A multi-time-period variable-speed operation intelligent pumping unit posture control method

Abstract

The application discloses a posture control method of a smart pumping unit running in multiple time periods with variable speed. The method sets the running time of a single stroke of the pumping unit, divides the running path of each stroke of the pumping unit into multiple segment paths, sets the distance of each segment path, sets the running mode and running time of the horse head of the pumping unit in each segment path, and makes the pumping unit start working with the calculated initial speed, end speed and acceleration initial value of the horse head in each segment path. Then, the initial speed, end speed and acceleration of the horse head in each segment path are adjusted according to the measured actual running time of a single stroke of the pumping unit, so that the absolute error value between the total running time of the preset single stroke and the total running time of the actual single stroke of the pumping unit is not more than a preset value. The application can make the pumping unit normally run in the working condition of a low-yield oil well, reduce the invalid stroke and stroke loss, improve the efficiency, and reduce the electricity cost and maintenance cost generated by the running of the pumping unit.

Description

Technical Field

[0001] This invention belongs to the field of oilfield well production, specifically relating to a smart pumping unit attitude control method that operates at variable speeds in multiple time periods. Background Technology

[0002] Currently, there are approximately 200,000 low-yield oil wells in China. However, most existing oilfield pumping units operate at industrial frequency. Because their speed changes abruptly (usually maintaining a certain speed but changing direction) when reaching the top and bottom dead centers during reciprocating motion, inertia is generated, leading to alternating loads. This easily causes uneven wear on the pumping unit's tubing and sucker rod, reducing their service life, shortening pump inspection cycles, increasing downtime for maintenance, and raising maintenance costs. Furthermore, this results in a relatively high average speed near the bottom dead center and a short dwell time. Without correction for the operating stroke, accumulated errors cause a significant deviation between the actual speed near the bottom dead center and the design speed. When insufficient fluid supply occurs, "dry pumping" or "partial dry pumping" can easily occur, increasing stroke loss and ineffective strokes. To increase oil production, the stroke frequency must be increased, resulting in generally low system efficiency and an inability to effectively adapt to the fluid supply speed of low-yield oil wells. The low oil extraction volume caused by "dry pumping" or "partial dry pumping" means that the economic value generated cannot offset the electricity and maintenance costs of the pumping unit, resulting in low production wells having low exploitation value. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and propose an intelligent attitude control method for pumping units that operates at variable speeds in multiple time periods.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention discloses an intelligent attitude control method for a pumping unit that operates at variable speeds across multiple time periods, as detailed below:

[0006] Step 1: Let the distance between the top dead center and the bottom dead center of the pumping unit be S. Divide the running path of each stroke of the pumping unit into multiple segments. Set the distance of each segment and the running mode of the pumping unit's head in each segment. Let the running time of each stroke of the pumping unit be T. The running speed of the head at the top dead center and the bottom dead center is 0. Also, set the running time of the head in each segment.

[0007] Step 2: Calculate the initial velocity, final velocity, and initial acceleration of the donkey head on each segment of the path.

[0008] Step 3: The pumping unit head operates at the starting speed, ending speed, and acceleration of each segment path, and the actual running time T of each pumping stroke is detected using proximity switches installed on the pumping unit body. 实 .

[0009] Step 4: Calculate the actual operating time T of each pumping unit stroke obtained through testing. 实 If the absolute error value of the running time T of each stroke of the pumping unit is greater than the preset value, the starting speed, ending speed and acceleration of the donkey head in each segment path are corrected, and then the process returns to step three. Otherwise, the donkey head continues to work with the current starting speed, ending speed and acceleration of the donkey head in each segment path.

[0010] Preferably, the operating path of each stroke of the pumping unit is divided into 10 segments. The donkey head operates in a uniform acceleration mode in the first, second, sixth, and seventh segments, in a uniform deceleration mode in the fourth, fifth, ninth, and tenth segments, and in a uniform speed mode in the third and eighth segments.

[0011] More preferably, the running time of the donkey head in each segment path is

[0012] t i =α i T

[0013] In the formula, t i α represents the running time of the donkey head in the i-th segment of the path. i This represents the running time coefficient of the donkey head in the i-th segment of the path, where i = 1, 2, 3, ..., 10, and t1 + t2 + t3 + t4 + t5 = t6 + t7 + t8 + t9 + t 10 =T / 2.

[0014] More preferably, t1=t5=t6=t 10 , t2=t4=t7=t9, t3=t8.

[0015] More preferably, the initial values ​​of the donkey's head's starting speed, ending speed, and acceleration in each segment of the path are calculated using the following formula:

[0016]

[0017] In the formula, S i Let S1+S2+S3+S4+S5=S6+S7+S8+S9+S 10 =S; Let V be the average speed of the donkey's head on the i-th segment of the path.ia is the starting speed of the donkey head on the i-th segmented path, V ib is the ending speed of the donkey head on the i-th segmented path, a i is the acceleration of the donkey head on the i-th segmented path;

[0018] Among them, the starting speed of the donkey head on each segmented path except the first segmented path is equal to the ending speed of the donkey head on the previous segmented path, and the speed of the donkey head at the top dead center position and the bottom dead center position is 0, that is, V 1a = V 5b = V 6a = V 10b = 0, and then the initial values of the starting speed, ending speed and acceleration of the donkey head on each segmented path are obtained through calculation.

[0019] More preferably, the real-time speed of the donkey head on each segmented path is

[0020] V ij = V ia + a i ·t ij

[0021] In the formula, t ij is the j-th time point during the operation of the donkey head on the i-th segmented path, V ij is the running speed of the donkey head at t ij .

[0022] Preferably, the process of correcting the starting speed, ending speed and acceleration of the donkey head on each segmented path is as follows: when T 实 > T, then increase the starting speed of the donkey head on each segmented path to α times the starting speed of the donkey head on the corresponding segmented path in the previous calculation, and α > 1. When T 实 < T, then reduce the starting speed of the donkey head on each segmented path to β times the starting speed of the donkey head on the corresponding segmented path in the previous calculation, and β < 1.

[0023] The present invention has the following beneficial effects:

[0024] 1. This invention enables pumping units to operate normally under low-production well conditions, reduces stroke loss and ineffective strokes, improves system efficiency, and lowers electricity and maintenance costs associated with pumping unit operation. Specifically, this invention divides the pumping unit's stroke path into multiple segmented paths, allowing the pumping head to perform segmented speed-changing motion within a single stroke. The actual runtime of a single pumping unit stroke is measured. If the absolute error between the preset runtime of a single stroke and the actual runtime of a single pumping unit stroke exceeds a preset value, the starting speed, ending speed, and acceleration of the pumping head in each segmented path are corrected. This allows the pumping unit to make corrections after each operating stroke, reducing stroke loss. Furthermore, by setting the pumping unit to perform segmented speed-variable motion in a single stroke, and setting the speed of the sucker head to 0 at the top dead center and bottom dead center positions, the phenomenon of the sucker head leading the piston in the pumping unit can be eliminated. This eliminates the compressive load generated by the sucker rod during the rising phase to the top dead center position, reduces sucker rod bending, reduces wear on the sucker rod and tubing, and eliminates the tensile load generated by the sucker rod during the descending phase to the bottom dead center position. Consequently, it eliminates the alternating load on the sucker rod during reciprocating motion, reduces uneven wear on the sucker rod and tubing, increases the service life of the sucker rod and tubing, thereby extending the pump inspection cycle, reducing downtime for maintenance, lowering maintenance costs, and increasing the residence time of the pumping unit piston near the top and bottom dead centers, thus increasing the liquid extraction volume per stroke of the pumping unit. This further reduces ineffective strokes and stroke losses, improving pump efficiency. Therefore, this invention enables the pumping unit to operate normally at low stroke rates (0.5 to 2 strokes / minute) using a segmented speed-changing motion mode. In fact, it can even produce higher oil output than existing pumping units with high stroke rates when operating at low stroke rates, and can better adapt to low-production well conditions.

[0025] 2. This invention can obtain the real-time running speed of the pumping unit head through real-time calculation, which solves the problems of the existing method of detecting the real-time running speed of the pumping unit head by adding a motor rotary transformer, which requires damaging the pumping unit drive motor structure and has a long installation time. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the running speed and trajectory curve of the donkey head in a single stroke in this invention. Detailed Implementation

[0027] The present invention will now be further described with reference to the accompanying drawings.

[0028] This invention discloses an intelligent attitude control method for a pumping unit that operates at variable speeds across multiple time periods, as detailed below:

[0029] Step 1, such as Figure 1As shown, let S be the distance between the top dead center and the bottom dead center of the pumping unit's pumping head. Divide the pumping unit's path for each stroke into 10 segments, and set the distance for each segment. Set the operating mode of the pumping unit's pumping head in each segment, and set the running time T for each stroke (including the upstroke and downstroke, i.e., the process of the pumping unit's pumping head moving from the bottom dead center to the top dead center and back to the bottom dead center). Set the speed of the pumping head at both the top dead center and bottom dead center positions to 0, and set the running time of the pumping head in each segment. Specifically, the pumping head operates with uniform acceleration in the first, second, sixth, and seventh segments; uniform deceleration in the fourth, fifth, ninth, and tenth segments; and uniform speed in the third and eighth segments. Let S be the distance of the i-th segment. i , and i=1, 2, 3, ..., 10, S1+S2+S3+S4+S5=S6+S7+S8+S9+S 10 =S; Let the running time of the donkey head in each segment path be S.

[0030] t i =α i T

[0031] In the formula, t i α represents the running time of the donkey head in the i-th segment of the path. i Let t1+t2+t3+t4+t5=t6+t7+t8+t9+t 10 =T / 2, in this embodiment, S1=S2=…=S 10 =0.2S, t1=t5=t6=t 10 =0.095T, t2=t4=t7=t9=0.12T, t3=t8=0.07T.

[0032] Step Two: Based on the distances of each path segment set in Step One, the donkey's running time and running mode in each path segment, and its speed at the top and bottom endpoints, calculate the donkey's initial speed, final speed, and initial acceleration value for each path segment. The formulas for calculating the donkey's initial speed, final speed, and initial acceleration value for each path segment are as follows:

[0033]

[0034] In the formula, Let V be the average speed of the donkey's head on the i-th segment of the path. ia Let V be the initial velocity of the donkey's head in the i-th segment of the path. ib Let a be the final speed of the donkey's head in the i-th segment of the path.i Let be the acceleration of the donkey's head in the i-th segment of the path;

[0035] In this scenario, the donkey's initial speed in each segment of the path, excluding the first segment, is equal to its ending speed in the previous segment. Furthermore, the donkey's speed at the top and bottom endpoints is zero, i.e., V. 1a =V 5b =V 6a =V 10b =0, and then the initial speed, ending speed and initial acceleration of the donkey head in each segment path are obtained by calculation. Figure 1 The speed curve shown in the diagram only indicates the magnitude of the speed, not its direction.

[0036] Step 3: The pumping unit head operates at the starting speed, ending speed, and acceleration of each segment path, and the actual running time T of each pumping stroke is detected using proximity switches installed on the pumping unit body. 实 .

[0037] Step 4: Calculate the actual operating time T of each pumping unit stroke obtained through testing. 实 The absolute error value |T| between the set operating time T of each pumping unit stroke and the actual operating time T. 实 -T|, if |T| 实 If -T|>0.1s, then the starting speed, ending speed, and acceleration of the donkey head on each segment of the path are corrected. Then, return to step three, so that the donkey head works with the corrected starting speed, ending speed, and acceleration on each segment of the path. If |T 实 If -T|≤0.1s, then the donkey head continues working with the starting speed, ending speed, and acceleration of each segment of the path, and the real-time speed of the donkey head on each segment of the path is...

[0038] V ij =V ia +a i ·t ij

[0039] In the formula, t ij Let V be the j-th time point during the i-th segmented path journey of the donkey head. ij Let be the running speed of the donkey head at the j-th time point during the i-th segmented path.

[0040] The process of correcting the donkey's initial velocity, final velocity, and acceleration in each segment of the path is as follows: when T 实 When T > T, the starting speed of the donkey head in each segment of the path is increased to 1.05 times the starting speed of the donkey head in the corresponding segment of the path calculated in the previous time. 实

Claims

1. A method for attitude control of an intelligent pumping unit operating at variable speeds over multiple time periods, characterized in that: Step 1: Let the distance between the top dead center and the bottom dead center of the pumping unit be S. Divide the running path of each stroke of the pumping unit into multiple segments. Set the distance of each segment and the running mode of the pumping unit's head in each segment. Let the running time of each stroke of the pumping unit be T. The running speed of the head at the top dead center and the bottom dead center is 0. Also, set the running time of the head in each segment. Step 2: Calculate the initial velocity, final velocity, and initial acceleration of the donkey head on each segment of the path; Step 3: The pumping unit head operates at the starting speed, ending speed, and acceleration of each segment path, and the actual running time T of each pumping stroke is detected using proximity switches installed on the pumping unit body. 实 ; Step 4: Calculate the actual operating time T of each pumping unit stroke obtained through testing. 实 The absolute error value of the running time T of each stroke of the pumping unit is set. If the absolute error value is greater than the preset value, the starting speed, ending speed and acceleration of the donkey head in each segment path are corrected, and then the process returns to step three. Otherwise, the donkey head continues to work with the current starting speed, ending speed and acceleration of the donkey head in each segment path. The operating path of each stroke of the pumping unit is divided into 10 segments. The donkey head operates in the first, second, sixth, and seventh segments with uniform acceleration, in the fourth, fifth, ninth, and tenth segments with uniform deceleration, and in the third and eighth segments with uniform speed. The running time of the donkey head in each segment path is: t i =α i T In the formula, t i α represents the running time of the donkey head in the i-th segment of the path. i This represents the running time coefficient of the donkey head in the i-th segment of the path, i=1,2,3,…,10, and is set as t1+t2+t3+t4+t5=t6+t7+t8+t9+t 10 =T / 2; t1=t5=t6=t 10 t2=t4=t7=t9, t3=t8; The formulas for calculating the initial values ​​of the donkey's starting speed, ending speed, and acceleration in each segment of the path are as follows: In the formula, S i Let S1+S2+S3+S4+S5=S6+S7+S8+S9+S 10 =S; Let be the average speed of the donkey's head on the i-th segment of the path. Let be the initial speed of the donkey's head in the i-th segment of the path. Let be the speed at the end of the i-th segment of the path. Let be the acceleration of the donkey's head in the i-th segment of the path; In this scenario, the donkey's initial speed in each segment of the path, excluding the first segment, is equal to its ending speed in the previous segment. Furthermore, the donkey's speed at the top and bottom endpoints is zero. Then, the initial velocity, final velocity, and initial acceleration of the donkey head in each segment of the path are calculated.

2. The intelligent oil pumping unit attitude control method for multi-time-segment variable speed operation according to claim 1, characterized in that: The real-time speed of the donkey head on each segmented path is: In the formula, Let j be the time point in the i-th segment of the path that the donkey is running. For the donkey's head The running speed at that time.

3. The intelligent oil pumping unit attitude control method for multi-time-segment variable speed operation according to claim 1 or 2, characterized in that: The process of correcting the starting speed, ending speed and acceleration of the donkey head in each segmented path is as follows: When T 实 > T, the starting speed of the donkey head in each segmented path is increased to α times the starting speed of the donkey head in the corresponding segmented path calculated last time, and α > 1. When T 实 < T, the starting speed of the donkey head in each segmented path is decreased to β times the starting speed of the donkey head in the corresponding segmented path calculated last time, and β < 1.

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