Electric submersible diaphragm pump suitable for low-liquid-yield well

Abstract

According to the electric submersible diaphragm pump suitable for the low-liquid-yield well, a bevel gear assembly, a crank assembly and a crosshead assembly of a transmission system are sequentially connected from bottom to top, a diaphragm assembly, a crosshead and a diaphragm are fixedly installed at the upper end of the crosshead assembly, and an inner cavity of a pump cylinder is divided into a transmission cavity, a diaphragm lower cavity and a diaphragm upper cavity from bottom to top; the liquid suction valve and the liquid discharge valve are communicated with the diaphragm upper cavity; the eccentric shaft fixedly connected with the driven bevel gear, the crank, the crosshead and the diaphragm are sequentially connected from bottom to top, and in the process that the crosshead drives the diaphragm to blast up and down to change the volume of the upper cavity of the diaphragm, the liquid suction valve and the liquid discharge valve suck well liquid and discharge the well liquid out of the upper cavity of the diaphragm. The diaphragm pump has the beneficial effects that the structural design is reasonable, the diaphragm is continuously driven to do work through a transmission connection mode of the bevel gear, the crank and the crosshead, the energy consumption is low, and the efficiency is high; the circulating lubricating oil can reduce the oil temperature, the service life of the electric submersible pump is effectively prolonged, the exploitation requirement of a low-liquid-yield well is met, and the oil development operation cost is reduced.

Description

Technical Field

[0001] The invention relates to a submersible electric pump, in particular to an electric submersible diaphragm pump suitable for low-liquid-production wells, belonging to the technical field of oil and gas development. Background Art

[0002] With the increase in the number of low-permeability, low-abundance, and low-productivity oil wells in the process of oil and gas extraction, the phenomenon of declining production of old oil wells is becoming more and more common. Most of them use small-displacement centrifugal submersible electric pumps, screw pumps, or small-displacement walking beam pumping units for extraction operations. Centrifugal submersible electric pumps are mainly suitable for production of 30m 3 / d or more, its working characteristics are not suitable for low-yield wells (especially 10m 3 / d or less), although the frequency conversion technology can meet the production requirements of small-displacement wells, the operation efficiency is low and the energy consumption is high; the operation of the beam pumping unit has high energy consumption, low efficiency, short life, and is not suitable for high-angle wells and horizontal wells, and cannot meet the production needs of low-liquid production wells. Summary of the invention

[0003] In order to overcome the shortcomings of existing centrifugal submersible electric pumps and beam pumping units in the exploitation of low liquid production wells, such as high energy consumption, low efficiency, short life, and unsuitability for the production requirements of highly deviated wells and horizontal wells, the present invention provides an electric submersible diaphragm pump suitable for low liquid production wells.

[0004] The technical solution adopted by the present invention to solve its technical problems is: an electric submersible diaphragm pump suitable for low liquid production wells, including a pump barrel, a submersible motor, a suction valve, and a discharge valve. The suction valve is connected to the well barrel, and the discharge valve is connected to the oil pipe. The bevel gear assembly, crank assembly, and crosshead assembly of the transmission system are connected in sequence from bottom to top. The diaphragm assembly is fixedly installed on the upper end of the crosshead assembly. The crosshead and the diaphragm divide the inner cavity of the pump barrel into a transmission cavity, a diaphragm lower cavity, and a diaphragm upper cavity from bottom to top. The suction valve and the discharge valve are connected to the diaphragm upper cavity.

[0005] The driving bevel gear and the driven bevel gear transmission pair of the bevel gear assembly convert the power of the submersible motor into the rotation of the driven bevel gear arranged along the radial direction of the pump barrel; the eccentric shaft, crank, crosshead and diaphragm fixedly connected to the driven bevel gear are connected in sequence from bottom to top, and when the crosshead drives the diaphragm to move up and down to change the volume of the upper cavity of the diaphragm, the suction valve and the discharge valve suck and discharge the well fluid into and out of the upper cavity of the diaphragm.

[0006] The lower pump barrel, the middle pump barrel and the upper pump barrel of the pump barrel are fixedly connected in sequence from bottom to top; and the transmission system is located in the lower pump barrel.

[0007] The driven bevel gear, eccentric shaft and centering shaft arranged radially along the lower pump barrel in the bevel gear assembly are connected in sequence, and centering bearings are installed at the ends of the driven bevel gear and the centering shaft. The two centering bearings are respectively arranged in the end covers, and the two end covers are fixedly arranged on both sides of the lower pump barrel.

[0008] The lower end of the crank of the crank assembly is connected to the eccentric shaft diameter of the eccentric shaft.

[0009] The upper end of the crank is connected to the lower end of the crosshead of the crosshead assembly, and the crank and the crosshead are connected through a radially installed pin shaft.

[0010] The upper end of the crosshead is connected to the connecting shaft, and the diaphragm assembly is fixedly mounted on the upper end of the connecting shaft.

[0011] The outer edge of the diaphragm is arranged in an annular groove formed by the fixed connection between the middle pump barrel and the upper pump barrel.

[0012] A linear bearing is arranged between the outer circle of the crosshead and the lower pump barrel.

[0013] The lower chamber of the diaphragm is communicated with the oil inlet channel of the lubricating oil, and the transmission chamber is communicated with the oil outlet channel of the lubricating oil; an oil inlet check valve is arranged in the oil inlet channel, and an oil outlet check valve is arranged in the oil outlet channel.

[0014] The oil inlet channel and the oil outlet channel are both arranged along the axial direction of the lower pump barrel, and the oil inlet check valve and the oil outlet check valve are arranged at the lower end of the lower pump barrel.

[0015] In the process of the diaphragm moving up and down to change the volume of the lower cavity of the diaphragm, the lubricating oil enters the lower cavity of the diaphragm through the oil inlet channel, then passes through the linear bearing downward into the transmission cavity, and is discharged through the oil outlet channel.

[0016] When the diaphragm is agitated downward, the pressure in the upper cavity of the diaphragm decreases, and the well fluid enters the upper cavity of the diaphragm through the suction valve; when the diaphragm is agitated upward, the pressure in the upper cavity of the diaphragm increases, and the well fluid in the upper cavity of the diaphragm is discharged from the upper cavity of the diaphragm through the discharge valve and output through the oil pipe.

[0017] Furthermore, a pin bearing is arranged in the crank pin hole, and the pin is arranged in the pin bearing.

[0018] Furthermore, a crank bearing is installed in the eccentric shaft diameter matching hole between the crank and the eccentric shaft.

[0019] The beneficial effects of the present invention are that the structural design is reasonable, and the diaphragm is continuously driven to do work through the transmission connection mode of the bevel gear, crank, and crosshead, with low energy consumption and high efficiency; the circulating lubricating oil can reduce the oil temperature, effectively increase the service life of the submersible electric pump, meet the requirements for the exploitation of low-liquid-production wells, and reduce the cost of oil development operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The diagram is a schematic diagram of the structure of an electric submersible diaphragm pump suitable for low-liquid-production wells according to the present invention.

[0021] Figure 2 yes Figure 1 AA view of the .

[0022] Figure 3 It is a schematic diagram of the structure of the oil inlet channel in the lubrication system of the present invention.

[0023] Figure 4 It is a schematic diagram of the structure of the oil outlet channel in the lubrication system of the present invention.

[0024] Figure 5 yes Figure 1 Bottom view of .

[0025] In the figure: 1. Pump barrel, 2. End cover, 3. Cable channel, 4. Lower pump barrel, 5. Transmission chamber, 6. Straightening shaft, 7. Pin shaft, 8. Crosshead, 9. Linear bearing, 10. Circlip, 11. Intermediate pump barrel, 12. Upper pump barrel, 13. Lock nut, 14. Connecting shaft, 15. Upper pressure plate, 16. Diaphragm, 17. Lower pressure plate, 18. Bevel gear assembly, 19. Diaphragm assembly, 20. Circlip, 21. Ten Prefix assembly, 22. Crank assembly, 23. Pin bearing, 24. Crank, 25. Crank bearing, 26. Diaphragm lower chamber, 27. Diaphragm upper chamber, 28. Eccentric shaft, 29. Straightening bearing, 30. Driven bevel gear, 31. Pumping system, 32. Active bevel gear, 33. Discharge valve, 34. Suction valve, 45. Oil outlet check valve, 46. Oil inlet check valve, 47. Oil outlet channel, 48. Oil inlet channel. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. However, those skilled in the art should be aware that the present invention is not limited to the specific embodiments listed, and all embodiments should be included in the protection scope of the present invention as long as they conform to the spirit of the present invention.

[0027] In the description of the present invention, it should be noted that the terms "vertical", "up", "down", "left", "right", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing or simplifying the description of the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0028] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connection", and "seal" should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection, a direct connection, an indirect connection, or an integral connection; it can be a mechanical connection, an indirect connection through an intermediate medium, or a communication between the two components. The seal can be an oil seal, a packing seal, or other forms of seals. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] See attached Figure 1 , 2 The present invention discloses an electric submersible diaphragm pump suitable for low-liquid-production wells, comprising a pump barrel 1, a submersible motor, a discharge valve 33, and a suction valve 34. The suction valve 34 is connected to the wellbore, the discharge valve 33 is connected to the oil pipe, and a cable channel 3 is axially arranged on the body of the pump barrel 1.

[0030] The electric submersible diaphragm pump suitable for low-liquid production wells comprises a transmission system for transmitting power, a lubrication system for lubricating the transmission system, and a pumping system 31 for transporting wellbore liquid to the surface.

[0031] The transmission system includes a bevel gear assembly 18, a crank assembly 22, and a crosshead assembly 21, which are connected in sequence from bottom to top. A diaphragm assembly 19 is fixedly mounted on the upper end of the crosshead assembly 21. The crosshead 8 and the diaphragm 16 divide the inner cavity of the pump barrel 1 from bottom to top into a transmission cavity 5, a diaphragm lower cavity 26, and a diaphragm upper cavity 27. The suction valve 34 and the discharge valve 33 are connected to the diaphragm upper cavity 27.

[0032] The driving bevel gear 32 and the driven bevel gear 30 transmission pair of the bevel gear assembly 18 convert the power of the submersible motor into the rotation of the driven bevel gear 30 arranged radially along the pump barrel 1; the eccentric shaft 28, the crank 24, the crosshead 8, and the diaphragm 16 fixedly connected to the driven bevel gear 30 are connected in sequence from bottom to top. When the crosshead 8 drives the diaphragm 16 to move up and down to change the volume of the upper cavity 27 of the diaphragm, the suction valve 34 and the discharge valve 33 suck and discharge the well fluid from the upper cavity 27 of the diaphragm.

[0033] The pump barrel 1 includes a lower pump barrel 4, an intermediate pump barrel 11, and an upper pump barrel 12, which are fixedly connected in sequence from bottom to top. Preferably, the lower pump barrel 4, the intermediate pump barrel 11, and the upper pump barrel 12 are fixedly connected by bolts, and a sealing device is provided between the end faces of the lower pump barrel 4 and the intermediate pump barrel 11, and between the end faces of the intermediate pump barrel 11 and the upper pump barrel 12.

[0034] The bevel gear assembly 18 of the transmission system is located in the transmission cavity 5 of the lower pump barrel 4. The bevel gear assembly 18 includes an active bevel gear 32, a driven bevel gear 30, an eccentric shaft 28, a straightening shaft 6, etc.

[0035] The active bevel gear 32 is vertically arranged, and the lower end of the active bevel gear 32 extends from the lower end of the lower pump barrel 4 and is connected to the submersible motor shaft (not shown in the figure). The submersible motor drives the active bevel gear 32 to rotate.

[0036] The driven bevel gear 30 is arranged along the radial direction of the lower pump barrel 4. The driven bevel gear 30, the eccentric shaft 28, and the centering shaft 6 are connected in sequence and rotate synchronously. The eccentric shaft diameter of the eccentric shaft 28 is located at the axial position of the lower pump barrel 4. Centering bearings 29 are installed at the ends of the driven bevel gear 30 and the centering shaft 6. Two centering bearings 29 are respectively arranged in the end covers 2. The two end covers 2 are fixedly arranged on both sides of the lower pump barrel 4. Preferably, the end covers 2 are fixedly connected to the lower pump barrel 4 by screws, and a sealing ring is arranged between the end covers 2 and the lower pump barrel 4.

[0037] Furthermore, the centering bearing 29 is a ball bearing, the inner ring of the centering bearing 29 is mounted on the shaft diameter of the driven bevel gear 30 and the centering shaft 6 , and the outer ring of the centering bearing 29 is arranged in the bearing mounting hole of the end cover 2 .

[0038] The crank assembly 22 includes a crank 24, a crank bearing 25, a pin bearing 23, etc. The radial through hole at the lower end of the crank 24 is connected to the eccentric shaft diameter of the eccentric shaft 28, and the crank bearing 25 is installed in the matching hole of the eccentric shaft diameter of the crank 24 and the eccentric shaft 28, which effectively prevents wear between the crank 24 and the eccentric shaft 28.

[0039] The upper end of the crank 24 is connected to the lower end of the crosshead 8 of the crosshead assembly 21, and the crank 24 and the crosshead 8 are connected through a radially installed pin 7. Preferably, a pin bearing 23 is provided in the pin hole of the crank 24, and the pin 7 is arranged in the pin bearing 23 to ensure that the crank and the crosshead are reliably connected during operation of the submersible electric pump and can rotate freely within a limited angle.

[0040] The crosshead assembly 21 includes a crosshead 8, a connecting shaft 14, and a linear bearing 9. The upper end of the crosshead 8 is connected to the connecting shaft 14, and a linear bearing 9 is provided between the outer circle of the crosshead 8 and the lower pump barrel 4. Preferably, the upper end of the linear bearing 9 is axially fixed by a retaining ring 10 and a retaining spring 20.

[0041] The diaphragm assembly 19 includes a diaphragm 16, an upper pressing plate 15, a lower pressing plate 17, and a locking nut 13, and the diaphragm assembly 19 is fixedly mounted on the upper end of the connecting shaft 14. Specifically, the lower pressing plate 17, the diaphragm 16, and the upper pressing plate 15 are sequentially mounted on the upper end of the connecting shaft 14 from bottom to top, and the diaphragm 16 is axially fixed by threading the locking nut 13 with the connecting shaft 14. The outer edge of the diaphragm 16 is disposed in an annular groove formed by the fixed connection between the middle pump barrel 11 and the upper pump barrel 12.

[0042] See attached Figure 3 , 4 The lubrication system includes an oil inlet channel 48 , an oil outlet channel 47 , an oil inlet check valve 46 , and an oil outlet check valve 45 . The oil inlet channel 48 and the oil outlet channel 47 are arranged on the body of the lower pump barrel 4 .

[0043] The oil inlet passage 48 is in communication with the diaphragm lower chamber 26 , and the oil outlet passage 47 is in communication with the transmission chamber 5 ; an oil inlet check valve 46 is provided in the oil inlet passage 48 , and an oil outlet check valve 45 is provided in the oil outlet passage 47 .

[0044] Preferably, the oil inlet channel 48 and the oil outlet channel 47 are both arranged along the axial direction of the lower pump barrel 4, and the oil inlet check valve 46 and the oil outlet check valve 45 are arranged at the lower end of the lower pump barrel 4 (such as the attached Figure 5 shown).

[0045] As the crosshead 8 reciprocates up and down, in the process of the diaphragm 16 agitating up and down to change the volume of the diaphragm lower chamber 26, the lubricating oil enters the diaphragm lower chamber 26 through the oil inlet check valve 46 and the oil inlet channel 48. Under the action of pressure, the lubricating oil in the diaphragm lower chamber 26 passes through the linear bearing 9 and enters the transmission chamber 5 downward, and then is discharged through the oil outlet channel 47 and the oil outlet check valve 45, thereby realizing the lubricating oil circulation. The heat generated by the transmission system during operation is brought out of the pump barrel through the lubricating oil circulation, which effectively reduces the operating temperature of the submersible electric pump and extends the service life of the submersible electric pump.

[0046] The pumping system 31 includes a suction valve 34 and a discharge valve 33, both of which are one-way valves. The suction valve 34 and the discharge valve 33 are connected to the upper chamber 27 of the diaphragm. When the diaphragm 16 is agitated downward, the volume of the upper chamber 27 of the diaphragm increases and the pressure decreases, the discharge valve 33 is closed, the suction valve 34 is opened, and the well fluid enters the upper chamber 27 of the diaphragm through the suction valve 34 to complete the suction process; when the diaphragm 16 is agitated upward, the volume of the upper chamber 27 of the diaphragm decreases and the pressure increases, the suction valve 34 is closed, the discharge valve 33 is opened, and the well fluid in the upper chamber 27 of the diaphragm is discharged from the upper chamber 27 of the diaphragm through the discharge valve 33 and output upward to the ground through the oil pipe.

[0047] The present invention discloses an electric submersible diaphragm pump suitable for low-liquid-production wells. The diaphragm is driven to move up and down by a crank and a crosshead transmission structure to transport the well fluid to the ground, thereby improving the pump efficiency and meeting the production needs of low-liquid-production wells. Bearings are arranged at the connection between the crank, the crosshead and the eccentric shaft to avoid vibration and heat generated by friction, thereby solving the problem of contact surface wear. The lubricating oil circulates in the pump barrel, thereby achieving good heat dissipation effect and effectively reducing the temperature of the pump barrel.

[0048] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the claims of this patent.

Claims

1. An electric submersible diaphragm pump suitable for low-liquid-production wells, comprising a pump barrel, a submersible motor, a liquid suction valve, and a liquid discharge valve, wherein the liquid suction valve is connected to the well barrel, and the liquid discharge valve is connected to the oil pipe, and is characterized in that: The bevel gear assembly, crank assembly and crosshead assembly of the transmission system are connected in sequence from bottom to top. The upper end of the crosshead assembly is fixedly installed with a diaphragm assembly. The crosshead and diaphragm divide the inner cavity of the pump barrel into a transmission cavity, a diaphragm lower cavity and a diaphragm upper cavity from bottom to top. The suction valve and the discharge valve are connected to the diaphragm upper cavity. The driving bevel gear and the driven bevel gear transmission pair of the bevel gear assembly convert the power of the submersible motor into the rotation of the driven bevel gear arranged along the radial direction of the pump barrel; the eccentric shaft, crank, crosshead and diaphragm fixedly connected to the driven bevel gear are connected in sequence from bottom to top, and when the crosshead drives the diaphragm to move up and down to change the volume of the upper cavity of the diaphragm, the suction valve and the discharge valve suck and discharge the well fluid into and out of the upper cavity of the diaphragm.

2. The electric submersible diaphragm pump suitable for low-liquid production wells according to claim 1, characterized in that: The lower pump barrel, the middle pump barrel and the upper pump barrel of the pump barrel are fixedly connected in sequence from bottom to top; the transmission system is located in the lower pump barrel; The driven bevel gear, eccentric shaft and centering shaft arranged radially along the lower pump barrel in the bevel gear assembly are connected in sequence, and centering bearings are installed at the ends of the driven bevel gear and the centering shaft. The two centering bearings are respectively arranged in the end covers, and the two end covers are fixedly arranged on both sides of the lower pump barrel.

3. The electric submersible diaphragm pump suitable for low-liquid-production wells according to claim 2, characterized in that: The lower end of the crank of the crank assembly is connected to the eccentric shaft diameter of the eccentric shaft; The upper end of the crank is connected to the lower end of the crosshead of the crosshead assembly, and the crank and the crosshead are connected through a radially installed pin shaft.

4. The electric submersible diaphragm pump suitable for low-liquid production wells according to claim 3, characterized in that: The upper end of the crosshead is connected to the connecting shaft, and the diaphragm assembly is fixedly mounted on the upper end of the connecting shaft; The outer edge of the diaphragm is arranged in an annular groove formed by the fixed connection between the middle pump barrel and the upper pump barrel.

5. The electric submersible diaphragm pump suitable for low-liquid production wells according to claim 4, characterized in that: A linear bearing is arranged between the outer circle of the crosshead and the lower pump barrel.

6. The electric submersible diaphragm pump suitable for low-liquid production wells according to claim 1, characterized in that: The lower chamber of the diaphragm is communicated with the oil inlet channel of the lubricating oil, and the transmission chamber is communicated with the oil outlet channel of the lubricating oil; an oil inlet check valve is arranged in the oil inlet channel, and an oil outlet check valve is arranged in the oil outlet channel.

7. The electric submersible diaphragm pump suitable for low-liquid production wells according to claim 6, characterized in that: The oil inlet channel and the oil outlet channel are both arranged along the axial direction of the lower pump barrel, and the oil inlet check valve and the oil outlet check valve are arranged at the lower end of the lower pump barrel; In the process of the diaphragm moving up and down to change the volume of the lower cavity of the diaphragm, the lubricating oil enters the lower cavity of the diaphragm through the oil inlet channel, then passes through the linear bearing downward into the transmission cavity, and is discharged through the oil outlet channel.

8. The electric submersible diaphragm pump suitable for low-liquid-production wells according to claim 7, characterized in that: When the diaphragm is pushed downward, the pressure in the upper cavity of the diaphragm is reduced, and the well fluid enters the upper cavity of the diaphragm through the suction valve; When the diaphragm moves upward, the pressure in the upper cavity of the diaphragm increases, and the well fluid in the upper cavity of the diaphragm is discharged from the upper cavity of the diaphragm through the discharge valve and output through the oil pipe.

9. The electric submersible diaphragm pump suitable for low-liquid-production wells according to claim 3, characterized in that: A pin bearing is arranged in the crank pin hole, and the pin is arranged in the pin bearing.

10. The electric submersible diaphragm pump suitable for low-liquid-production wells according to claim 3, characterized in that: A crank bearing is installed in the eccentric shaft diameter matching hole between the crank and the eccentric shaft.

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