A downhole gas compression assembly, compression device, and multi-stage gas recovery apparatus

Abstract

The application discloses a downhole gas compression assembly, a compression device and a multistage gas extraction equipment. The downhole gas compression assembly comprises a pipe shell, a rotating shaft, a driving structure and a magnetic suspension connecting assembly. The rotating shaft is arranged in the pipe shell and is a hollow shaft body. A first cavity, a second cavity and a third cavity are sequentially arranged in the rotating shaft from top to bottom. The upper half of the second cavity is gradually contracted from bottom to top. The lower half of the first cavity is gradually expanded from bottom to top. A plurality of blades are arranged on the inner wall of the second cavity. The driving structure comprises a stator core, a stator winding, a rotor core and a magnetic steel. The magnetic suspension connecting assembly comprises a first pressing plate and a radial magnetic suspension bearing. The power source of the driving structure and the gas compression structure are arranged at the second cavity in the middle of the rotating shaft, so that the cantilever distance of the rotating shaft is short, the deformation of the rotating shaft is reduced, and the hollow rotating shaft can flow through the gas when rotating, so that the heat can be taken away and the operation temperature of the device is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural gas exploitation, and in particular to a downhole gas compression assembly, a compression device and a multi-stage gas extraction equipment. BACKGROUND

[0002] After a certain period of service, the pressure in the gas well decreases, and the gas cannot be lifted to the surface, resulting in a decrease in extraction efficiency. Therefore, in order to improve the extraction efficiency, it is necessary to increase the gas pressure in the pipeline. Through technical iteration, the latest artificial lifting technology is to configure a downhole gas compressor. The gas compressor is placed near the position of 2KM underground, so that the natural gas has greater pressure and more kinetic energy in the downhole to reach the ground and complete the gas extraction process.

[0003] The current downhole gas compressor is usually composed of a power driving part, a rotating shaft and an axial compression component. The rotating shaft is driven to rotate by the power driving part, and the rotor blades in the axial compression component are driven to rotate by the rotating shaft. By cooperating with the stator blades in the flow compression component, the gas compression process is realized. However, since the power driving part is arranged at one end of the rotating shaft, the torque is transmitted to the axial compression component on the other side of the rotating shaft through the rotating shaft. This will result in a long torque transmission distance, causing a large deflection of the rotating shaft, resulting in problems in the cooperation between the rotating shaft and the bearing, increasing friction and wear, and thus affecting the normal operation and service life of the compressor. For example, the patent with publication number CN115355181A uses the above structure for gas compression and extraction process. It is composed of a lower driving motor, a middle magnetic coupling shaft coupling and an upper axial compressor. The driving motor, the magnetic coupling shaft coupling and the axial compressor are not uniformly stressed. The power source is on one side of the slender shaft, and the power is provided from the side of the lower driving motor. The torque is transmitted to the upper compressor end through the magnetic coupling shaft coupling. The overall size is long, the effective compression length is short, and the torque transmission distance is long, which will cause the shaft body to deform and affect the operation of the compressor. SUMMARY

[0004] The purpose of the present application is to provide a downhole gas compression assembly, a compression device and a multi-stage gas extraction equipment to solve the problem that the current downhole gas compressor has an unreasonable structure arrangement and the torque transmission distance of the rotating shaft is long, which will cause deformation and affect the operation of the compressor.

[0005] The technical solution of the present application is:

[0006] The application discloses a downhole gas compression assembly which comprises a vertically arranged pipe shell, a rotating shaft, a driving structure and a magnetic suspension connecting assembly; the rotating shaft is coaxially arranged in the pipe shell and is a hollow shaft body, the inside of the rotating shaft is sequentially provided with a first cavity, a second cavity and a third cavity from top to bottom, the upper half of the second cavity is gradually contracted from bottom to top, the lower half of the first cavity is gradually expanded from bottom to top, a plurality of blades are arranged on the inner wall of the second cavity, and a plurality of blades are arranged on the inner wall of the second cavity; the driving structure is arranged at the second cavity of the rotating shaft and is used for driving the rotating shaft to rotate, the driving structure comprises a stator core, a stator winding, a rotor core and a magnetic steel, the stator core is in interference fit with the inner wall of the pipe shell, the stator winding is wound on the stator core provided with a framework, the rotor core is sleeved in the stator core, the inner ring surface of the rotor core is in interference fit with the outer wall of the rotating shaft, and the magnetic steel is embedded in the magnetic steel groove arranged on the outer wall of the rotor core; the magnetic suspension connecting assembly comprises a first pressing plate and a radial magnetic suspension bearing, the first pressing plate is fixed on the inner wall of the upper end of the pipe shell, the inner wall of the pipe shell at the first cavity is provided with a boss, the radial magnetic suspension bearing is connected between the rotating shaft and the pipe shell, and the upper and lower end surfaces of the radial magnetic suspension bearing are respectively in abutment with the first pressing plate and the boss.

[0007] Preferably, as a further improvement of the application, the plurality of blades are longitudinally and evenly arranged on the inner wall of the second cavity, and the number of the blades is at least 5.

[0008] Preferably, as a further improvement of the application, the lower end of the rotating shaft is connected with an air inlet ring, and the upper end of the rotating shaft is connected with an air outlet ring.

[0009] Preferably, as a further improvement of the application, the outer ring surface of the air inlet ring is provided with external threads, the lower inner wall of the pipe shell is provided with internal threads, the air inlet ring is threadedly connected with the pipe shell, the lower end of the rotating shaft is arranged in the air inlet ring, the rotating shaft and the air inlet ring are connected through a first magnetic suspension axial bearing, the upper end of the air inlet ring is fixed with a second pressing plate, and the bottom of the second pressing plate is in abutment with the first magnetic suspension axial bearing.

[0010] Preferably, as a further improvement of the application, the inside of the air outlet ring is sequentially provided with a first hole cavity and a second hole cavity from top to bottom, the diameter of the first hole cavity is smaller than that of the second hole cavity, the upper end of the rotating shaft extends into the first hole cavity after passing through the second hole cavity, the upper outer wall of the pipe shell is provided with a static sealing ring, and the static sealing ring is sealingly connected with the inner wall of the second hole cavity.

[0011] The application further discloses a downhole gas compression device which comprises two groups of the downhole gas compression assemblies and a coupling connector, the two groups of the downhole gas compression assemblies are vertically arranged side by side, the rotating shafts in the two groups of the downhole gas compression assemblies are connected through the coupling connector, wherein the downhole gas compression assembly located at the lower side is a primary compression assembly, the downhole gas compression assembly located at the upper side is a secondary compression assembly, the gas inlet ring and the gas outlet ring are arranged respectively, the gas inlet ring is connected at the lower end of the rotating shaft in the primary compression assembly, the gas outlet ring is connected at the upper end of the rotating shaft in the secondary compression assembly, and the rotating speed of the rotating shaft in the secondary compression assembly is greater than that of the rotating shaft in the primary compression assembly.

[0012] Preferably, as a further improvement of the application, the coupling connector comprises a first connecting sleeve, a second magnetic suspension axial bearing and a second connecting sleeve; an outer thread is arranged on the outer circumferential surface of the upper end of the first connecting sleeve, and the first connecting sleeve is threadedly connected with the inner wall of the lower side of the pipe shell in the secondary compression assembly through the outer thread; the lower end of the rotating shaft in the secondary compression assembly penetrates into the first connecting sleeve and is connected with the inner wall of the first connecting sleeve through the first needle bearing assembly; the second magnetic suspension axial bearing is connected between the inner wall of the upper end port of the first connecting sleeve and the outer wall of the rotating shaft in the secondary compression assembly; a third pressing plate is fixed to the upper end of the first connecting sleeve, and the bottom of the third pressing plate abuts against the second magnetic suspension axial bearing; the second connecting sleeve is sleeved on the outer side of the lower part of the first connecting sleeve, and the second connecting sleeve and the first connecting sleeve are connected through the second needle bearing assembly; a clamping groove is arranged on the outer wall of the upper end of the rotating shaft in the primary compression assembly, a clamping plate is fixed to the inner wall of the second connecting sleeve, and the upper end of the rotating shaft in the primary compression assembly penetrates into the second connecting sleeve and is clamped with the clamping plate through the clamping groove.

[0013] Preferably, as a further improvement of the application, an end cover is fixed to the upper end surface of the pipe shell in the primary compression assembly, a through hole is arranged in the middle of the end cover and penetrates the rotating shaft, and the through hole and the rotating shaft are connected through a dynamic sealing ring.

[0014] The application further discloses a downhole gas multistage gas extraction equipment which comprises a plurality of the downhole gas compression devices, the plurality of the downhole gas compression devices are vertically arranged side by side, and the gas inlet ring and the gas outlet ring between the upper and lower adjacent two downhole gas compression devices are detachably connected.

[0015] Preferably, as a further improvement of the application, a tapered threaded hole is arranged on the inner wall of the lower side of the gas inlet ring, the outer wall of the upper side of the gas outlet ring is tapered and is provided with a tapered outer thread, and the gas inlet ring is threadedly connected with the tapered outer thread on the gas outlet ring through the tapered threaded hole.

[0016] Compared with the prior art, the application has the following beneficial effects:

[0017] 1. The power source and gas compression components of the drive structure of the downhole gas compression assembly are all concentrated in the second cavity in the middle of the shaft, which effectively reduces the length of the shaft and the torque transmission distance, resulting in a shorter shaft cantilever distance, better mechanical performance of the shaft, and less susceptibility to deformation.

[0018] 2. The downhole gas compression assembly uses a drive structure to drive the hollow shaft to rotate for gas compression. Compared with the traditional internal rotor with shaft motor, the hollow structure has gas flowing through it, which can carry away a lot of heat generated when the rotor rotates, reduce the operating temperature of the drive structure, and improve the life of the device.

[0019] 3. Compared to the traditional side-wall air intake structure, the hollow structure design makes the device space smaller.

[0020] 4. The downhole gas compression device consists of a primary compression assembly and a secondary compression assembly, thus having two gas compression sections with a relatively long compression length, enabling a large compression ratio.

[0021] 5. The downhole gas compression device can effectively configure the rotational speed of the rotating shaft in the primary compression component and the rotational speed of the rotating shaft in the secondary compression component, thereby achieving a wider speed regulation range and a wider production control range.

[0022] 6. By connecting the upper and lower air inlets of multiple downhole gas compression devices in series to form a multi-stage gas production equipment, a larger compression ratio can be provided as required. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the main cross-sectional structure of a downhole gas compression assembly according to the present invention.

[0024] Figure 2 This is a schematic diagram of the main cross-sectional structure of the air intake ring of a downhole gas compression assembly according to the present invention.

[0025] Figure 3 This is a schematic diagram of the main cross-sectional structure of the outlet ring of a downhole gas compression assembly according to the present invention.

[0026] Figure 4 This is a schematic diagram of the front cross-sectional structure of a downhole gas compression device according to the present invention.

[0027] Figure 5 This is a schematic diagram of the main cross-sectional structure of the coupling connector in a downhole gas compression device according to the present invention.

[0028] Figure 6 This is a schematic diagram of the main cross-sectional structure of the connecting end cap in a downhole gas compression device according to the present invention.

[0029] Figure 7A structure schematic diagram of a multi-stage gas extraction equipment of the present application.

[0030] Figure 8 A connecting structure of the multi-stage gas extraction equipment of the present application, in which the gas inlet ring and the gas outlet ring are connected; a connecting structure schematic diagram. DETAILED DESCRIPTION

[0031] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. Figure 1 to the accompanying drawings, Figure 8 The specific embodiments of the present application are described in detail. In the description of the application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0032] The terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features; in the description of the application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0033] Example 1

[0034] As Figures 1 to 3As shown, the embodiment of the present application provides a downhole gas compression assembly, which comprises a vertically arranged pipe shell 1, a rotating shaft 2, a driving structure and a magnetic suspension connecting assembly; the rotating shaft 2 is coaxially arranged in the pipe shell 1, the rotating shaft 2 is a hollow shaft body, and a first cavity 21, a second cavity 22 and a third cavity 23 are sequentially arranged in the rotating shaft 2 from top to bottom, the upper half diameter of the second cavity 22 is gradually reduced from bottom to top, the lower half diameter of the first cavity 21 is gradually expanded from bottom to top, and a plurality of blades 24 are arranged on the inner wall of the second cavity 22; the driving structure is arranged at the second cavity 22 of the rotating shaft 2 and used for driving the rotating shaft 2 to rotate, the driving structure comprises a stator core 31, a stator winding 32, a rotor core 33 and a magnetic steel 34, the stator core 31 is in interference fit with the inner wall of the pipe shell 1, the stator winding 32 is wound on the stator core 31 provided with a skeleton and immersed in insulating resin, the rotor core 33 is sleeved in the stator core 31, and the inner ring surface of the rotor core 33 is in interference fit with the outer wall of the rotating shaft 2, and the magnetic steel 34 is embedded in the magnetic steel groove arranged on the outer wall of the rotor core 33; the magnetic suspension connecting assembly comprises a first pressing plate 41 and a radial magnetic suspension bearing 42, the first pressing plate 41 is fixed on the inner wall of the upper end of the pipe shell 1, a boss 11 is arranged on the inner wall of the pipe shell 1 at the first cavity 21, and the radial magnetic suspension bearing 42 is connected between the rotating shaft 2 and the pipe shell 1, and the upper and lower end surfaces of the radial magnetic suspension bearing 42 are respectively in abutment with the first pressing plate 41 and the boss 11.

[0035] In the embodiment, when the gas compression is performed, the stator winding 32 on the stator core 31 is passed through current, the magnetic steel 34 and the rotor core 33 are driven to rotate under the action of the magnetic force, the rotating shaft 2 is driven to rotate, the gas is sucked into the second cavity 22 through the third cavity 23 under the action of the plurality of blades 24, the upper half diameter of the second cavity 22 is gradually reduced from bottom to top, the lower half diameter of the first cavity 21 is gradually expanded from bottom to top, the first cavity 21 and the second cavity 22 form a Laval nozzle structure to serve as a compression cavity, the speed of the gas is sharply amplified when the gas passes through the structure, the gas compression process is realized, the gas is discharged through the first cavity 21, and in the rotating process of the rotating shaft 2, the radial magnetic suspension bearing 42 is passed through current, and the posture of the rotor is continuously adjusted, so that the rotor is suspended in the air, and there is no mechanical contact between the rotor and the stator, thereby realizing the non-contact support of the radial bearing and reducing the friction loss in the rotating process.

[0036] Therefore, the application integrates the driving power source and the gas pressurizing structure at the middle position of the rotating shaft 2 by arranging the driving structure on the outer wall where the rotating shaft 2 is located at the second cavity 22 and arranging the gas compression component on the inner wall where the rotating shaft 2 is located at the second cavity 22, so that the cantilever distance of the rotating shaft 2 is short, the torque transmission distance is reduced, the mechanical performance of the rotating shaft 2 is better, and the rotating shaft 2 is not easy to deform. In addition, since the rotating shaft 2 is a hollow structure, compared with the inner rotor with rotating shaft motor, the gas flows through the inside of the hollow structure, which can take away heat, reduce the operating temperature of the device, and improve the service life of the device. Moreover, compared with the traditional structure with side wall gas inlet, the hollow structure design makes the device smaller.

[0037] The driving structure adopts direct current driving, which can reduce the risk of downhole discharge breakdown.

[0038] Further, the plurality of blades 24 are arranged longitudinally and uniformly along the inner wall of the second cavity 22, and the number of the blades 24 is at least 5, which ensures a certain compression efficiency.

[0039] The lower end of the rotating shaft 2 is connected with the gas inlet ring 5, and the upper end of the rotating shaft 2 is connected with the gas outlet ring 6. The gas inlet ring 5 can effectively suck more gas from the rotating shaft 2 into the rotating shaft 2 for compression, and the gas outlet ring 6 can facilitate the discharge of the pressurized gas in the rotating shaft 2.

[0040] Further, in order to realize the axial positioning of the rotating shaft 2, an external thread is arranged on the outer ring surface of the gas inlet ring 5, an internal thread is arranged on the lower inner wall of the tube shell 1, the gas inlet ring 5 is threadedly connected with the tube shell 1, the lower end of the rotating shaft 2 penetrates into the gas inlet ring 5, the rotating shaft 2 is connected with the gas inlet ring 5 through the first magnetic suspension axial bearing 51, the upper end of the gas inlet ring 5 is fixed with a second pressing plate 52, the bottom of the second pressing plate 52 abuts against the first magnetic suspension axial bearing 51, the first magnetic suspension axial bearing 51 can realize the non-contact support of the axial bearing, which can maintain the axial support of the rotating shaft 2 in the process of reducing the friction loss in the rotating process, so that the rotating shaft 2 can be supported in the tube shell 1.

[0041] The rotating shaft 2 is connected with the gas inlet ring 5 through the first magnetic suspension axial bearing 51. Figure 1As shown, in order to protect the rotating shaft 2 and make it rotate more smoothly when the rotating shaft 2 rotates to compress the gas, a first step 25 and a second step 26 are arranged on the outer wall of the rotating shaft 2, the first step 25 is located at the junction of the first cavity 21 and the second cavity 22, the second step 26 is located at the junction of the second cavity 22 and the third cavity 23, a first protection bearing 27 is arranged at the first step 25, a second protection bearing 28 is arranged at the second step 26, the lower end surface of the first protection bearing 27 abuts against the first step 25, the upper end surface of the first protection bearing 27 is connected with the boss 11 arranged on the inner wall of the tube shell 1 through a wave-shaped elastic gasket 29, the upper end surface of the second protection bearing 28 abuts against the second step 26, and the lower end surface of the second protection bearing 28 is connected with a bearing seat fixed on the top of the second pressing plate 52.

[0042] Further, the inside of the gas outlet ring 6 is sequentially provided with a first hole cavity 61 and a second hole cavity 62 from top to bottom, the diameter of the first hole cavity 61 is smaller than that of the second hole cavity 62, the upper end of the rotating shaft 2 extends into the first hole cavity 61 after passing through the second hole cavity 62, and the upper outer wall of the tube shell 1 is provided with a static sealing ring 63 which is sealingly connected with the inner wall of the second hole cavity 62, and the static sealing ring 63 can effectively prevent the gas from leaking from other positions when the gas is discharged.

[0043] Embodiment 2

[0044] This embodiment is based on embodiment 1 and discloses a downhole gas compression device, as shown in the figure. Figure 4 As shown, the downhole gas compression device comprises two groups of the above-mentioned downhole gas compression assemblies and a coupling connector 7, the two groups of downhole gas compression assemblies are arranged vertically and side by side, the rotating shafts 2 in the two groups of downhole gas compression assemblies are connected through the coupling connector 7, the downhole gas compression assembly located at the lower side is a primary compression assembly 81, the downhole gas compression assembly located at the upper side is a secondary compression assembly 82, there is one gas inlet ring 5 and one gas outlet ring 6 respectively, the gas inlet ring 5 is connected at the lower end of the rotating shaft 2 in the primary compression assembly 81, the gas outlet ring 6 is connected at the upper end of the rotating shaft 2 in the secondary compression assembly 82, and the rotating speed of the rotating shaft 2 in the secondary compression assembly 82 is greater than that of the rotating shaft 2 in the primary compression assembly 81.

[0045] In this embodiment, the downhole gas compression device is composed of a primary compression assembly 81, a coupling connector 7 and a secondary compression assembly 82. When working, the driving structure of the primary compression assembly 81 is supplied with current, and under the action of magnetic force, the rotating shaft 2 is driven to rotate. Under the action of multiple groups of multiple blades 24, the gas is sucked into the second cavity 22 through the gas inlet ring 5 and is continuously compressed. The first cavity 21 and the second cavity 22 form a Laval nozzle structure, and the speed of the gas is sharply amplified when passing through this structure. The gas is discharged through the first cavity 21. At this time, the pressure and flow rate of the gas have been greatly improved compared with the gas inlet ring 5. Then the gas enters the secondary compression assembly 82 through the coupling connector 7. The working principle of the secondary compression assembly 82 is similar to that of the primary compression assembly 81. The gas will be compressed twice to obtain a higher compression ratio. Unlike the compression process of the primary compression assembly 81, the gas entering the secondary compression assembly 82 is the gas compressed by the primary compression assembly 81. Because the gas has higher energy, the driving structure in the secondary compression assembly 82 requires higher rotating speed. Since the rotating speeds of the rotating shafts 2 of the primary compression assembly 81 and the secondary compression assembly 82 are different, they cannot be connected by a common coupling. Therefore, the coupling connector 7 is needed for connection. Compared with the prior art, if the compression device wants to increase the gas production, it can only single-regulate the motor speed. Through the above setting, the rotating speeds of the rotating shafts in the primary compression assembly and the secondary compression assembly can be effectively configured, a wider speed regulation range can be obtained, and the yield regulation range is wider.

[0046] Specifically, as Figure 5As shown, the coupling connector 7 comprises a first connecting sleeve 71, a second magnetic suspension axial bearing 73 and a second connecting sleeve 75; the upper end outer ring surface of the first connecting sleeve 71 is provided with external threads, and is threadedly connected with the lower side inner wall of the pipe shell 1 in the secondary compression assembly 82; the lower end of the rotating shaft 2 in the secondary compression assembly 82 penetrates into the first connecting sleeve 71, and is connected with the inner wall of the first connecting sleeve 71 through the first needle bearing assembly 72; the second magnetic suspension axial bearing 73 is connected between the upper end port inner wall of the first connecting sleeve 71 and the outer wall of the rotating shaft 2 in the secondary compression assembly 82; the upper end of the first connecting sleeve 71 is fixedly provided with a third pressing plate 74, and the bottom of the third pressing plate 74 abuts against the second magnetic suspension axial bearing 73; the second connecting sleeve 75 is sleeved on the lower outer side of the first connecting sleeve 71, and is connected between the first connecting sleeve 71 and the second connecting sleeve 75 through the second needle bearing assembly 76; the upper end outer wall of the rotating shaft 2 in the primary compression assembly 81 is provided with a clamping groove 201, and the inner wall of the second connecting sleeve 75 is fixedly provided with a clamping plate 77; the upper end of the rotating shaft 2 in the primary compression assembly 81 penetrates into the second connecting sleeve 75, and is clamped with the clamping plate 77 through the clamping groove 201; the second magnetic suspension axial bearing 73 can support the rotating shaft 2 in the secondary compression assembly 82 in the axial direction, and reduce the rotating friction force; the first needle bearing assembly 72 can position the rotating shaft 2 in the secondary compression assembly 82 in the radial direction; the second needle bearing assembly 76 can position the rotating shaft 2 in the primary compression assembly 81 and the second connecting sleeve 75 in the radial direction, so as to keep the rotating shaft 2 in the primary compression assembly 81 coaxial with the rotating shaft 2 in the secondary compression assembly 82.

[0047] As shown in the drawings, Figure 5 As shown, the first needle bearing assembly 72 comprises a first sealing cover 721, a first retainer 722, a plurality of first needles 723, a second retainer 724 and a second sealing cover 725 arranged in sequence from top to bottom; the first sealing cover 721 and the second sealing cover 725 are respectively connected to the inner wall of the first connecting sleeve 71; the plurality of needles 723, the first retainer 722 and the second retainer 724 are arranged between the first sealing cover 721 and the second sealing cover 725, and the plurality of first needles 723 are in clearance fit with the first retainer 722 and the second retainer 724, and lubricating oil is injected therebetween; the circumferential side wall of the rotating shaft 2 is connected with the plurality of first needles 723; the first sealing cover 721 and the second sealing cover 725 play the sealing and limiting roles.

[0048] As shown in the drawings, Figure 5As shown, the second needle bearing assembly 76 includes a third sealing cover 761, a third retainer 762, a plurality of second needles 763, a fourth retainer 764 and a fourth sealing cover 765 arranged in sequence from top to bottom, the third sealing cover 761 and the fourth sealing cover 765 are respectively clamped and connected between the first connecting sleeve 71 and the second connecting sleeve 75, the plurality of second needles 763, the third retainer 762 and the fourth retainer 764 are all arranged between the third sealing cover 761 and the fourth sealing cover 765, and the plurality of second needles 763 are in clearance fit with the third retainer 762 and the fourth sealing cover 765, and the lubricating oil is injected therebetween, the circumferential side wall of the rotating shaft 2 is connected with the plurality of first needles 723, and the third sealing cover 761 and the fourth sealing cover 765 play a sealing and limiting role.

[0049] As shown in Figure 4 and Figure 6 In order to be able to install the downhole gas compression device in the gas well or oil and gas pipeline for gas production, the support plate 12 is fixed on the outer wall of the shell 1, and the downhole gas compression device is clamped and fixed on the inner wall of the gas well or oil and gas pipeline by the support plate 12.

[0050] Further, as shown in Figure 6 The end cover 91 is fixed at the upper end face of the shell 1 in the primary compression assembly 81, the middle part of the end cover 91 is provided with a through hole through which the rotating shaft 2 passes, and the through hole and the rotating shaft 2 are connected through the dynamic sealing ring 92. The end cover 91 can fix the support plate 12, so that the support plate 12 can play a limiting role in the oil and gas pipeline, and the end cover 91 can maintain the sealing environment in the compressor cavity, avoiding corrosion and failure of key parts.

[0051] Example 3

[0052] This embodiment is based on example 2, and discloses a downhole gas multi-stage gas recovery equipment, as shown in Figure 7 and Figure 8 The multi-stage gas recovery equipment includes a plurality of downhole gas compression devices as described above, the plurality of downhole gas compression devices are arranged vertically and in parallel, and the gas inlet ring 5 and the gas outlet ring 6 between the two adjacent downhole gas compression devices are detachably connected.

[0053] In this embodiment, the multi-stage gas recovery equipment is composed of a plurality of downhole gas compression devices in series, which can provide a larger compression ratio. When connected in series, only the adjacent two downhole gas compression devices need to be connected through the gas inlet ring 5 and the gas outlet ring 6.

[0054] Specifically, as shown in Figure 8As shown, the lower inner wall of the air inlet ring 5 is provided with a tapered threaded hole 53, the upper outer wall of the air outlet ring 6 is tapered and provided with a tapered external thread 64, and the air inlet ring 5 is threadedly connected to the air outlet ring 6 through the tapered threaded hole 53 and the tapered external thread 64.

[0055] The above disclosed are only several preferred specific embodiments of the present application, but the embodiments of the present application are not limited thereto, and any changes that can be thought of by those skilled in the art shall fall within the protection scope of the present application.

Claims

1. A downhole gas compression assembly, comprising a vertically arranged casing (1), characterized in that, Also includes: A rotating shaft (2) is coaxially inserted inside the tube shell (1). The rotating shaft (2) is a hollow shaft. Its interior is provided with a first cavity (21), a second cavity (22) and a third cavity (23) from top to bottom. The upper half of the second cavity (22) gradually narrows from bottom to top, and the lower half of the first cavity (21) gradually expands from bottom to top. Multiple blades (24) are provided on the inner wall of the second cavity (22). A drive structure is provided at the second cavity (22) of the rotating shaft (2) to drive the rotating shaft (2) to rotate. The drive structure includes a stator core (31), a stator winding (32), a rotor core (33) and a magnet (34). The stator core (31) is interference-fitted with the inner wall of the tube shell (1). The stator winding (32) is wound on the stator core (31) with a skeleton. The rotor core (33) is sleeved in the stator core (31), and the inner ring surface of the rotor core (33) is interference-fitted with the outer wall of the rotating shaft (2). The magnet (34) is embedded in the magnet groove opened on the outer wall of the rotor core (33). The magnetic levitation connection assembly includes a first pressure plate (41) and a radial magnetic levitation bearing (42). The first pressure plate (41) is fixed on the inner wall of the upper port of the tube shell (1). The inner wall of the tube shell (1) located at the first cavity (21) is provided with a boss (11). The radial magnetic levitation bearing (42) is connected between the rotating shaft (2) and the tube shell (1), and the upper and lower end faces of the radial magnetic levitation bearing (42) abut against the first pressure plate (41) and the boss (11) respectively.

2. The downhole gas compression assembly according to claim 1, characterized in that, The plurality of blades (24) are evenly distributed longitudinally along the inner wall of the second cavity (22), and the number of blades (24) is at least 5.

3. The downhole gas compression assembly according to claim 2, characterized in that, An air intake ring (5) is connected to the lower port of the rotating shaft (2), and an air outlet ring (6) is connected to the upper port of the rotating shaft (2).

4. The downhole gas compression assembly according to claim 3, characterized in that, The outer ring of the air intake ring (5) is provided with an external thread, and the inner wall of the lower side of the tube shell (1) is provided with an internal thread. The air intake ring (5) and the tube shell (1) are threadedly connected. The lower end of the rotating shaft (2) passes through the air intake ring (5). The rotating shaft (2) and the air intake ring (5) are connected by a first magnetic levitation axial bearing (51). The upper end of the air intake ring (5) is fixed with a second pressure plate (52), and the bottom of the second pressure plate (52) abuts against the first magnetic levitation axial bearing (51).

5. The downhole gas compression assembly according to claim 3, characterized in that, The air outlet ring (6) has a first cavity (61) and a second cavity (62) arranged sequentially from top to bottom. The diameter of the first cavity (61) is smaller than the diameter of the second cavity (62). The upper end of the rotating shaft (2) passes through the second cavity (62) and extends into the first cavity (61). A static sealing ring (63) is provided on the upper outer wall of the tube shell (1), and the static sealing ring (63) is sealed to the inner wall of the second cavity (62).

6. A downhole gas compression device, characterized in that, The assembly includes two sets of downhole gas compression components as described in any one of claims 3-5 and a coupling connector (7). The two sets of downhole gas compression components are arranged vertically side by side. The rotating shafts (2) in the two sets of downhole gas compression components are connected by the coupling connector (7). The downhole gas compression component located on the lower side is a primary compression component (81), and the downhole gas compression component located on the upper side is a secondary compression component (82). There is one inlet ring (5) and one outlet ring (6). The inlet ring (5) is connected to the lower end of the rotating shaft (2) in the primary compression component (81), and the outlet ring (6) is connected to the upper end of the rotating shaft (2) in the secondary compression component (82). The rotational speed of the rotating shaft (2) in the secondary compression component (82) is greater than the rotational speed of the rotating shaft (2) in the primary compression component (81).

7. The downhole gas compression device according to claim 6, characterized in that, The coupling connector (7) includes: The first connecting sleeve (71) has an external thread on its upper outer ring surface and is threaded to the lower inner wall of the tube shell (1) in the secondary compression assembly (82) through the external thread. The lower end of the rotating shaft (2) in the secondary compression assembly (82) passes through the first connecting sleeve (71) and is connected to the inner wall of the first connecting sleeve (71) through the first needle roller bearing assembly (72). The second magnetic levitation axial bearing (73) is connected between the inner wall of the upper port of the first connecting sleeve (71) and the outer wall of the rotating shaft (2) in the secondary compression assembly (82). The upper end of the first connecting sleeve (71) is fixed with a third pressure plate (74), and the bottom of the third pressure plate (74) abuts against the second magnetic levitation axial bearing (73). The second connecting sleeve (75) is sleeved on the lower outer side of the first connecting sleeve (71). The second connecting sleeve (75) and the first connecting sleeve (71) are connected by a second needle roller bearing assembly (76). A slot (201) is provided on the upper outer wall of the rotating shaft (2) in the first-stage compression assembly (81). A retaining plate (77) is fixed on the inner wall of the second connecting sleeve (75). The upper end of the rotating shaft (2) in the first-stage compression assembly (81) passes through the second connecting sleeve (75) and is engaged with the retaining plate (77) through the slot (201).

8. The downhole gas compression device according to claim 6, characterized in that, An end cap (91) is fixed at the upper end face of the tube shell (1) in the primary compression assembly (81). The end cap (91) has a through hole in the middle for the rotating shaft (2) to pass through, and the through hole is connected to the rotating shaft (2) by a dynamic sealing ring (92).

9. A multi-stage downhole gas production device, characterized in that, It includes multiple downhole gas compression devices as described in any one of claims 6-8, the multiple downhole gas compression devices are arranged vertically side by side, and the air inlet ring (5) and air outlet ring (6) between two adjacent downhole gas compression devices are detachably connected.

10. The downhole gas multi-stage gas production equipment according to claim 9, characterized in that, The lower inner wall of the air intake ring (5) is provided with a tapered threaded hole (53), and the upper outer wall of the air outlet ring (6) is tapered and provided with a tapered external thread (64). The air intake ring (5) is threadedly connected to the tapered external thread (64) on the air outlet ring (6) through the tapered threaded hole (53).

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