Stepless regulation hydraulic pumping unit system and electrical control method thereof

Abstract

The invention discloses a stepless regulation hydraulic oil pumping unit system and an electrical control method thereof. The stepless regulation hydraulic oil pumping unit system comprises a common direct current bus, a rectifier module and a plurality of oil pumping units. The common direct-current bus is connected with a power grid through a rectifier module and is connected with a plurality of oil pumping units through an inverter; each oil pumping unit comprises a power module, a safe overflow module and an oil pumping module; the common direct current buses are connected with the power modules through the inverters, the power modules and the oil pumping modules are connected in a one-to-one correspondence mode so as to drive the oil pumping modules to work and pump oil, and safety overflow modules are arranged between the power modules and the oil pumping modules in parallel. According to the hydraulic pumping unit system, through the arrangement of the common direct-current bus, the hydraulic pumping unit scheme that multiple oil pumping units are driven by one is achieved, and through the arrangement of the servo motor and the four-quadrant hydraulic pump motor, the stroke and the stroke frequency of the oil pumping module are effectively adjusted, so that the stroke and the stroke frequency of each pumping unit can be independently adjusted.

Description

Technical Field

[0001] This invention belongs to the field of oil pumping unit technology, and specifically discloses a steplessly adjustable hydraulic oil pumping unit system and its electrical control method. Background Technology

[0002] The walking beam pumping unit is one of the main types of pumping units currently used in oil fields. It mainly consists of four parts: the walking beam, the connecting rod, the crank mechanism, the gearbox, the power equipment, and the auxiliary equipment. During operation, the rotation of the electric motor is converted into the up-and-down movement of the walking beam through the gearbox and the crank-connecting rod mechanism. The walking beam drives the plunger of the downhole pump to move up and down through the polished rod and the sucker rod, thereby continuously pumping crude oil out of the wellbore.

[0003] Beam pumping units are widely used in major oilfields due to their reliable performance, simple structure, and convenient operation and maintenance. Their disadvantages include a large footprint, difficulty in adjusting the stroke and frequency, which can only be achieved by stopping the machine and adjusting mechanical components.

[0004] With technological advancements, hydraulic pumping units have emerged. These units utilize hydraulic energy supplied by a hydraulic station to drive the piston rod of a hydraulic cylinder to rise and fall. The piston rod is connected to the sucker rod, thus enabling oil extraction. Because the hydraulic cylinder is equipped with a displacement sensor, closed-loop control allows for stepless adjustment of the pumping unit's stroke and frequency, representing a significant technological advancement compared to beam pumping units. Furthermore, accumulators or other hydraulic energy recovery methods can achieve potential energy recovery in single or dual wells, saving energy. However, existing hydraulic pumping units often suffer from inconvenient control and difficulty in simultaneously operating multiple wells. For example, patent CN116877540A describes a single-well energy-saving hydraulic pumping unit that utilizes an accumulator to store the potential energy of the descending piston rod, offering some energy savings. However, it suffers from drawbacks such as accumulator malfunctions and complex control mechanisms. Patent CN115977583A describes a multi-functional hydraulic pumping unit that uses a bidirectional hydraulic pump, with the two wells acting as counterweights for each other. While its principle is simple and advanced, and it offers advantages such as energy recovery, its drawback is that it requires the two wells to be used in pairs, and the stroke and frequency of both wells must be identical; otherwise, it cannot function properly. However, oilfields often prefer to adjust the stroke and frequency of each pumping unit according to actual conditions to increase production. Furthermore, a hydraulic station equipped with only two hydraulic pumping units makes it difficult to achieve "one-to-many" operation, undoubtedly leading to low pumping efficiency.

[0005] In summary, developing a new type of hydraulic pumping unit that allows for independent adjustment of the stroke and frequency of each unit, and enables multiple units to be configured simultaneously on a single hydraulic station to achieve "one-to-many" operation, thereby further improving pumping efficiency, has become a pressing technical challenge in the field of pumping unit technology. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] Based on this, the present invention provides a continuously adjustable hydraulic pumping unit system and its electrical control method to solve the technical problems in the prior art where it is inconvenient to adjust the stroke and number of strokes of the pumping unit according to the actual situation, and it is difficult to configure multiple pumping units in a single hydraulic station at the same time.

[0008] (II) Technical Solution

[0009] To solve the above technical problems, the present invention proposes a stepless adjustable hydraulic pumping unit system, which includes: a common DC bus, a rectifier module, and multiple pumping units; the common DC bus is connected to the power grid through the rectifier module, and each of the common DC bus is connected to multiple pumping units through an inverter;

[0010] Each pumping unit includes a power module, a safety overflow module, and a pumping module; the common DC bus is connected to the power module through an inverter, and the power module and the pumping module are connected one-to-one to drive the pumping module to work and pump oil. The safety overflow module is connected in parallel between the power module and the pumping module.

[0011] Preferably, the power module includes a four-quadrant hydraulic pump motor and a servo motor;

[0012] The servo motor is electrically connected to the common DC bus via the inverter. The output end of the servo motor is connected to the four-quadrant hydraulic pump motor to drive the four-quadrant hydraulic pump motor to rotate. The oil outlet of the four-quadrant hydraulic pump motor is connected to the oil pumping module.

[0013] Preferably, the power module further includes an oil tank, and the oil suction port of the four-quadrant hydraulic pump motor is connected to the oil tank.

[0014] Preferably, the oil extraction module includes a hydraulic cylinder and a sucker rod;

[0015] The lower chamber of the hydraulic cylinder is connected to the oil outlet of the four-quadrant hydraulic pump motor, and the piston rod of the hydraulic cylinder is connected to the sucker rod to drive the sucker rod to draw oil.

[0016] Preferably, the oil extraction module further includes a displacement sensor, which is disposed in the hydraulic cylinder to monitor the stroke of the piston rod.

[0017] Preferably, the hydraulic cylinder includes a cylinder body, a cylinder head, a piston and a piston rod, and a guide sleeve;

[0018] The cylinder head is sealed at one end of the cylinder body, the guide sleeve is sealed at the other end of the cylinder body, the piston is sealed inside the cylinder body, one end of the piston rod is connected to the sucker rod, and the other end of the piston rod passes through the guide sleeve and extends into the cylinder body and is connected to the piston. The cylinder body has a lower chamber on the side of the piston near the sucker rod, and the cylinder body has an upper chamber on the other side of the piston.

[0019] Preferably, the safety overflow module includes an overflow valve and a pressure sensor;

[0020] The overflow valve is connected in parallel between the lower chamber of the hydraulic cylinder and the oil outlet of the four-quadrant hydraulic pump motor to protect the pumping unit from pressure overload. The pressure sensor is connected in parallel between the lower chamber of the hydraulic cylinder and the oil outlet of the four-quadrant hydraulic pump motor to monitor the outlet pressure of the four-quadrant hydraulic pump motor.

[0021] The present invention also provides an electrical control method for a continuously variable hydraulic pumping unit system. The control method is implemented according to the above-mentioned continuously variable hydraulic pumping unit system. The control method includes: the continuously variable hydraulic pumping unit system includes two working states: a hydraulic pump state and a hydraulic motor state.

[0022] A. Hydraulic pump status: When the servo motor rotates forward, the power grid and the common DC bus discharge. The servo motor rotates forward to drive the four-quadrant hydraulic pump motor to rotate forward. At this time, the four-quadrant hydraulic pump motor works as a hydraulic pump. The hydraulic oil output by the four-quadrant hydraulic pump motor is pumped into the lower chamber of the hydraulic cylinder, driving the piston rod of the hydraulic cylinder to rise. The piston rod of the hydraulic cylinder drives the sucker rod to rise.

[0023] B. Hydraulic motor status: When the servo motor reverses, the four-quadrant hydraulic pump motor works as a hydraulic motor. Under the action of gravitational potential energy, the piston rod of the hydraulic cylinder falls and the oil in the lower chamber pushes the four-quadrant hydraulic pump motor to rotate, thereby driving the servo motor to generate electricity. The electrical energy generated by the servo motor is charged to the common DC bus and the power grid through the inverter. At this time, the sucker rod descends.

[0024] (III) Beneficial Effects

[0025] Compared with the prior art, the stepless adjustable hydraulic pumping unit system and its electrical control method of the present invention have the following advantages:

[0026] This continuously variable hydraulic pumping unit system, through the setting of a rectifier module and a common DC bus, enables the hydraulic station to connect multiple pumping units via the rectifier module and the common DC bus, thus realizing a "one-to-many" hydraulic pumping unit solution. The setting of servo motor and four-quadrant hydraulic pump motor in the power module effectively realizes the adjustment of the stroke and frequency of the pumping unit, so that the stroke and frequency of each pumping unit can be adjusted independently, allowing them to adjust their pumping efficiency according to the actual working conditions. This solves the problem that traditional hydraulic pumping units have difficulty controlling the stroke and frequency of each pumping unit.

[0027] Furthermore, the four-quadrant hydraulic pump motor configuration allows the hydraulic pumping unit system to operate in multiple modes. In pump mode, it outputs flow to control the rise and speed of the hydraulic cylinder, consuming energy. When the pumping unit switches from pump mode to motor mode, the servo motor functions as a generator, feeding back energy and reusing the recovered electrical energy, thereby reducing energy waste and improving energy reuse efficiency. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the overall structure of the stepless adjustable hydraulic pumping unit system of the present invention.

[0030] Figure 2 This is a schematic diagram of the overall structure of the continuously adjustable hydraulic pumping unit system of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Four-quadrant hydraulic pump motor; 2. Servo motor; 3. Relief valve; 4. Pressure sensor; 5. Hydraulic cylinder; 5.1 Upper chamber; 5.2 Lower chamber; 6. Inverter; 7. Common DC bus; 8. Rectifier module; 9. Displacement sensor. Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] The following is in conjunction with the appendix Figure 1-2 The continuously variable hydraulic pumping unit system and its electrical control method of the present invention will be further described.

[0035] Please refer to this carefully. Figure 1-2 This invention discloses a steplessly adjustable hydraulic pumping unit system, which includes: a common DC bus 7, a rectifier module 8, and multiple pumping units; the common DC bus 7 is connected to the power grid through the rectifier module 8, and each common DC bus 7 is connected to multiple pumping units through an inverter 6; each pumping unit includes a power module, a safety overflow module, and a pumping module; the common DC bus 7 is connected to the power module through the inverter 6, and the power module and the pumping module are connected one-to-one to drive the pumping module to work and pump oil, and a safety overflow module is connected in parallel between the power module and the pumping module.

[0036] In this embodiment, the hydraulic pumping unit system incorporates a common DC bus 7, enabling the hydraulic station to connect to multiple pumping units via the rectifier module 8 and the common DC bus 7, thus achieving a "one-to-many" hydraulic pumping unit solution. The inclusion of a four-quadrant hydraulic pump motor 1 in the power module integrates hydraulic and electrical control, effectively combining the four-quadrant principle of the pump control system with the recovery of the common DC bus 7, reducing energy waste and improving the reuse rate of electrical energy. Furthermore, the inclusion of a servo motor 2 in the power module effectively adjusts the stroke and frequency of the pumping modules, allowing independent adjustment of the stroke and frequency of each pumping unit. This enables the adjustment of pumping efficiency according to actual working conditions, solving the problem of traditional hydraulic pumping units struggling to control the stroke and frequency of each pumping unit.

[0037] See Figure 1 The power module includes a four-quadrant hydraulic pump motor 1 and a servo motor 2. The servo motor 2 is electrically connected to the common DC bus 7 via an inverter 6. The output end of the servo motor 2 is connected to the four-quadrant hydraulic pump motor 1 to drive the four-quadrant hydraulic pump motor 1 to rotate. The oil outlet of the four-quadrant hydraulic pump motor 1 is connected to the oil suction module. The power module also includes an oil tank, and the oil suction port of the four-quadrant hydraulic pump motor 1 is connected to the oil tank.

[0038] In this embodiment, the servo motor 2 not only drives the four-quadrant hydraulic pump motor 1 but also allows the user to control its output. This enables independent adjustment of the stroke and frequency of each pumping unit, allowing for adjustments to pumping efficiency based on actual working conditions. This effectively solves the problem of traditional hydraulic pumping units struggling to control the stroke and frequency of each unit. The four-quadrant hydraulic pump motor 1 allows the hydraulic pumping unit system to operate in multiple modes. In pump mode, it outputs flow to control the rise and speed of the hydraulic cylinder 5, consuming energy. When the pumping unit switches from pump mode to motor mode, the servo motor 2 functions as a generator, feeding back energy. In the next energy-consuming mode, the recovered electrical energy is reused, improving energy utilization efficiency.

[0039] In one embodiment, the oil extraction module includes a hydraulic cylinder 5 and a sucker rod. The lower chamber 5.2 of the hydraulic cylinder 5 is connected to the oil outlet of the four-quadrant hydraulic pump motor 1. The piston rod of the hydraulic cylinder 5 is connected to the sucker rod to drive the sucker rod to extract oil. The oil extraction module also includes a displacement sensor 9, which is disposed in the hydraulic cylinder 5 to monitor the stroke of the piston rod. The hydraulic cylinder 5 includes a cylinder body, a cylinder head, a piston, and a piston rod. The cylinder head is sealed at one end of the cylinder body, the guide sleeve is sealed at the other end of the cylinder body, the piston is sealed inside the cylinder body, one end of the piston rod is connected to the sucker rod, and the other end of the piston rod extends through the guide sleeve into the cylinder body and is connected to the piston. A lower chamber 5.2 is provided inside the cylinder body on the side of the piston near the sucker rod, and an upper chamber 5.1 is provided inside the cylinder body on the other side of the piston. The displacement sensor 9 can monitor the displacement signal of the hydraulic cylinder 5 in real time, which facilitates the adjustment and control of the stroke and frequency of the hydraulic oil extraction unit. The displacement sensor 9 can be installed either inside or outside the cavity of the hydraulic cylinder 5. For those skilled in the art, the placement of the displacement sensor 9 is sufficient to effectively monitor the stroke of the hydraulic cylinder. In a preferred embodiment, the displacement sensor 9 is installed inside the cavity of the hydraulic cylinder 5, and by monitoring the displacement of the piston, the stroke and number of strokes of the hydraulic pumping unit are effectively monitored.

[0040] See Figure 1 and Figure 2The safety overflow module includes an overflow valve 3 and a pressure sensor 4. The overflow valve 3 is connected in parallel between the lower chamber 5.2 of the hydraulic cylinder 5 and the outlet of the four-quadrant hydraulic pump motor 1 to protect the pumping unit from pressure overload. The pressure sensor 4 is connected in parallel between the lower chamber 5.2 of the hydraulic cylinder 5 and the outlet of the four-quadrant hydraulic pump motor 1 to monitor the outlet pressure of the four-quadrant hydraulic pump motor 1. In this embodiment, the overflow valve 3 can protect the outlet pressure of the four-quadrant hydraulic pump motor 1 from exceeding the safety set value, and the pressure sensor 4 can monitor the outlet pressure of the four-quadrant hydraulic pump motor 1 in real time to facilitate control of the outlet pressure of the four-quadrant hydraulic pump motor 1 and can be used for fault diagnosis of the system.

[0041] Based on the above-mentioned continuously variable hydraulic pumping unit system, the present invention also provides an electrical control method for the continuously variable hydraulic pumping unit system. The control method is implemented according to the continuously variable hydraulic pumping unit system and includes: the continuously variable hydraulic pumping unit system includes two working states: hydraulic pump state and hydraulic motor state.

[0042] A. Hydraulic pump status: When the servo motor 2 rotates forward, the power grid and the common DC bus 7 discharge. The servo motor 2 rotates forward to drive the four-quadrant hydraulic pump motor 1 to rotate forward. At this time, the four-quadrant hydraulic pump motor 1 works as a hydraulic pump. The hydraulic oil output by the four-quadrant hydraulic pump motor 1 is pumped into the lower chamber 5.2 of the hydraulic cylinder 5, which drives the piston rod of the hydraulic cylinder 5 to rise. The piston rod of the hydraulic cylinder 5 drives the sucker rod to rise.

[0043] B. Hydraulic motor status: When the servo motor 2 reverses, the four-quadrant hydraulic pump motor 1 works as a hydraulic motor. Under the action of gravitational potential energy, the piston rod of the hydraulic cylinder 5 falls and the oil in the lower chamber 5.2 pushes the four-quadrant hydraulic pump motor 1 to rotate, thereby driving the servo motor 2 to generate electricity. The electrical energy generated by the servo motor 2 is charged to the common DC bus 7 and the power grid through the inverter 6. At this time, the sucker rod descends.

[0044] This continuously variable hydraulic pumping unit system drives the plunger of the downhole pump to move up and down through two working states: hydraulic pump state and hydraulic motor state, thereby continuously extracting crude oil from the well.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can also refer to a "transmission connection," that is, a power connection through various suitable methods such as belt drive, gear drive, or sprocket drive. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A continuously variable hydraulic pumping unit system, characterized in that, The continuously variable hydraulic pumping unit system includes: a common DC bus, a rectifier module, and multiple pumping units; the common DC bus is connected to the power grid through the rectifier module, and each common DC bus is connected to multiple pumping units through an inverter; Each pumping unit includes a power module, a safety overflow module, and a pumping module; the common DC bus is connected to the power module through an inverter, and the power module and the pumping module are connected one-to-one to drive the pumping module to work and pump oil. The safety overflow module is connected in parallel between the power module and the pumping module.

2. The continuously variable hydraulic pumping unit system according to claim 1, characterized in that, The power module includes a four-quadrant hydraulic pump motor and a servo motor; The servo motor is electrically connected to the common DC bus via the inverter. The output end of the servo motor is connected to the four-quadrant hydraulic pump motor to drive the four-quadrant hydraulic pump motor to rotate. The oil outlet of the four-quadrant hydraulic pump motor is connected to the oil pumping module.

3. The continuously variable hydraulic pumping unit system according to claim 2, characterized in that, The power module also includes an oil tank, and the oil suction port of the four-quadrant hydraulic pump motor is connected to the oil tank.

4. The continuously variable hydraulic pumping unit system according to claim 2, characterized in that, The oil extraction module includes a hydraulic cylinder and a sucker rod; The lower chamber of the hydraulic cylinder is connected to the oil outlet of the four-quadrant hydraulic pump motor, and the piston rod of the hydraulic cylinder is connected to the sucker rod to drive the sucker rod to draw oil.

5. The continuously variable hydraulic pumping unit system according to claim 4, characterized in that, The oil extraction module also includes a displacement sensor, which is installed at the hydraulic cylinder to monitor the stroke of the piston rod.

6. The continuously variable hydraulic pumping unit system according to claim 4, characterized in that, The hydraulic cylinder includes a cylinder body, a cylinder head, a piston, a piston rod, and a guide sleeve; The cylinder head is sealed at one end of the cylinder body, the guide sleeve is sealed at the other end of the cylinder body, the piston is sealed inside the cylinder body, one end of the piston rod is connected to the sucker rod, and the other end of the piston rod passes through the guide sleeve and extends into the cylinder body and is connected to the piston. The cylinder body has a lower chamber on the side of the piston near the sucker rod, and the cylinder body has an upper chamber on the other side of the piston.

7. The continuously variable hydraulic pumping unit system according to claim 4, characterized in that, The safety overflow module includes an overflow valve and a pressure sensor; The overflow valve is connected in parallel between the lower chamber of the hydraulic cylinder and the oil outlet of the four-quadrant hydraulic pump motor to protect the pumping unit from pressure overload. The pressure sensor is connected in parallel between the lower chamber of the hydraulic cylinder and the oil outlet of the four-quadrant hydraulic pump motor to monitor the outlet pressure of the four-quadrant hydraulic pump motor.

8. An electrical control method for a continuously variable hydraulic pumping unit system, characterized in that, The control method is implemented according to any one of claims 1-7 of the stepless adjustable hydraulic pumping unit system, and the control method includes: the stepless adjustable hydraulic pumping unit system includes two working states: hydraulic pump state and hydraulic motor state. A. Hydraulic pump status: When the servo motor rotates forward, the power grid and the common DC bus discharge. The servo motor rotates forward to drive the four-quadrant hydraulic pump motor to rotate forward. At this time, the four-quadrant hydraulic pump motor works as a hydraulic pump. The hydraulic oil output by the four-quadrant hydraulic pump motor is pumped into the lower chamber of the hydraulic cylinder, driving the piston rod of the hydraulic cylinder to rise. The piston rod of the hydraulic cylinder drives the sucker rod to rise. B. Hydraulic motor status: When the servo motor reverses, the four-quadrant hydraulic pump motor works as a hydraulic motor. Under the action of gravitational potential energy, the piston rod of the hydraulic cylinder falls and the oil in the lower chamber pushes the four-quadrant hydraulic pump motor to rotate, thereby driving the servo motor to generate electricity. The electrical energy generated by the servo motor is fed back to the common DC bus and the power grid through the inverter. At this time, the sucker rod descends.

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