

[0022] Furthermore, considering the balance block as undergoing uniform circular motion, m = r(1 - cosωt), ωt = 180° * AD / AC, S represents the stroke of the polished rod, and the formula for calculating the filling coefficient β is:

[0023]

[0024] The beneficial effects of this invention are as follows: The method of this invention only uses electrical parameter curves, requiring no synchronous testing with a dynamometer, and is unaffected by balancing, parameter adjustment, belt replacement, or mechanical vibration. The calculation formula utilizes the simple harmonic motion model of the pumping unit, resulting in more accurate calculations of the well filling coefficient. This invention solves the problem of inaccurate well filling coefficient calculations due to unstable indicator diagram data caused by mechanical vibration or frequent equipment failures in pumping units. It provides a method suitable for beam pumping units, using electrical parameter curves to calculate the well filling coefficient, featuring stable data transmission, immunity to pumping unit interference, simple calculation method, and high accuracy of the filling coefficient. Specifically, it has the following advantages:

[0025] 1. Good stability: The electrical parameter curve replaces the indicator diagram to calculate the filling coefficient, and the curve has an efficiency of 100%.

[0026] 2. Remote calculation: The curve is transmitted back and calculated at any time as needed.

[0027] 3. Convenient and fast: The calculation time for a single stroke is less than 1 minute, and the changes are quickly detected.

[0028] 4. High accuracy: When compared with the dynamometer card, the average difference is less than 0.05. Attached Figure Description

[0029] Figure 1 Identify stroke polishing stroke and unloading stroke data graphs for electrical parameter curves;

[0030] Figure 2A comparison chart of the filling coefficients for calculating the time ratio and displacement ratio is provided.

[0031] Figure 3 A graph showing the conversion of the electrical parameter fill factor from time ratio to stroke ratio.

[0032] Figure 4 This is a schematic diagram of a four-bar linkage mechanism for an oil pumping unit. Detailed Implementation

[0033] Example 1

[0034] To make the technical means and objectives of this invention easier to understand, the invention is further described below with reference to specific embodiments. A method for calculating the fill factor of a pumping well based on electrical parameter curves includes the following steps:

[0035] S1. Measured electrical parameter curves of the pumping unit motor, such as... Figure 1 As shown, the horizontal axis of the curve represents the sampling points, and the vertical axis represents the power. There are a total of 600 sampling points, with an interval of 120 milliseconds between each point. The power unit is watts.

[0036] S2. Determine that one reciprocating unit in the measured curve represents one cycle of the pumping unit. Mark the horizontal coordinate of the uppermost point of the pumping unit's movement within the cycle curve using the letter C, and the horizontal coordinate of the lowermost point using the letter A. The trajectory from the uppermost point C to the lowermost point A represents the downstroke of the pumping unit. The time taken for the downstroke is the polished rod stroke time, calculated using the formula AC = (AC) * 120 milliseconds.

[0037] S3. By monitoring the operating electrical parameters, find the point of sudden change in load at the suspension point of the oil pumping unit between point C and point A within one cycle of the oil pumping unit. The horizontal axis is represented by the letter D. The time from point D to the adjacent point A is the unloading stroke time. The calculation formula is AD = (AD) * 120 milliseconds.

[0038] S4. The ratio of the unloading stroke time to the polished rod stroke time is β', and the calculation formula is β' = AD / AC.

[0039] S5. Based on the calculation method of the filling coefficient of the indicator diagram, the ratio of the unloading stroke displacement to the polished rod stroke displacement is adopted. Considering that the pumping unit is a non-uniform motion, the simple harmonic motion model formula of the pumping unit is applied to convert the time ratio into the displacement ratio.

[0040] like Figure 4 The diagram shows a four-bar linkage of a pumping unit. The motion of the pumping unit is simplified to a simple harmonic motion model, with the displacement of suspension point A' being s. A’ , a is the distance from the head of the walking beam pumping unit to the fulcrum, b is the distance from the fulcrum to the tail of the walking beam, ωt is the crank angle, ω is the crank rotational angular velocity, t is time, and r is the crank radius.

[0041]

[0042] like Figure 3 As shown, C is the position of the balance block corresponding to the donkey's head reaching the top, A is the position of the balance block corresponding to the donkey's head reaching the bottom, and D is the position of the balance block corresponding to the start of unloading during the descent.

[0043] Using the formula for the simple harmonic motion model of an oil pumping well, the curve is calculated to transform from uniform motion to simple harmonic motion.

[0044] The relationship between the motion of the balance block and the motion of the suspension point:

[0045] (2r-m) / 2r=n / S=S AD / S AC ;

[0046] at the same time:

[0047] m = r(1 - cosωt), ωt = 180° * AD / AC, S represents the stroke of the polished rod, and the formula for calculating the fill factor β is:

[0048]

[0049] like Figure 2 As shown, the blue straight line represents the ratio β' of the time taken for the unloading stroke and the polished rod stroke during the calculation of the filling coefficient, and the red curve is the ratio β of the displacement of the unloading stroke and the polished rod stroke after optimization by the simple harmonic motion model, which is the filling coefficient of the pumping well. The comparison shows that there is a large difference between the filling coefficient without model optimization and the actual filling coefficient.

[0050] Example 2

[0051] This invention discloses a method for calculating the well fill factor of a pumping unit using the electrical parameter curve of a pumping unit, comprising the following steps:

[0052] Curve recognition: Identify the polished rod stroke time and unloading stroke time in the same downstroke curve of the pumping unit;

[0053] Formula calculation: Using the simple harmonic motion model of the walking beam pumping unit, the time ratio of the unloading stroke to the polished rod stroke is converted into a displacement ratio, and the filling coefficient of the pumping unit well is finally determined.

[0054] This invention uses a one-time acquisition of electrical parameter data from the pumping well. By identifying the electrical parameter curves and calculating the formula model, the well fill factor of the pumping unit can be obtained. This eliminates the need for separate data acquisition equipment, reducing costs and ensuring safety.

[0055] The calculation of the filling coefficient using electrical parameters involves identifying the downstroke of the electrical parameter curve. By analyzing the abrupt changes in electrical parameters at the unloading point, the unloading time for a single stroke is obtained. The ratio of the actual unloading time to the time taken during the polished rod stroke is calculated, and this time ratio is converted into a displacement ratio using a simple harmonic motion model of the pumping unit. The time ratio before optimization by the simple harmonic motion model is represented by β', which is crucial for the calculation of the filling coefficient. β' is determined primarily based on the positions of the top dead center, bottom dead center, and unloading point corresponding to the tip of the pumping unit in the electrical parameter curve.

[0056] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for calculating the fill factor of a pumping well based on electrical parameter curves, characterized in that, Includes the following steps: S1. Curve Understanding: Measured operating electrical parameter curves of the pumping unit motor; S2. Determine that one reciprocating unit in the measured curve is one cycle of the pumping unit, and mark the x-coordinates of the points where the donkey head reaches the top and bottom of the cycle curve. S3. By monitoring the operating electrical parameters, find the sudden change point of the load at the suspension point of the oil pumping unit between the two points where the donkey head moves to the uppermost and lowermost ends within one cycle of the oil pumping unit. The horizontal coordinate is represented by the letter D. S4. Calculate the ratio β' of the unloading stroke time to the polished rod stroke time; S5. Apply the formula of the simple harmonic motion model of the oil pumping unit to convert the time ratio into the displacement ratio to obtain the filling coefficient β.

2. The method for calculating the fill factor of a pumping well based on electrical parameter curves as described in claim 1, characterized in that, In step S1, the operating electrical parameter curve of the pumping unit motor is measured. The horizontal axis of the curve represents the sampling point, and the vertical axis represents the power.

3. The method for calculating the fill factor of a pumping unit well based on electrical parameter curves as described in claim 2, characterized in that, In step S2, the horizontal coordinate of the donkey head running to the top is marked with the letter C, and the horizontal coordinate of the donkey head running to the bottom is marked with the letter A. The trajectory from the top C of the donkey head to the bottom A of the donkey head is the downstroke of the pumping unit. The downstroke time is the polished rod stroke time, and the calculation formula is AC = (AC) * 120 milliseconds.

4. The method for calculating the fill factor of a pumping unit well based on electrical parameter curves as described in claim 3, characterized in that, In step S3, the time from point D to the adjacent point A is the unloading stroke time, and the calculation formula is AD = (AD) * 120 milliseconds.

5. The method for calculating the fill factor of a pumping unit well based on electrical parameter curves as described in claim 4, characterized in that, In step S4, the ratio of the unloading stroke time to the polished rod stroke time is β', and the calculation formula is β' = AD / AC.

6. The method for calculating the fill factor of a pumping unit well based on electrical parameter curves as described in claim 5, characterized in that, In step S5, the ratio of the unloading stroke displacement to the polished rod stroke displacement is used according to the calculation method of the filling coefficient of the indicator diagram. Considering that the pumping unit is a non-uniform motion, the motion of the pumping unit is simplified into a simple harmonic motion model.

7. The method for calculating the fill factor of a pumping unit well based on electrical parameter curves as described in claim 6, characterized in that, The displacement of suspension point A' is s A’ a is the distance from the head of the walking beam pumping unit to the fulcrum, b is the distance from the fulcrum to the tail of the walking beam, ωt is the crank angle, ω is the crank rotational angular velocity, t is time, and r is the crank radius.

8. The method for calculating the fill factor of a pumping unit well based on electrical parameter curves as described in claim 7, characterized in that, C represents the position of the balance block at the top of the donkey's head, A represents the position of the balance block at the bottom of the donkey's head, and D represents the position of the balance block at the start of unloading during the downward movement. Using the formula of the simple harmonic motion model of the pumping well, the curve is calculated to transform from uniform motion to simple harmonic motion.

9. The method for calculating the fill factor of a pumping unit well based on electrical parameter curves as described in claim 8, characterized in that, The relationship between the motion of the balance block and the motion of the suspension point: (2r-m) / 2r=n / S=S AD / S AC Where S AD S represents the displacement between AD. AC This represents the displacement between AC.

10. The method for calculating the fill factor of a pumping well based on electrical parameter curves as described in claim 9, characterized in that, m = r(1 - cosωt), ωt = 180° * AD / AC, S represents the stroke of the polished rod, and the formula for calculating the fill factor β is:

Images