Drillable hydraulic releasing tool and working method thereof

Abstract

The invention belongs to the field of petroleum downhole tool operation, and particularly relates to a drillable hydraulic releasing tool and a working method thereof.The tool comprises an upper connector and a lower shell, and the upper connector is connected into the lower shell in an inserted mode; the upper connector and the lower shell are both hollow pipe bodies. An elastic locking device is mounted at the lower end of the upper joint; the elastic locking device comprises a connector and an elastic barrel, the upper end of the connector is connected with the upper connector, and the lower end of the connector is connected with the upper end of the elastic barrel. A plurality of elastic steel sheets are annularly distributed in the elastic barrel, a gap is formed between every two adjacent elastic steel sheets, and the elastic steel sheets and the elastic barrel form an elastic locking structure; pressure transmission holes are prefabricated in the outer walls of the upper connector and the lower shell, and pins are installed in the pressure transmission holes. A limiting piston is mounted in the upper joint; when in use, the rubber plug is sunk into the upper joint and is positioned above the limiting piston. The problem that an existing safety connector cannot safely and efficiently achieve releasing or back-off is solved.

Description

Technical Field

[0001] This invention belongs to the field of oil well downhole tool operation, specifically relating to a drillable hydraulic release tool and its working method. Background Technology

[0002] Currently, during major workover operations, safety joints are generally installed on the work string to enhance construction safety. A safety joint is a safety tool that is easily detached and reconnected to the work string inside the well. It is installed at the position where the work string needs to be detached and can transmit torque and withstand various complex stresses together with the work string. In case of failure or the work string getting stuck, the work string can be detached and reconnected through wellhead operation, so that the work tools can be withdrawn from the safety joint.

[0003] Conventional safety joints are removed by mechanical rotation. However, in complex well sections or when large-diameter tools are stuck inside the well, they can only be unstuck by reverse rotation. The tubing above the stuck point is then unstuck and pulled out of the well. However, due to uncontrollable factors such as inaccurate calculation of the stuck point, large-diameter tools often fall apart. In addition, in order to meet the requirements of more precise construction in the straightening of misaligned well sections, the existing safety joints cannot be rotated freely after the casing is straightened, and the up-and-down movement load is restricted, making them unsuitable for the application of existing straightening of misaligned well sections.

[0004] Invention

[0005] The purpose of this invention is to provide a drillable hydraulic release tool and its working method, which solves the problem that existing safety connectors cannot safely and efficiently release or lock the hand.

[0006] This invention is achieved through the following technical solution:

[0007] A drillable hydraulic release tool includes an upper connector and a lower housing, wherein the upper connector is inserted into and connected to the lower housing; both the upper connector and the lower housing are hollow tubes.

[0008] The lower end of the upper connector is equipped with an elastic locking device;

[0009] The elastic locking device includes a connector and an elastic cylinder. The upper end of the connector is connected to the upper connector, and the lower end is connected to the upper end of the elastic cylinder.

[0010] Several elastic steel sheets are arranged in a ring in the elastic cylinder, with gaps between adjacent elastic steel sheets, forming an elastic locking structure with the elastic cylinder;

[0011] Pressure transmission holes are pre-drilled on the outer walls of the upper connector and the lower housing, and pins are installed in the pressure transmission holes.

[0012] A limit piston is installed in the upper connector; during use, a rubber plug is inserted into the upper connector, with the rubber plug positioned above the limit piston.

[0013] Furthermore, the lower shell is made of aluminum, while the elastic cylinder is made of rubber.

[0014] Furthermore, the upper connector includes an upper connecting section, an intermediate section, and a lower connecting connector that are integrally connected from top to bottom, with an elastic locking device threadedly connected to the lower end of the lower connecting connector; and a pressure transmission hole pre-fabricated on the intermediate section.

[0015] Furthermore, two annular sealing grooves are prefabricated on the wall of the middle section, and a sliding sleeve sealing ring is installed in the annular sealing groove;

[0016] The upper and lower ends of the limiting piston are both machined with annular grooves for placing the sealing ring;

[0017] An upper piston seal is installed in the annular groove at the upper end of the limiting piston, and a lower piston seal is installed in the annular groove at the lower end of the limiting piston.

[0018] Furthermore, the upper end of the upper connector is threaded to the delivery pipe column, and the lower end of the lower housing is threaded to the straightening tool.

[0019] Furthermore, the rubber stopper includes an upper end head, a trapezoidal column, a connecting section, and a lower end head connected sequentially from top to bottom;

[0020] There are multiple trapezoidal columns connected in series.

[0021] Furthermore, the upper end of the limiting piston is pre-fabricated with a conical seat cover, and the lower end is a conical body, which is in contact with and connected to the conical seat cover.

[0022] Furthermore, a pin anti-detachment cap is installed at the end of the pressure transmission hole in the lower housing.

[0023] Furthermore, the lower end of the elastic cylinder is prefabricated with a protrusion.

[0024] The present invention also discloses a method for operating the drillable hydraulic release tool, comprising the following steps:

[0025] Insert the rubber stopper, and press it against the upper end of the limit piston;

[0026] As pressure continues to be applied, the rubber stopper is pressed and drives the limiting piston to slide downward. The elastic locking device is squeezed by the limiting piston, the elastic steel sheet opens, and the elastic cylinder expands outward, clamping the upper connector and the lower shell.

[0027] Continue to pressurize, and under the push of the rubber stopper, the limiting piston continues to slide downward. When the upper end of the limiting piston moves to below the pin, some liquid enters the pressure transmission hole. The liquid pushes the pin to move outward axially, causing the pin to completely separate from the pressure transmission hole of the upper connector.

[0028] Continue applying pressure, and the limiting piston continues to move downward until the upper end of the limiting piston disengages from the lower end of the elastic locking device, and the limiting piston falls into the lower housing.

[0029] Lifting the rubber stopper causes the elastic cylinder and elastic steel sheet of the elastic locking device to retract, disengaging the upper connector from the lower housing, causing the lower housing to fall off, thus releasing the user's grip.

[0030] Compared with the prior art, the present invention has the following beneficial technical effects:

[0031] This invention discloses a drillable hydraulic release tool, comprising an upper connector and a lower housing, with the upper connector inserted into the lower housing. An elastic locking device is installed at the lower end of the upper connector, comprising an elastic cylinder and elastic steel plates. The spring steel plates are arranged in multiple rings and enclosed within a highly elastic rubber cylinder, forming an elastic locking structure. The upper connector and the elastic steel plate frame are steel components. When the elastic steel plates tighten, the upper connector locks into a limiting piston. Pressure transmission holes are pre-drilled on the outer walls of the upper connector and the lower housing, and pins are installed in these holes. A limiting piston is installed in the upper connector. During the release operation, a rubber plug is inserted into the upper connector, positioned above the limiting piston. Under high-pressure liquid, the rubber stopper descends, driving the limiting piston downwards. This first causes the pin to move outwards, disengaging the upper connector from the lower housing. As pressure continues to increase, the limiting piston disengages from the elastic locking device and falls into the lower housing. The rubber stopper is then prevented from falling out by the elasticity of the rubber. After the stopper is lifted, the elastic steel plate and elastic cylinder of the elastic locking device contract, causing the lower housing to fall, thus releasing the tool. This hydraulic tool release connector has few components and a simple structure. The lower housing can be released simply by the contraction of the elastic locking device. After the casing is aligned, the upper housing can rotate freely. No torque is required for tool release, solving the problem of tool loss during construction. It is particularly effective for the complex well conditions of workover wells.

[0032] The drillable hydraulic release tool designed in this invention makes a significant contribution to the safe release of tools and the reduction of construction risks. The aluminum hydraulic release connector is easier to drill and remove, and can simultaneously perform plugging agent injection. In actual operation, the use of this tool can simplify the construction process, effectively reduce the occurrence of engineering accidents, reduce construction costs and economic losses, thereby creating great economic and social benefits and promoting harmony.

[0033] This invention also discloses a working method for a drillable hydraulic release tool, which has high operating efficiency and reduces construction costs due to improved construction efficiency and fewer construction steps. This process is simple to implement, completely simplifying the previously complex construction process. It is easy to operate, completing the well-working fluid and tool release steps in one step, greatly simplifying the workload; at the same time, it is inexpensive and has low costs.

[0034] Furthermore, the lower casing is made of aluminum, making it easier to drill through.

[0035] Furthermore, the connecting section of the rubber stopper adopts a multi-annular groove design, which increases the elastic deformation of the rubber stopper head and also increases the toughness of the rubber stopper head.

[0036] Furthermore, a pin anti-dislodgement cap is installed at the end of the pressure transmission hole to limit the movement distance of the pin and prevent the pin from dislodging from the lower housing.

[0037] Furthermore, the inner end of the elastic cylinder protrudes outward, which can better clamp the upper connector and the lower shell. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the drillable hydraulic release tool of the present invention;

[0039] Figure 2 for Figure 1 Schematic diagram of the upper and middle connector 1;

[0040] Figure 3 for Figure 1 The enlarged view at point A shows a schematic diagram of the installation of the rubber plug and pin in a drillable hydraulic release tool.

[0041] Figure 4 for Figure 1 Schematic diagram of the elastic structure of rubber in China;

[0042] Figure 5 for Figure 1 Enlarged view of a section at point B in the middle;

[0043] Figure 6 for Figure 1 Enlarged view of a section at point C;

[0044] Figure 7 Figure a is a schematic diagram of the limiting piston in the drillable hydraulic release tool of the present invention; Figure a shows the external structure of the limiting piston; Figure b is a cross-sectional schematic diagram of Figure a.

[0045] Figure 8 This is a diagram showing the initial state of the drillable hydraulic release tool of the present invention when the tool is inserted into the well.

[0046] Figure 9 This is a diagram showing the state of the rubber plug in the drillable hydraulic release tool of the present invention, after the rubber plug is inserted, as the rubber plug descends to the elastic locking device.

[0047] Figure 10 This is a schematic diagram showing the positions of the rubber plug and the limiting piston after the drillable hydraulic release tool of the present invention is released by pressure.

[0048] The components include: 1. Upper connector; 2. Limiting piston; 3. Lower housing; 4. Pin; 5. Rubber plug; 6. Sliding sleeve sealing ring; 7. Upper piston sealing ring; 8. Lower piston sealing ring; 9. Pin anti-dislodgement cap.

[0049] 10. Elastic locking device; 101. Connector; 102. Elastic steel sheet; 103. Elastic cylinder; 104. Rubber ring;

[0050] 11. Upper connecting section; 12. Middle section; 13. Lower connecting joint; 14. Pressure transmission hole; 15. Annular sealing groove;

[0051] 51. Top end; 52. Trapezoidal column; 53. Connecting section; 54. Bottom end. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0053] The components described and illustrated in the accompanying drawings and embodiments of this invention can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment of the invention. All other embodiments obtained by those skilled in the art based on the accompanying drawings and embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0054] It should be noted that the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that a process, element, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to the process, element, method, article, or apparatus. Furthermore, the terms "above" and "below" are based on the orientation and positional relationship of the devices or components shown in the accompanying drawings and are used only for better description of the invention, not to require that the shown devices, components, or apparatus must have that specific orientation, and therefore should not be construed as limiting the invention.

[0055] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0056] like Figure 1 As shown, this invention discloses a drillable hydraulic release tool, comprising an upper connector 1 and a lower housing 3, with the upper connector 1 inserted into the lower housing 3. A limit piston 2 is installed in the upper connector 1, and a rubber plug 5 is pumped in during use.

[0057] like Figure 2 As shown, the upper connector 1 is a hollow tube body, including an upper connecting section 11, a middle section 12 and a lower connecting connector 13 connected from top to bottom.

[0058] The upper connecting section 11 is a Ф73mm flat oil pipe thread, which is connected to the threaded delivery pipe string. The lower connecting joint 13 is a standard pipe thread, which is connected to the connector 101.

[0059] like Figure 2 and Figure 3 As shown, an annular sealing groove 15 is prefabricated on the wall of the middle section 12, and a sliding sealing ring 6 is installed in the annular sealing groove 15.

[0060] like Figure 2 As shown, the upper connector 1 and the lower housing 3 are sealed together by a sliding sleeve sealing ring 6 and a pin 4.

[0061] like Figure 2 and Figure 3 As shown, the upper connector 1 has a pressure-transmitting hole 14 at a position corresponding to the lower housing 3, through which a pin 4 is installed. A pin anti-detachment cap 9 is installed on the outer circumference of the lower housing 3, and the pin anti-detachment cap 9 is located at the end of the pressure-transmitting hole 14. When the pin 4 moves into the pin anti-detachment cap 9, the upper connector 1 and the lower housing 3 are no longer fixedly connected.

[0062] like Figures 4-6 As shown, the elastic locking device 10 includes a connector 101 and an elastic cylinder 103. The upper end of the connector 101 is connected to the upper connector 1, and the lower end is connected to the upper end of the elastic cylinder 103.

[0063] Several elastic steel sheets 102 are arranged in a ring in the elastic cylinder 103, with gaps between adjacent elastic steel sheets 102, forming an elastic locking structure with the elastic cylinder 103.

[0064] Specifically, the inner circumference of the cavity of the elastic cylinder 103 is provided with 10 elastic steel sheets 102, and there are annular gaps between the elastic steel sheets 102. The elastic steel sheets 102 are embedded in the elastic cylinder 103, and there are gaps between the elastic steel sheets 102 to form an elastic locking structure.

[0065] Specifically, the elastic cylinder 103 is made of rubber.

[0066] More preferably, the end of the elastic cylinder 103 protrudes outward to form a rubber ring 104, which can better clamp the upper connector 1 and the lower housing 3.

[0067] Even better, such as Figure 7As shown in Figures a and b, the upper end of the limiting piston 2 has a conical seat surface for contacting and connecting with the lower end of the rubber stopper 5. The lower end face of the limiting piston 2 extends to the elastic locking device 10. Both the upper and lower ends of the limiting piston 2 are machined with annular grooves for placing the sealing ring.

[0068] like Figure 1 As shown, the upper connector 1 and the limiting piston 2 are sealed by the upper sealing ring 7 of the piston; Figure 1 As shown, a lower sealing ring 8 for the limiting piston is installed in the annular groove at the lower end of the limiting piston 2.

[0069] like Figure 1 As shown, the lower housing 3 is cylindrical, and four radially evenly distributed pressure transmission holes 14 are pre-drilled on the outer circular surface of the lower housing 3 for installing pins 4; the lower end of the lower housing 3 has external threads for connecting with construction tools via pipe threads.

[0070] Generally, the pin 4 is a copper cylinder that is connected to the pressure transmission hole 14 on the upper connector 1 and the lower housing 3 by means of an interference fit. The pin 4 is used to connect the upper connector 1 and the lower housing 3 to prevent breakage during the well entry process.

[0071] like Figure 3 As shown, the rubber stopper 5 includes an upper end head 51, a trapezoidal column 52, a connecting section 53 and a lower end head 54 connected sequentially from top to bottom. Multiple trapezoidal columns 52 are provided and connected in series. The connecting section 53 adopts a multi-annular groove design to increase the elastic deformation of the head of the rubber stopper 5 and increase the toughness of the head of the rubber stopper 5.

[0072] Specifically, the upper end 51 is made of aluminum alloy, while the trapezoidal column 52, the connecting section 53, and the lower end 54 are all made of rubber.

[0073] Specifically, the lower end 54 matches the conical seat cover of the limiting piston 2 and is also designed as a conical surface.

[0074] The working method of the drillable hydraulic release tool of the present invention is as follows:

[0075] like Figure 8 As shown, the rubber plug 5 is not initially in the upper connector 1. The displacement fluid, i.e. the workover fluid, is pumped into the tubing using a pump truck. The rubber plug 5 is then lowered into the tubing, allowing it to smoothly reach the upper end of the limit piston 2 and press against it, thus sealing the tubing string and achieving pressure buildup.

[0076] The rubber stopper 5 is pressed and drives the limiting piston 2 to slide downward. The elastic locking device 10 is squeezed by the limiting piston 2, the elastic steel sheet 102 opens outward, the elastic cylinder 103 expands outward, and the rubber ring 104 at the lower end clamps the upper connector 1 and the lower housing 3.

[0077] Under the push of the rubber stopper 5, the limiting piston 2 continues to slide downward. When the upper end of the limiting piston 2 slides to below the pin 4, some liquid enters the pressure transmission hole 14. The liquid pushes the pin 4 to move outward axially until the pin 4 is completely inserted into the pin anti-dislodgement cap 9, causing the pin 4 to be completely separated from the pressure transmission hole 14 of the upper connector 1.

[0078] Limit piston 2 continues to move downwards, as... Figure 9 As shown, the lower end of the limiting piston 2 enters the lower housing 3 until the upper end of the limiting piston 2 disengages from the lower end of the elastic locking device 10, and the limiting piston 2 falls into the lower housing 3.

[0079] At this point, the tubing is lifted, bringing out the rubber plug 5, and the elastic locking device 10 retracts, as... Figure 10 As shown, the upper connector 1 is completely detached from the lower housing 3, as... Figure 7 As shown, the lower shell 3 falls off, completing the process of dropping the item.

[0080] The following is a specific application example for illustration.

[0081] The drillable hydraulic release tool of the present invention can release the straightening tool, and at the same time complete the subsequent cement injection, waiting for setting, drilling and removing the drillable casing straightening guide and aluminum release tool, and restoring a new wellbore passage.

[0082] The specific implementation method during construction is as follows:

[0083] The lower end of the working tubing is connected to the upper connector 1 of the drillable hydraulic release tool, and the lower end of the lower housing 3 of the drillable hydraulic release tool is connected to the drillable guide and centering tool, forming the entire instrument string. The instrument string is placed into the oil well to the casing damage position. Smooth operation is required, and sudden lifting and lowering are prohibited. The pressure should not exceed 20.0kN.

[0084] Once the drillable directional straightening tool is lowered to the predetermined position, complete the pre-well entry preparation work. Begin well flushing and circulation. After the circulation is normal, lower the displacement plug 5 into the tubing and continue pumping in working fluid to ensure that the plug 5 smoothly reaches the conical seat of the limit piston 2.

[0085] Continue to pressurize to 10.0MPa, and apply hydraulic pressure to the oil pipe to 15-20MPa. When the upper end of the limit piston 2 slides to below the pin 4, some liquid enters the pressure transmission hole 14. The liquid pushes the pin 4 to move outward axially, causing the pin 4 to displace into the pin anti-dislodgement cap 9, so that the pin 4 is completely separated from the pressure transmission hole 14 of the upper connector 1.

[0086] The limiting piston 2 continues to move downward until the upper end of the limiting piston 2 disengages from the lower end of the elastic locking device 10, at which point the limiting piston 2 falls into the lower housing 3.

[0087] Lifting the tubing column brings out the rubber plug 5, the elastic locking device 10 retracts, and the upper connector 1 completely separates from the lower housing 3. Figure 8 As shown, the lower shell 3 falls off, completing the process of dropping the item.

[0088] The drill bit is lowered and the lower housing 3 of the hydraulic release joint and the limiting piston 2 are drilled out in one go. Finally, the construction purpose of the construction section or the casing damaged section is achieved through major workover.

[0089] This drillable hydraulic release tool has the following advantages:

[0090] I. Convenient and efficient operation

[0091] The release operation is achieved using a hydraulic system. The entire release process can be completed by inserting a rubber stopper and gradually increasing pressure. This eliminates the need for complex mechanical structures and cumbersome operating procedures, greatly improving work efficiency.

[0092] The components work closely together and move in a continuous manner, enabling them to respond quickly to pressure changes and achieve precise release operation.

[0093] II. Reliable locking

[0094] The elastic locking device includes a connector, an elastic cylinder, and several elastic steel plates, forming an elastic locking structure. Under pressure, the elastic steel plates open, and the elastic cylinder expands outward, which can firmly lock the upper connector and the lower housing, ensuring the reliability of the connection during operation.

[0095] The design of the pressure transmission hole and pin further enhances the stability of the connection. When the limit piston moves to a specific position, the liquid pushes the pin outward axially, completely separating the pin from the pressure transmission hole of the upper connector, providing a reliable guarantee for subsequent release operations.

[0096] III. Safety from Dropping Hands

[0097] When the rubber stopper is lifted, the elastic cylinder and elastic steel plate of the elastic locking device contract, allowing the upper connector to smoothly disengage from the lower housing. The lower housing then falls, completing the release. The entire release process is smooth and reliable, preventing any unexpected situations and ensuring operational safety.

[0098] The design of the limit piston makes the release operation more precise and controllable. During pressurization, the position change of the limit piston can accurately trigger each step, ensuring that the release operation is carried out according to the predetermined procedure.

[0099] IV. High drillability

[0100] This tool is drillable; after the initial release, it can be drilled if needed, facilitating subsequent operations and maintenance.

[0101] In summary, this drillable hydraulic release tool offers advantages such as convenient and efficient operation, reliable locking, safe release, and strong drillability, meeting the operational needs of various complex working conditions.

[0102] The drillable hydraulic release tool designed in this invention has a compact structure and is easy to install. It can release the tool in the well and complete the injection of chemical plugging agent into the damaged well section during the major workover of oil and water wells. The use of this release connector simplifies the operation procedure and reduces the construction risk. The drillable hydraulic release tool of this invention is made of aluminum alloy and is connected to a new type of aluminum casing straightening guide, which is easy to drill and does not produce pollution during drilling.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A drillable hydraulic release tool, characterized in that, It includes an upper connector (1) and a lower housing (3), with the upper connector (1) inserted into the lower housing (3); both the upper connector (1) and the lower housing (3) are hollow tubes. An elastic locking device (10) is installed at the lower end of the upper connector (1); The elastic locking device (10) includes a connector (101) and an elastic cylinder (103). The upper end of the connector (101) is connected to the upper connector (1), and the lower end is connected to the upper end of the elastic cylinder (103). Several elastic steel sheets (102) are arranged in a ring in the elastic cylinder (103), and there is a gap between adjacent elastic steel sheets (102), forming an elastic locking structure with the elastic cylinder (103); Pressure transmission holes (14) are pre-made on the outer walls of the upper connector (1) and the lower housing (3), and pins (4) are installed in the pressure transmission holes (14); A limiting piston (2) is installed in the upper connector (1); when in use, a rubber plug (5) is inserted into the upper connector (1), with the rubber plug (5) positioned above the limiting piston (2).

2. A drillable hydraulic backoff tool as defined in claim 1, wherein, The lower shell (3) is made of aluminum; the elastic cylinder (103) is made of rubber.

3. The drillable hydraulic backoff tool of claim 1, wherein, The upper connector (1) includes an upper connecting section (11), an intermediate section (12) and a lower connecting connector (13) that are integrally connected from top to bottom. The elastic locking device (10) is threadedly connected to the lower end of the lower connecting connector (13). The pressure transmission hole (14) is prefabricated on the intermediate section (12).

4. The drillable hydraulic backoff tool of claim 3, wherein, Two annular sealing grooves (15) are prefabricated on the wall of the middle section (12), and a sliding sleeve sealing ring (6) is installed in the annular sealing groove (15); The upper and lower ends of the limiting piston (2) are both machined with annular grooves for placing the sealing ring; An upper piston seal (7) is installed in the annular groove at the upper end of the limiting piston (2), and a lower piston seal (8) is installed in the annular groove at the lower end of the limiting piston (2).

5. The drillable hydraulic backoff tool of claim 1, wherein, The upper end of the upper connector (1) is threaded to the delivery pipe column, and the lower end of the lower housing (3) is threaded to the straightening tool.

6. A drillable hydraulic backoff tool as defined in claim 1, wherein, The rubber stopper (5) includes an upper end (51), a trapezoidal column (52), a connecting section (53), and a lower end (54) connected from top to bottom; Multiple trapezoidal columns (52) are provided and connected in series.

7. A drillable hydraulic backoff tool as defined in claim 6, wherein, The upper end of the limiting piston (2) is pre-made with a conical seat cover, and the lower end (54) is a conical body, which is in contact with the conical seat cover.

8. The drillable hydraulic backoff tool of claim 1, wherein, A pin anti-detachment cap (9) is installed at the end of the pressure transmission hole (14) of the lower housing (3).

9. The drillable hydraulic backoff tool of claim 1, wherein, The lower end of the elastic cylinder (103) is also prefabricated with a protrusion.

10. The method of operating the drillable hydraulic backoff tool of any of claims 1-9, wherein, Includes the following steps: Insert the rubber plug (5), and the rubber plug (5) reaches the upper end of the limiting piston (2) and presses against it; As pressure continues to be applied, the rubber stopper (5) is pressed and drives the limiting piston (2) to slide downward. The elastic locking device (10) is squeezed by the limiting piston (2), the elastic steel sheet (102) opens, and the elastic cylinder (103) expands outward, clamping the upper connector (1) and the lower shell (3). Continue to pressurize, and under the push of the rubber stopper (5), the limiting piston (2) continues to slide downward. When the upper end of the limiting piston (2) moves to below the pin (4), some liquid enters the pressure transmission hole (14). The liquid pushes the pin (4) to move outward axially, causing the pin (4) to completely separate from the pressure transmission hole (14) of the upper connector (1). As pressure continues to be applied, the limiting piston (2) continues to move downward until the upper end of the limiting piston (2) disengages from the lower end of the elastic locking device (10), and the limiting piston (2) falls into the lower housing (3). When the rubber plug (5) is lifted, the elastic cylinder (103) and elastic steel sheet (102) of the elastic locking device (10) retract, the upper connector (1) separates from the lower housing (3), the lower housing (3) falls off, and the release is completed.

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