A downhole tool, a multiphase flow motor and its drive shaft assembly

Abstract

This invention provides a downhole tool, a multiphase flow motor, and a drive shaft assembly thereof. The drive shaft assembly includes: a drive shaft, a drive shaft housing, and, from top to bottom, an upper piston assembly, a pressure-bearing assembly, and a lower piston assembly, sequentially arranged between the drive shaft and the drive shaft housing. The multiphase flow motor includes, from top to bottom, an anti-drop assembly, a motor assembly, a universal joint assembly, and the aforementioned drive shaft assembly. The downhole tool includes the aforementioned multiphase flow motor. The advantages of this invention include: the use of a hydraulically sealed drive shaft assembly improves the lifespan of the drive shaft assembly; it provides a multiphase flow motor powered by multiphase fluid, with high torque, high strength, and long lifespan, providing technical support and safety assurance for drilling in complex formations.

Description

Technical Field

[0001] This invention relates to the field of petroleum equipment technology, specifically to a downhole tool, a multiphase flow motor and its drive shaft assembly. Background Technology

[0002] The advancement and development of industrial technology and productivity are inseparable from the innovation of power devices. Current conventional tubing and coiled tubing well workover operations (drilling, fishing, cleaning) play a crucial role in oil and gas, as well as shale gas development. However, due to the unique characteristics of tubing and coiled tubing operations, the probability of encountering complex situations during these operations is significantly higher than in conventional well operations. Furthermore, once complex situations arise, the difficulty of subsequent handling increases dramatically, and the available tools are currently extremely limited. Most current drive shafts are open-type ball joints, which are susceptible to cavitation under multiphase flow conditions, reducing their service life. Additionally, the compressibility of gases leads to a decrease in screw torque, and some tools lack special anti-drop designs, resulting in repeated downhole accidents caused by the wear and tear of the anti-drop rings. Therefore, it is necessary to develop superior handling tools to adapt to complex operating environments.

[0003] For example, Chinese Patent CN106194715A discloses a layered water injection hydraulically driven screw pump system. The single screw motor rotor of this hydraulically driven screw pump system is connected to the motor outlet drive shaft assembly via a motor outlet universal joint assembly. The motor outlet drive shaft housing is connected to the inner connector at the lower end of the cross water pipe, and the cross water pipe is connected to the oil pipe via an upper connector. This ensures that the axial hydraulic load generated on the single screw motor rotor from bottom to top is transmitted to the oil pipe through the motor outlet drive shaft assembly and the motor outlet universal joint assembly. This effectively avoids the motor inlet universal joint assembly bearing the axial hydraulic load on the single screw motor rotor, ensuring that the motor inlet universal joint assembly is only used to transmit the torque output by the single screw motor rotor. This reduces the design difficulty of the motor inlet universal joint assembly and increases its service life, but it only improves the service life and safety of the layered water injection hydraulically driven screw pump system. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to solve one or more of the problems existing in the prior art. For example, one objective of the present invention is to improve the service life of the drive shaft assembly by adopting a hydraulically sealed structure; another objective is to provide a multiphase flow motor that uses multiphase fluid as power, has high torque, high strength, and long service life, providing technical support and safety assurance for drilling in complex formations.

[0005] To achieve the above objectives, the present invention provides a transmission shaft assembly with a hydraulic sealing structure. The transmission shaft assembly may include: a transmission shaft, a transmission shaft housing, and, from top to bottom, an upper piston assembly, a pressure-bearing assembly, and a lower piston assembly disposed between the transmission shaft and the transmission shaft housing.

[0006] A central flow channel may be provided on the drive shaft along the axial direction;

[0007] The drive shaft housing can be sleeved on the outside of the drive shaft and coaxially arranged, and may include an upper piston sleeve, a positive pressure outer sleeve assembly, a middle sleeve assembly, and a lower piston sleeve connected sequentially from top to bottom. A first annular cavity is formed between the inner wall of the upper piston sleeve, the outer wall of the drive shaft, and the top of the positive pressure outer sleeve assembly; a second annular cavity is formed between the inner wall of the positive pressure outer sleeve assembly, the outer wall of the drive shaft, and the top of the middle sleeve assembly; and a third annular cavity is formed between the inner wall of the lower piston sleeve, the bottom of the middle sleeve assembly, and the outer wall of the drive shaft; the first annular cavity, the second annular cavity, and the third annular cavity are axially connected.

[0008] The upper piston assembly can be disposed in the first annular cavity and form a dynamic seal in the radial direction; the pressure-bearing assembly can be disposed in the second annular cavity and can withstand the axial load transmitted from the drive shaft housing to the drive shaft; the lower piston assembly can be disposed in the third annular cavity and form a dynamic seal in the radial direction.

[0009] A hydraulic sealing cavity is formed between the upper piston assembly, the inner wall of the drive shaft housing, the outer wall of the drive shaft, and the lower piston assembly. The internal pressure of the hydraulic sealing cavity can balance the pressure at the top of the upper piston assembly and / or the bottom of the lower piston assembly.

[0010] Furthermore, the upper piston assembly may include an upper balance piston, and the lower piston assembly may include a lower balance piston, a K-seal connector, and a double convex oil seal, wherein the K-seal connector and the double convex oil seal are located at the upper and lower ends of the lower balance piston, respectively.

[0011] Furthermore, both the upper and lower balance pistons can be equipped with rotary seals.

[0012] Furthermore, the positive pressure outer sleeve assembly may be provided with an L-shaped injection hole communicating with the hydraulic sealing cavity; the lower piston sleeve may be provided with a pressure relief hole communicating with the hydraulic sealing cavity; the liquid in the hydraulic sealing cavity may be hydraulic oil.

[0013] Furthermore, the pressure-bearing assembly may include a load ring, a retaining ring, a first thrust bearing, and two second thrust bearings. The load ring may have internal threads, and the outer wall of the drive shaft at the corresponding position may have matching external threads. The retaining ring can pass through the load ring to fix the drive shaft, and the outer wall of the drive shaft at the corresponding position may have matching fixed mounting positions. The two second thrust bearings may be installed at the upper and lower ends of the load ring, respectively. The first thrust bearing is installed at the lower end of the second thrust bearings.

[0014] Furthermore, the drive shaft housing may also include a centralizer, which may be fixedly connected to the outside of the positive pressure outer sleeve assembly, the middle sleeve assembly, and the lower piston sleeve.

[0015] Furthermore, the drive shaft assembly may also include a radial bearing and a thrust bearing, both of which can be sealed within the hydraulic sealing cavity.

[0016] To achieve the above objectives, another aspect of the present invention provides a multiphase flow motor, which may include: an anti-drop assembly, a motor assembly, a universal joint assembly, and the aforementioned drive shaft assembly, connected sequentially from top to bottom.

[0017] The anti-drop assembly may include an upper connector, an anti-drop ring, and an anti-drop connecting rod. A limiting element may be provided on the inner wall of the upper connector. The anti-drop ring may be disposed inside the upper connector and located above the limiting element. The upper end of the anti-drop connecting rod passes through the limiting element and is connected to the anti-drop ring.

[0018] The motor assembly may include a stator, a rotor, and a stator housing. The stator and rotor may include a stator and a rotor. The stator is fixed to the inner wall of the stator housing, and the rotor is located inside the stator and meshes with the stator. The upper end of the rotor is connected to the lower end of the anti-drop connecting rod, and the upper end of the stator housing is connected to the lower end of the upper connector.

[0019] The universal joint assembly may include a universal joint housing and a universal joint. The universal joint may be disposed within the universal joint housing. The upper end of the universal joint is fixedly connected to the lower end of the rotor, and the lower end of the universal joint is connected to the upper end of the drive shaft. The upper end of the universal joint housing is fixedly connected to the lower end of the stator housing, and the lower end of the universal joint housing is fixedly connected to the upper end of the drive shaft housing.

[0020] Furthermore, the lower end of the universal joint and the upper end of the drive shaft can be connected by a water cap, which can change the flow direction of the drilling fluid flowing through the universal joint and then enter the central flow channel of the drive shaft.

[0021] Furthermore, the anti-drop assembly may also include an upper wear-resistant pad and a lower wear-resistant pad, wherein the upper wear-resistant pad may be disposed at the bottom of the anti-drop ring, and the lower wear-resistant pad may be disposed on the step inside the upper connector.

[0022] Furthermore, both the upper and lower wear-resistant pads can be made of hard alloy material; the stator can be made of high-performance rubber material, which generates 50% more torque than standard rubber under the same conditions; the universal joint can be made of high-strength titanium alloy, and the drive shaft can be made of high-strength alloy structural steel.

[0023] Furthermore, the stator can be a rubber bushing, and its inner hole can be set to the shape of a helical curved surface; the rotor can be a hollow rotor, and there is a lead difference between the rotor and the stator to form a helical sealing cavity.

[0024] To achieve the above objectives, the present invention further provides a downhole tool, which may include the aforementioned multiphase flow motor.

[0025] Compared with the prior art, the beneficial effects of the present invention may include at least one of the following:

[0026] (1) The universal joint assembly of the present invention generates large torque and high strength.

[0027] (2) The transmission shaft assembly of the present invention adopts an oil sealing method to improve the service life of the motor bearing.

[0028] (3) The anti-fall assembly of the present invention adopts a wear-resistant and anti-detachment mechanism, which increases construction safety.

[0029] (4) The hollow rotor used in the motor assembly of the present invention has a larger diameter and no limitation on the nozzle size.

[0030] (5) The multiphase flow motor of the present invention has been comprehensively improved and can be applied to complex geological working environments. Attached Figure Description

[0031] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A schematic diagram of the drive shaft assembly of the present invention is shown;

[0033] Figure 2 A three-dimensional structural schematic diagram of the drive shaft assembly of the present invention is shown;

[0034] Figure 3A three-dimensional structural schematic diagram of the upper balance piston of the present invention is shown;

[0035] Figure 4 A three-dimensional structural schematic diagram of the lower balance piston of the present invention is shown;

[0036] Figure 5 A schematic diagram of the multiphase flow motor of the present invention is shown.

[0037] Explanation of key figure labels:

[0038] 1-Drive shaft, 101-Central flow channel; 2-Upper piston assembly, 201-Upper balance piston; 3-Lower piston assembly, 301-Lower balance piston, 302-K oil seal connector, 303-Double convex oil seal; 4-Upper piston sleeve; 5-Positive pressure outer sleeve assembly, 501-L-shaped injection hole; 6-Middle sleeve assembly; 7-Lower piston sleeve, 701-Pressure relief hole; 8-Load ring; 9-Fixing ring; 10-First thrust bearing; 11-Second thrust bearing; 12-Centering device; 13-Upper connector; 14-Anti-drop ring; 15-Anti-drop connecting rod; 16-Stator housing; 17-Stator; 18-Rotor; 19-Universal shaft housing; 20-Universal shaft; 21-Water cap; 22-Upper wear-resistant pad; 23-Lower wear-resistant pad. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. Contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0040] It should be noted that terms such as "first," "second," and "third" are merely for ease of description and distinction, and should not be interpreted as indicating or implying relative importance. Terms such as "up," "down," "front," "back," "left," "right," "inner," and "outer" are merely for ease of description and to establish relative orientations or positional relationships, and do not indicate or imply that the component referred to must have that specific orientation or position.

[0041] Exemplary Example 1

[0042] This exemplary embodiment provides a drive shaft assembly with a hydraulic sealing structure. The following is in conjunction with... Figures 1 to 4 Describe it.

[0043] like Figure 1 and Figure 2As shown, the drive shaft assembly may include: a drive shaft 1, a drive shaft housing, and an upper piston assembly 2, a pressure-bearing assembly, and a lower piston assembly 3 arranged sequentially from top to bottom between the drive shaft 1 and the drive shaft housing.

[0044] The drive shaft 1 may be provided with a central flow channel 101 along the axial direction, which can be used for drilling fluid flow.

[0045] The drive shaft housing can be sleeved on the drive shaft 1 and coaxially arranged with the drive shaft 1. The drive shaft housing may include an upper piston sleeve 4, a positive pressure outer sleeve assembly 5, a middle sleeve assembly 6, and a lower piston sleeve 7 connected sequentially from top to bottom. Here, the connection between the upper piston sleeve 4, the positive pressure outer sleeve assembly 5, the middle sleeve assembly 6, and the lower piston sleeve 7 can be a threaded connection. A first annular cavity is formed between the inner wall of the upper piston sleeve 4, the outer wall of the drive shaft 1, and the top of the positive pressure outer sleeve assembly 5; a second annular cavity is formed between the inner wall of the positive pressure outer sleeve assembly 5, the outer wall of the drive shaft 1, and the top of the middle sleeve assembly 6; and a third annular cavity is formed between the inner wall of the lower piston sleeve 7, the bottom of the middle sleeve assembly 6, and the outer wall of the drive shaft 1. Here, the first annular cavity, the second annular cavity, and the third annular cavity are axially connected. Specifically, the outer wall of the drive shaft 1 between the first annular cavity and the second annular cavity does not form a seal with the inner wall of the positive pressure outer sleeve assembly 5, leaving a certain flow space; the outer wall of the drive shaft 1 between the second annular cavity and the third annular cavity does not form a seal with the inner wall of the middle sleeve assembly 6, leaving a certain flow space.

[0046] The upper piston assembly 2 can be disposed in the first annular cavity and form a dynamic seal in the radial direction; the pressure-bearing assembly can be disposed in the second annular cavity and can withstand the axial load transmitted from the drive shaft housing to the drive shaft 1; and the lower piston assembly 3 can be disposed in the third annular cavity and form a dynamic seal in the radial direction.

[0047] A hydraulic sealing cavity is formed between the upper piston assembly 2, the inner wall of the drive shaft housing, the outer wall of the drive shaft 1, and the lower piston assembly 3. The internal pressure of the hydraulic sealing cavity can balance the pressure at the top of the upper piston assembly 2 and / or the bottom of the lower piston assembly 3.

[0048] Specifically, the hydraulic sealing cavity enables the drive shaft 1 to operate in an oil-sealed environment, which can reduce the impact of cavitation on the drive shaft 1 under multiphase flow conditions and extend the service life of the equipment.

[0049] In this embodiment, as Figures 1 to 4 As shown, the upper piston assembly 2 may include an upper balance piston 201. The lower piston assembly 3 may include a lower balance piston 301, a K-seal connector 302, and a double convex oil seal 303, with the K-seal connector 302 and the double convex oil seal 303 located at the upper and lower ends of the lower balance piston 301, respectively.

[0050] Specifically, the upper balance piston 201 balances the pressure between its lower cavity and the upper cavity of the upper piston assembly 2; the lower balance piston 301 balances the pressure between its upper cavity and the drilling fluid in the lower part of the lower piston assembly 3. The K-seal connector 302 and the double-convex seal 303 ensure the sealing of the bottom of the hydraulic sealing cavity and balance the pressure at the upper and lower ends of the lower balance piston 301. Here, to ensure the upper balance piston 201 can guarantee the sealing of the top of the hydraulic sealing cavity, sealing rings can be installed at both ends of the upper balance piston 201, or the upper balance piston 201 itself can have good sealing performance.

[0051] In this embodiment, as Figure 3 and Figure 4 As shown, both the upper balance piston 201 and the lower balance piston 301 can use rotary seals.

[0052] In this embodiment, as Figure 1 and Figure 2 As shown, the positive pressure outer sleeve assembly 5 may be provided with an L-shaped injection hole 501 communicating with the hydraulic sealing cavity; the lower piston sleeve 7 may be provided with a pressure relief hole 701 communicating with the hydraulic sealing cavity. The liquid in the hydraulic sealing cavity may be hydraulic oil.

[0053] Specifically, after the drive shaft 1 is assembled, tighten the screw of the pressure relief hole 701, inject oil into the hydraulic sealing cavity through the L-shaped injection hole 501, and tighten the screw of the L-shaped injection hole 501 after the oil injection is completed. The upper piston assembly 2 and the lower piston assembly 3 can move freely according to the working conditions of the drive shaft assembly to achieve the balance between the internal pressure and the external pressure of the hydraulic sealing cavity.

[0054] In this embodiment, as Figure 1As shown, the pressure-bearing assembly may include a load ring 8, a retaining ring 9, a first thrust bearing 10, and two second thrust bearings 11. The inner wall of the load ring 8 may have internal threads, and the outer wall of the corresponding drive shaft 1 may have matching external threads. The retaining ring 9 can pass through the load ring 8 to fix the drive shaft 1, preventing axial movement, and the outer wall of the corresponding drive shaft 1 may have a matching fixed mounting position. The two second thrust bearings 11 can be installed at the upper and lower ends of the load ring 8, respectively. The first thrust bearing 10 is installed at the lower end of the second thrust bearings 11. This arrangement of the pressure-bearing assembly ensures that the drive shaft 1 of the drive shaft assembly can only rotate within the drive shaft housing and cannot move axially. The load ring 8, retaining ring 9, first thrust bearing 10, and second thrust bearings 11 are placed between the inner wall of the positive pressure outer sleeve assembly 5, the outer wall of the drive shaft 1, and the top of the middle sleeve assembly 6, forming a second annular cavity, constituting the screw thrust bearing portion. The upper drilling pressure is transmitted to the second thrust bearing 11 through the drive shaft housing, and then to the drive shaft 1 through the load ring 8, the retaining ring 9, and the first thrust bearing 10, thereby realizing the transmission of axial load from the drive shaft housing to the drive shaft 1.

[0055] In this embodiment, as Figure 1 As shown, the drive shaft housing may also include a stabilizer 12, which can be fixedly connected to the outside of the positive pressure outer sleeve assembly 5, the middle sleeve assembly 6 and the lower piston sleeve 7.

[0056] Specifically, the centralizer 12 is connected to the positive pressure outer sleeve assembly 5, the middle sleeve assembly 6, and the lower piston sleeve 7 via threaded connections. The centralizer 12 can straighten the drive shaft assembly, ensuring that the equipment is in its normal operating position.

[0057] In this embodiment, the drive shaft assembly may further include a radial bearing and a thrust bearing (not shown in the figure), both of which can be sealed in a hydraulically sealed cavity.

[0058] Specifically, radial and thrust bearings are high-performance. Because the external drilling fluid and the internal pressure of the hydraulic seal cavity are balanced, the thrust bearing does not need to balance the fluid thrust load. At the same time, the high-performance radial bearing is sufficient to bear the radial alternating load generated during drilling.

[0059] Exemplary Example 2

[0060] This exemplary embodiment provides a multiphase flow motor, which will be described below in conjunction with... Figure 5 Describe it.

[0061] The multiphase flow motor may include, in sequence from top to bottom, an anti-drop assembly, a motor assembly, a universal joint assembly, and the drive shaft assembly of the exemplary embodiment 1 described above.

[0062] like Figure 5As shown, the anti-drop assembly may include an upper connector 13, an anti-drop ring 14, and an anti-drop connecting rod 15. A limiting element (not shown in the figure) may be provided on the inner wall of the upper connector 13. The anti-drop ring 14 may be provided inside the upper connector 13 and above the limiting element. The upper end of the anti-drop connecting rod 15 passes through the limiting element and is connected to the anti-drop ring 14. The connection method may be a threaded connection.

[0063] The motor assembly may include a stator, a rotor, and a stator housing 16. The stator and rotor may include a stator 17 and a rotor 18. The stator 17 is fixed to the inner wall of the stator housing 16, and the rotor 18 is located inside the stator 17 and meshes with the stator 17. When the motor assembly is working, the rotor 18 performs planetary motion inside the stator 17. The upper end of the rotor 18 is a free end and is connected to the lower end of the anti-drop connecting rod 15. The upper end of the stator housing 16 is connected to the lower end of the upper connector 13, and the connection method may be a threaded connection.

[0064] The universal joint assembly may include a universal joint housing 19 and a universal joint 20. The universal joint 20 may be disposed within the universal joint housing 19. The upper end of the universal joint 20 is fixedly connected to the lower end of the rotor 18, and the lower end of the universal joint 20 is connected to the upper end of the drive shaft 1. The connection method can be an API drill rod threaded connection. The upper end of the universal joint housing 19 is fixedly connected to the lower end of the stator housing 16, and the lower end of the universal joint housing 19 is fixedly connected to the upper end of the drive shaft housing. The fixed connection method can be a threaded connection.

[0065] In this embodiment, as Figure 5 As shown, the lower end of the universal joint 20 can be connected to the upper end of the drive shaft 1 via a water cap 21, and the upper end of the drive shaft 1 can be connected to the water cap 21 via a drill pipe thread. The water cap 21 can change the flow direction of the drilling fluid flowing through the universal joint 20 and then enter the central flow channel 101 of the drive shaft 1.

[0066] In this embodiment, as Figure 5 As shown, the anti-drop assembly may also include an upper wear-resistant pad 22 and a lower wear-resistant pad 23. The upper wear-resistant pad 22 can be installed at the bottom of the anti-drop ring 14, and the lower wear-resistant pad 23 can be installed on the step inside the upper connector 13. In the event of a housing breakage or disengagement due to abnormal reasons, the anti-drop assembly prevents the device from falling and simultaneously increases the pump pressure, allowing the ground to detect the problem promptly and prevent accidents. The upper connector 13, anti-drop ring 14, anti-drop connecting rod 15, upper wear-resistant pad 22, and lower wear-resistant pad 23 form a wear-resistant and anti-disengagement mechanism, which increases construction safety.

[0067] Specifically, when the housing breaks or disengages due to abnormal reasons, the anti-drop ring 14 and the upper wear-resistant pad 22 fall from the limiting member and are placed at the step inside the upper connector 13. The anti-drop ring 14 presses against the step of the upper connector 13, thus preventing it from falling. When the anti-drop ring 14 comes into contact with the upper connector 13, the upper wear-resistant pad 22 and the lower wear-resistant pad 23 will play a wear-resistant role, preventing the anti-drop ring 14 from wearing.

[0068] In this embodiment, both the upper wear-resistant pad 22 and the lower wear-resistant pad 23 can be made of hard alloy material; the stator 17 can be made of high-performance rubber material, which generates 50% more torque than standard rubber under the same conditions. The universal joint 20 can be made of high-strength titanium alloy, and the drive shaft 1 can be made of high-strength alloy structural steel.

[0069] High-strength titanium alloys possess mechanical properties comparable to high-quality alloy structural steel, while having a lower elastic modulus. Therefore, they can achieve flexing on a smaller scale, withstand higher torque output, and perfectly transmit power without any wear issues, resulting in an extremely long service life.

[0070] In this embodiment, the stator 17 can be a rubber bushing, and its inner hole can be set to the shape of a helical curved surface; the rotor 18 can be a hollow rotor, and there is a lead difference between it and the stator 17 to form a helical sealing cavity.

[0071] Specifically, the stator 17 and the rotor 18 mesh with each other, forming a spiral sealed cavity by the difference in their leads to complete the energy conversion. The rotor 18 is a hollow rotor with nozzles, which can provide a larger fluid passage.

[0072] To better understand the above exemplary embodiments of the present invention, the following is in conjunction with... Figure 1 and Figure 5 The working process of the present invention will be further explained.

[0073] The path of drilling fluid flow through a multiphase flow motor includes, but is not limited to, the following:

[0074] Multiphase drilling fluid flows in from above the upper connector 13, passes through the spiral sealing cavity of the stator rotor and the nozzle of the hollow rotor, then passes through the channel formed by the universal joint 20 and the universal joint housing 19, and then enters the central flow channel 101 of the drive shaft 1 through the water cap 21 connected to the lower end of the universal joint 20. Finally, it flows out from the lower end of the drive shaft 1. A small portion of the drilling fluid enters the upper part of the first annular cavity of the drive shaft assembly, but because the upper piston assembly 2 does not form a fluid channel, it blocks this small portion of the drilling fluid from flowing downward.

[0075] Exemplary Example 3

[0076] This exemplary embodiment provides a downhole tool, which is described below.

[0077] Downhole tools may include the multiphase flow motor of the exemplary embodiment 2 described above.

[0078] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A transmission shaft assembly with a hydraulic sealing structure, characterized in that, The drive shaft assembly includes: a drive shaft, a drive shaft housing, and, from top to bottom, an upper piston assembly, a pressure-bearing assembly, and a lower piston assembly, which are sequentially arranged between the drive shaft and the drive shaft housing. A central flow channel is provided on the drive shaft along the axial direction; The drive shaft housing is sleeved on the outside of the drive shaft and coaxially arranged, and includes an upper piston sleeve, a positive pressure outer sleeve assembly, a middle sleeve assembly, and a lower piston sleeve connected sequentially from top to bottom; a first annular cavity is formed between the inner wall of the upper piston sleeve, the outer wall of the drive shaft, and the top of the positive pressure outer sleeve assembly; a second annular cavity is formed between the inner wall of the positive pressure outer sleeve assembly, the outer wall of the drive shaft, and the top of the middle sleeve assembly; and a third annular cavity is formed between the inner wall of the lower piston sleeve, the bottom of the middle sleeve assembly, and the outer wall of the drive shaft; the first annular cavity, the second annular cavity, and the third annular cavity are axially connected. The upper piston assembly is disposed in the first annular cavity and forms a dynamic seal in the radial direction; the pressure-bearing assembly is disposed in the second annular cavity and is capable of bearing the axial load transmitted from the drive shaft housing to the drive shaft; the lower piston assembly is disposed in the third annular cavity and forms a dynamic seal in the radial direction. A hydraulic sealing cavity is formed between the upper piston assembly, the inner wall of the drive shaft housing, the outer wall of the drive shaft, and the lower piston assembly. The internal pressure of the hydraulic sealing cavity can balance the pressure at the top of the upper piston assembly and / or the bottom of the lower piston assembly. The pressure-bearing assembly includes a load ring, a retaining ring, a first thrust bearing, and two second thrust bearings, wherein... The load ring is provided with an internal thread, and the outer wall of the transmission shaft at the corresponding position is provided with a matching external thread; The retaining ring can pass through the load ring to fix the drive shaft, and the outer wall of the drive shaft at the corresponding position has a matching fixing mounting position; The two second thrust bearings are respectively installed at the upper and lower ends of the load ring; The first thrust bearing is installed at the lower end of the second thrust bearing.

2. The transmission shaft assembly with a hydraulic sealing structure according to claim 1, characterized in that, The upper piston assembly includes an upper balance piston; The lower piston assembly includes a lower balance piston, a K-seal connector, and a double convex oil seal, with the K-seal connector and the double convex oil seal located at the upper and lower ends of the lower balance piston, respectively.

3. The transmission shaft assembly with a hydraulic sealing structure according to claim 2, characterized in that, Both the upper and lower balance pistons use rotary seals.

4. The transmission shaft assembly with a hydraulic sealing structure according to claim 1, characterized in that, The positive pressure outer sleeve assembly is provided with an L-shaped injection hole that communicates with the hydraulic sealing cavity; the lower piston sleeve is provided with a pressure relief hole that communicates with the hydraulic sealing cavity; The liquid inside the hydraulic sealing cavity is hydraulic oil.

5. The transmission shaft assembly with a hydraulic sealing structure according to claim 1, characterized in that, The drive shaft housing also includes a centralizer, which is fixedly connected to the outside of the positive pressure outer sleeve assembly, the middle sleeve assembly, and the lower piston sleeve.

6. The drive shaft assembly with a hydraulic sealing structure according to claim 1, characterized in that, The drive shaft assembly also includes a radial bearing and a thrust bearing, both of which are sealed within the hydraulic sealing cavity.

7. A multiphase flow motor, characterized in that, The multiphase flow motor includes, from top to bottom, an anti-drop assembly, a motor assembly, a universal joint assembly, and a transmission shaft assembly as described in any one of claims 1 to 6, wherein... The anti-drop assembly includes an upper connector, an anti-drop ring, and an anti-drop connecting rod. A limiting member is provided on the inner wall of the upper connector. The anti-drop ring is disposed inside the upper connector and located above the limiting member. The upper end of the anti-drop connecting rod passes through the limiting member and is connected to the anti-drop ring. The motor assembly includes a stator, a rotor, and a stator housing. The stator and rotor include a stator and a rotor. The stator is fixed to the inner wall of the stator housing, and the rotor is located inside the stator and meshes with the stator. The upper end of the rotor is connected to the lower end of the anti-drop connecting rod, and the upper end of the stator housing is connected to the lower end of the upper connector. The universal joint assembly includes a universal joint housing and a universal joint. The universal joint is disposed in the universal joint housing. The upper end of the universal joint is fixedly connected to the lower end of the rotor, and the lower end of the universal joint is connected to the upper end of the drive shaft. The upper end of the universal joint housing is fixedly connected to the lower end of the stator housing, and the lower end of the universal joint housing is fixedly connected to the upper end of the drive shaft housing.

8. The multiphase flow motor according to claim 7, characterized in that, The lower end of the universal joint is connected to the upper end of the drive shaft via a water cap. The water cap can change the flow direction of the drilling fluid flowing through the universal joint and then enter the central flow channel of the drive shaft.

9. The multiphase flow motor according to claim 7, characterized in that, The anti-drop assembly also includes an upper wear-resistant pad and a lower wear-resistant pad. The upper wear-resistant pad is disposed at the bottom of the anti-drop ring, and the lower wear-resistant pad is disposed on the step inside the upper connector.

10. The multiphase flow motor according to claim 9, characterized in that, Both the upper and lower wear-resistant pads are made of hard alloy material; The stator is made of high-performance rubber material; The universal joint is made of high-strength titanium alloy, and the drive shaft is made of high-strength alloy structural steel.

11. The multiphase flow motor according to claim 10, characterized in that, The stator is a rubber bushing, and its inner hole is set in the shape of a helical curved surface; The rotor is a hollow rotor, and a lead difference exists between it and the stator to form a spiral sealed cavity.

12. A downhole tool, characterized in that, The downhole tool includes a multiphase flow motor as described in any one of claims 7 to 11.

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