A dual pressure oil chamber rodless oil and gas lifting device and working method

Abstract

The application provides a double-pressure oil chamber rodless oil and gas lifting device and a working method, and belongs to the technical field of oil well production, and comprises an outer cylinder assembly and a plunger assembly; the plunger assembly is arranged in the inner portion of the outer cylinder assembly; the outer cylinder assembly comprises an upper outer cylinder, a first connecting head, a middle outer cylinder and a second connecting head which are sequentially connected from top to bottom; a flow joint, a second fixed valve cover, a second double-end thread and an inner cylinder are sequentially arranged in the middle outer cylinder from top to bottom, and oil channels are formed between the middle outer cylinder and the flow joint, the second fixed valve cover, the second double-end thread and the inner cylinder; a second fixed valve is arranged between the first connecting head and the second double-end thread; the plunger assembly is arranged in the inner cylinder, and a first pressure oil chamber is formed between the plunger assembly and the second fixed valve; a lower portion of the plunger assembly forms a second pressure oil chamber together with the inner cylinder and the second connecting head, and the first pressure oil chamber is communicated with the second pressure oil chamber through the oil channels. The problems of small displacement and large load of the existing oil and gas lifting device are solved.

Description

Technical Field

[0001] This invention belongs to the field of oil well production technology, specifically relating to a rodless oil and gas lifting device with dual-pressure oil chambers and its working method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In the oilfield development sector, while traditional rod-type pumping units are technologically mature and widely used, their inherent limitations are becoming increasingly apparent. These devices have complex structures, high manufacturing and maintenance costs, and are prone to wear and tear on their components, leading to difficult maintenance, long downtimes, and severely impacting production continuity. Furthermore, their operating principle heavily relies on the vertical reciprocating motion of the sucker rod, making them ill-suited to the increasing number of horizontal wells and complex geological conditions.

[0004] To overcome these bottlenecks, existing technologies have developed rodless oil and gas lift technology. This technology places the drive unit directly downhole, driving the downhole pump via hydraulic, pneumatic, or electric means, completely eliminating the sucker rod. This fundamentally solves the problem of rod wear and significantly improves operational reliability and stability in complex well conditions such as horizontal wells. Simultaneously, the rodless lift system offers higher energy transmission efficiency and more precise control, which is beneficial for improving oil production efficiency and aligns with the development direction of intelligent and automated oilfields, facilitating remote monitoring and intelligent control. However, the outer diameter of the downhole drive equipment is limited by the inner diameter of the casing, resulting in limited output driving force. This leads to a smaller displacement and a larger load on the oil and gas lift equipment, resulting in lower oil production efficiency and extremely high requirements for the load-bearing capacity of the equipment. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a rodless oil-gas lifting device with dual-pressure oil chambers and its operating method, which solves the problems of small displacement and large load on existing oil-gas lifting devices.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, the present invention provides a rodless oil-gas lifting device with dual pressure chambers, comprising: an outer cylinder assembly and a plunger assembly; the plunger assembly is disposed inside the outer cylinder assembly;

[0008] The outer cylinder assembly includes, from top to bottom, an upper coupling, an upper outer cylinder, a first connector, a middle outer cylinder, a second connector, a screen pipe, and a lower coupling. Inside the middle outer cylinder, from top to bottom, are arranged an overflow connector, a second fixed valve cover, a second double-ended thread, and an inner cylinder, with gaps forming oil passages between the middle and outer cylinders and the overflow connector, the second fixed valve cover, the second double-ended thread, and the inner cylinder. One end of the overflow connector is connected to the first connector, and the other end is connected to one end of the second fixed valve cover. The other end of the second fixed valve cover is connected to the second double-ended thread. One end of the inner cylinder is connected to the second double-ended thread, and the other end of the inner cylinder is connected to the second connector. The connection is as follows: a first spring, a first slider, and a second fixed valve are sequentially arranged between the overflow connector and the second double-ended thread from top to bottom, and both are arranged inside the second fixed valve cover; the plunger assembly is movably disposed in the inner cylinder, and a first oil pressure chamber is formed between the plunger assembly and the second fixed valve; the lower part of the plunger assembly forms an annular second oil pressure chamber with the inner cylinder and the second connector, respectively, and the first oil pressure chamber is connected to the second oil pressure chamber through the oil passage; oil and gas enter the first and second oil pressure chambers from the bottom of the equipment through the core of the plunger assembly, and the oil and gas are lifted upward along the core of the outer cylinder assembly by the alternating pressure of the first and second oil pressure chambers.

[0009] As a further implementation, the flow connector is provided with a first liquid inlet hole, and the inner cylinder is provided with a second liquid inlet hole at one end near the second connector. The first oil pressure chamber is connected to the oil passage through the first liquid inlet hole, and the second oil pressure chamber is connected to the oil passage through the second liquid inlet hole.

[0010] As a further implementation, the upper outer cylinder is provided with a first fixed valve cover and a first double-ended threaded tube arranged sequentially from top to bottom. The first fixed valve cover is connected to one end of the first double-ended threaded tube, and the other end of the first double-ended threaded tube is connected to the first connector. The first fixed valve cover is provided with a first fixed valve, which abuts against the top end of the first double-ended threaded tube under the action of gravity.

[0011] As a further implementation, the plunger assembly includes, from top to bottom, a traveling valve cover, a third double-ended thread, a large plunger, a plunger connector, and a small plunger. Inside the traveling valve cover, from top to bottom, are arranged a second spring, a second slider, and a traveling valve. One end of the second spring abuts against the traveling valve cover, and the other end abuts against the second slider. The second slider presses the traveling valve against the top of the third double-ended thread.

[0012] As a further implementation, both the first spring and the second spring have a preload.

[0013] As a further implementation, the upper coupling, upper outer cylinder, first connector, middle outer cylinder, second connector, screen tube, lower coupling, overflow connector, second double-threaded joint, inner cylinder, third double-threaded joint, large plunger, plunger connector and small plunger are all hollow tubular structures.

[0014] As a further implementation, a pump cylinder is provided in the screen tube, and the top end of the pump cylinder is connected to the bottom end of the second connector.

[0015] As a further implementation, the large plunger and the inner cylinder are in clearance fit; the small plunger and the pump cylinder are in clearance fit, so that the large plunger can reciprocate within the inner cylinder and the small plunger can reciprocate within the pump cylinder.

[0016] As a further implementation, a fourth liquid inlet hole is provided on the bottom side of the small plunger, which is used to introduce the oil and gas passing through the screen tube into the core of the plunger assembly.

[0017] Secondly, the present invention also provides a method for operating a rodless oil-gas lifting device with dual-pressure oil chambers, comprising the following steps:

[0018] Step 1: Connect and fix the lower end of the lower coupling to the upper end of the drive equipment housing, connect and fix the lower end of the small plunger to the upper end of the drive equipment mover, and lower the upper end of the upper coupling to the lower end of the oil pipe into the oil well.

[0019] Step 2: As the plunger assembly moves upward, the traveling valve seals the channel of the core of the third double-threaded cylinder. The volume of the first pressure chamber decreases, and the pressure increases. At the same time, the volume of the second pressure chamber increases. When the pressure in the first pressure chamber is greater than the pressure of the hydraulic column in the oil pipe above the first fixed valve, the first fixed valve opens, and the second fixed valve opens against the preload of the first spring. When the liquid in the first pressure chamber passes through the second fixed valve and the flow connector, part of the liquid is discharged to the ground through the first fixed valve and the oil pipe, completing the upward stroke drainage process. The other part of the liquid enters the second pressure chamber through the first inlet hole, the annular flow channel between the inner cylinder and the middle and outer cylinders, and the second inlet hole.

[0020] Step 3: As the plunger assembly descends, the second fixed valve seat closes, the volume of the first pressure chamber increases, and the pressure decreases. When the casing submersion pressure exceeds the pressure within the first pressure chamber, the traveling valve overcomes the spring force of the second spring and opens. Liquid in the casing sequentially enters the first pressure chamber through the third and fourth inlet holes of the screen tube, the inner hole of the small plunger, the inner hole of the large plunger, and the traveling valve, completing the liquid suction process. Simultaneously, the volume of the second pressure chamber decreases, and the pressure increases. When the pressure within the second pressure chamber exceeds the pressure of the liquid column in the oil pipe above the first fixed valve, the first fixed valve opens, and liquid in the second pressure chamber enters the oil pipe through the first fixed valve and is discharged to the ground, completing the downstroke drainage process.

[0021] Compared with the prior art, the advantages and positive effects of this invention are:

[0022] In this invention, the outer and inner cylinders have gaps forming oil passages with the flow connector, the second fixed valve cover, the second double-threaded joint, and the inner cylinder, respectively. A plunger assembly is movably disposed within the inner cylinder, forming a first pressure chamber between the plunger assembly and the second fixed valve. The lower part of the plunger assembly forms an annular second pressure chamber with the inner cylinder and the second connector, respectively. The first pressure chamber communicates with the second pressure chamber through an oil passage. Oil and gas enter the first and second pressure chambers from the bottom of the device via the core of the plunger assembly. The alternating pressure between the first and second pressure chambers lifts the oil and gas upwards along the core of the outer cylinder assembly. Liquid in the first pressure chamber passes through the second fixed valve and the flow connector, forming two channels. A portion of the liquid passes through the first fixed valve and is discharged to the ground via an oil pipe, completing the upward stroke discharge process. The other portion of the liquid passes sequentially through the flow connector and the annular flow channel between the inner and outer cylinders, entering the second pressure chamber. This allows the oil and gas lifting device to have a larger displacement under the same load and a smaller load under the same displacement. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 This is a structural diagram of the rodless oil-gas lifting device with dual-pressure oil chambers according to the present invention.

[0025] In the diagram: 1. Upper coupling; 2. Upper outer cylinder; 3. First fixed valve cover; 4. First fixed valve; 5. First double-threaded pipe; 6. First connector; 7. Overflow connector; 71. First inlet hole; 8. Second fixed valve cover; 9. First spring; 10. First slider; 11. Second fixed valve; 12. Second double-threaded pipe; 13. Inner cylinder; 131. Second inlet hole; 14. Middle and outer cylinder; 15. Second connector; 16. Pump cylinder; 17. Screen pipe; 171. Third inlet hole; 18. Lower coupling; 19. Floating valve cover; 20. Second spring; 21. Second slider; 22. Floating valve; 23. Third double-threaded pipe; 24. Large plunger; 25. Plunger connector; 26. Small plunger; 261. Fourth inlet hole; 27. First pressure chamber; 28. Second pressure chamber. Detailed Implementation

[0026] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] Example 1

[0029] This embodiment provides a rodless oil-gas lifting device with dual-pressure oil chambers, such as... Figure 1 As shown, it includes: an outer cylinder assembly and a plunger assembly; the plunger assembly is disposed inside the outer cylinder assembly;

[0030] The outer cylinder assembly includes, from top to bottom, an upper coupling 1, an upper outer cylinder 2, a first connector 6, a middle outer cylinder 14, a second connector 15, a screen pipe 17, and a lower coupling 18. Inside the middle outer cylinder 14, from top to bottom, are arranged an overflow connector 7, a second fixed valve cover 8, a second double-ended thread 12, and an inner cylinder 13, with gaps forming oil passages between the middle outer cylinder 14 and the overflow connector 7, the second fixed valve cover 8, the second double-ended thread 12, and the inner cylinder 13. One end of the overflow connector 7 is connected to the first connector 6, and the other end is connected to one end of the second fixed valve cover 8. The other end of the second fixed valve cover 8 is connected to the second double-ended thread 12. One end of the inner cylinder 13 is connected to the second double-ended thread 12, and the other end of the inner cylinder 13 is connected to the second connector 6. 15 Connection; A first spring 9, a first slider 10, and a second fixed valve 11 are sequentially abutted between the overflow connector 7 and the second double-ended thread 12 from top to bottom, and are all arranged inside the second fixed valve cover 8; The plunger assembly is movably disposed in the inner cylinder 13, and a first oil pressure chamber 27 is formed between the plunger assembly and the second fixed valve 11; The lower part of the plunger assembly forms an annular second oil pressure chamber 28 with the inner cylinder 13 and the second connector 15 respectively, and the first oil pressure chamber 27 is connected to the second oil pressure chamber 28 through an oil passage; Oil and gas enter the first oil pressure chamber 27 and the second oil pressure chamber 28 from the bottom of the equipment through the core of the plunger assembly, and the oil and gas are lifted upward along the core of the outer cylinder assembly by the alternating oil pressure of the first oil pressure chamber 27 and the second oil pressure chamber 28. When the liquid in the first pressure oil chamber 27 passes through the second fixed valve 11 and the flow connector 7, it forms two channels. Part of the liquid is discharged to the ground through the first fixed valve 4 and the oil pipe, completing the upward stroke liquid discharge process. The other part of the liquid passes through the flow connector 7 and the annular flow channel between the inner cylinder 13 and the middle and outer cylinders 14 in sequence, and enters the second pressure oil chamber 28. This enables the oil and gas lifting equipment to have a larger displacement under the same load and a smaller load under the same displacement.

[0031] As a further implementation, the overflow connector 7 is provided with a first liquid inlet hole 71, and the inner cylinder 13 is provided with a second liquid inlet hole 131 at the end near the second connector 15. The first oil pressure chamber 27 is connected to the oil passage through the first liquid inlet hole 71, and the second oil pressure chamber 28 is connected to the oil passage through the second liquid inlet hole 131. This allows part of the oil and gas in the first oil pressure chamber 27 to enter the second oil pressure chamber 28, and part to enter the oil pipe and be discharged to the ground. This allows the first oil pressure chamber 27 and the second oil pressure chamber 28 to alternately press oil, thereby reducing the load on the equipment.

[0032] As a further implementation, a first fixed valve cover 3 and a first double-ended threaded pipe 5 are arranged sequentially from top to bottom in the upper outer cylinder 2. The first fixed valve cover 3 is connected to one end of the first double-ended threaded pipe 5, and the other end of the first double-ended threaded pipe 5 is connected to the first connector 6. The first fixed valve cover 3 is provided with a through hole, and a first fixed valve 4 is provided in the first fixed valve cover 3. Under the action of gravity, the first fixed valve 4 abuts against the top end of the first double-ended threaded pipe 5 to prevent the oil and gas in the oil pipe that lifts the oil and gas upward from flowing back to the ground.

[0033] As a further implementation, the plunger assembly includes, from top to bottom, a traveling valve cover 19, a third double-ended thread 23, a large plunger 24, a plunger connector 25, and a small plunger 26. Inside the traveling valve cover 19, from top to bottom, are arranged a second spring 20, a second slider 21, and a traveling valve 22. One end of the second spring 20 abuts against the traveling valve cover 19, and the other end abuts against the second slider 21. The second slider 21 presses the traveling valve 22 against the top of the third double-ended thread 23.

[0034] As a further implementation, both the first spring 9 and the second spring 20 have preload, so that the second fixed valve 11 and the floating valve 22 are in a closed state.

[0035] As a further implementation, the upper coupling 1, upper outer cylinder 2, first connector 6, middle outer cylinder 14, second connector 15, screen tube 17, lower coupling 18, flow connector 7, second double-ended thread 12, inner cylinder 13, third double-ended thread 23, large plunger 24, plunger connector 25 and small plunger 26 are all hollow tubular structures, and the connection between each component is a threaded connection.

[0036] As a further implementation, a pump cylinder 16 is provided in the screen tube 17, and the top end of the pump cylinder 16 is connected to the bottom end of the second connector 15.

[0037] As a further implementation, the large plunger 24 and the inner cylinder 13 are clearance-fitted; the small plunger 26 and the pump cylinder 16 are clearance-fitted, allowing the large plunger 24 to reciprocate within the inner cylinder 13 and the small plunger 26 to reciprocate within the pump cylinder 16. The lower end of the lower coupling 18 has a pre-threaded connection, which, during well running, connects and fixes to the upper end of the outer cylinder 14 of the drive equipment, including a submersible hydraulic cylinder, a submersible pneumatic cylinder, or a submersible reciprocating motor, driving the small plunger 26 to reciprocate.

[0038] As a further implementation, a fourth liquid inlet hole 261 is provided on the bottom side of the small plunger 26 for introducing oil and gas passing through the screen tube 17 into the core of the plunger assembly.

[0039] Example 2

[0040] This embodiment provides a working method for a rodless oil-gas lifting device with dual-pressure oil chambers, including the following steps:

[0041] Step 1: The lower end of the lower coupling 18 is connected and fixed to the upper end of the housing of the drive equipment, including the submersible hydraulic cylinder, the submersible air cylinder, or the submersible reciprocating motor. The lower end of the small plunger 26 is connected and fixed to the upper end of the mover of the drive equipment, including the piston of the submersible hydraulic cylinder, the piston of the submersible air cylinder, or the submersible reciprocating motor. The upper end of the upper coupling 1 is connected to the lower end of the oil pipe and lowered into the oil well.

[0042] Step 2: As the plunger assembly moves upward, the traveling valve 22 seals the channel at the core of the third double-threaded 23, causing the volume of the first pressure chamber 27 to decrease and the pressure to increase. At the same time, the volume of the second pressure chamber 28 increases. When the pressure in the first pressure chamber 27 is greater than the pressure of the oil column above the first fixed valve 4, the first fixed valve 4 opens and the second fixed valve 11 opens against the preload of the first spring 9. When the liquid in the first pressure chamber 27 passes through the second fixed valve 11 and the flow connector 7, a portion of the liquid is discharged to the ground through the oil pipe via the first fixed valve 4, completing the upward stroke discharge process. The other portion of the liquid passes sequentially through the first inlet hole 71, the annular flow channel between the inner cylinder 13 and the middle and outer cylinders 14, and the second inlet hole 131, entering the second pressure chamber 28. At this time, the load on the upward stroke plunger pump is the load borne by the cross section of the small plunger 26, and the displacement is the displacement of the small pump.

[0043] Step 3: The plunger assembly descends, the second fixed valve 11 sets, the volume of the first pressure chamber 27 increases, and the pressure decreases. When the casing submersion pressure is greater than the pressure inside the first pressure chamber 27, the traveling valve 22 opens against the elastic force of the second spring 20. The liquid in the casing enters the first pressure chamber 27 sequentially through the third inlet hole 171, the fourth inlet hole 261, the inner hole of the small plunger 26, the inner hole of the large plunger 24, and the traveling valve 22, completing the liquid suction process. At the same time, the volume of the second pressure chamber 28 decreases, and the pressure increases. When the pressure inside the second pressure chamber 28 is greater than the pressure of the oil column above the first fixed valve 4, the first fixed valve 4 opens, and the liquid in the second pressure chamber 28 enters the oil pipe through the first fixed valve 4 and is discharged to the ground, completing the downstroke discharge process. At this time, the load of the downstroke plunger pump is the load borne by the cross section of the large plunger 24 minus the cross section of the plunger 26, and the displacement is the displacement of the large pump minus the pump.

[0044] When a complete stroke is completed, the actual displacement is the displacement of the large pump, which is divided into two parts: the upper stroke is the displacement of the small pump, and the lower stroke is the displacement of the large pump minus the small pump. The total load is the load of the large pump, which is also divided into two parts: the upper stroke bears the load of the small pump, and the lower stroke bears the load of the large pump minus the load of the small pump. In reality, the load borne by each stroke is smaller than the load of the large pump.

[0045] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A rodless oil-gas lifting device with dual-pressure oil chambers, characterized in that, include: An outer cylinder assembly and a plunger assembly; the plunger assembly is disposed inside the outer cylinder assembly; The outer cylinder assembly includes, from top to bottom, an upper coupling, an upper outer cylinder, a first connector, a middle outer cylinder, a second connector, a screen pipe, and a lower coupling. Inside the middle outer cylinder, from top to bottom, are arranged an overflow connector, a second fixed valve cover, a second double-ended thread, and an inner cylinder, with gaps forming oil passages between the middle and outer cylinders and the overflow connector, the second fixed valve cover, the second double-ended thread, and the inner cylinder. One end of the overflow connector is connected to the first connector, and the other end is connected to one end of the second fixed valve cover. The other end of the second fixed valve cover is connected to the second double-ended thread. One end of the inner cylinder is connected to the second double-ended thread, and the other end of the inner cylinder is connected to the second connector. The connection is as follows: A first spring, a first slider, and a second fixed valve are sequentially arranged between the overflow connector and the second double-ended thread, from top to bottom, and are all arranged within the second fixed valve cover; the plunger assembly is movably disposed within the inner cylinder, and a first oil pressure chamber is formed between the plunger assembly and the second fixed valve; the lower part of the plunger assembly forms an annular second oil pressure chamber with the inner cylinder and the second connector, respectively, and the first oil pressure chamber communicates with the second oil pressure chamber through the oil passage; oil and gas enter the first and second oil pressure chambers from the bottom of the equipment through the core of the plunger assembly, and are alternately pressurized by the first and second oil pressure chambers, thereby lifting the oil and gas upward along the core of the outer cylinder assembly; The plunger assembly includes, from top to bottom, a traveling valve cover, a third double-ended thread, a large plunger, a plunger connector, and a small plunger. Inside the traveling valve cover, from top to bottom, are arranged a second spring, a second slider, and a traveling valve. One end of the second spring abuts against the traveling valve cover, and the other end abuts against the second slider. The second slider presses the traveling valve against the top of the third double-ended thread. The overflow connector is provided with a first liquid inlet hole, and the inner cylinder is provided with a second liquid inlet hole at one end near the second connector. The first oil pressure chamber is connected to the oil passage through the first liquid inlet hole, and the second oil pressure chamber is connected to the oil passage through the second liquid inlet hole. The bottom side of the small plunger is provided with a fourth liquid inlet hole, which is used to introduce the oil and gas passing through the screen tube into the core of the plunger assembly.

2. The rodless oil-gas lifting device with dual-pressure oil chambers as described in claim 1, characterized in that, The upper outer cylinder is provided with a first fixed valve cover and a first double-ended threaded tube arranged sequentially from top to bottom. The first fixed valve cover is connected to one end of the first double-ended threaded tube, and the other end of the first double-ended threaded tube is connected to the first connector. The first fixed valve cover is provided with a first fixed valve, which abuts against the top end of the first double-ended threaded tube under the action of gravity.

3. The rodless oil-gas lifting device with dual-pressure oil chambers as described in claim 1, characterized in that, Both the first spring and the second spring have preload.

4. The rodless oil-gas lifting device with dual-pressure oil chambers as described in claim 1, characterized in that, The upper coupling, upper outer cylinder, first connector, middle outer cylinder, second connector, screen tube, lower coupling, overflow connector, second double-threaded joint, inner cylinder, third double-threaded joint, large plunger, plunger connector and small plunger are all hollow tubular structures.

5. The rodless oil-gas lifting device with dual-pressure oil chambers as described in claim 4, characterized in that, A pump cylinder is installed in the screen tube, and the top end of the pump cylinder is connected to the bottom end of the second connector.

6. The rodless oil-gas lifting device with dual-pressure oil chambers as described in claim 5, characterized in that, The large plunger is clearance-fitted with the inner cylinder; the small plunger is clearance-fitted with the pump barrel; this allows the large plunger to reciprocate within the inner cylinder and the small plunger to reciprocate within the pump barrel.

7. The working method of a rodless oil-gas lifting device with dual-pressure oil chambers as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Connect and fix the lower end of the lower coupling to the upper end of the drive equipment housing, connect and fix the lower end of the small plunger to the upper end of the drive equipment mover, and lower the upper end of the upper coupling to the lower end of the oil pipe into the oil well. Step 2: As the plunger assembly moves upward, the traveling valve seals the channel of the core of the third double-threaded cylinder, reducing the volume of the first pressure chamber and increasing the pressure. Simultaneously, the volume of the second pressure chamber increases. When the pressure in the first pressure chamber exceeds the pressure of the hydraulic column in the oil pipe above the first fixed valve, the first fixed valve opens, and the second fixed valve opens against the preload of the first spring. When the liquid in the first pressure chamber passes through the second fixed valve and the flow connector, a portion of the liquid is discharged to the ground through the oil pipe via the first fixed valve, completing the upward stroke drainage process. The other portion of the liquid sequentially passes through the first inlet hole, the annular flow channel between the inner cylinder and the middle and outer cylinders, and the second inlet hole, entering the second pressure chamber. Step 3: As the plunger assembly descends, the second fixed valve seat closes, the volume of the first pressure chamber increases, and the pressure decreases. When the casing submersion pressure exceeds the pressure within the first pressure chamber, the traveling valve overcomes the second spring force and opens. Liquid in the casing sequentially enters the first pressure chamber through the third and fourth inlet holes of the screen tube, the inner hole of the small plunger, the inner hole of the large plunger, and the traveling valve, completing the liquid suction process. Simultaneously, the volume of the second pressure chamber decreases, and the pressure increases. When the pressure within the second pressure chamber exceeds the pressure of the liquid column in the oil pipe above the first fixed valve, the first fixed valve opens, and liquid in the second pressure chamber enters the oil pipe through the first fixed valve and is discharged to the ground, completing the downstroke drainage process.

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