Lead screw driving rodless reciprocating type single-action electric submersible pump and control method

Abstract

The invention belongs to the technical field of oil and gas exploitation and pressurized transportation, and discloses a lead screw driven rodless reciprocating type single-action electric submersible pump and a control method. The electric pump is characterized in that a working cavity is formed between a plunger and an upper working cavity end cover, and a lower cavity is formed between the plunger and a lower cavity end cover; the plunger does reciprocating motion in the working cavity to finish suction and discharge of liquid; the lower working cavity end cover is installed at the bottom of the cylinder body, and a lead screw is fixed to the lower working cavity end cover and connected with the plunger. The lead screw is connected with a motor. The plunger is driven by the lead screw to reciprocate in the cylinder body, and suction and discharge of liquid and control and continuous conveying of liquid in a working cavity are sequentially completed in the up-down stroke of the plunger by means of one-way opening and closing of the liquid inlet valve and the liquid discharge valve. The lead screw driving rodless reciprocating type single-action electric submersible pump is higher in efficiency under the complex well condition. The optimized reciprocating type driving mechanism can achieve efficient one-way conveying, the sealing design can prolong the service life of equipment, and the maintenance cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas exploitation and pressurized transportation, and in particular relates to a screw-driven rodless reciprocating single-acting submersible electric pump and a control method thereof. Background Art

[0002] With the continued development of oil and gas resources, especially in deep and ultra-deep wells and complex operating conditions, efficient and stable artificial lift technologies are becoming increasingly important. Traditional submersible electric pumps primarily utilize centrifugal pumps, progressive cavity pumps, and rod plunger pumps. However, over time, these devices have gradually exposed numerous limitations, impacting their adaptability and service life in wells with high viscosity, high gas content, and high sand content. Centrifugal pumps rely on the rotation of their impellers to transport liquids, and operate stably in low-viscosity wells. However, they are less efficient and consume more energy in high-viscosity, low-flow conditions. Gas lock is more likely to occur in high-gas conditions, impacting normal operation and increasing maintenance costs. Progressive cavity pumps propel liquids through a sealed cavity between the screw and stator. Over long-term operation, wear of the screw and stator weakens the seal, leading to reduced pump efficiency. Furthermore, progressive cavity pumps are sensitive to solid particles and prone to clogging and abnormal wear in high-sand content wells. Their high specific energy consumption makes them less economical, making them difficult to meet energy conservation and consumption reduction requirements. Summary of the Invention

[0003] In order to overcome the problems existing in the related art, the embodiments disclosed in the present invention provide a screw-driven rodless reciprocating single-acting submersible electric pump and a control method. The purpose of the present invention is to achieve oil and gas lifting and transportation by driving the movement of the plunger through the screw. The design has the characteristics of compact structure, high energy efficiency, and high reliability. It is particularly suitable for complex fluid environments with high viscosity and impurities, such as submarine oil and gas transportation, deep well mining and other fields.

[0004] The technical solution is as follows: a screw-driven rodless reciprocating single-acting submersible electric pump, the electric pump comprising:

[0005] An oil inlet cavity cover plate is provided, which is mounted on the top of the cylinder body and has a through hole connected to the oil pipe to form a drainage channel;

[0006] A drain cavity is provided in the middle between the oil inlet cavity cover plate and the upper working cavity end cover, and a drain valve is provided inside the drain cavity;

[0007] Liquid inlet cavities are respectively provided on both sides between the oil inlet cavity cover plate and the upper working cavity end cover, and liquid inlet valves are provided in the liquid inlet cavities;

[0008] The upper working chamber end cover is fixedly mounted on the upper end of the cylinder body and supports the liquid inlet valve and the liquid discharge valve;

[0009] A working chamber is formed between the plunger and the upper working chamber end cover, and a lower chamber is formed between the plunger and the lower chamber end cover; the plunger reciprocates in the working chamber to complete the suction and discharge of liquid;

[0010] The lower working chamber end cover is installed at the bottom of the cylinder body. A lead screw is fixed on the lower working chamber end cover. The lead screw is connected to the plunger; the lead screw is connected to the motor.

[0011] The screw drives the plunger to reciprocate in the cylinder body, and the one-way opening and closing of the liquid inlet valve and the liquid discharge valve are used to complete the suction and discharge of liquid in sequence during the up and down stroke of the plunger, thereby controlling and continuously delivering the liquid in the working chamber.

[0012] The motor is installed at the lower part of the cylinder body, and drives the lead screw to move up and down, causing the plunger to move back and forth along the axial direction, completing the liquid suction and discharge process.

[0013] The drainage chamber is connected to the working chamber through the drainage and drainage channels;

[0014] The cross-section of the upper working chamber end cover is an annular flange type with a flow channel and a mounting structure, and the cross-section of the lower working chamber end cover is a solid disc type; the liquid inlet chamber is connected to the working chamber through the liquid inlet valve and the flow channel; the upper working chamber end cover is connected to the cylinder body through the mounting structure.

[0015] The opening directions of the liquid inlet valve and the liquid discharge valve are both toward the oil pipe;

[0016] An oil inlet chamber static sealing device is provided between the oil inlet chamber cover plate and the cylinder body, an upper working chamber static sealing device is provided between the upper working chamber end cover and the cylinder body; a dynamic sealing device is provided between the plunger and the lead screw.

[0017] A radial rolling bearing is provided in the end cover of the lower working chamber;

[0018] The radial rolling bearing is a deep groove ball bearing or a cylindrical roller bearing; the motor is a servo motor or a bidirectional motor; the screw realizes the up and down reciprocating motion of the screw by connecting to the servo motor or the bidirectional motor; the servo motor uses position feedback and closed-loop control to provide feedback according to preset parameters and actual conditions, adjust the reciprocating motion stroke, speed and frequency of the plunger, complete the control during the liquid delivery process, and meet the operating requirements under different working conditions; the screw adopts a ball screw or a threaded screw.

[0019] One end of the lead screw is fixed to the upper working chamber end cover through a rotary bearing, and the other end is fixed to the lower working chamber end cover. The lead screw rotates to drive the plunger to move axially.

[0020] The drainage chamber is communicated with the working chamber through the drainage and drainage channels.

[0021] Another object of the present invention is to provide a control method for a screw-driven rodless reciprocating single-acting submersible electric pump, the method comprising:

[0022] The servo motor provides feedback based on preset parameters and actual conditions through position feedback and improved closed-loop control, adjusts the plunger's reciprocating motion stroke, speed and frequency, completes control during the liquid delivery process, and meets operating requirements under different working conditions.

[0023] The servo motor uses position feedback and improved closed-loop control to provide feedback based on preset parameters and actual conditions, adjusting the plunger's reciprocating stroke, speed, and frequency, including:

[0024] S1, obtaining the current position of the plunger in the working chamber during liquid inflow and liquid outflow through an external laser position detector, and sending the current position information to the control unit of the servo motor. The pressure sensing chip in the control unit collects the current servo motor output pressure signal;

[0025] S2, comparing the current position information and the current servo motor output pressure signal with preset standard positions of the plunger in the working chamber during liquid inlet and liquid discharge, and standard information of the servo motor output pressure during liquid discharge, and adjusting the comparison results using an improved closed-loop control method;

[0026] S3, based on the adjustment result, the control unit adjusts the plunger's reciprocating motion stroke, speed and frequency by regulating the operating state of the servo motor.

[0027] In step S2, the adjustment by the improved closed-loop control method includes:

[0028] The digital signal is transmitted to the PID controller based on the set PID control rules and PID control algorithm. It is used as the input variable of the PID controller to perform PID inference and the initial inference result is subjected to inverse PID processing. The output result determines the length of the plunger's reciprocating motion, the rate of change of liquid inlet and discharge, and the operating frequency of the servo motor.

[0029] The PID input variables include: the amount of liquid inflow and the negative pressure level of the working chamber. After the PID controller is passed, the output variables are: the length of the plunger's reciprocating motion, the rate of change of liquid inflow and discharge, and the operating frequency of the servo motor. The PID inference rules specifically include:

[0030] (1) Reasoning about the change rate of liquid inlet and discharge: the change rate of liquid inlet and discharge is divided into "low", "normal" and "high";

[0031] The control rules for the change rate of liquid inlet and discharge are as follows: ① If the liquid inlet amount is small, the change rate of liquid inlet and discharge is relatively small; ② If the liquid inlet amount is moderate, the change rate of liquid inlet and discharge is normal; ③ If the liquid inlet amount is large, the change rate of liquid inlet and discharge is long;

[0032] (2) Reasoning about the operating frequency of the servo motor: The operating frequency of the servo motor is divided into "slightly low", "normal" and "high";

[0033] The control rules for the servo motor operating frequency are as follows: ① If the amount of liquid inflow is small, the servo motor operating frequency is slightly lower; ② If the amount of liquid inflow is moderate, the servo motor operating frequency is normal;

[0034] (3) Reasoning of plunger reciprocating motion stroke: The plunger reciprocating motion stroke is divided into “relatively short”, “short”, “moderate”, “long” and “relatively long”; the rules of the five PID modes are as follows: ① If the amount of liquid inflow is small and the negative pressure of the working chamber is low, the plunger reciprocating motion stroke is short; ② If the amount of liquid inflow is small and the negative pressure of the working chamber is moderate, the plunger reciprocating motion stroke is short; ③ If the amount of liquid inflow is small and the negative pressure of the working chamber is high, the plunger reciprocating motion stroke is moderate; ④ If the amount of liquid inflow is moderate and the negative pressure of the working chamber is high, the plunger reciprocating motion stroke is moderate. ⑤ If the liquid inlet is moderate and the negative pressure in the working chamber is moderate, the reciprocating stroke of the plunger will be moderate; ⑥ If the liquid inlet is moderate and the negative pressure in the working chamber is high, the reciprocating stroke of the plunger will be long; ⑦ If the liquid inlet is large and the negative pressure in the working chamber is low, the reciprocating stroke of the plunger will be moderate; ⑧ If the liquid inlet is large and the negative pressure in the working chamber is moderate, the reciprocating stroke of the plunger will be long; ⑨ If the liquid inlet is large and the negative pressure in the working chamber is high, the reciprocating stroke of the plunger will be long;

[0035] The PID inference result is de-PIDed to convert the inference result into an accurate value. The maximum weight method is used. The maximum weight method does not consider the shape of the output weight function, but only considers the output value at the maximum weight. The maximum weight de-PID method selects the element with the largest weight in the PID quantity of the inference result as the output value:

[0036]

[0037] If there is more than one output value corresponding to the maximum weight in the output domain S, then the average of the outputs with the maximum weight is taken:

[0038]

[0039] Where M is the total number of outputs with the same maximum weight.

[0040] In combination with all the above technical solutions, the beneficial effects of the present invention are as follows:

[0041] This invention achieves oil and gas lifting and delivery by rotating the screw forward to drive the plunger. The single-acting pump has a simpler structure and is easier to maintain. It is suitable for small-displacement but high-pressure delivery in harsh environments such as deep wells, high-temperature and high-pressure environments, and highly corrosive environments.

[0042] The screw-driven rodless reciprocating single-acting submersible electric pump provided by the present invention uses a screw mechanism to directly drive the plunger to perform reciprocating motion. It has a compact structure and high transmission efficiency, and is particularly suitable for complex working conditions such as high viscosity and high sand content. Compared with traditional submersible electric pumps, the screw drive improves volumetric efficiency and reduces energy consumption. The elimination of the sucker rod design allows the pump to effectively avoid problems such as eccentric wear of the rod and pipe. The pump body seal is stable and reliable. A static seal is provided between the cylinder body and the upper working chamber end cover to prevent liquid leakage; a dynamic seal is provided between the plunger and the cylinder body to ensure the working chamber is sealed; and a seal is provided between the screw and the end cover to improve system stability. The use of wear-resistant sealing materials combined with a pressure balance design can effectively reduce seal wear and extend service life.

[0043] Compared to centrifugal and progressive cavity pumps, screw-driven rodless reciprocating single-acting submersible electric pumps offer higher efficiency in complex well conditions. The optimized reciprocating drive mechanism enables efficient unidirectional delivery, and the seal design extends equipment life and reduces maintenance costs. This technology provides an efficient and reliable solution for oil and gas lift in deep and ultra-deep wells and harsh operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure;

[0045] Figure 1 Schematic diagram of a screw-driven rodless reciprocating single-acting submersible electric pump provided in Example 1 of the present invention;

[0046] Figure 2 Schematic diagram of a screw-driven rodless reciprocating single-acting submersible electric pump provided in Example 2 of the present invention;

[0047] Figure 3 The servo motor of the present invention adjusts the reciprocating stroke, speed and frequency of the plunger through position feedback and improved closed-loop control according to preset parameters and actual conditions;

[0048] Numbers in the figure: 1. Oil pipe; 2. Oil inlet chamber cover; 3. Liquid inlet valve; 4. Liquid drain valve; 5. Upper working chamber end cover; 6. Cylinder body; 7. Plunger; 8. Screw; 9. Lower chamber end cover; 10. Motor; 11. Lower chamber; 12. Flow channel; 13. Mounting structure; 14. Oil chamber static sealing device; 15. Upper working chamber static sealing device; 16. Dynamic sealing device; 17. Radial rolling bearing; 18. Drainage channel; 19. Rotating bearing; 20. Drainage channel; A. Liquid inlet chamber; B. Working chamber; C. Drainage chamber. DETAILED DESCRIPTION

[0049] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0050] Example 1, as Figure 1 As shown, the screw-driven rodless reciprocating single-acting submersible electric pump provided in an embodiment of the present invention is used for oil and gas lifting, and mainly includes an oil pipe 1, an oil inlet chamber cover plate 2, a liquid inlet valve 3, a liquid discharge valve 4, an upper working chamber end cover 5, a cylinder body 6, a plunger 7, a screw 8, a lower chamber end cover 9, and a motor 10.

[0051] The oil inlet cover plate 2 is mounted on top of the cylinder body 6. A through hole is provided in the cover plate 2, connecting to the oil pipe 1 to form a drainage channel 18, allowing the oil to drain smoothly. A single working chamber B is formed between the plunger and the upper working chamber end cap. The plunger 7 reciprocates within this working chamber B, achieving the intake and discharge of liquid.

[0052] The upper working chamber end cover 5 is fixedly mounted on the upper end of the cylinder body 6 and supports the liquid inlet valve 3 and the liquid discharge valve 4 to ensure smooth flow of the fluid channel.

[0053] The lower working chamber end cover 9 is installed at the bottom of the cylinder body 6. Its main function is to provide support for the screw 8 so that the screw 8 can stably drive the plunger 7 to move up and down.

[0054] In this structure, the plunger 7 is installed between the upper working chamber end cover 5 and the lower working chamber end cover 9 so as to slide up and down. The plunger 7 is used in conjunction with the screw 8. The upper end of the screw 8 is supported by the plunger 8, and the lower end is supported by the lower chamber end cover 9. The plunger 7 reciprocates up and down in the axial direction under the drive of the screw 8. In order to limit the rotation of the plunger 7 with the screw 8, the inner wall of the cylinder body and the outer wall of the plunger are matched through a keyway, or a cylinder body and plunger with a non-circular cross-section can be used. This movement allows the plunger 7 to form a periodically changing working chamber between the upper working chamber end cover 5 and the plunger 7, thereby realizing the process of sucking in, pressurizing, and discharging the medium. In addition, the inlet valve 3 and the drain valve 4 are oriented toward the oil pipe 1, and their valve cores are spherical in design to ensure unidirectional flow of the fluid.

[0055] Among them, the plunger 7 is driven to reciprocate in the cylinder 6 by the screw 8, and the one-way opening and closing of the liquid inlet valve 3 and the liquid discharge valve 4 are relied upon to complete the suction and discharge of the liquid in sequence during the up and down stroke of the plunger 7, thereby realizing effective control and continuous delivery of the liquid in the working chamber.

[0056] The motor 10 is installed at the lower part of the cylinder body 6 and is connected to the screw 8. By driving the screw 8 to reciprocate up and down, the plunger 7 is reciprocated along the axial direction to complete the liquid suction and discharge process.

[0057] For example, a drain cavity C is provided in the middle between the oil inlet cavity cover plate 2 and the upper working cavity end cover 5, and a drain valve 4 is provided inside the drain cavity C;

[0058] Liquid inlet cavities A are respectively provided on both sides between the oil inlet chamber cover plate 2 and the upper working chamber end cover 5, a working chamber B is formed between the plunger 7 and the upper working chamber end cover 5, and a lower chamber 11 is formed between the plunger 7 and the lower chamber end cover 9.

[0059] The drainage chamber C is connected to the working chamber B through the drainage valve 4 and the drainage channel 18.

[0060] For example, the upper working chamber end cap 5 has an annular flange cross-section with a flow channel 12 and a mounting structure 13, while the lower working chamber end cap 9 has a solid disc cross-section. The liquid inlet chamber A communicates with the working chamber B via the liquid inlet valve 3 and the flow channel 12; the upper working chamber end cap 5 is connected to the cylinder body 6 via the mounting structure 13.

[0061] For example, the working chamber B is the only working chamber; the lower chamber 11 only plays a supporting role and has the function of stabilizing the screw 8, and does not participate in the liquid inlet and outlet, ensuring the simplicity and stability of the system structure.

[0062] For example, the opening directions of the liquid inlet valve 3 and the liquid outlet valve 4 are both toward the oil pipe 1. The valve cores of the liquid inlet valve 3 and the liquid outlet valve 4 are both spherical.

[0063] Illustratively, an oil inlet chamber static sealing device 14 is provided between the oil inlet chamber cover plate 2 and the cylinder body 6 to prevent oil leakage; an upper working chamber static sealing device 15 is provided between the upper working chamber end cover 5 and the cylinder body 6; a dynamic sealing device 16 is provided between the plunger 7 and the lead screw 8 to prevent oil and impurities from flowing into the connection between the plunger 7 and the lead screw 8, thereby wearing the lead screw 8 and the plunger 7, and at the same time preventing oil leakage in the upper working chamber B.

[0064] Exemplarily, a radial rolling bearing 17 is disposed within the lower working chamber end cap 9 to support the rotation of the lead screw 8 while allowing it to move freely in the axial direction. The plunger 7 is connected to the lead screw 8 via a ball screw pair, and a pre-tightening nut is used to eliminate clearance, ensuring that the lead screw maintains a stable pulling or pushing effect on the plunger 7 during rotation. Simultaneously, the lead screw 8 can also undergo axial linear motion under the action of the motor 10. This design ensures that the lead screw 8 maintains a constant pulling or pushing effect on the plunger 7, reducing the thrust applied to the lead screw 8 and improving the system's operational stability and service life.

[0065] For example, the radial rolling bearing 17 mounted on the lower working chamber end cover 9 is a deep groove ball bearing or a cylindrical roller bearing. The motor 10 is a servo motor or a bidirectional motor; the screw 8 is connected to the servo motor or the bidirectional motor to achieve the up and down reciprocating motion of the screw 8.

[0066] Exemplarily, the cylinder body 6 adopts an integrally processed and formed structure to improve structural strength and sealing performance, and the remaining components are installed on the cylinder body 6 by bolt connections to facilitate disassembly and maintenance.

[0067] Exemplarily, the screw 8 is a ball screw or a threaded screw.

[0068] As can be seen from the above embodiments, the screw 8 of the present invention, driven by the actuator 10, periodically rotates forward and reverse, thereby driving the piston 7 in axial reciprocation. During the reciprocating motion of the piston 7, a periodically changing working chamber B is formed between the upper working chamber end cap 5 and the piston 7. When the piston 7 moves downward, the volume of the working chamber B increases. Under the action of the pressure differential, the inlet valve 3 opens, and oil continuously enters the working chamber B. Conversely, when the piston 7 moves upward, the volume of the working chamber B decreases, the internal oil pressure increases, and under the action of the pressure differential, the oil is discharged through the drain valve 4. With the periodic changes in the working chamber B, the oil is eventually sucked into the liquid chamber A and discharged into the drain chamber C after being pressurized, completing the pressurization and delivery of the medium. The pressure differential control process is naturally generated by the volume change of the working chamber B caused by the axial reciprocating motion of the piston. No electronic sensors or control devices are required. Adaptive opening and closing are achieved by presetting the valve opening pressure, ensuring that the one-way suction and discharge of liquid can be stably completed under different working conditions.

[0069] The inlet valve 3, the flow channel 12 within the upper working chamber end cap 5, the working chamber B, the drain valve 4, and the drain channel 18 of the present invention collectively constitute the working chamber medium pressurization delivery channel. The inlet valve 3 is used to control the entry of downhole liquid into the working chamber B. The flow channel 12 and the drain channel 18 within the upper working chamber end cap 5 connect the inlet valve 3 and the drain valve 4, ensuring the flow path of the liquid during the reciprocating motion of the plunger. The working chamber B undergoes pressure changes through the reciprocating action of the plunger 7, and the drain valve 4 ultimately completes the liquid delivery. During operation, when the plunger 7 descends, the inlet valve 3 opens, and downhole liquid enters the working chamber B through the flow channel 12 under the action of the pressure differential. When the plunger 7 ascends, the inlet valve 3 closes and the drain valve 4 opens, allowing the liquid to be discharged from the working chamber B into the oil pipe 1, completing the pressurization delivery process. The inlet valve 3 and the drain valve 4 cooperate with the plunger movement to achieve unidirectional flow of the medium within the working chamber B through the pressure differential, thereby improving the stability and efficiency of liquid delivery.

[0070] In the present invention, a static sealing device is provided between the oil inlet chamber cover and the cylinder body to prevent oil leakage; a static sealing device is provided between the upper working chamber end cover and the cylinder body; a dynamic sealing device is provided between the plunger and the screw rod to prevent oil and impurities from flowing into the connection between the plunger and the screw rod, thereby wearing the screw rod and the plunger, and preventing oil leakage in the upper working chamber B.

[0071] In the present invention, radial rolling bearings 17 are incorporated into the lead screw 8 and the lower working chamber end cap 9. A ball screw pair connects the lead screw 8 and plunger 7. Driven by a motor 10, the lead screw 8 is supported by the radial rolling bearings 17, ensuring rotational stability. A preloaded nut eliminates transmission backlash and ensures precise control of the plunger's motion.

[0072] The liquid inlet valve 3 and the liquid discharge valve 4 described in the present invention are both one-way ball valves, and their opening directions are both toward the oil pipe, ensuring the unidirectionality of fluid transportation and improving the working efficiency and stability of the system.

[0073] The present invention adopts a high-strength integrally processed cylinder body to enhance structural strength and sealing performance. The remaining components are connected by bolts, which is convenient for disassembly and maintenance, thereby improving the service life and reliability of the equipment.

[0074] The screw 8 of the present invention can adopt a ball screw or a threaded screw to adapt to the needs of different working environments. It can also be used with a servo motor or a bidirectional motor. The servo motor has position feedback and closed-loop control functions. It can provide feedback according to preset parameters and actual conditions, adjust the reciprocating motion stroke, speed and frequency of the plunger, and achieve precise control during the liquid delivery process to meet the operating requirements under different working conditions.

[0075] In Example 2, the screw 8 and the plunger 7 of the present invention are connected in two configurations. As in Example 1, one end of the screw is fixed to the plunger, and the other end is fixed to the lower working chamber end cover 9. The screw 8 can move both in rotation and in the axial direction.

[0076] As another embodiment of the present invention, one end of the screw 8 may be fixed to the upper working chamber end cover 5, and the other end may be fixed to the lower working chamber end cover 9. The screw 8 can only perform rotational motion to drive the plunger 7 to perform axial motion.

[0077] See also Figure 2The screw-driven rodless reciprocating single-acting submersible electric pump provided in an embodiment of the present invention has its screw 8 movement mode and discharge flow channel 20 modified. The screw 8 passes through the plunger 7 and is connected by a spiral thread. The upper end of the screw 8 is connected to the upper working chamber end cover 5, and the lower end of the screw 8 is connected to the lower chamber end cover 9. The screw 8 only performs rotational motion, and drives the plunger 7 to perform reciprocating motion through rotation. The flow channel design bypasses the rotary bearing 19 connecting the screw 8 and the upper working chamber end cover 5, which can more accurately control the pressure, provide a better throttling effect, and improve the overall working efficiency of the submersible electric pump of the present invention. The other structures are the same as the structure and connection relationship shown in Example 1.

[0078] Working principle.

[0079] The present invention uses a motor to drive a lead screw to achieve axial reciprocating motion of the plunger. The plunger's upward and downward strokes respectively discharge and inhale liquid. As plunger 7 descends, the volume of working chamber B increases, creating a negative pressure. The inlet valve 3 automatically opens under the pressure differential, allowing well fluid to enter working chamber B. As plunger 7 ascends, the liquid in working chamber B is pressurized, opening drain valve 4 and discharging the fluid through oil pipe 1. This has a wide range of applications.

[0080] Example 3, a control method for a screw-driven rodless reciprocating single-acting submersible electric pump, comprising:

[0081] The servo motor provides feedback according to preset parameters and actual conditions through position feedback and improved closed-loop control, adjusts the reciprocating stroke, speed and frequency of the plunger 7, completes the control of the liquid delivery process, and meets the operating requirements under different working conditions.

[0082] like Figure 3 As shown, the servo motor adjusts the reciprocating stroke, speed and frequency of the plunger 7 through position feedback and improved closed-loop control according to preset parameters and actual conditions.

[0083] S1, using an external laser position detector to obtain the current position of the plunger 7 in the working chamber B during liquid inflow and liquid outflow, and sending the current position information to the control unit of the servo motor. The pressure sensing chip in the control unit collects the current servo motor output pressure signal;

[0084] S2, comparing the current position information and the current servo motor output pressure signal with the preset standard position of the plunger 7 in the working chamber B during liquid inlet and liquid discharge, and the servo motor output pressure standard information during liquid discharge, and adjusting the comparison results using an improved closed-loop control method;

[0085] S3, according to the adjustment result, the control unit adjusts the reciprocating stroke, speed and frequency of the plunger 7 by regulating the operating state of the servo motor.

[0086] In step S2, the adjustment by the improved closed-loop control method includes:

[0087] The digital signal is transmitted to the PID controller based on the set PID control rules and PID control algorithm. It is used as the input variable of the PID controller to perform PID inference and the initial inference result is subjected to inverse PID processing. The output result determines the length of the plunger's reciprocating motion, the rate of change of liquid inlet and discharge, and the operating frequency of the servo motor.

[0088] The PID input variables include: the amount of liquid inflow and the negative pressure level of the working chamber. After the PID controller is passed, the output variables are: the length of the plunger's reciprocating motion, the rate of change of liquid inflow and discharge, and the operating frequency of the servo motor. The PID inference rules specifically include:

[0089] (1) Reasoning about the change rate of liquid inlet and discharge: the change rate of liquid inlet and discharge is divided into "low", "normal" and "high";

[0090] The control rules for the change rate of liquid inlet and discharge are as follows: ① If the liquid inlet amount is small, the change rate of liquid inlet and discharge is relatively small; ② If the liquid inlet amount is moderate, the change rate of liquid inlet and discharge is normal; ③ If the liquid inlet amount is large, the change rate of liquid inlet and discharge is long;

[0091] (2) Reasoning about the operating frequency of the servo motor: The operating frequency of the servo motor is divided into "slightly low", "normal" and "high";

[0092] The control rules for the servo motor operating frequency are as follows: ① If the amount of liquid inflow is small, the servo motor operating frequency is slightly lower; ② If the amount of liquid inflow is moderate, the servo motor operating frequency is normal;

[0093] (3) Reasoning of plunger reciprocating motion stroke: The plunger reciprocating motion stroke is divided into “relatively short”, “short”, “moderate”, “long” and “relatively long”; the rules of the five PID modes are as follows: ① If the amount of liquid inflow is small and the negative pressure of the working chamber is low, the plunger reciprocating motion stroke is short; ② If the amount of liquid inflow is small and the negative pressure of the working chamber is moderate, the plunger reciprocating motion stroke is short; ③ If the amount of liquid inflow is small and the negative pressure of the working chamber is high, the plunger reciprocating motion stroke is moderate; ④ If the amount of liquid inflow is moderate and the negative pressure of the working chamber is high, the plunger reciprocating motion stroke is moderate. ⑤ If the liquid inlet is moderate and the negative pressure in the working chamber is moderate, the reciprocating stroke of the plunger will be moderate; ⑥ If the liquid inlet is moderate and the negative pressure in the working chamber is high, the reciprocating stroke of the plunger will be long; ⑦ If the liquid inlet is large and the negative pressure in the working chamber is low, the reciprocating stroke of the plunger will be moderate; ⑧ If the liquid inlet is large and the negative pressure in the working chamber is moderate, the reciprocating stroke of the plunger will be long; ⑨ If the liquid inlet is large and the negative pressure in the working chamber is high, the reciprocating stroke of the plunger will be long;

[0094] The PID inference result is de-PIDed to convert the inference result into an accurate value. The maximum weight method is used. The maximum weight method does not consider the shape of the output weight function, but only considers the output value at the maximum weight. The maximum weight de-PID method selects the element with the largest weight in the PID quantity of the inference result as the output value:

[0095]

[0096] If there is more than one output value corresponding to the maximum weight in the output domain S, then the average of the outputs with the maximum weight is taken:

[0097]

[0098] Where M is the total number of outputs with the same maximum weight.

[0099] The above method can achieve more precise pressure control, provide better throttling effect, and improve the overall working efficiency of the submersible electric pump of the present invention.

[0100] Application examples.

[0101] Application in deep wells and high-temperature wells: The present invention adopts a downhole motor direct-drive screw structure, which avoids the energy loss and structural fatigue problems caused by the excessive weight of the sucker rod in deep wells. Compared with the traditional sucker rod pump in deep wells with reduced energy efficiency and the risk of rod string breakage, the present invention has more stable operation and higher pump efficiency.

[0102] Application in Deviated Wells: Traditional sucker rod systems in deviated or horizontal wells are prone to problems such as rod-tubing eccentric wear and pump sticking, leading to frequent maintenance. This new system eliminates the sucker rod structure and is suitable for highly deviated wells with inclinations greater than 70°, avoiding these problems.

[0103] The above embodiments show that the present invention adopts screw drive technology to improve energy conversion efficiency, reduce energy consumption, and achieve higher liquid delivery efficiency under the same power conditions, making it suitable for energy-intensive environments; the present invention has a compact structure and only has one working chamber B, which reduces the complexity of the liquid flow path and improves the stability and maintenance convenience of the system; the present invention adopts a ball screw pair transmission, combined with rolling bearings and pre-tightening nuts, to improve transmission accuracy, reduce mechanical loss, and extend the service life of the screw; the cylinder body of the present invention adopts integral processing to enhance the sealing and strength of the equipment, reduce leakage problems caused by high-pressure fluids, and is suitable for complex oil and gas transportation environments; the present invention is suitable for the transportation of high-viscosity and high-impurity liquids, and is particularly suitable for high-load operations in submarine oil and gas production and deep-well oil fields, and has wide application value. The present invention provides an efficient, stable, and durable screw-driven rodless reciprocating single-acting submersible electric pump that can meet the needs of the modern energy industry for high-performance submersible electric pumps.

[0104] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0105] The information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the embodiment of the method of the present invention. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0106] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment.

[0107] An embodiment of the present invention also provides a computer device, which includes: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, wherein the processor implements the steps of any of the above-mentioned method embodiments when executing the computer program.

[0108] An embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments can be implemented.

[0109] An embodiment of the present invention also provides an information data processing terminal, which is used to provide user input to implement the steps in the above-mentioned method embodiments when executed on an electronic device. The information data processing terminal is not limited to mobile phones, computers, and switches.

[0110] An embodiment of the present invention further provides a server, which is used to provide a user input interface to implement the steps in the above method embodiments when executed on an electronic device.

[0111] An embodiment of the present invention provides a computer program product. When the computer program product is run on an electronic device, the electronic device can implement the steps of the above-mentioned method embodiments when executing the computer program product.

[0112] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of each of the above-mentioned method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium can at least include: any entity or device that can carry the computer program code to the camera / terminal device, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk.

[0113] The above description is only a preferred specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A screw-driven rodless reciprocating single-acting submersible electric pump, characterized in that: The electric pump comprises: an oil inlet cavity cover plate (2), the oil inlet cavity cover plate (2) being mounted on the top of a cylinder body (6), a through hole being provided on the oil inlet cavity cover plate (2) and being in communication with an oil pipe (1) to form a liquid discharge channel (18); A drain cavity (C) is provided in the middle between the oil inlet cavity cover plate (2) and the upper working cavity end cover (5), and a drain valve (4) is provided inside the drain cavity (C); Liquid inlet cavities (A) are respectively provided on both sides between the oil inlet cavity cover plate (2) and the upper working cavity end cover (5), and a liquid inlet valve (3) is provided in the liquid inlet cavity (A); The upper working chamber end cover (5) is fixedly mounted on the upper end of the cylinder body (6) and supports the liquid inlet valve (3) and the liquid discharge valve (4); A working chamber (B) is formed between the plunger (7) and the upper working chamber end cover (5), and a lower chamber (11) is formed between the plunger (7) and the lower chamber end cover (9); the plunger (7) performs reciprocating motion in the working chamber (B) to complete the suction and discharge of liquid; The lower working chamber end cover (9) is installed at the bottom of the cylinder body (6). A lead screw (8) is fixed on the lower working chamber end cover (9). The lead screw (8) is connected to the plunger (7); the lead screw (8) is connected to the motor (10).

2. The screw-driven rodless reciprocating single-acting submersible electric pump according to claim 1, characterized in that: The plunger (7) is driven to reciprocate in the cylinder (6) by the lead screw (8). By utilizing the one-way opening and closing of the liquid inlet valve (3) and the liquid discharge valve (4), the liquid is sucked in and discharged in sequence during the up and down strokes of the plunger (7), thereby controlling and continuously delivering the liquid in the working chamber (B).

3. The screw-driven rodless reciprocating single-acting submersible electric pump according to claim 1, characterized in that: The motor (10) is installed at the lower part of the cylinder body (6) and drives the lead screw (8) to move up and down, causing the plunger (7) to move back and forth in the axial direction, thereby completing the process of sucking and discharging the liquid.

4. The screw-driven rodless reciprocating single-acting submersible electric pump according to claim 1, characterized in that: The drainage chamber (C) is in communication with the working chamber (B) via the drainage (4) and the drainage channel (18); The cross section of the upper working chamber end cover (5) is an annular flange type with a flow channel (12) and a mounting structure (13), and the cross section of the lower working chamber end cover (9) is a solid disc type; the liquid inlet chamber (A) is connected to the working chamber (B) through the liquid inlet valve (3) and the flow channel (12); the upper working chamber end cover (5) is connected to the cylinder body (6) through the mounting structure (13).

5. The screw-driven rodless reciprocating single-acting submersible electric pump according to claim 1, characterized in that: The opening directions of the liquid inlet valve (3) and the liquid discharge valve (4) are both toward the direction of the oil pipe (1); An oil inlet chamber static sealing device (14) is provided between the oil inlet chamber cover plate (2) and the cylinder body (6), an upper working chamber static sealing device (15) is provided between the upper working chamber end cover (5) and the cylinder body (6); and a dynamic sealing device (16) is provided between the plunger (7) and the lead screw (8).

6. The screw-driven rodless reciprocating single-acting submersible electric pump according to claim 1, characterized in that: A radial rolling bearing (17) is provided in the lower working chamber end cover (9); The radial rolling bearing (17) is a deep groove ball bearing or a cylindrical roller bearing; the motor (10) is a servo motor or a bidirectional motor; the screw (8) realizes the up and down reciprocating motion of the screw (8) by connecting to the servo motor or the bidirectional motor; the servo motor performs feedback according to preset parameters and actual conditions through position feedback and closed-loop control, adjusts the reciprocating motion stroke, speed and frequency of the plunger (7), completes the control during the liquid delivery process, and meets the operation requirements under different working conditions; the screw (8) adopts a ball screw or a threaded screw.

7. The screw-driven rodless reciprocating single-acting submersible electric pump according to claim 1, characterized in that: One end of the lead screw (8) is fixed to the upper working chamber end cover (5) through a rotary bearing (19), and the other end is fixed to the lower working chamber end cover (9). The lead screw (8) performs a rotational motion to drive the plunger (7) to perform an axial motion. The drainage chamber (C) is communicated with the working chamber (B) through the drainage (4) and the drainage channel (20).

8. A control method for a screw-driven rodless reciprocating single-acting submersible electric pump, characterized in that: The method for operating the screw-driven rodless reciprocating single-acting submersible electric pump according to any one of claims 1 to 7 comprises: The servo motor provides feedback according to preset parameters and actual conditions through position feedback and improved closed-loop control, adjusts the reciprocating stroke, speed and frequency of the plunger (7), completes the control during the liquid delivery process, and meets the operation requirements under different working conditions.

9. The control method of the screw-driven rodless reciprocating single-acting submersible electric pump according to claim 8, characterized in that: The servo motor provides feedback according to preset parameters and actual conditions through position feedback and improved closed-loop control to adjust the reciprocating stroke, speed and frequency of the plunger (7) including: S1, obtaining the current position of the plunger (7) in the working chamber (B) during liquid inlet and liquid discharge through an external laser position detector, sending the current position information to a control unit of a servo motor, and a pressure sensing chip in the control unit collecting the current servo motor output pressure signal; S2, comparing the current position information and the current servo motor output pressure signal with the preset standard position of the plunger (7) in the working chamber (B) during liquid inlet and liquid discharge, and the servo motor output pressure standard information during liquid discharge, and adjusting the comparison result through an improved closed-loop control method; S3, according to the adjustment result, the control unit adjusts the reciprocating stroke, speed and frequency of the plunger (7) by regulating the operating state of the servo motor.

10. The control method of the screw-driven rodless reciprocating single-acting submersible electric pump according to claim 9, characterized in that: In step S2, the adjustment by the improved closed-loop control method includes: The digital signal is transmitted to the PID controller based on the set PID control rules and PID control algorithm. It is used as the input variable of the PID controller to perform PID inference and the initial inference result is subjected to inverse PID processing. The output result determines the length of the plunger's reciprocating motion, the rate of change of liquid inlet and discharge, and the operating frequency of the servo motor. The PID input variables include: the amount of liquid inflow and the negative pressure level of the working chamber. After the PID controller is passed, the output variables are: the length of the plunger's reciprocating motion, the rate of change of liquid inflow and discharge, and the operating frequency of the servo motor. The PID inference rules specifically include: (1) Reasoning about the change rate of liquid inlet and discharge: The change rate of liquid inlet and discharge is divided into "low", "normal" and "high"; The control rules for the change rate of liquid inlet and discharge are as follows: ① If the liquid inlet amount is small, the change rate of liquid inlet and discharge is relatively small; ② If the liquid inlet amount is moderate, the change rate of liquid inlet and discharge is normal; ③ If the liquid inlet amount is large, the change rate of liquid inlet and discharge is long; (2) Reasoning about the operating frequency of the servo motor: The operating frequency of the servo motor is divided into "slightly low", "normal" and "higher"; The control rules for the servo motor operating frequency are as follows: ① If the amount of liquid inflow is small, the servo motor operating frequency is slightly lower; ② If the amount of liquid inflow is moderate, the servo motor operating frequency is normal; (3) Reasoning about the reciprocating stroke of the plunger: The reciprocating stroke of the plunger is divided into "relatively short", "short", "moderate", "long" and "slightly long". The rules of the five PID modes are as follows: ① If the amount of liquid inflow is small and the negative pressure of the working chamber is low, the reciprocating stroke of the plunger is short; ② If the amount of liquid inflow is small and the negative pressure of the working chamber is moderate, the reciprocating stroke of the plunger is short; ③ If the amount of liquid inflow is small and the negative pressure of the working chamber is high, the reciprocating stroke of the plunger is moderate; ④ If the amount of liquid inflow is moderate and the negative pressure of the working chamber is high, the reciprocating stroke of the plunger is moderate. ⑤ If the liquid inlet is moderate and the negative pressure in the working chamber is moderate, the reciprocating stroke of the plunger will be moderate; ⑥ If the liquid inlet is moderate and the negative pressure in the working chamber is high, the reciprocating stroke of the plunger will be long; ⑦ If the liquid inlet is large and the negative pressure in the working chamber is low, the reciprocating stroke of the plunger will be moderate; ⑧ If the liquid inlet is large and the negative pressure in the working chamber is moderate, the reciprocating stroke of the plunger will be long; ⑨ If the liquid inlet is large and the negative pressure in the working chamber is high, the reciprocating stroke of the plunger will be long; The PID inference result is de-PIDed to convert the inference result into an accurate value. The maximum weight method is used. The maximum weight method does not consider the shape of the output weight function, but only considers the output value at the maximum weight. The maximum weight de-PID method selects the element with the largest weight in the PID quantity of the inference result as the output value: If there is more than one output value corresponding to the maximum weight in the output domain S, then the average of the outputs with the maximum weight is taken: Where M is the total number of outputs with the same maximum weight.

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