Downhole efficient hydraulic pump

Abstract

The invention relates to an underground efficient hydraulic pump, and belongs to the technical field of oil and gas well lifting equipment, the underground efficient hydraulic pump comprises an external connection cylinder, a central pipe, a power pump cylinder, a lifting pump cylinder and a drainage and mining connection cylinder, and an upward flow channel and a downward flow channel which are communicated with high-pressure power liquid are formed in the external connection cylinder; the power pump cylinder forms a pump cavity A above the power piston and forms a pump cavity B below the power piston, and the downstream runner is communicated with the pump cavity A; a liquid inlet hole a communicated with the upstream runner is formed in the pump cavity B; the energy recovery assembly is located in the pump cavity A and used for enabling the pump cavity A to communicate with the pump cavity B when the power piston ascends to the highest position, and high-pressure power liquid is injected into the pump cavity A, so that the energy utilization rate of the pump body is increased; and the lower buffering assembly is located in the pump cavity B and installed at the bottom of the power piston and the top of the lifting pump cylinder, and the lower buffering assembly is used for relieving impact generated when the power piston descends to the lowest position, so that the plunger reversing impact is reduced, and meanwhile the use range is widened.

Description

Technical Field

[0001] This application relates to the field of oil and gas well lifting equipment technology, and in particular to a downhole high-efficiency hydraulic pump. Background Technology

[0002] Existing hydraulic pumps often require customized pump models to handle different oil and gas wells (such as different production rates and depths), resulting in long development cycles, high costs, and complex spare parts management. At the same time, traditional pumps generally suffer from low energy utilization and large plunger reversal impact.

[0003] Although some design improvements exist, most are limited to optimizing a single pump type and fail to achieve standardization and serialization of core components from the perspective of product platform. They also fail to meet diverse market demands quickly and economically while ensuring high performance. Summary of the Invention

[0004] In order to design a hydraulic pump that improves pump body energy utilization, reduces plunger reversing impact, and expands the application range, this application provides a downhole high-efficiency hydraulic pump.

[0005] This application provides a technical solution for a downhole high-efficiency hydraulic pump as follows: A downhole high-efficiency hydraulic pump includes an external casing, a central pipe, a power pump casing, a lifting pump casing, and a discharge casing. The central tube is located inside the outer cylinder, and the top of the central tube is fixedly sealed to the outer cylinder. The outer cylinder has an upward flow channel for connecting high-pressure power fluid and a downward flow channel for connecting low-pressure power fluid.

[0006] The power pump cylinder is located inside the outer cylinder, and the upper end of the power pump cylinder is connected to the central pipe. The lifting pump cylinder is located inside the outer cylinder, and the upper end of the lifting pump cylinder is connected to the bottom end of the power pump cylinder. The drainage and extraction connecting cylinder is sealed to the bottom of the outer cylinder and the bottom end of the lifting pump cylinder. The power pump cylinder has a first chamber that communicates with the downflow channel, and an annular second chamber is formed between the power pump cylinder and the outer connecting cylinder. The second chamber is connected to the upflow channel. The lifting pump cylinder has a third chamber that communicates with the first chamber, and an annular fourth chamber is formed between the lifting pump cylinder and the outer connecting cylinder. The fourth chamber is connected to the second chamber. The discharge connection cylinder has a discharge channel that connects the downhole and the third chamber.

[0007] The piston assembly includes a detachably connected power piston and a lifting piston. The power piston is installed inside the power pump cylinder and is slidably and sealed to it. The lifting piston is installed inside the lifting pump cylinder and is slidably and sealed to it. The power pump cylinder forms a pump chamber above the power piston and a pump chamber B below the power piston. The downward flow channel is connected to the first flow channel through the pump chamber A. The lower part of the power pump cylinder is provided with an inlet hole a, which connects the pump chamber B and the second chamber. The upward flow channel is connected to the pump chamber B through the second chamber and the inlet hole a. The energy recovery component is located inside pump chamber A and installed at the top of the power piston and the bottom of the central tube. The energy recovery component is used to connect pump chamber A and pump chamber B when the power piston rises to the highest position, and high-pressure power fluid is injected into pump chamber A. The lower buffer assembly is located inside pump chamber B and is installed at the bottom of the power piston and the top of the lifting pump cylinder. The lower buffer assembly is used to reduce the impact when the power piston descends to its lowest position.

[0008] By adopting the above technical solution, when the power piston rises to its highest point, pump chamber B is filled with high-pressure power fluid. The energy recovery assembly connects pump chamber A and pump chamber B, allowing some of the high-pressure power fluid to enter pump chamber B, thus mitigating the impact of the power piston's upward movement and simultaneously achieving energy recovery. When the power piston descends, the high-pressure power fluid in pump chamber B overflows through inlet a. The lower buffer assembly further mitigates the impact of the power piston's downward movement. Furthermore, the detachable connection between the power piston and the lifting piston allows for the connection of lifting pistons with different inner diameters to suit various operating conditions.

[0009] Optionally, the power piston has an axially penetrating first flow channel, and the lifting piston has an axially penetrating second flow channel, with the first flow channel and the second flow channel connected. The lifting pump cylinder forms a pump chamber C below the lifting piston. An upstream dynamic drain valve is installed on the lifting piston at the second flow channel. The upstream dynamic drain valve is unidirectionally connected from the pump chamber C to the second flow channel. A downstream dynamic drain valve is installed in the drainage channel. The downstream dynamic drain valve is unidirectionally connected from the drainage channel to the pump chamber C.

[0010] Optionally, the energy recovery assembly includes a pressure relief sleeve, a pressure relief spring, and a pressure relief ring; The power piston has a pressure relief channel that connects the first flow channel and the pump chamber B. Multiple pressure relief channels are arranged circumferentially around the axis of the power piston. The upper port of the pressure relief channel is connected to the first flow channel. The pressure relief sleeve is located inside the first flow channel and is axially and slidably sealed to the power piston; the two ends of the pressure relief spring are respectively fixed to the bottom of the pressure relief sleeve and the top of the lifting piston; the top of the pressure relief spring is located below the upper port of the pressure relief channel. The pressure relief ring is located inside pump chamber A and installed at the lower end of the central tube. An upper pressure relief chamber is formed between the outer ring wall of the pressure relief ring and the inner wall of the power pump cylinder. The pressure relief ring and the pressure relief sliding sleeve are arranged coaxially. The downward flow channel passes through the inner ring cavity of the pressure relief ring and communicates with pump chamber A.

[0011] Optionally, the outer diameter of the pressure relief ring is between the inner and outer diameters of the pressure relief sleeve; the height of the pressure relief ring is greater than the distance from the upper port of the pressure relief channel to the upper end face of the power piston.

[0012] Optionally, the lower buffer assembly includes a buffer boss and a lower buffer ring; The buffer boss is installed on the lower end face of the power piston, and multiple pressure relief channels are arranged around the buffer boss, with the first flow channel penetrating the buffer boss. The lower buffer ring is installed at the upper end of the lifting pump cylinder and located in the pump chamber B. The lower buffer ring, the buffer boss, and the power piston are all coaxially arranged. The inner diameter of the lower buffer ring is larger than the outer diameter of the buffer boss. The inner ring wall of the lower buffer ring forms a lower buffer cavity for the buffer boss to insert into.

[0013] Optionally, the upper end of the lifting piston is inserted into the first flow channel and is threadedly sealed to the power piston. The buffer boss has a through hole for the lifting piston to pass through. The plug segments of the lifting piston in the first flow channel and the plug segments in the buffer boss are arranged in a stepped manner. The inner diameter of the first flow channel is larger than the inner diameter of the second flow channel.

[0014] Optionally, multiple sealing structures are provided between the power piston and the power pump cylinder, and between the lifting piston and the lifting pump cylinder, with the multiple sealing structures arranged at intervals along the axis of the power piston.

[0015] Optionally, the sealing structure includes an annular sealing groove formed on the outer peripheral wall of the power piston and a sealing ring strip located in the sealing groove; the sealing ring strip has a "Y" shaped cross-section and abuts against the inner wall of the power pump cylinder and the groove wall of the sealing groove.

[0016] Optionally, the inlet hole a is an oblique hole and is arranged inclined downwards along the direction from pump chamber B to the second chamber. The bottom end of the inlet hole a at the port of pump chamber B is flush with the top end of the lifting pump cylinder. The top end of the inlet hole a at the port of pump chamber B is higher than the upper end face of the lower buffer ring. The top end of the inlet hole a at the port of the second chamber is lower than the upper end face of the lower buffer ring.

[0017] In summary, this application includes at least one of the following beneficial technical effects of downhole high-efficiency hydraulic pumps: 1. When the power piston reaches its highest point, pump chamber B is filled with high-pressure hydraulic fluid. Pump chambers A and B are connected via an energy recovery assembly, allowing some of the high-pressure hydraulic fluid to enter pump chamber B, thus mitigating the impact of the upward movement of the power piston and simultaneously recovering energy. When the power piston moves downward, the high-pressure hydraulic fluid in pump chamber B overflows through inlet a. The lower buffer assembly further reduces the impact of the downward movement of the power piston. Furthermore, the detachable connection between the power piston and the lifting piston allows for the connection of lifting pistons with different inner diameters to suit various operating conditions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the downhole high-efficiency hydraulic pump in the embodiments of this application.

[0019] Figure 2 This is a schematic diagram of the piston assembly in an embodiment of this application.

[0020] Figure 3 This is an enlarged schematic diagram of part A in the embodiments of this application.

[0021] Figure 4 This is an enlarged schematic diagram of part B in the embodiments of this application.

[0022] Figure 5 This is a schematic diagram showing the connection between the control component and the pump assembly in an embodiment of this application.

[0023] In the diagram: 1. Pump cylinder assembly; 11. External connecting cylinder; 12. Central pipe; 121. Upward flow channel; 122. Downward flow channel; 13. Power pump cylinder; 14. Lifting pump cylinder; 15. Drainage connecting cylinder; 151. Drainage channel; 16. First chamber; 161. Pump chamber A; 162. Pump chamber B; 163. Inlet a; 164. Upper pressure relief chamber; 17. Second chamber; 18. Third chamber; 181. Pump chamber C; 19. Fourth chamber; 2. Live 21. Plug assembly; 21. Power piston; 211. First flow channel; 212. Pressure relief channel; 22. Lifting piston; 221. Second flow channel; 3. Energy recovery assembly; 31. Pressure relief sleeve; 32. Pressure relief spring; 33. Pressure relief ring; 4. Lower buffer assembly; 41. Buffer boss; 42. Lower buffer ring; 421. Lower buffer chamber; 5. Upstream moving drain valve; 6. Downstream moving drain valve; 7. Sealing structure; 71. Sealing groove; 72. Sealing ring strip. Detailed Implementation

[0024] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.

[0025] Note: Due to the attached Figure 1 The number of chambers and holes is relatively large. To avoid confusion in labeling, the leads for the holes and chambers are not distinguished when labeling the higher-level technical features. Figures 2 to 4To facilitate differentiation, the leads for marking the upper-level technical features, holes, and chambers are all arrows for easy understanding.

[0026] This application discloses a high-efficiency downhole hydraulic pump. (Refer to...) Figure 1 and Figure 2 It includes a pump cylinder assembly 1, a piston assembly 2, an energy recovery assembly 3, and a lower buffer assembly 4.

[0027] The pump cylinder assembly 1 includes an outer cylinder 11, a central pipe 12, a power pump cylinder 13, a lifting pump cylinder 14, and a drainage and extraction connection cylinder 15.

[0028] The central tube 12 is located inside the outer tube 11. The top of the central tube 12 is fixed and sealed to the outer tube 11. The outer tube 11 has an upward flow channel 121 for connecting high-pressure power fluid and a downward flow channel 122 for connecting low-pressure power fluid.

[0029] The power pump cylinder 13 is located inside the outer connecting cylinder 11, and its upper end is threadedly connected to and sealed to the bottom of the central tube 12. The lifting pump cylinder 14 is located inside the outer connecting cylinder 11, and its upper end is threadedly connected to and sealed to the bottom end of the power pump cylinder 13. The discharge connecting cylinder 15 is threadedly connected to and sealed to the bottom of the outer connecting cylinder 11 and the bottom end of the lifting pump cylinder 14.

[0030] The power pump cylinder 13 has a first chamber 16 communicating with the downflow channel 122. A second annular chamber 17 is formed between the power pump cylinder 13 and the outer connecting cylinder 11, and the second chamber 17 is connected to the upflow channel 121. The lifting pump cylinder 14 has a third chamber 18 communicating with the first chamber 16. A fourth annular chamber 19 is formed between the lifting pump cylinder 14 and the outer connecting cylinder 11, and the fourth chamber 19 is connected to the second chamber 17. The drainage connection cylinder 15 forms a drainage channel 151 connecting the downhole and the third chamber 18.

[0031] The inner diameter of the first chamber 16 is larger than the inner diameter of the third chamber 18.

[0032] In addition, piston assembly 2 includes power piston 21 and lifting piston 22.

[0033] The power piston 21 is installed inside the power pump cylinder 13 and is slidably and sealed to it. The lifting piston 22 is installed inside the lifting pump cylinder 14 and is slidably and sealed to it. The upper end of the lifting piston 22 is threadedly connected to the power piston 21 and sealed.

[0034] The power piston 21 has an axially penetrating first flow channel 211, and the lifting piston 22 has an axially penetrating second flow channel 221. The first flow channel 211 and the second flow channel 221 are connected.

[0035] The power pump barrel 13 forms a pump chamber A161 above the power piston 21, and a pump chamber B162 below the power piston 21. The downward flow channel 122 communicates with the first flow channel 211 through the pump chamber A161. The lower part of the power pump barrel 13 is provided with an inlet hole a163, which connects the pump chamber B162 and the second chamber 17, so that the upward flow channel 121 communicates with the pump chamber B162 through the second chamber 17 and the inlet hole a163.

[0036] The lifting pump cylinder 14 forms a pump chamber C181 below the lifting piston 22. An upstream movable drain valve 5 is installed at the second flow channel 221 on the lifting piston 22, and the upstream movable drain valve 5 is unidirectionally connected from the pump chamber C181 to the second flow channel 221. A downstream movable drain valve 6 is installed in the drainage channel 151, and the downstream movable drain valve 6 is unidirectionally connected from the drainage channel 151 to the pump chamber C181.

[0037] In addition, the energy recovery component 3 includes a pressure relief sleeve 31, a pressure relief spring 32, and a pressure relief ring 33.

[0038] The power piston 21 has a pressure relief channel 212 that connects the first flow channel 211 and the pump chamber B162. Multiple pressure relief channels 212 are arranged circumferentially around the axis of the power piston 21. The pressure relief channels 212 are arranged in an inverted "L" shape, and the upper port of the pressure relief channel 212 is connected to the first flow channel 211.

[0039] The pressure relief sleeve 31 is located within the first flow channel 211 and is axially and slidably sealed to the power piston 21. The pressure relief spring 32 is located within the first flow channel 211, with its two ends fixed to the bottom of the pressure relief sleeve 31 and the top of the lifting piston 22, respectively. The top of the pressure relief spring 32 is located below the upper port of the pressure relief channel 212, so that the pressure relief sleeve 31 can cover the upper port of the pressure relief channel 212. The pressure relief ring 33 is located within the pump chamber A161 and is installed at the lower end of the central tube 12. The downward flow channel 122 passes through the inner ring cavity of the pressure relief ring 33 and communicates with the pump chamber A161. An upper pressure relief chamber 164 is formed between the outer ring wall of the pressure relief ring 33 and the inner wall of the power pump cylinder 13.

[0040] The pressure relief ring 33 and the pressure relief sleeve 31 are coaxially arranged. The outer diameter of the pressure relief ring 33 is between the inner and outer diameters of the pressure relief sleeve 31, so that when the power piston 21 rises to its highest position, the pressure relief ring 33 can push the pressure relief sleeve 31 downward relative to the power piston 21. The height of the pressure relief ring 33 is greater than the distance from the upper port of the pressure relief channel 212 to the upper end face of the power piston 21, so that the pressure relief sleeve 31 can slide downward below the upper port of the pressure relief channel 212.

[0041] When the power piston 21 has not risen to its highest position, the outer peripheral wall of the pressure relief sleeve 31 covers the upper port of the pressure relief channel 212, and the upper end of the pressure relief sleeve 31 is flush with the upper end of the power piston 21.

[0042] When the power piston 21 moves to the highest position, the pressure relief ring 33 is inserted into the first flow channel 211 and pushes the pressure relief sleeve 31 to compress the pressure relief spring 32 until the pressure relief sleeve 31 moves away from the upper port of the pressure relief channel 212. The pressure relief channel 212 connects the pump chamber B162 and the upper pressure relief chamber 164. The upper pressure relief chamber 164 is part of the pump chamber A161. That is, at this time, the pump chamber A161 and the pump chamber B162 are connected for pressure relief, so that the pressure of the pump chamber A161 and the pump chamber B162 reaches balance.

[0043] During the aforementioned pressure relief process, a portion of the high-pressure hydraulic fluid flows from pump chamber B162 into pump chamber A161, achieving energy recovery. Furthermore, as the high-pressure hydraulic fluid surges into the upper pressure relief chamber 164, it also buffers the upward movement of the power piston 21, achieving a dual effect of energy recovery and upward buffering. This makes the hydraulic pump more efficient and energy-saving while also protecting the piston assembly 2 and extending its service life.

[0044] In addition, the lower buffer assembly 4 includes a buffer boss 41 and a lower buffer ring 42.

[0045] The buffer boss 41 is installed on the lower end face of the power piston 21 and is integrally formed with the power piston 21. Multiple pressure relief channels 212 are arranged around the buffer boss 41, and the first flow channel 211 passes through the buffer boss 41, so that the buffer boss 41 is arranged in a ring.

[0046] The lower buffer ring 42 is installed at the upper end of the lifting pump cylinder 14 and located in the pump chamber B162. The lower buffer ring 42, the buffer boss 41, and the power piston 21 are all coaxially arranged. The inner diameter of the lower buffer ring 42 is larger than the outer diameter of the buffer boss 41. The inner ring wall of the lower buffer ring 42 forms a lower buffer cavity 421 for the buffer boss 41 to be inserted.

[0047] When the power piston 21 moves downward, the pressure inside the pump barrel B increases, and the high-pressure power fluid inside the pump barrel B flows back to the second chamber 17 through the inlet hole a163. Some of the high-pressure power fluid will accumulate in the lower buffer chamber 421. As the buffer boss 41 moves down to the lower buffer chamber 421, the pressure of the liquid accumulated in the lower buffer chamber 421 gradually increases because it cannot be discharged in time, thereby reducing the impact when the power piston 21 moves downward, protecting the piston assembly 2, and extending the service life of the piston assembly 2.

[0048] Furthermore, the height of the lower buffer ring 42 is greater than or equal to the thickness of the buffer boss 41. This allows the buffer boss 41 to move down into the lower buffer ring 42 while reducing the contact force with the lifting pump cylinder 14, further mitigating the impact when the power piston 21 moves downward.

[0049] Reference Figure 1 and Figure 2 The upper end of the lifting piston 22 is inserted into the first flow channel 211 and is threadedly sealed to the power piston 21. A through hole is provided on the buffer boss 41 for the lifting piston 22 to pass through. The plug sections of the lifting piston 22 located in the first flow channel 211 and the plug sections located in the buffer boss 41 are arranged in a stepped manner to facilitate control of the connection length between the lifting piston 22 and the power piston 21 and to enhance the connection strength between them. Therefore, the inner diameter of the first flow channel 211 is larger than the inner diameter of the second flow channel 221.

[0050] The difference between different models and sizes of lifting piston 22 is that they have the same outer diameter but different inner diameters. Therefore, the detachable connection between the power piston 21 and the lifting piston 22 in this application allows the power piston 21 to be matched with different types of lifting piston 22.

[0051] In this embodiment, if the nominal diameter of the power piston 21 is 70 mm, it can be combined with lifting pistons 22 with nominal diameters of 38 mm, 44 mm, 51 mm, and 57 mm to form a pump set. Different pump set combinations have different displacements and lifting capacities to adapt to different oil and gas well operating conditions.

[0052] Because the cross-sectional area of ​​the power piston 21 is fixed, when combined with a smaller diameter lifting piston 22 (e.g., 38 mm), the resulting pump assembly has a higher output pressure but a smaller displacement, suitable for deep wells or heavy oil wells. When combined with a larger diameter lifting piston 22 (e.g., 57 mm), the resulting pump assembly has a larger displacement but a lower output pressure, suitable for shallow to medium-yield wells with higher production. This combination allows for the coverage of a wide range of applications using only a few standardized modules.

[0053] Reference Figure 1 and Figure 2 In order to extend the service life and sealing performance of the power piston 21 and the lifting piston 22, multiple sealing structures 7 are provided between the power piston 21 and the power pump cylinder 13, and between the lifting piston 22 and the lifting pump cylinder 14. The multiple sealing structures 7 are arranged at intervals along the axis of the power piston 21 to form a gap seal to improve the sealing performance of the pump cylinder assembly 1 and the piston assembly 2.

[0054] The sealing structure 7 includes a sealing groove 71 formed on the outer peripheral wall of the power piston 21 and a sealing ring 72 located within the sealing groove 71. The sealing groove 71 is arranged in a ring shape, and the sealing ring 72 has a "Y" shaped cross-section with three ends. The bottom end of the sealing ring 72 abuts against the bottom of the sealing groove 71.

[0055] For the sealing ring 72 mounted on the power piston 21, its upwardly inclined ends abut against the groove wall of the sealing groove 71 and the inner wall of the power pump cylinder 13, respectively. For the sealing ring 72 mounted on the lifting piston 22, its upwardly inclined ends abut against the groove wall of the sealing groove 71 and the inner wall of the lifting pump cylinder 14, respectively. This enhances the sealing performance of the first chamber 16 and the third chamber 18.

[0056] Because impurities may accumulate inside the hydraulic pump, in order to further collect and clean these accumulated impurities and mitigate the situation where impurities entering the first chamber 16 accelerate the wear of the power piston 21, refer to... Figure 1 and Figure 4 The inlet hole a163 is an oblique hole and is arranged inclined downwards along the direction from pump chamber B162 to the second chamber 17, that is, the inlet hole a163 is inclined towards the fourth chamber 19. At this time, pump chamber B162 is connected to the second chamber 17 and the fourth chamber 19 through the inlet hole a163.

[0057] The liquid inlet a163 is located at the bottom of the port of pump chamber B162 and is flush with the top of the lifting pump cylinder 14. The top of the liquid inlet a163 is located at the top of the port of pump chamber B162 and is higher than the upper end face of the lower buffer ring 42. The top of the liquid inlet a163 is located at the top of the port of the second chamber 17 and is lower than the upper end face of the lower buffer ring 42.

[0058] When the power piston 21 moves upward, high-pressure power fluid is injected into the upward flow channel 121. As the high-pressure power fluid enters the pump chamber B162 through the second chamber 17, the fourth chamber 19, and the inlet hole a163, impurities in the high-pressure power fluid will be deposited in the fourth chamber 19. The high-pressure power fluid that overflows from the fourth chamber 19 to the second chamber 17 will be injected into the pump chamber B162 to push the power piston 21 upward.

[0059] When the power piston 21 moves downward, due to the inclined arrangement of the inlet hole a163, the impurities in the pump chamber B162 will enter the fourth chamber 19 during the process of the high-pressure power fluid flowing from the pump chamber B162 to the second chamber 17, so as to maintain the environment inside the pump chamber B162.

[0060] Reference Figure 1 In order to enable the hydraulic pump of this application to simultaneously meet the working environment of both diameter and horizontal wells, the downstream dynamic discharge valve 6 and the upstream dynamic discharge valve 5 have the same structure and are both one-way valves.

[0061] This design allows the downhole raw fluid to flow only from the downstream dynamic drain valve 6 into the pump chamber C181 and then through the upstream dynamic drain valve 5 into the second flow channel 221, thus making it suitable for both diameter and horizontal well working environments and expanding the applicability of the hydraulic pump of this application.

[0062] The implementation principle of a downhole high-efficiency hydraulic pump in Embodiment 1 of this application is as follows: When piston assembly 2 moves upward: First, high-pressure power fluid is injected into the upward flow channel 121. The high-pressure power fluid enters the pump chamber B162 through the second chamber 17, the fourth chamber 19, and the inlet hole a163. Impurities in the high-pressure power fluid remain in the fourth chamber 19. The pump chamber B162 is filled with high-pressure power fluid. The power piston 21 drives the lifting piston 22 to move upward together. The liquid in the pump chamber A161 enters the surface production pool. The pressure in the pump chamber C181 decreases, and the downstream dynamic discharge valve 6 opens, allowing the downhole raw fluid to enter the pump chamber C181.

[0063] As the power piston 21 rises to its highest point, the pressure relief ring 33 inserts into the first flow channel 211 and pushes the pressure relief sleeve 31 to compress the pressure relief spring 32 until the pressure relief sleeve 31 moves away from the upper port of the pressure relief channel 212. The pressure relief channel 212 connects the pump chamber B162 and the upper pressure relief chamber 164. The upper pressure relief chamber 164 is part of the pump chamber A161. At this time, the pump chamber A161 and the pump chamber B162 are connected for pressure relief, so that the pressure of the pump chamber A161 and the pump chamber B162 reaches a balance. While realizing energy recovery, as the high-pressure power fluid flows into the upper pressure relief chamber 164, it can also buffer the upward movement of the power piston 21, realizing the dual effect of energy recovery and upward buffering. This makes the hydraulic pump more efficient and energy-saving, while also protecting the piston assembly 2 and extending the service life of the piston assembly 2.

[0064] When piston assembly 2 descends, low-pressure power fluid is injected into the descending flow channel 122. The low-pressure power fluid enters pump chamber A161, and power piston 21 drives lifting piston 22 to descend together. The upstream dynamic discharge valve 5 opens, and the downhole raw fluid in pump chamber C181 enters the second flow channel 221. At this time, high-pressure power fluid in pump chamber B162 overflows through inlet hole a163. Some high-pressure power fluid will accumulate in the lower buffer chamber 421. As the buffer boss 41 moves down to the lower buffer chamber 421, the power fluid accumulated in the lower buffer chamber 421 cannot be discharged in time, and the pressure gradually increases, thereby reducing the impact when power piston 21 descends, protecting piston assembly 2, and extending the service life of piston assembly 2.

[0065] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A downhole high-efficiency hydraulic pump, characterized in that, The device comprises an outer cylinder (11), a central tube (12), a power pump cylinder (13), a lifting pump cylinder (14) and a drainage connection cylinder (15); The central tube (12) is located in the outer cylinder (11), the top of the central tube (12) is fixedly sealed with the outer cylinder (11), and the outer cylinder (11) is provided with an uplink flow channel (121) for connecting high-pressure power liquid and a downlink flow channel (122) for connecting low-pressure power liquid. The power pump cylinder (13) is located in the outer cylinder (11), the upper end of the power pump cylinder (13) is connected with the central tube (12), the lifting pump cylinder (14) is located in the outer cylinder (11), the upper end of the lifting pump cylinder (14) is connected with the bottom end of the power pump cylinder (13), and the drainage connection cylinder (15) is connected and sealed with the bottom of the outer cylinder (11) and the bottom end of the lifting pump cylinder (14). The power pump cylinder (13) is provided with a first chamber (16) communicated with the downlink flow channel (122), an annular second chamber (17) is formed between the power pump cylinder (13) and the outer cylinder (11), the second chamber (17) is communicated with the uplink flow channel (121), the lifting pump cylinder (14) is provided with a third chamber (18) communicated with the first chamber (16), an annular fourth chamber (19) is formed between the lifting pump cylinder (14) and the outer cylinder (11), the fourth chamber (19) is communicated with the second chamber (17), and the drainage connection cylinder (15) forms a drainage channel (151) communicated with the downhole and the third chamber (18). The piston assembly (2) comprises a power piston (21) and a lifting piston (22) which are detachably connected, the power piston (21) is installed in the power pump cylinder (13) and is in sliding and sealing connection with the power pump cylinder (13), and the lifting piston (22) is installed in the lifting pump cylinder (14) and is in sliding and sealing connection with the lifting pump cylinder (14). The power pump cylinder (13) forms a pump cavity A (161) above the power piston (21) and a pump cavity B (162) below the power piston (21), the downlink flow channel (122) is communicated with the first flow channel (211) through the pump cavity A (161), the lower part of the power pump cylinder (13) is provided with a liquid inlet hole a (163), the liquid inlet hole a (163) is communicated with the pump cavity B (162) and the second chamber (17), and the uplink flow channel (121) is communicated with the pump cavity B (162) through the second chamber (17) and the liquid inlet hole a (163). The energy recovery assembly (3) is located in the pump cavity A (161) and is installed at the top of the power piston (21) and the bottom of the central tube (12), the energy recovery assembly (3) is used for connecting the pump cavity A (161) and the pump cavity B (162) when the power piston (21) rises to the highest position, and high-pressure power liquid is injected into the pump cavity A (161). The lower buffer assembly (4) is located in the pump cavity B (162) and is installed at the bottom of the power piston (21) and the top of the lifting pump cylinder (14), and the lower buffer assembly (4) is used for reducing the impact when the power piston (21) descends to the lowest position.

2. A downhole high-efficiency hydraulic pump according to claim 1, characterized in that: The power piston (21) is provided with an axially-through first flow channel (211), and the lifting piston (22) is provided with an axially-through second flow channel (221), and the first flow channel (211) and the second flow channel (221) are communicated; The lifting pump barrel (14) forms a pump cavity C (181) below the lifting piston (22), the lifting piston (22) is provided with an upstream dynamic discharge valve (5) at the second flow channel (221), the upstream dynamic discharge valve (5) is one-way communicated from the pump cavity C (181) to the second flow channel (221), and the drainage channel (151) is provided with a downstream dynamic discharge valve (6), and the downstream dynamic discharge valve (6) is one-way communicated from the drainage channel (151) to the pump cavity C (181).

3. A downhole high-efficiency hydraulic pump according to claim 2, characterized in that: The energy recovery assembly (3) comprises a pressure relief sliding sleeve (31), a pressure relief spring (32) and a pressure relief ring (33); The power piston (21) is provided with a pressure relief channel (212) which is communicated with the first flow channel (211) and the pump cavity B (162), the pressure relief channel (212) is provided with a plurality of and is circumferentially spaced around the axis of the power piston (21), and the upper port of the pressure relief channel (212) is communicated with the first flow channel (211); The pressure relief sliding sleeve (31) is located in the first flow channel (211) and is axially slidingly and sealingly connected with the power piston (21), the two ends of the pressure relief spring (32) are fixed to the bottom of the pressure relief sliding sleeve (31) and the top of the lifting piston (22) respectively, and the top end of the pressure relief spring (32) is located below the upper port of the pressure relief channel (212); The pressure relief ring (33) is located in the pump cavity A (161) and is installed at the lower end of the central pipe (12), an upper pressure relief cavity (164) is formed between the outer ring wall of the pressure relief ring (33) and the inner wall of the power pump barrel (13), the pressure relief ring (33) is coaxially arranged with the pressure relief sliding sleeve (31), and the downward flow channel (122) is communicated with the pump cavity A (161) by passing through the inner ring cavity of the pressure relief ring (33).

4. A downhole high-efficiency hydraulic pump according to claim 3, characterized in that: The outer diameter size of the pressure relief ring (33) is between the inner diameter size and the outer diameter size of the pressure relief sliding sleeve (31); The height of the pressure relief ring (33) is greater than the distance from the upper port of the pressure relief channel (212) to the upper end surface of the power piston (21).

5. A downhole high-efficiency hydraulic pump according to claim 3, characterized in that: The lower buffer assembly (4) comprises a buffer boss (41) and a lower buffer ring (42); The buffer boss (41) is installed at the lower end surface of the power piston (21), a plurality of pressure relief channels (212) are arranged around the buffer boss (41), and the first flow channel (211) penetrates the buffer boss (41); The lower buffer ring (42) is installed at the upper end of the lifting pump barrel (14) and is located in the pump cavity B (162), the lower buffer ring (42), the buffer boss (41) and the power piston (21) are coaxially arranged, the inner diameter size of the lower buffer ring (42) is greater than the outer diameter size of the buffer boss (41), and the inner ring wall of the lower buffer ring (42) forms a lower buffer cavity (421) for inserting the buffer boss (41).

6. A downhole high-efficiency hydraulic pump according to claim 5, characterized in that: The upper end of the lifting piston (22) is inserted into the first flow channel (211) and is in threaded sealing connection with the power piston (21), a through hole is formed in the buffer boss (41) for the lifting piston (22) to pass through, the plug section of the lifting piston (22) in the first flow channel (211) and the plug section in the buffer boss (41) are arranged in a stepped manner, and the inner diameter of the first flow channel (211) is larger than that of the second flow channel (221).

7. A downhole high-efficiency hydraulic pump according to claim 6, characterized in that: A plurality of sealing structures (7) are arranged between the power piston (21) and the power pump cylinder (13) and between the lifting piston (22) and the lifting pump cylinder (14).

8. A downhole high-efficiency hydraulic pump according to claim 7, characterized in that: The sealing structure (7) comprises an annular sealing sliding groove (71) formed on the outer peripheral wall of the power piston (21) and a sealing ring strip (72) located in the sealing sliding groove (71); the cross section of the sealing ring strip (72) is arranged in a "Y" shape, and the sealing ring strip (72) abuts against the inner wall of the power pump cylinder (13) and the groove wall of the sealing sliding groove (71).

9. A downhole high-efficiency hydraulic pump according to claim 5, characterized in that: The liquid inlet hole a (163) is an inclined hole and is arranged obliquely downward from the pump cavity B (162) to the second cavity (17), the bottom end of the liquid inlet hole a (163) at the port of the pump cavity B (162) is flush with the top end of the lifting pump cylinder (14), the top end of the liquid inlet hole a (163) at the port of the pump cavity B (162) is higher than the upper end face of the lower buffer ring (42), and the top end of the liquid inlet hole a (163) at the port of the second cavity (17) is lower than the upper end face of the lower buffer ring (42).

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