Hydraulic oil drainage type tubing anchor capable of testing pressure in midway and using method of hydraulic oil drainage type tubing anchor

Abstract

The invention relates to the technical field of oil well operation tools, in particular to a midway pressure test hydraulic oil drainage type tubing anchor and a using method thereof.The hydraulic tubing anchor comprises a center pipe, a cone connector, an anchor tile and a piston assembly, the cone connector is arranged at the top of the center pipe, and a sealing ring I is arranged between the cone connector and the center pipe for sealing; the center pipe is connected with an oil pipe through the cone connector, the anchor tile and the piston assembly are sleeved on the center pipe, the anchor tile is arranged between the cone connector and the piston assembly, one end of the anchor tile is provided with a cone hole matched with the cone connector, and the other end of the anchor tile is connected with the piston assembly. The oil drainage action can be completed by adopting a mode of directly pressing into the oil pipe, and any tool does not need to be put into the oil pipe; mainly solves the problem that in the operation process of an oil well, under the condition that a tubular column is not moved, the oil drainage function of the tubular column is realized, so that conventional well washing can be carried out, an oil tube and a sucker rod are cleaned together, and crude oil brought out and environment pollution caused by tube and rod lifting are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of oil well operation tools, and particularly to an intermediate pressure testable hydraulic oil-discharging tubing anchor and its usage method. Background Art

[0002] During the process of oil well operation, it is necessary to discharge the crude oil in the tubing to avoid environmental pollution. During the oil discharge process, after all the operation equipment such as workover rigs is laid out, the tubing needs to be lifted and the sucker rods need to be removed before reverse flushing the well to wash the crude oil in the tubing clean. However, the removed sucker rods cannot be washed clean, and the entire well flushing process also involves tripping the tubing string, increasing the operation procedures and reducing the operation efficiency.

[0003] In the patent with the application number CN109931031A and the patent name of a hydraulic oil-discharger, when discharging oil with this oil-discharger, the sucker rods need to be removed in advance, and valve balls of corresponding specifications need to be put into the tubing. When the balls are seated, a sealed space is formed between the valve balls and the oil-discharger, and then pressure is applied to complete the oil discharge. Currently, this oil-discharger has the following several disadvantages: 1. When performing the oil discharge operation, the operation can only be carried out after the sucker rods are removed. The crude oil on the sucker rods cannot be pretreated through the well flushing operation, and the crude oil on the sucker rods needs to be treated additionally, increasing the workload of the operators and reducing the operation efficiency; 2. During the operation, if the plunger of the oil pump cannot be lifted due to reasons such as sand production, or the sucker rods are broken for other reasons and cannot be normally removed, when putting the balls, the valve balls cannot reach the position, a sealed space cannot be formed, and the oil cannot be discharged; 3. Currently, most production tubing is lined tubing, which is corrosion-resistant and has a long service life. However, as the production time of the lined tubing extends, the inner lining rubber of the lined tubing is likely to fall off. When it falls into the tubing, it will reduce the inner diameter of the tubing, and there is a high probability that the valve ball will be blocked when it falls, and the valve ball cannot be seated, resulting in the inability to discharge oil; 4. When encountering a viscous oil well, the density of the crude oil is very high. When putting the balls, the valve balls are likely to not reach the position. If you want to continue discharging oil, reverse flushing the well is required, increasing the operation procedures, time-consuming, costly and laborious. Summary of the Invention

[0004] Aiming at the deficiencies of the existing background art, the purpose of the present invention is to provide an intermediate pressure testable and oil-discharging hydraulic tubing anchor with a simple structure and convenient use and its usage method. The present invention can complete the oil discharge action by directly applying pressure to the tubing without putting any tools into the tubing; mainly solves the problem of realizing the oil discharge function of the tubing string without moving the tubing string during the oil well operation process, so that forward well flushing can be carried out to wash the tubing and the sucker rods together, reducing the crude oil brought out during the tubing and rod tripping and polluting the environment.

[0005] To achieve the above, the technical solution of the present invention is: A hydraulic oil-discharging tubing anchor that can be pressure-tested midway, including a central tube, further including a cone joint, an anchor shoe, and a piston assembly. The cone joint is arranged at the top of the central tube, and the central tube is connected to the tubing through the cone joint. Both the anchor shoe and the piston assembly are sleeved on the central tube. The anchor shoe is arranged between the cone joint and the piston assembly. One end of the anchor shoe is provided with a conical groove for cooperating with the cone joint, and the other end of the anchor shoe is connected to the piston assembly. The piston assembly includes an upper piston and a lower piston. Both the upper piston and the lower piston are sleeved on the central tube and can move along the central tube under the action of oil pressure. The upper end of the upper piston is connected to the lower end of the anchor shoe, and the other end of the upper piston is connected to an oil-discharging sleeve. A seal ring II is provided between the upper piston and the central tube for sealing, and a seal ring VII is provided between the lower piston and the central tube for sealing.

[0006] Further, the piston assembly further includes an oil-discharging sleeve. The oil-discharging sleeve is arranged between the upper piston and the lower piston. One end of the oil-discharging sleeve is connected to the lower end of the upper piston through a set screw, and the other end of the oil-discharging sleeve is connected to the lower piston through an oil-discharging shear pin.

[0007] Further, the central tube is provided with a liquid inlet hole and an oil-discharging hole. The liquid inlet hole is located in the upper part of the central tube corresponding to the upper piston, and a pressure-test shear pin is installed on the liquid inlet hole. The oil-discharging hole is located in the lower part of the central tube corresponding to the oil-discharging sleeve. A seal ring V is provided between the oil-discharging sleeve and the central tube above the oil-discharging hole, and a seal ring VI is provided between the oil-discharging sleeve and the central tube below the oil-discharging hole.

[0008] Further, the piston assembly further includes a lower pressure cap. The lower pressure cap is sleeved on the central tube. The lower pressure cap is arranged inside the upper piston above the oil-discharging sleeve, and the lower part of the upper piston is connected to the lower pressure cap through an internal hexagonal screw.

[0009] Further, the piston assembly further includes a hot-fitted part. The hot-fitted part is fixedly connected to the central tube. A seal ring III is provided between the hot-fitted part and the central tube for sealing. The hot-fitted part is located inside the upper piston. The outer side surface of the hot-fitted part is in contact with the inner surface of the upper piston and is sealed through a seal ring IV. The hot-fitted part is located above the lower pressure cap, and the upper piston is connected to the hot-fitted part through an anchoring shear pin.

[0010] Further, the piston assembly further includes a spring. The spring is sleeved on the central tube. The spring is arranged inside the upper piston between the hot-fitted part and the lower pressure cap. One end of the spring is connected to the lower end of the hot-fitted part, and the other end of the spring is connected to the upper end of the lower pressure cap.

[0011] Further, the hydraulic tubing anchor further includes a retaining ring. The retaining ring is fixedly connected to the lower part of the central tube. The retaining ring is located below the lower piston, and the outer diameter of the retaining ring is larger than the outer diameter of the lower piston.

[0012] The present invention also relates to a method for using a hydraulic oil-discharging tubing anchor that can be pressure-tested midway. Based on the above-mentioned hydraulic oil-discharging tubing anchor that can be pressure-tested midway, the method for use includes: a. Pressure testing process: After the hydraulic tubing anchor is normally lowered to the designated depth, connect the pump truck tubing to apply positive pressure to test the tubing string for leaks. Since the liquid inlet holes on the central tube are blocked by the pressure-testable shear pins, the pressure inside the tubing cannot enter the interior of the hydraulic tubing anchor through the liquid inlet holes. Therefore, the hydraulic tubing anchor is not anchored and can be normally lowered after the pressure test. b. Anchoring process: When the hydraulic tubing anchor is lowered to the designated depth and the sucker rod is lowered, the piston breaks the pressure-testable shear pins. At this time, the liquid inlet holes are opened. When the liquid level inside the tubing gradually rises during production and the pressure inside the tubing also gradually increases, the pressure inside the tubing enters through the liquid inlet holes on the central tube. When the pressure enters the interior of the hydraulic tubing anchor, it pushes the upper piston to move upward. At this time, the upper part of the upper piston drives the anchor shoe to expand outward along the tapered joint to complete the anchoring action. c. Oil-discharging action: When it is necessary to discharge the oil in the tubing string during operation, directly apply positive pressure to the tubing. At this time, the hydraulic tubing anchor is in the anchored state, and the pressure enters the annulus of the lower piston from the central tube through the oil-discharging hole. Continue to apply pressure. When the pressure exceeds the rated value of the oil-discharging shear pin, the oil-discharging shear pin is broken, and the lower piston moves downward under the action of the pressure and disengages from the oil-discharging sleeve and is blocked by the retaining ring. At this time, the liquid level flows out from the oil-discharging hole through the oil-discharging sleeve to complete the oil discharge. d. Unanchoring process: After the oil discharge is completed, the inside and outside of the tubing are connected and the pressure is balanced. Under the action of the spring, the lower pressing cap is pushed downward, successively driving the socket head cap screw, the upper piston, and the anchor shoe downward, and the tubing is lifted to complete the unanchoring.

[0013] Further, the b. anchoring process further includes: When the upper piston moves upward, the anchoring shear pins are cut. The lower part of the upper piston is connected to the lower pressing cap through a socket head cap screw and is connected to the oil-discharging sleeve through a set screw. The oil-discharging sleeve is connected to the lower piston through an oil-discharging shear pin. When the upper piston moves upward, it drives the lower pressing cap, the oil-discharging sleeve, and the lower piston to move upward. When the lower pressing cap moves upward, the spring is compressed. Before the hydraulic tubing anchor is anchored, the oil-discharging hole is sealed by seal ring V and seal ring VI, and the pressure inside the tubing cannot be transmitted to the lower piston. When the hydraulic tubing anchor is anchored, the oil-discharging sleeve is driven upward by the upper piston, and the pressure can enter the piston cavity. The pressure inside the tubing during production will not cut the oil-discharging shear pin to ensure the normal production of the tubing string.

[0014] The advantages of adopting the technical solution of the present invention are as follows: 1. The present invention adopts the method of directly applying pressure to the tubing to complete the oil-discharging action, without putting any tools into the tubing. As long as there is a gap inside the tubing and the pressure can be conducted, the oil discharge can be completed. Moreover, the sucker rod inside the tubing does not need to be removed. After the oil discharge is completed, normal well flushing can clean the rod and tubing together, which can effectively reduce the workload of on-site operators and improve the operation efficiency.

[0015] 2. The hydraulic tubing anchor of the present invention has a pressure test shear pin inside, which can perform pressure test and leak detection on the tubing string at any time, effectively reducing the repeated operations caused by tubing leakage, improving the operation efficiency, and reducing the workload of on-site operators.

[0016] 3. The present invention adopts the oil drainage method of injecting pressure into the tubing. The operation is simple, without pulling and running the tubing string, nor pulling and running the sucker rod, and the oil drainage can be completed. After the oil drainage is completed, forward flushing can be carried out, which can wash the crude oil on the tubing and the sucker rod clean, with better effect and higher efficiency than reverse flushing. Moreover, the oil drainage operation is simpler, conforming to the operation habits of on-site operators and effectively improving the operation efficiency.

[0017] 4. The present invention has its own anchoring function. After anchoring, the sucker pump can be anchored on the casing together, reducing the peristalsis of the sucker pump caused by production, improving the pump efficiency. After anchoring, it can also effectively prevent the tubing string from breaking and disconnecting. Brief Description of the Drawings

[0018] 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 use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only those of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic structural diagram of the hydraulic tubing anchor of the present invention.

[0020] The marks in the above figures are respectively: 1, cone joint; 2, seal ring I; 3, anchor tile; 4, central tube; 5, seal ring II; 6, pressure test shear pin; 7, seal ring III; 8, seal ring IV; 9, hot-fitted part; 10, anchoring shear pin; 11, upper piston; 12, spring; 13, hexagon socket head screw; 14, lower pressure cap; 15, set screw; 16, seal ring V; 17, seal ring VI; 18, seal ring VII; 19, oil drainage shear pin; 20, oil drainage sleeve; 21, lower piston; 22, oil drainage hole; 23, retaining ring. Detailed Description of the Embodiment

[0021] In order to make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the following further details the present invention in combination with specific embodiments.

[0022] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those with ordinary skills in the field to which the present invention pertains. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to represent relative position relationships, and when the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0023] As Figure 1 shown, a hydraulic oil-draining tubing anchor that can be pressure-tested midway includes a central tube 4, and also includes a cone joint 1, an anchor shoe 3 and a piston assembly. The cone joint 1 is arranged at the top of the central tube 4, and a sealing ring I 2 is provided between the cone joint 1 and the central tube 4 for sealing. The central tube 4 is connected to the tubing through the cone joint 1. Both the anchor shoe 3 and the piston assembly are sleeved on the central tube 4. The anchor shoe 3 is arranged between the cone joint 1 and the piston assembly. One end of the anchor shoe 3 is provided with a conical groove for cooperating with the cone joint 1, and the other end of the anchor shoe 3 is connected to the piston assembly. The cone joint 1 integrates the upper joint and the cone, making the processing and assembly simpler.

[0024] By adopting the method of directly pressurizing the tubing, the present invention can complete the oil-draining action without putting any tools into the tubing. As long as there is a gap in the tubing and the pressure can be conducted, the oil-draining can be completed. Moreover, the sucker rod in the tubing does not need to be taken out. After the oil-draining is completed, the tubing and the rod can be washed clean together by normal well flushing, which can effectively reduce the workload of on-site operators and improve the operation efficiency.

[0025] The piston assembly includes an upper piston 11 and a lower piston 21. Both the upper piston 11 and the lower piston 21 are sleeved on the central tube 4 and can move along the central tube 4 under the action of oil pressure. The upper end of the upper piston 11 is connected to the lower end of the anchor shoe 3, and the other end of the upper piston 11 is connected to the oil-draining sleeve 20. A sealing ring II 5 is provided between the upper piston 11 and the central tube 4 for sealing, and a sealing ring VII 18 is provided between the lower piston 21 and the central tube 4 for sealing.

[0026] The piston assembly further includes an oil drain sleeve 20 which is arranged between the upper piston 11 and the lower piston 21. One end of the oil drain sleeve 20 is connected to the lower end of the upper piston 11 by a set screw 15, and the other end of the oil drain sleeve 20 is connected to the lower piston 21 by an oil drain shear pin 19. There are multiple rubber seals between the oil drain sleeve and the lower piston, forming a piston chamber. There is an annular groove at the lower part of the upper piston, and there are bolt holes at the upper part of the oil drain sleeve. The upper piston and the oil drain sleeve are connected by a set nut. When the tool is in the unanchored state, the set nut is at the lower end of the annular groove.

[0027] The central tube 4 is provided with a liquid inlet hole and an oil drain hole 22. The liquid inlet hole is located in the upper part of the central tube 4 corresponding to the upper piston 11, and a test pressure shear pin 6 is installed on the liquid inlet hole. The oil drain hole 22 is located in the lower part of the central tube 4 corresponding to the oil drain sleeve 20. A seal ring Ⅴ 16 is provided between the oil drain sleeve 20 and the central tube 4 above the oil drain hole 22, and a seal ring Ⅵ 17 is provided between the oil drain sleeve 20 and the central tube 4 below the oil drain hole 22.

[0028] The piston assembly further includes a lower pressing cap 14 which is sleeved on the central tube 4. The lower pressing cap 14 is arranged inside the upper piston 11 above the oil drain sleeve 20, and the lower part of the upper piston is connected to the lower pressing cap 14 by an internal hexagonal screw 13.

[0029] The piston assembly further includes a hot-fitted part 9 which is fixedly connected to the central tube 4. A seal ring Ⅲ 7 is provided between the hot-fitted part 9 and the central tube 4 for sealing. The hot-fitted part 9 is located inside the upper piston 11. The outer side surface of the hot-fitted part 9 is in contact with the inner surface of the upper piston 11 and is sealed by a seal ring Ⅳ 8. The hot-fitted part 9 is located above the lower pressing cap 14, and the upper piston 11 and the hot-fitted part 9 are connected by an anchor shear pin 10.

[0030] The piston assembly further includes a spring 12 which is sleeved on the central tube 4. The spring 12 is arranged inside the upper piston 11 between the hot-fitted part 9 and the lower pressing cap 14. One end of the spring 12 is connected to the lower end of the hot-fitted part 9, and the other end of the spring 12 is connected to the upper end of the lower pressing cap 14.

[0031] To prevent the lower piston from falling off, the hydraulic tubing anchor further includes a retaining ring 23 which is fixedly connected to the lower part of the central tube 4. The retaining ring 23 is located below the lower piston 21, and the outer diameter of the retaining ring 23 is larger than the outer diameter of the lower piston 21.

[0032] The specific working process is as follows: When the tubing anchor is lowered to the specified depth and the sucker rod is lowered, the piston of the sucker rod pump breaks the pressure-testable shear pin 6 inside the tubing anchor through the tubing anchor. The pressure-testable shear pin falls off. Since the density of the pressure-testable shear pin is less than that of water, it moves upward under the action of buoyancy after falling off. At this time, the liquid inlet hole is opened. When in production, the liquid level in the tubing gradually rises, and the pressure in the tubing also gradually rises. At this time, the pressure in the tubing enters from the liquid inlet hole on the central tube 4. There are sealing rings above and below the upper piston 11 and the hot-fitted part 9, and the hot-fitted part 9 is fixed on the central tube 4 and cannot move. When the pressure enters the tool, it can only push the upper piston 11 to move upward. At this time, the upper part of the upper piston 11 drives the anchor shoe 3 to expand outward along the cone joint 1 to complete the anchoring action. While the upper piston 11 moves upward, it cuts off the anchoring shear pin 10. The lower part of the upper piston is connected to the lower pressure cap 14 through the hexagon socket head cap screw 13 and is connected to the drain sleeve 20 through the set screw 15. The drain sleeve 20 is connected to the lower piston 21 through the drain shear pin 19. Similarly, when the upper piston 11 moves upward, it also drives the lower pressure cap 14, the drain sleeve 20, and the lower piston 21 to move upward. When the lower pressure cap 14 moves upward, the spring 12 is compressed. Before the tool is anchored, the drain hole 22 is sealed by the sealing ring Ⅴ 16 and the sealing ring Ⅵ 17, and the pressure in the tubing cannot be transmitted to the lower piston 21. When anchored, the drain sleeve 20 is driven upward by the upper piston 11, and the pressure can enter the piston cavity. The pressure in the tubing during production will not cut off the drain shear pin 19 to ensure the normal production of the pipe string.

[0033] When tubing string draining is required during operation, directly apply positive pressure to the tubing. At this time, the tool is in the anchored state. The pressure enters the annulus of the lower piston 21 from the central tube 4 through the drain hole 22. Continue to apply pressure. When the pressure exceeds the rated value of the drain shear pin 19, the drain shear pin 19 is broken. The lower piston 21 moves downward under the action of pressure and disengages from the drain sleeve 20 and is blocked by the retaining ring 23. At this time, the liquid level flows out from the drain hole 22 through the drain sleeve 20 to complete the draining.

[0034] Based on the above hydraulic tubing anchor that can be pressure-tested and drained midway, the present invention also provides a usage method for the hydraulic tubing anchor that can be pressure-tested and drained hydraulically midway. The usage method includes: a. Pressure-testing process: After the hydraulic tubing anchor is normally lowered to the specified depth, connect the pump truck tubing and apply positive pressure to test the leak of the tubing string. Since the liquid inlet hole on the central tube 4 is blocked by the pressure-testable shear pin 6, the pressure in the tubing cannot enter the inside of the hydraulic tubing anchor through the liquid inlet hole. Therefore, the hydraulic tubing anchor is not anchored and can be normally lowered after the pressure test. b. Anchoring process: When the hydraulic tubing anchor is lowered to the specified depth and the sucker rod is lowered, the pressure-testable shear pin 6 is broken. At this time, the liquid inlet hole is opened. When production is in progress, the liquid level in the tubing gradually rises and the pressure in the tubing also gradually increases. At this time, the pressure in the tubing enters from the liquid inlet hole on the central tube 4. When the pressure enters the inside of the hydraulic tubing anchor, it pushes the upper piston 11 upward. At this time, the upper part of the upper piston 11 drives the anchor shoe 3 to expand outward along the tapered joint 1, completing the anchoring action; While the upper piston 11 moves upward, the anchoring shear pin 10 is cut off. The lower part of the upper piston is connected to the lower pressure cap 14 through the socket head cap screw 13 and is connected to the drain sleeve 20 through the set screw 15. The drain sleeve 20 is connected to the lower piston 21 through the drain shear pin 19; while the upper piston 11 moves upward, it drives the lower pressure cap 14, the drain sleeve 20, and the lower piston 21 upward. When the lower pressure cap 14 moves upward, the spring 12 is compressed; before the hydraulic tubing anchor is anchored, the drain hole 22 is sealed by the seal ring Ⅴ16 and the seal ring Ⅵ17, and the pressure in the tubing cannot be transmitted to the lower piston 21; when the hydraulic tubing anchor is anchored, the drain sleeve 20 is driven upward by the upper piston 11, and the pressure can enter the piston cavity. The pressure in the tubing during production will not cut off the drain shear pin 19, ensuring the normal production of the pipe string; c. Drainage action: When tubing drainage is required during operation, directly apply positive pressure to the tubing. At this time, the hydraulic tubing anchor is in the anchored state. The pressure enters the annulus of the lower piston 21 from the central tube 4 through the drain hole 22. Continue to apply pressure. When the pressure exceeds the rated value of the drain shear pin 19, the drain shear pin 19 is broken. The lower piston 21 moves downward under the action of pressure and disengages from the drain sleeve 20 and is blocked by the retaining ring 23. At this time, the liquid level flows out from the drain hole 22 through the drain sleeve 20, completing the drainage; d. Unanchoring process: After the drainage is completed, the inside and outside of the tubing are connected and the pressure is balanced. Under the action of the spring 12, the lower pressure cap 14 is pushed downward, driving the socket head cap screw 13, the upper piston 11, and the anchor shoe 3 downward in sequence. The tubing is lifted to complete the unanchoring.

[0035] The hydraulic tubing anchor of the present invention has a pressure-test shear pin inside, which can test the tubing for leaks at any time, effectively reducing the repeated operations caused by tubing leaks, improving the operation efficiency, and reducing the workload of on-site operators.

[0036] The present invention adopts the drainage method of applying pressure to the tubing, which is simple to operate. Without pulling out and running in the tubing or pulling out the sucker rod, the drainage can be completed. After the drainage is completed, forward flushing can be carried out, which can wash the crude oil on the tubing and the sucker rod clean. It has a better effect and higher flushing efficiency than reverse flushing. Moreover, the drainage operation is simpler, which conforms to the operation habits of on-site operators and effectively improves the operation efficiency.

[0037] The present invention has an anchoring function by itself. After anchoring, the oil production pump can be anchored on the casing together, reducing the peristalsis of the oil production pump caused by production, improving the pump efficiency, and effectively preventing the tubing string from breaking and disconnecting after anchoring.

[0038] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

[0039] Therefore, any omissions, modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A mid-stream pressure-testable hydraulic oil-draining oil pipe anchor, comprising a central pipe (4), characterized in that: The invention also comprises a cone joint (1), an anchor shoe (3) and a piston assembly. The cone joint (1) is arranged at the top of a center tube (4). The center tube (4) is connected to an oil pipe via the cone joint (1). The anchor shoe (3) and the piston assembly are both sleeved on the center tube (4). The anchor shoe (3) is arranged between the cone joint (1) and the piston assembly. One end of the anchor shoe (3) is provided with a cone groove for matching with the cone joint (1). The other end of the anchor shoe (3) is connected to the piston assembly. The piston assembly comprises an upper piston (11), a lower piston (21), an oil drain sleeve (20) and a lower pressure cap (14). The oil drain sleeve (20) is arranged between the upper piston (11) and the lower piston (21). The upper piston (11) and the lower piston (21) are both sleeved on the center tube ( 4), can move along the center tube (4) under the action of oil pressure, the upper end of the upper piston (11) is connected to the lower end of the anchor shoe (3), the other end of the upper piston (11) is connected to the oil drain sleeve (20) through a set screw (15), the other end of the oil drain sleeve (20) is connected to the lower piston (21) through an oil drain shear nail (19), a sealing ring II (5) is provided between the upper piston (11) and the center tube (4) for sealing, and a sealing ring VII (18) is provided between the lower piston (21) and the center tube (4) for sealing; a lower pressure cap (14) is sleeved on the center tube (4), the lower pressure cap (14) is arranged in the upper piston (11) above the oil drain sleeve (20), and the lower part of the upper piston is connected to the lower pressure cap (14) through a hexagon socket screw (13).

2. The mid-stream pressure-testing hydraulic oil-draining oil pipe anchor according to claim 1, characterized in that: The central tube (4) is provided with a liquid inlet hole and an oil drain hole (22). The liquid inlet hole is located at the upper part of the central tube (4) and corresponds to the upper piston (11). A pressure-testable shear pin (6) is installed on the liquid inlet hole. The oil drain hole (22) is located at the lower part of the central tube (4) and corresponds to the oil drain sleeve (20). A sealing ring V (16) is provided between the oil drain sleeve (20) and the central tube (4) above the oil drain hole (22). A sealing ring VI (17) is provided between the oil drain sleeve (20) and the central tube (4) below the oil drain hole (22).

3. The mid-stream pressure-testable hydraulic oil-draining oil pipe anchor as claimed in claim 2, characterized in that: The piston assembly further comprises a heat-inserted component (9), which is fixedly connected to the central tube (4), a sealing ring III (7) is provided between the heat-inserted component (9) and the central tube (4) for sealing, the heat-inserted component (9) is located in the upper piston (11), the outer side surface of the heat-inserted component (9) is in contact with the inner surface of the upper piston (11) and is sealed by a sealing ring IV (8), the heat-inserted component (9) is located above the lower pressure cap (14), and the upper piston (11) and the heat-inserted component (9) are connected by anchor shear pins (10).

4. The mid-stream pressure-testable hydraulic oil-draining oil pipe anchor as claimed in claim 3, characterized in that: The piston assembly further comprises a spring (12), which is sleeved on the central tube (4). The spring (12) is arranged in the upper piston (11) between the heat-inserted component (9) and the lower pressing cap (14), one end of the spring (12) is connected to the lower end of the heat-inserted component (9), and the other end of the spring (12) is connected to the upper end of the lower pressing cap (14).

5. The mid-stream pressure-testable hydraulic oil-draining oil pipe anchor as claimed in claim 4, characterized in that: The hydraulic oil pipe anchor also includes a retaining ring (23), which is fixedly connected to the lower part of the central pipe (4). The retaining ring (23) is located below the lower piston (21), and the outer diameter of the retaining ring (23) is greater than the outer diameter of the lower piston (21).

6. A method for using a mid-course pressure-testing hydraulic oil-draining oil pipe anchor, characterized in that: Based on the mid-stream pressure-testable hydraulic oil-draining oil pipe anchor as claimed in claim 5, the method of use includes: a. Pressure test process: After the hydraulic tubing anchor is lowered normally to the specified depth, the oil pipe connected to the pump truck is pressurized to test the pipe string for leaks. Since the liquid inlet hole on the center pipe (4) is blocked by the pressure test shear nail (6), the pressure in the oil pipe cannot enter the hydraulic tubing anchor through the liquid inlet hole, so the hydraulic tubing anchor is not anchored. After the pressure test, it can be lowered normally; b. Anchoring process: When the hydraulic tubing anchor is lowered to the specified depth, the pumping rod is lowered to break the pressure-testing shear nail (6). At this time, the liquid inlet hole is opened. During production, the liquid level in the tubing gradually rises, and the pressure in the tubing also gradually rises. At this time, the pressure in the tubing enters from the liquid inlet hole on the center tube (4). When the pressure enters the inside of the hydraulic tubing anchor, it pushes the upper piston (11) to move upward. At this time, the upper part of the upper piston (11) drives the anchor shoe (3) to expand outward along the cone joint (1), completing the anchoring action; c. Oil drainage action: When the operation requires oil drainage from the tubing, the oil pipe is directly pressurized. At this time, the hydraulic tubing anchor is in the anchored state. The pressure enters the annulus of the lower piston (21) from the center pipe (4) through the oil drainage hole (22). The pressure is continued. When the pressure exceeds the rated value of the oil drainage shear pin (19), the oil drainage shear pin (19) is broken. The lower piston (21) moves downward under the pressure and separates from the oil drainage sleeve (20). It is blocked by the retaining ring (23). At this time, the liquid flows out from the oil drainage hole (22) through the oil drainage sleeve (20), and the oil drainage is completed. d. Anchor release process: After the oil is drained, the inside and outside of the oil pipe are connected and the pressure is balanced. Under the action of the spring (12), the pressure cap (14) is pushed downward, which in turn drives the hexagon socket screw (13), the upper piston (11) and the anchor shoe (3) downward, and the oil pipe is lifted to complete the anchor release.

7. The method for using a mid-stream pressure-testing hydraulic oil-draining oil pipe anchor as claimed in claim 6, characterized in that: b. The anchoring process also includes: the upper piston (11) moves upward while the anchoring shear pin (10) is cut off; the lower part of the upper piston is connected to the lower pressure cap (14) via the hexagon socket screw (13), and is connected to the oil drain sleeve (20) via the set screw (15); the oil drain sleeve (20) is connected to the lower piston (21) via the oil drain shear pin (19); while the upper piston (11) moves upward, it drives the lower pressure cap (14), the oil drain sleeve (20), and the lower piston (21) to move upward, and the lower pressure cap (14), the oil drain sleeve (20), and the lower piston (21) are connected to the lower piston (21) via the oil drain shear pin (19); When the cap (14) moves upward, the spring (12) is compressed; before the hydraulic tubing anchor is anchored, the oil drain hole (22) is sealed by the sealing ring V (16) and the sealing ring VI (17), and the pressure in the tubing cannot be transmitted to the lower piston (21); after the hydraulic tubing anchor is anchored, the oil drain sleeve (20) is driven upward by the upper piston (11), and the pressure can enter the piston cavity. During production, the pressure in the tubing will not shear the oil drain shear pin (19), thereby ensuring normal production of the tubing string.

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