A negative pressure drainage pump

Abstract

The present invention relates to the technical field of coalbed methane extraction equipment, and in particular to a negative pressure drainage pump, which includes a working pump barrel and a production pump core. The working pump barrel is formed with a working annular cavity and a working inner cavity. The production pump core is detachably connected to the working inner cavity. A liquid passage and a mixing cavity are formed inside the production pump core. The top of the liquid passage communicates with the working inner cavity and the bottom end communicates with the working annular cavity. The mixing cavity communicates with the working annular cavity and the liquid passage. The bottom end of the working annular cavity communicates with the working inner cavity. The present invention provides a negative pressure drainage pump, which solves the drawback of replacing the pump core when the working conditions change greatly in traditional construction, reduces the production cost, and improves the drainage efficiency of coalbed methane.

Description

Technical Field

[0001] The present invention relates to the technical field of coalbed methane extraction equipment, and particularly to a negative pressure drainage pump. Background Art

[0002] In the process of coalbed methane drainage, a jet pump uses high-pressure water as the power fluid to lift the underground liquid. First, the high-pressure power fluid descends from the wellhead along the power fluid string to the underground jet pump. When the power fluid passes through the nozzle in the pump, the pressure energy is converted into kinetic energy, resulting in a sharp drop in the fluid pressure and forming a negative pressure zone around the nozzle. At this time, the formation fluid enters the pump under the action of the formation pressure and is sucked into the negative pressure zone. The formation fluid entering the negative pressure zone mixes with the high-speed jet fluid at the nozzle outlet to form a mixed fluid in the throat tube. During this process, the kinetic energy of the mixed fluid is converted into pressure energy, and the formation fluid obtains the energy from the power fluid and gradually increases in pressure. Finally, the liquid is lifted to the ground through the mixed fluid string.

[0003] In a coalbed methane well, the underground space is small. If other devices are to be installed underground, the existing negative pressure drainage pump is not large enough to accommodate its pipelines. Moreover, the negative pressure drainage pump must be designed according to a certain working condition. In practical applications, when the working condition of the coalbed methane well changes greatly, in order to ensure the drainage efficiency, a pump core suitable for this working condition must be replaced, resulting in an increase in production costs. To solve the above problems, this patent proposes a negative pressure drainage pump with a novel structure. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the related art. For this purpose, the present invention provides a negative pressure drainage pump, which solves the drawback of replacing the pump core when the working condition changes greatly in traditional construction, reduces the production cost, and improves the drainage efficiency of coalbed methane.

[0005] The present invention provides a negative pressure drainage pump, which includes a working pump barrel and a production pump core. The working pump barrel forms a working annular cavity and a working inner cavity. The production pump core is detachably connected to the working inner cavity. The inside of the production pump core forms a liquid channel and a mixing cavity. The top of the liquid channel is connected to the working inner cavity and the bottom end is connected to the working annular cavity. The mixing cavity is connected to the working annular cavity and the liquid channel. The bottom end of the working annular cavity is connected to the working inner cavity.

[0006] A further improvement of the negative pressure drainage pump of the present invention lies in that the working pump barrel includes a pump core pipe, an inner pump barrel and a jet pump barrel. The second end of the inner pump barrel is inserted into the pump core pipe. The first end of the jet pump barrel is sleeved and connected to the second end of the inner pump barrel. The production pump core is located inside the inner pump barrel and the jet pump barrel. The working annular cavity is formed between the pump core pipe and the inner pump barrel and between the pump core pipe and the jet pump barrel. The inside of the inner pump barrel and the jet pump barrel forms the working inner cavity.

[0007] A further improvement of the negative pressure drainage pump of the present invention lies in that a number of pump barrel support blocks are formed on the outer side wall of the jet pump barrel. The pump barrel support blocks abut against the inner side wall of the pump core pipe. One pump barrel support block at the bottommost end of the jet pump barrel is annular.

[0008] A further improvement of the negative pressure drainage pump of the present invention lies in that the production pump core includes an upper fishing head, an upper liquid inlet bridge, an upper sealing cavity, a nozzle, a positioning sleeve, a pressurizing cavity, a lower sealing cavity, a lower liquid inlet bridge, a locking sleeve and a lower fishing head. A mixing cavity is formed between the outer side wall of the nozzle and the positioning sleeve. The positioning sleeve is provided with a fourth through hole.

[0009] A mixing cavity is formed between the nozzle and the positioning sleeve. The mixing cavity is communicated with the working annular cavity. A part of the inner side wall of the jet pump barrel corresponding to the mixing cavity is recessed inward to form a first buffer groove. A first through hole is opened on the inner side wall of the jet pump barrel corresponding to the mixing cavity. A part of the inner side wall of the jet pump barrel corresponding to the locking sleeve protrudes inward to form a shoulder. The locking sleeve is inserted and connected to the shoulder. A third through hole is opened at the position below the shoulder of the jet pump barrel. A second through hole is opened at the position of the jet pump barrel corresponding to the lower liquid inlet bridge. The fourth through hole is communicated with the first buffer groove and the first through hole.

[0010] A further improvement of the negative pressure drainage pump of the present invention lies in that a pressurizing communication groove is formed at the position of the pressurizing cavity corresponding to the nozzle. A pressurizing cavity channel is formed inside the pressurizing cavity. The pressurizing cavity channel is communicated with the pressurizing communication groove. The inner diameter of the pressurizing cavity channel near the nozzle is smaller than the inner diameter of the position far from the nozzle.

[0011] A further improvement of the negative pressure drainage pump of the present invention lies in that the inner diameter of the nozzle near the pressurizing cavity is smaller than the inner diameter of the position far from the pressurizing cavity.

[0012] A further improvement of the negative pressure drainage pump of the present invention lies in that a number of upper liquid inlet channels are spaced apart at the top of the upper liquid inlet bridge. A first channel is formed in the middle of the upper liquid inlet bridge. The first channel is a part of the liquid channel.

[0013] A further improvement of the negative pressure drainage pump of the present invention lies in that a lower liquid inlet channel is provided in the middle of the lower liquid inlet bridge, the bottom end of the lower liquid inlet channel is in a closed state, the lower liquid inlet channel is a part of the liquid channel, and a lower liquid inlet channel is provided on the side of the lower liquid inlet bridge, and the lower liquid inlet channel communicates with the second through hole.

[0014] A further improvement of the negative pressure drainage pump of the present invention lies in that an upper sealing rubber cylinder is sleeved on the outer side wall of the upper sealing cavity, and the upper sealing rubber cylinder abuts against the inner side wall of the inner pump cylinder;

[0015] A lower sealing rubber cylinder is sleeved on the outer side wall of the lower sealing cavity, and the lower sealing rubber cylinder abuts against the inner side wall of the jet pump cylinder.

[0016] A further improvement of the negative pressure drainage pump of the present invention lies in that the lock sleeve is provided with an insertion cavity, the lower fishing head is inserted into the insertion cavity, and a plurality of fixing ears are provided on the side of the lock sleeve. By inserting the fixing ears into the shoulder, the lock sleeve is fixed to the jet pump cylinder.

[0017] The production pump core in the embodiment of the present invention can be selected whether to add a working pump cylinder according to needs, avoiding the replacement of the entire negative pressure drainage pump and the pump pipe, improving the construction efficiency, and reducing the production cost. In this application, by setting the lock sleeve, shoulder and pump cylinder support block, the connection stability of the production pump core in the working pump cylinder is improved. Through the nozzle, positioning sleeve and pressurization cavity of the production pump core, the dynamic state of the mixed liquid can be conveniently changed, facilitating the drainage operation of coalbed methane.

[0018] The additional aspects and advantages of the present invention will be given in part in the following description, will become obvious in part from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a schematic diagram of the negative pressure drainage pump provided by the embodiment of the present invention.

[0021] Figure 2 It is a node schematic diagram of the negative pressure drainage pump provided by the embodiment of the present invention.

[0022] Figure 3 It is a node schematic diagram of the negative pressure drainage pump installed on the screen pipe provided by the embodiment of the present invention.

[0023] Figure 4 It is a schematic diagram of the working pump barrel of the negative pressure drainage pump provided by an embodiment of the present invention.

[0024] Figure 5 It is a schematic diagram of the production pump core of the negative pressure drainage pump provided by an embodiment of the present invention.

[0025] Figure 6 It is a schematic diagram of the lock sleeve of the negative pressure drainage pump provided by an embodiment of the present invention.

[0026] Reference numerals:

[0027] 1. First tubing coupling; 2. Inner pump barrel; 3. Second tubing coupling; 4. Pump barrel reducer joint; 5. Pump core pipe; 6. Upper fishing head; 7. Upper liquid inlet bridge; 8. Upper sealing cavity; 9. Upper sealing rubber cylinder; 10. Jet pump barrel; 11. Nozzle; 12. Positioning sleeve; 13. Boosting cavity; 14. Lower sealing cavity; 15. Lower sealing rubber cylinder; 16. Lower liquid inlet bridge; 17. Lock sleeve; 18. Lower fishing head; 19. Inner cylinder fixing sleeve; 20. Adapter; 21. Screen pipe plug; 22. Coupling; 23. Screen pipe joint; 24. Third tubing coupling; 25. Screen pipe; 26. Jet pipe string; 1001. First through hole; 1002. Second through hole; 1003. Third through hole; 1004. Shoulder; 1701. Fixed ear; 1702. Insertion cavity. Detailed implementation manners

[0028] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments in the present invention belong to the scope protected by the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0029] The following combines Figure 1 Describe the negative pressure drainage pump of the present invention, which includes a working pump barrel and a production pump core. The working pump barrel forms a working annular cavity and a working inner cavity. The production pump core is detachably connected to the working inner cavity. A liquid channel and a mixing cavity are formed inside the production pump core. The top of the liquid channel is connected to the working inner cavity and the bottom end is connected to the working annular cavity. The mixing cavity is connected to the working annular cavity and the liquid channel. The bottom end of the working annular cavity is connected to the working inner cavity.

[0030] In a preferred embodiment of the negative pressure drainage pump of the present invention, as Figure 2As shown, the working pump barrel includes a pump core tube 5, an inner pump barrel 2, and a jet pump barrel 10. The second end of the inner pump barrel 2 is inserted into the pump core tube 5, and the first end of the jet pump barrel 10 is sleeved and connected to the second end of the inner pump barrel 2. The production pump core is located inside the inner pump barrel 2 and the jet pump barrel 10. The working annular cavity is formed between the pump core tube 5 and the inner pump barrel 2 and between the pump core tube 5 and the jet pump barrel 10. The interior of the inner pump barrel 2 and the jet pump barrel 10 forms a working inner cavity.

[0031] Preferably, as Figure 2 and Figure 4 shown, the pump core tube 5 and the inner pump barrel 2 are connected by a pump barrel reducer joint 4. A second tubing coupling 3 is sleeved on the outside of the pump barrel reducer joint 4, and through the second tubing coupling 3, it can be connected to other tubular structures. The end of the inner pump barrel 2 extending out of the pump core tube 5 can be connected to other tubular structures through the first tubing coupling 1.

[0032] Preferably, as Figure 2 and Figure 4 shown, the first end of the jet pump barrel 10 forms a first insertion platform, and the inner pump barrel 2 is inserted into the first insertion platform. Thus, the inner pump barrel 2 is overly inserted into the jet pump barrel 10 and undergoes relative displacement with the jet pump barrel 10 under the influence of the pressure change inside the inner pump barrel 2, improving the connection stability between the jet pump barrel 10 and the inner pump barrel 2.

[0033] Specifically, as Figure 4 shown, several pump barrel support blocks are formed on the outer sidewall of the jet pump barrel 10. The pump barrel support blocks abut against the inner sidewall of the pump core tube 5. One pump barrel support block at the bottommost end of the jet pump barrel 10 is annular, thus closing the bottom end of the working annular cavity. The pump barrel support blocks can improve the stability of the jet pump barrel 10, prevent the production pump core from being too long and swinging inside the pump core tube 5, and improve the stability of the production pump core.

[0034] Specifically, as <� Figure 3 shown, a conversion joint 20 is sleeved on the outside of the pump core tube 5. The conversion joint 20 is connected to a coupling 22. A screen pipe joint 23 is inserted into the coupling 22. The screen pipe joint 23 is connected to a screen pipe 25 through a third tubing coupling 24. A jet pipe string 26 is arranged inside the screen pipe 25. Screen pipe plugs 21 are provided at the bottom end of the jet pipe string 26 and the bottom end of the screen pipe 25.

[0035] Preferably, as Figure 2 and Figure 4 shown, an inner barrel fixing sleeve 19 is inserted at the bottom end of the jet pump barrel 10, improving the connection stability between the jet pump barrel 10 and the pump core tube 5.

[0036] Furthermore, as Figure 2 and Figure 5As shown, the production pump core includes an upper fishing head 6, an upper liquid inlet bridge 7, an upper sealing cavity 8, a nozzle 11, a positioning sleeve 12, a pressurizing cavity 13, a lower sealing cavity 14, a lower liquid inlet bridge 16, a locking sleeve 17, and a lower fishing head 18. A mixing cavity is formed between the outer sidewall of the nozzle 11 and the positioning sleeve 12, and a fourth through hole is provided on the positioning sleeve 12;

[0037] A mixing cavity is formed between the nozzle 11 and the positioning sleeve 12. The mixing cavity is connected to the working ring cavity. The inner sidewall of the jet pump barrel 10 is partially recessed inward at the position corresponding to the mixing cavity to form a first buffer groove. A first through hole 1001 is provided on the inner sidewall of the jet pump barrel 10 at the position corresponding to the mixing cavity. The inner sidewall of the jet pump barrel 10 is partially protruded inward at the position corresponding to the locking sleeve 17 to form a shoulder 1004. The locking sleeve 17 is inserted and connected to the shoulder 1004. A third through hole 1003 is provided on the jet pump barrel 10 at the position below the shoulder 1004. A second through hole 1002 is provided on the jet pump barrel 10 at the position corresponding to the lower liquid inlet bridge 16. The fourth through hole is connected to the first buffer groove and the first through hole 1001.

[0038] Specifically, as Figure 2 and Figure 5 shown, the top end of the upper fishing head 6 is a frustum of a cone, which is convenient for the staff to fish and pull the production pump core. The bottom end of the upper fishing head 6 is inserted into the upper liquid inlet bridge 7 to connect the upper fishing head 6 and the upper liquid inlet bridge 7.

[0039] Specifically, as Figure 2 and Figure 5 shown, a number of upper liquid inlet channels are provided at intervals on the top of the upper liquid inlet bridge 7. A first channel is formed in the middle of the upper liquid inlet bridge 7. The top of the first channel is connected to the number of upper liquid inlet channels. The first channel is a part of the liquid channel.

[0040] Preferably, as Figure 2 and Figure 5 shown, the bottom end of the upper liquid inlet bridge 7 is inserted into the top end of the upper sealing cavity 8. An upper sealing rubber cylinder 9 is sleeved on the outer sidewall of the upper sealing cavity 8. The upper sealing rubber cylinder 9 abuts against the inner sidewall of the inner pump barrel 2. A second channel is provided in the middle of the upper sealing cavity 8. The second channel is a part of the liquid channel.

[0041] Preferably, as Figure 2 and Figure 5 shown, the bottom end of the upper sealing rubber cylinder 9 is inserted into the top end of the positioning sleeve 12. The nozzle 11 abuts against the bottom end of the upper sealing rubber cylinder 9. The pressurizing cavity 13 is inserted into the positioning sleeve 12. The top end of the lower sealing cavity 14 is inserted into the bottom end of the positioning sleeve 12. The bottom end of the pressurizing cavity 13 abuts against the top end of the lower sealing cavity 14.

[0042] Specifically, as Figure 2 and Figure 5As shown, a boosting connecting groove is formed at the position of the boosting cavity 13 corresponding to the nozzle 11, and a boosting cavity channel is formed inside the boosting cavity. The boosting cavity channel is connected to the boosting connecting groove. The inner diameter of the boosting cavity channel close to the nozzle 11 is smaller than the inner diameter away from the nozzle 11. The inner diameter of the nozzle 11 close to the boosting cavity 13 is smaller than the inner diameter away from the boosting cavity 13. Therefore, when the power fluid passes through the nozzle 11 and is sprayed into the boosting connecting groove and the mixing chamber, the pressure changes, so that a negative pressure is formed in the mixing chamber, which facilitates the coalbed methane formation fluid in the screen pipe 25 to be sucked into the mixing chamber.

[0043] Preferably, if Figure 2 and Figure 5 As shown, the inner wall of the nozzle 11 forms an injection channel, which is part of the liquid channel. The inner diameter of the injection channel close to the boost chamber 13 is smaller than the inner diameter away from the boost chamber 13. The boost connecting groove and the boost chamber channel are both part of the liquid channel.

[0044] Specifically, if Figure 2 and Figure 5 As shown, the outer wall of the lower sealing cavity 14 is sleeved with a lower sealing rubber tube 15, which abuts against the inner wall of the jet pump barrel 10. A third channel is opened inside the lower sealing cavity 14, and the third channel is part of the liquid channel.

[0045] Specifically, if Figure 2 and Figure 5 As shown, the top of the lower liquid inlet bridge 16 is inserted into the bottom end of the lower sealing cavity 14, and a lower liquid inlet channel is opened in the middle of the lower liquid inlet bridge 16. The bottom end of the lower liquid inlet channel is in a closed state. The lower liquid inlet channel is part of the liquid channel. A lower liquid inlet channel is opened on the side of the lower liquid inlet bridge 16, and the lower liquid inlet channel is connected to the second through hole 1002.

[0046] Specifically, if Figure 6 As shown, the locking sleeve 17 is provided with an insertion cavity 1702, and the lower fishing head 18 is inserted into the insertion cavity 1702. The side of the locking sleeve 17 is provided with a plurality of fixing ears 1701, which are inserted into the shoulder 1004 through the fixing ears 1701 to fix the locking sleeve 17 to the jet pump barrel 10.

[0047] Specifically, if Figure 2 and Figure 5 As shown, the liquid channels are, from top to bottom, an upper liquid inlet channel, a first channel, a second channel, an injection channel, a pressurizing connecting groove, a pressurizing chamber channel, a third channel, and a lower liquid inlet channel.

[0048] In a specific embodiment, coalbed methane drainage operation is required. The power fluid enters the working inner cavity of the inner pump barrel 2, and then enters the upper liquid inlet channel, the first channel, the second channel, the injection channel, the booster connection groove and the mixing chamber. At this time, a negative pressure state exists in the mixing chamber, and the coalbed methane formation fluid in the screen pipe 25 enters the working inner cavity of the inner pump barrel 2, and then enters the working annular cavity through the third through hole 1003, and then enters the mixing chamber through the first through hole 1001 to mix with the working fluid to form a mixed liquid. Then, the mixed liquid passes through the booster chamber channel, the third channel, the lower liquid inlet channel, and then enters the working annular cavity through the second through hole 1002 and flows upward to discharge the working annular cavity, realizing the drainage and pressure reduction of the coalbed methane well.

[0049] In another specific embodiment, when the negative pressure drainage pump is not needed or when the production pump core needs to be replaced due to blockage, the external high-pressure liquid enters the working annular cavity, and then enters the lower liquid inlet channel, the third channel, the booster chamber channel and the mixing chamber through the second through hole 1002. At this time, the high-pressure liquid forms an upward thrust on the nozzle 11 part, causing the lock sleeve 17 to disengage from the shoulder 1004, and then the production pump core moves upward along the inner pump barrel 2 to disengage from the inner pump barrel 2. Then, the staff can fish out the production pump core through the upper fishing head 6 to replace the production pump core, or make the inner pump barrel 2 conduct up and down at this time and can be used as a gas production pipeline.

[0050] The production pump core in the embodiment of the present invention can be selected to be added to the working pump barrel according to needs, avoiding the replacement of the entire negative pressure drainage pump and the pump pipe, improving the construction efficiency and reducing the production cost. In this application, by setting the lock sleeve 17, the shoulder 1004 and the pump barrel support block, the connection stability of the production pump core in the working pump barrel is improved. Through the nozzle 11, the positioning sleeve 12 and the booster cavity 13 of the production pump core, the dynamic state of the mixed liquid can be conveniently changed, facilitating the coalbed methane drainage operation.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A negative pressure drainage pump, characterized in that: The pump comprises a working pump barrel and a production pump core, wherein the working pump barrel is formed with a working annular cavity and a working inner cavity, the production pump core is detachably connected to the working inner cavity, and a liquid channel and a mixing cavity are formed inside the production pump core, the top of the liquid channel is connected to the working inner cavity and the bottom end is connected to the working annular cavity, the mixing cavity is connected to the working annular cavity and the liquid channel, and the bottom end of the working annular cavity is connected to the working inner cavity; The working pump barrel includes a pump core tube, an inner pump barrel and a jet pump barrel, the second end of the inner pump barrel is inserted into the pump core tube, the first end of the jet pump barrel is sleeved and connected to the second end of the inner pump barrel, the production pump core is located in the inner pump barrel and the jet pump barrel, the working annular cavity is formed between the pump core tube and the inner pump barrel and between the pump core tube and the jet pump barrel, and the interior of the inner pump barrel and the jet pump barrel forms the working inner cavity; The production pump core includes an upper fishing head, an upper liquid inlet bridge, an upper sealing cavity, a nozzle, a positioning sleeve, a pressurizing cavity, a lower sealing cavity, a lower liquid inlet bridge, a locking sleeve and a lower fishing head. The mixing cavity is formed between the outer wall of the nozzle and the positioning sleeve. The positioning sleeve is provided with a fourth through hole. A mixing chamber is formed between the nozzle and the positioning sleeve, and the mixing chamber is communicated with the working ring chamber. The inner side wall of the jet pump barrel corresponding to the position of the mixing chamber is partially recessed inward to form a first buffer groove. A first through hole is provided on the inner side wall of the jet pump barrel corresponding to the position of the mixing chamber. The inner side wall of the jet pump barrel corresponding to the position of the locking sleeve protrudes inward to form a shoulder. The locking sleeve is inserted and connected to the shoulder. A third through hole is provided on the jet pump barrel below the shoulder. A second through hole is provided on the jet pump barrel corresponding to the position of the lower liquid inlet bridge. The fourth through hole is communicated with the first buffer groove and the first through hole. A plurality of upper liquid inlet channels are spaced apart on the top of the upper liquid inlet bridge, and a first channel is formed in the middle of the upper liquid inlet bridge, which is a part of the liquid channel; A lower liquid inlet channel is opened in the middle of the lower liquid inlet bridge, the bottom end of the lower liquid inlet channel is in a closed state, the lower liquid inlet channel is part of the liquid channel, and a lower liquid inlet channel is opened on the side of the lower liquid inlet bridge, and the lower liquid inlet channel is connected to the second through hole.

2. The negative pressure drainage pump according to claim 1, characterized in that: A plurality of pump barrel support blocks are formed on the outer side wall of the jet pump barrel, and the pump barrel support blocks abut against the inner side wall of the pump core tube. A pump barrel support block located at the bottom end of the jet pump barrel is annular.

3. The negative pressure drainage pump according to claim 1, characterized in that: A boost connecting groove is formed in the boost cavity at a position corresponding to the nozzle, and a boost cavity channel is formed inside the boost cavity. The boost cavity channel is connected to the boost connecting groove, and the inner diameter of the boost cavity channel close to the nozzle position is smaller than the inner diameter away from the nozzle position.

4. The negative pressure drainage pump according to claim 1, characterized in that: The inner diameter of the nozzle at a position close to the pressurizing cavity is smaller than the inner diameter at a position far from the pressurizing cavity.

5. The negative pressure drainage pump according to claim 1, characterized in that: An upper sealing rubber sleeve is sleeved on the outer side wall of the upper sealing cavity, and the upper sealing rubber sleeve abuts against the inner side wall of the inner pump barrel; A lower sealing rubber tube is sleeved on the outer side wall of the lower sealing cavity, and the lower sealing rubber tube abuts against the inner side wall of the jet pump barrel.

6. The negative pressure drainage pump according to claim 1, characterized in that: The locking sleeve is provided with an insertion cavity, the lower fishing head is inserted into the insertion cavity, and the side of the locking sleeve is provided with a plurality of fixing ears, which are inserted into the shoulder through the fixing ears so that the locking sleeve is fixed to the jet pump barrel.

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