A mid-line pressure-testing hydraulic oil-draining oil pipe anchor and its use method

Abstract

The present invention relates to the technical field of oil well operation tools, and specifically to a hydraulic oil-draining oil pipe anchor capable of mid-stream pressure testing and a method for using the same. The hydraulic oil pipe anchor comprises a center pipe, a conical joint, an anchor shoe, and a piston assembly. The conical joint is arranged at the top of the center pipe, and a sealing ring I is provided between the conical joint and the center pipe for sealing. The center pipe is connected to the oil pipe through the conical joint. The anchor shoe and the piston assembly are both sleeved on the center pipe. The anchor shoe is arranged between the conical joint and the piston assembly. One end of the anchor shoe is provided with a conical hole for cooperating with the conical joint, and the other end of the anchor shoe is connected to the piston assembly. The present invention can complete the oil drainage action by directly applying pressure to the oil pipe without dropping any tools into the oil pipe. The main purpose is to achieve the oil drainage function of the pipe string without moving the pipe string during the operation of the oil well, so that the well can be washed directly, and the oil pipe and sucker rod can be cleaned together, reducing the pollution of the environment caused by the crude oil being brought out when the pipe and rod are lifted.

Description

Technical Field

[0001] The present invention relates to the technical field of oil well operation tools, and in particular to a mid-process pressure-testing hydraulic oil-draining type oil pipe anchor and a use method thereof. Background Art

[0002] During oil well operations, the crude oil in the oil pipe needs to be released to avoid polluting the environment. During the oil release process, after all the operating equipment such as the well repair rig are laid out, the oil pipe must be hoisted and the sucker rod pulled out before backwashing the well to clean the crude oil in the oil pipe. However, the pulled out sucker rod cannot be cleaned, and the entire well washing process also involves pulling in and out the tubing, which increases the operation process and reduces the operation efficiency.

[0003] Patent application number CN109931031A, titled "A Hydraulic Oil Drain," states that the pump rod must be raised in advance to drain oil, and a valve ball of appropriate specifications must be inserted into the oil pipe. Once the ball is seated, the valve ball and the oil drain form a sealed space, which then needs to be pressurized to complete the oil drain. This oil drain currently has the following disadvantages:

[0004] 1. When draining oil, the sucker rod must be pulled out before the operation can be carried out. The crude oil on the sucker rod cannot be processed in advance through well washing operations. The crude oil on the sucker rod needs additional processing, which increases the workload of the operators and reduces the operation efficiency.

[0005] 2. During operation, if the oil pump plunger cannot be lifted out due to sand or other reasons, or the sucker rod is broken for other reasons and cannot be lifted out normally, the valve ball cannot be put into place when the ball is dropped, and a closed space cannot be formed, and oil cannot be discharged;

[0006] 3. Most oil pipes currently produced are lined, which are corrosion-resistant and have a long service life. However, as the production time of lined oil pipes increases, the inner lining rubber of the lined oil pipe is easy to fall off. If it falls into the oil pipe, it will reduce the internal diameter of the oil pipe. There is a high probability that the valve ball will encounter resistance when falling, and the valve ball will not be able to seat, resulting in oil leakage.

[0007] 4. If you encounter a heavy oil well, the crude oil density is very high. When the ball is dropped, the valve ball is easy to be out of place. If you want to continue to drain the oil, you need to backwash the well, which increases the operation process and is time-consuming, costly and labor-intensive. Summary of the Invention

[0008] In response to the shortcomings of the existing background technology, the present invention aims to provide a simple, easy-to-use hydraulic tubing anchor capable of mid-stream pressure testing and oil drainage, and its use method. The present invention achieves oil drainage by directly applying pressure to the tubing, without requiring any tools to be inserted into the tubing. This primarily addresses the problem of achieving tubing drainage during well operation without moving the tubing, thereby enabling positive well cleaning of the tubing and pumping rods, reducing environmental contamination caused by the removal of crude oil from the tubing and rods during operation.

[0009] To achieve the above, the present invention provides a mid-stream hydraulic pressure-testable oil pipe anchor, comprising a center pipe, a conical joint, an anchor shoe, and a piston assembly. The conical joint is disposed at the top of the center pipe, which is connected to the oil pipe via the conical joint. The anchor shoe and the piston assembly are both sleeved onto the center pipe, with the anchor shoe disposed between the conical joint and the piston assembly. One end of the anchor shoe is provided with a conical groove for mating with the conical 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 of which are sleeved onto the center pipe and can move along the center pipe 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 the oil drain sleeve. A sealing ring II is provided between the upper piston and the center pipe for sealing, and a sealing ring VII is provided between the lower piston and the center pipe for sealing.

[0010] Furthermore, the piston assembly also includes an oil drain sleeve, which is arranged between the upper piston and the lower piston. One end of the oil drain sleeve is connected to the lower end of the upper piston through a set screw, and the other end of the oil drain sleeve is connected to the lower piston through an oil drain shear pin.

[0011] Furthermore, the central tube is provided with a liquid inlet hole and an oil drain hole. The liquid inlet hole is located at the upper part of the central tube and corresponds to the upper piston. A pressure-testable shear pin is installed on the liquid inlet hole. The oil drain hole is located at the lower part of the central tube and corresponds to the oil drain sleeve. A sealing ring V is provided between the oil drain sleeve and the central tube above the oil drain hole, and a sealing ring VI is provided between the oil drain sleeve and the central tube below the oil drain hole.

[0012] Furthermore, the piston assembly also includes a push-down cap, which is sleeved on the center tube. The push-down cap is arranged in the upper piston above the oil drain sleeve, and the lower part of the upper piston is connected to the push-down cap by a hexagon socket screw.

[0013] Furthermore, the piston assembly also includes a heat-insulating part, which is fixedly connected to the center tube. A sealing ring III is provided between the heat-insulating part and the center tube for sealing. The heat-insulating part is located in the upper piston. The outer side surface of the heat-insulating part is in contact with the inner surface of the upper piston and is sealed by a sealing ring IV. The heat-insulating part is located above the lower pressure cap, and the upper piston and the heat-insulating part are connected by anchoring shear pins.

[0014] Furthermore, the piston assembly also includes a spring, which is sleeved on the center tube. The spring is arranged in the upper piston between the thermal insert and the lower pressure cap. One end of the spring is connected to the lower end of the thermal insert, and the other end of the spring is connected to the upper end of the lower pressure cap.

[0015] Furthermore, the hydraulic oil pipe anchor also includes a retaining ring, which is fixedly connected to the lower part of the central pipe and located below the lower piston. The outer diameter of the retaining ring is larger than the outer diameter of the lower piston.

[0016] The present invention also relates to a method for using a mid-stream pressure-testing hydraulic oil-draining oil pipe anchor. Based on the mid-stream pressure-testing hydraulic oil-draining oil pipe anchor, the method comprises:

[0017] a. Pressure test process: After the hydraulic tubing anchor is lowered normally to the specified depth, it is connected to the pump truck and the tubing is pressurized to test the tubing string for leaks. Since the liquid inlet hole on the center pipe is blocked by the pressure test shear nail, the pressure in the tubing cannot enter the hydraulic tubing anchor through the liquid inlet hole. Therefore, the hydraulic tubing anchor is not anchored. After the pressure test, it can be lowered normally.

[0018] b. Anchoring process: When the hydraulic tubing anchor is lowered to the specified depth, the piston breaks the pressure-testing shear pin when the pumping rod is lowered. At this time, the liquid inlet hole opens. During production, 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 through the liquid inlet hole on the center tube. When the pressure enters the hydraulic tubing anchor, it pushes the upper piston upward. At this time, the upper part of the upper piston drives the anchor shoe to expand along the cone joint, completing the anchoring action;

[0019] c. Oil draining action: When the operation requires draining oil from the tubing, 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 from the center pipe through the drain hole. Continue to apply pressure. When the pressure exceeds the rated value of the drain shear pin, the drain shear pin is broken. The lower piston moves downward under the action of pressure and disengages from the drain sleeve. It is then blocked by the retaining ring. At this time, the liquid flows out from the drain hole through the drain sleeve, completing the oil draining.

[0020] 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, the pressure cap is pushed downward, which in turn drives the hexagon socket screw, upper piston and anchor shoe downward, and the oil pipe is lifted to complete the anchor release.

[0021] Furthermore, the b. anchoring process also includes: the anchoring shear pins are cut off while the upper piston moves upward, the lower part of the upper piston is connected to the lower pressure cap by a hexagon socket screw, and is connected to the oil drain sleeve by a set screw, and the oil drain sleeve is connected to the lower piston by the oil drain shear pins; while the upper piston moves upward, it drives the lower pressure cap, the oil drain sleeve and the lower piston to move upward, and the spring is compressed when the lower pressure cap moves upward; before the hydraulic oil pipe anchor is anchored, the oil drain hole is sealed by the sealing ring V and the sealing ring VI, and the pressure in the oil pipe cannot be transmitted to the lower piston; after the hydraulic oil pipe anchor is anchored, the oil drain sleeve is driven upward by the upper piston, and the pressure can enter the piston cavity. The pressure in the oil pipe during production will not shear the oil drain shear pins, thereby ensuring the normal production of the tubing string.

[0022] The advantages of adopting the technical solution of the present invention are:

[0023] 1. The present invention can complete the oil drainage by directly applying pressure to the oil pipe. There is no need to put any tools into the oil pipe. As long as there is a gap in the oil pipe, the pressure can be transmitted to complete the oil drainage. In addition, there is no need to lift the sucker rod in the oil pipe. After the oil drainage is completed, the rod and pipe can be cleaned together during the well washing, which can effectively reduce the workload of on-site operators and improve work efficiency.

[0024] 2. The hydraulic tubing anchor of the present invention has pressure-testing shear nails inside, which can test the tubing string for leaks at any time, effectively reducing repeated operations caused by pipe leaks, improving operating efficiency, and reducing the workload of on-site operators.

[0025] 3. This invention utilizes a simple oil drainage method by applying pressure to the tubing. This method eliminates the need to trip the tubing string or pull the pump rod to drain the oil. After draining the oil, forward flushing can be performed to remove crude oil from the tubing and pump rod, achieving greater effectiveness and efficiency than backwashing. Furthermore, the simplified oil drainage operation aligns with the work habits of on-site operators, significantly improving operational efficiency.

[0026] 4. The present invention has its own anchoring function. After anchoring, the oil well pump can be anchored on the casing together, reducing the peristalsis of the oil well pump caused by production and improving the pump efficiency. After anchoring, it can also effectively prevent the pipe string from breaking off. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 It is a structural schematic diagram of the hydraulic oil pipe anchor of the present invention.

[0029] The marks in the above figure are: 1. Conical joint; 2. Sealing ring I; 3. Anchor shoe; 4. Center tube; 5. Sealing ring II; 6. Pressure test shear pin; 7. Sealing ring III; 8. Sealing ring IV; 9. Hot-fitting part; 10. Anchor shear pin; 11. Upper piston; 12. Spring; 13. Hexagon socket screw; 14. Lower pressure cap; 15. Set screw; 16. Sealing ring V; 17. Sealing ring VI; 18. Sealing ring VII; 19. Drain shear pin; 20. Drain sleeve; 21. Lower piston; 22. Drain hole; 23. Retaining ring. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0031] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0032] like Figure 1 As shown, a mid-stream hydraulic pressure-testing oil-draining tubing anchor comprises a center tube 4, a conical joint 1, an anchor shoe 3, and a piston assembly. The conical joint 1 is mounted on top of the center tube 4, with a sealing ring I2 provided between the two for sealing. The center tube 4 is connected to the tubing via the conical joint 1. The anchor shoe 3 and the piston assembly are both sleeved onto the center tube 4, with the anchor shoe 3 positioned between the conical joint 1 and the piston assembly. One end of the anchor shoe 3 has a tapered groove for mating with the conical joint 1, while the other end of the anchor shoe 3 is connected to the piston assembly. The conical joint 1 integrates the upper joint and the cone, simplifying processing and assembly.

[0033] The present invention can complete the oil drainage action by directly applying pressure to the oil pipe, without putting any tools into the oil pipe. As long as there is a gap in the oil pipe, the pressure can be transmitted to complete the oil drainage. Moreover, there is no need to lift the sucker rod in the oil pipe. After the oil drainage is completed, the rod and pipe can be cleaned together during the well washing, which can effectively reduce the workload of on-site operators and improve work efficiency.

[0034] The piston assembly includes an upper piston 11 and a lower piston 21. Both pistons are sleeved onto the center tube 4 and 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, and the other end of the upper piston 11 is connected to the oil drain sleeve 20. A sealing ring II5 is provided between the upper piston 11 and the center tube 4 for sealing, and a sealing ring VII18 is provided between the lower piston 21 and the center tube 4 for sealing.

[0035] The piston assembly also includes a drain sleeve 20, positioned between the upper piston 11 and the lower piston 21. One end of the drain sleeve 20 is connected to the lower end of the upper piston 11 via a set screw 15, while the other end is connected to the lower piston 21 via a drain shear pin 19. Multiple rubber rings seal the drain sleeve and the lower piston, forming a piston chamber. An annular groove is located at the bottom of the upper piston, while a bolt hole is located at the top of the drain sleeve. A set nut connects the upper piston and the drain sleeve. When the tool is not anchored, the set nut is located at the bottom of the annular groove.

[0036] A liquid inlet hole and an oil drain hole 22 are provided on the central tube 4. 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 nail 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 V16 is provided between the oil drain sleeve 20 and the central tube 4 above the oil drain hole 22, and a sealing ring VI17 is provided between the oil drain sleeve 20 and the central tube 4 below the oil drain hole 22.

[0037] The piston assembly also includes a push-down cap 14 , which is sleeved on the center tube 4 . The push-down 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 push-down cap 14 via a hexagon socket screw 13 .

[0038] The piston assembly also includes a heat-insertion part 9, which is fixedly connected to the center tube 4. A sealing ring III 7 is provided between the heat-insertion part 9 and the center tube 4 for sealing. The heat-insertion part 9 is located in the upper piston 11. The outer side surface of the heat-insertion part 9 is in contact with the inner surface of the upper piston 11 and is sealed by a sealing ring IV 8. The heat-insertion part 9 is located above the lower pressure cap 14. The upper piston 11 and the heat-insertion part 9 are connected by an anchor shear nail 10.

[0039] The piston assembly also includes a spring 12, which is sleeved on the center tube 4. The spring 12 is arranged in the upper piston 11 between the thermal insert 9 and the lower pressure cap 14. One end of the spring 12 is connected to the lower end of the thermal insert 9, and the other end of the spring 12 is connected to the upper end of the lower pressure cap 14.

[0040] In order to prevent the lower piston from falling off, the hydraulic oil pipe anchor also 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.

[0041] The specific working process is: when the tubing anchor is lowered to the specified depth, when the sucker rod is lowered, the piston of the oil pump breaks the pressure test shear nail 6 through the inside of the tubing anchor, and the pressure test shear nail falls off. Because the density of the pressure test shear nail 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 production occurs, 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 center tube 4. The upper piston 11 and the thermal fitting 9 have sealing rings on the upper and lower parts, and the thermal fitting 9 is fixed on the center tube 4 and cannot move. When the pressure enters the inside of 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 along the cone joint 1 to complete the anchoring action. As the upper piston 11 moves upward, it shears the anchor shear pin 10. The lower portion of the upper piston is connected to the lower pressure cap 14 via the hexagon socket screw 13, and to the drain sleeve 20 via the set screw 15. The drain sleeve 20 is connected to the lower piston 21 via the drain shear pin 19. Similarly, as the upper piston 11 moves upward, it also 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 tool is anchored, the drain hole 22 is sealed by the sealing ring V16 and the sealing ring VI17, and the pressure in the oil pipe cannot be transmitted to the lower piston 21. After anchoring, the drain sleeve 20 is driven upward by the upper piston 11, and the pressure can enter the piston cavity. The pressure in the oil pipe during production will not shear the drain shear pin 19, ensuring normal production of the tubing string.

[0042] When the operation requires oil drainage from the tubing, positive pressure is directly applied to the tubing. At this time, the tool is in the anchored state, and the pressure enters the annulus of the lower piston 21 from the central tube 4 through the oil drain hole 22. When the pressure continues to exceed the rated value of the oil drain shear pin 19, the oil drain shear pin 19 is broken, and the lower piston 21 moves downward under the action of the pressure, disengaging from the oil drain sleeve 20 and being blocked by the retaining ring 23. At this time, the liquid level flows out from the oil drain hole 22 through the oil drain sleeve 20, completing the oil drainage.

[0043] Based on the above-mentioned hydraulic oil pipe anchor capable of mid-line pressure testing and oil drainage, the present invention further provides a method for using the hydraulic oil pipe anchor capable of mid-line pressure testing and oil drainage, the method comprising:

[0044] a. Pressure test process: After the hydraulic tubing anchor is lowered normally to the specified depth, it is connected to the pump truck and the tubing is pressurized to test the tubing string for leaks. Since the liquid inlet hole on the center tube 4 is blocked by the pressure test shear nail 6, the pressure in the tubing cannot enter the hydraulic tubing anchor through the liquid inlet hole. Therefore, the hydraulic tubing anchor is not anchored. After the pressure test, it can be lowered normally.

[0045] b. Anchoring process: When the hydraulic tubing anchor is lowered to the specified depth, the pumping rod is lowered, breaking the pressure-testing shear pin 6. The liquid inlet hole is now open. During production, the liquid level in the tubing gradually rises, and the pressure in the tubing also gradually increases. The pressure in the tubing enters through the liquid inlet hole on the center tube 4. When the pressure enters the hydraulic tubing anchor, it pushes the upper piston 11 upward. At this time, the upper portion of the upper piston 11 drives the anchor shoe 3 to expand outward along the cone joint 1, completing the anchoring action.

[0046] When the upper piston 11 moves upward, the anchor shear pin 10 is cut off. The lower part of the upper piston is connected to the lower pressure cap 14 by the hexagon socket screw 13, and is connected to the oil drain sleeve 20 by the set screw 15. The oil drain sleeve 20 is connected to the lower piston 21 by the oil drain shear pin 19. When 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. When the lower pressure cap 14 moves upward, the spring 12 is compressed. Before the hydraulic oil pipe anchor is anchored, the oil drain hole 22 is sealed by the sealing ring V16 and the sealing ring VI17, and the pressure in the oil pipe cannot be transmitted to the lower piston 21. After the hydraulic oil pipe anchor is anchored, the oil drain sleeve 20 is driven upward by the upper piston 11, and the pressure can enter the piston cavity. The pressure in the oil pipe during production will not shear the oil drain shear pin 19, thereby ensuring the normal production of the pipe string.

[0047] c. Oil drainage: When the operation requires oil drainage from the tubing, positive pressure is directly applied to the tubing. At this time, the hydraulic tubing anchor is in the anchored state. Pressure enters the annulus of the lower piston 21 from the center tube 4 through the oil drain hole 22. Continue to apply pressure. When the pressure exceeds the rated value of the oil drain shear pin 19, the oil drain shear pin 19 is broken. The lower piston 21 moves downward under the pressure and disengages from the oil drain sleeve 20. It is then blocked by the retaining ring 23. At this time, the liquid flows out from the oil drain hole 22 through the oil drain sleeve 20, completing the oil drainage.

[0048] 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.

[0049] The hydraulic oil pipe anchor of the present invention has pressure test shear nails inside, which can test the pressure of the pipe string at any time to find leaks, effectively reducing repeated operations caused by pipe leakage, improving operation efficiency, and reducing the workload of on-site operators.

[0050] This invention uses a simple oil drainage method by applying pressure to the tubing. It can be completed without tripping the tubing string or pumping the pump rod. After the oil is drained, forward well flushing can be performed to remove crude oil from the tubing and pump rod, achieving greater effectiveness and efficiency than backwashing. Furthermore, the oil drainage operation is simpler, aligning with the work habits of on-site operators and effectively improving operational efficiency.

[0051] The present invention has its own anchoring function, and after anchoring, the oil well pump can be anchored on the casing together, reducing the peristalsis of the oil well pump caused by production, improving the pump efficiency, and after anchoring, it can also effectively prevent the pipe column from breaking off.

[0052] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0053] Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A mid-test hydraulic oil-draining oil pipe anchor, comprising a central pipe (4), characterized in that: The invention also includes a cone joint (1), an anchor shoe (3) and a piston assembly. The cone joint (1) is arranged on the top of the center tube (4). The center tube (4) is connected to the oil pipe through 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 conical 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 includes 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), and 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; the 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-line 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 nail (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-line pressure-testing hydraulic oil-draining oil pipe anchor according to claim 2, characterized in that: The piston assembly also includes a heat-insulating component (9), which is fixedly connected to the central tube (4). A sealing ring III (7) is provided between the heat-insulating component (9) and the central tube (4) for sealing. The heat-insulating component (9) is located in the upper piston (11). The outer side surface of the heat-insulating 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-insulating component (9) is located above the lower pressure cap (14). The upper piston (11) and the heat-insulating component (9) are connected by an anchor shear nail (10).

4. The mid-line pressure-testing hydraulic oil-draining oil pipe anchor according to 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-insulating component (9) and the lower pressing cap (14). One end of the spring (12) is connected to the lower end of the heat-insulating 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-line pressure-testing hydraulic oil-draining oil pipe anchor according to claim 4, characterized in that: The retaining ring (23) is fixedly connected to the lower part of the central tube (4). The retaining ring (23) is located below the lower piston (21). The outer diameter of the retaining ring (23) is larger than the outer diameter of the lower piston (21).

6. A method for using a mid-process pressure-testing hydraulic oil-draining oil pipe anchor, characterized in that: The method for using the mid-line pressure-testing hydraulic oil-draining oil pipe anchor according to claim 5 includes: a. Pressure test process: After the hydraulic oil-draining type oil pipe anchor is lowered normally to the specified depth, it is connected to the pump truck oil pipe and pressure is applied to the pipe string to check for leaks. Since the liquid inlet hole on the center pipe (4) is blocked by the pressure-testable shear nail (6), the pressure in the oil pipe cannot enter the hydraulic oil-draining type oil pipe anchor through the liquid inlet hole, so the hydraulic oil-draining type oil pipe anchor is not anchored. After the pressure test, it can be lowered normally; b. Anchoring process: When the hydraulic oil-draining tubing anchor is lowered to the specified depth, the pumping rod is lowered, breaking the pressure-testing shear nail (6). At this time, the liquid inlet hole is opened. When the liquid level in the tubing gradually rises during production, 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 interior of the hydraulic oil-draining 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 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 oil drainage type 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) is moved downward by the pressure and separated from the oil drainage sleeve (20). It is blocked by the retaining ring (23). At this time, the liquid level 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-line pressure-testing hydraulic oil-draining oil pipe anchor according to claim 6, characterized in that: The anchoring process b. also includes: the upper piston (11) cuts off the anchoring shear pin (10) while the upper piston (11) moves upward, the lower part of the upper piston is connected to the lower pressure cap (14) through the hexagon socket screw (13), and is connected to the oil drain sleeve (20) through the set screw (15), and the oil drain sleeve (20) is connected to the lower piston (21) through 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) When the spring (12) moves upward, it is compressed; before the hydraulic oil-draining tubing anchor is anchored, the oil-draining 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 oil-draining tubing anchor is anchored, the oil-draining 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 shear the oil-draining shear pin (19), thereby ensuring normal production of the tubing string.

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