Explosive nut runner and method using axial shaped charge jet and blast impact

Abstract

The application discloses an explosion buckle loosening device and method using axial energy-gathering jet flow and explosion impact, and belongs to the technical field of oil and gas resource exploration and development, and comprises a joint, a bullet loading cylinder, an explosion rod and a lead cone which are sequentially connected, so that the basic function of explosion buckle loosening is realized; an electric detonator is arranged in the joint; a booster, a first detonating fuse and a perforating bullet are sequentially arranged in the bullet loading cylinder; explosion impact energy is collectively output through the electric detonator, the booster, the first detonating fuse, the perforating bullet and a second detonating fuse, so as to provide a power source for drill rod buckle loosening; the explosion rod and the lead cone are arranged to play a supporting and protecting role; a bullet pressing device is arranged to fix the detonating fuse and the perforating bullet; the explosion buckle loosening principle is clear from the arrangement of the device, and the success rate of explosion buckle loosening is ensured.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas resource exploration and development technology, specifically a device and method for explosive loosening using axial focused jet and explosive impact. Background Technology

[0002] As exploration and development continue to deepen, the structure of deep and ultra-deep wells is becoming increasingly complex. In some areas, drilling and completion operations are often carried out using small wellbores of 135.5 to 149.2 mm in the producing sections. Some sections are prone to leakage and collapse, resulting in a high risk of stuck drill pipe.

[0003] Types of stuck drill bit accidents include: stuck drill bit due to adhesion, stuck drill bit due to collapse, stuck drill bit due to sand bridging, stuck drill bit due to reduced diameter, stuck drill bit due to keyway, stuck drill bit due to mud bagging, stuck drill bit due to dry drilling, stuck drill bit due to falling objects, and stuck drill bit due to cement consolidation. Common methods for dealing with stuck drill bits include circulation, rotating the drill bit up and down, soaking in brine, and acid bath. Explosive loosening involves lowering explosives to the first coupling thread of the drill bit above the stuck point. The high-speed impact force generated by the explosive detonation instantly eliminates or greatly reduces the friction and self-locking property between the threads, causing the joint threads to loosen under the pre-applied counter-torque, thus achieving the purpose of loosening and reverse-threading.

[0004] CN217206371U discloses an explosive release device, including an ignition device and an explosive release mechanism. The ignition device and the explosive release mechanism are coaxially arranged and sealed together. The ignition device is used to ignite the explosive release mechanism, which is used to perform external work. One end of the ignition device has a first connector, and the other end has a detonator assembly. A high-voltage electronic ignition device is located inside the ignition device. The end of the explosive release mechanism connected to the ignition device has a detonation tube, and the other end has an explosive rod. The detonation tube is connected to the explosive rod via a detonating cord. This explosive release device simplifies the assembly process and improves the safety and stability of the explosive release mechanism during explosive release operations.

[0005] CN113137187A discloses an explosive loosening device for small-diameter drill pipe in ultra-deep and ultra-high-temperature wells, comprising a basket, an ignition assembly, a charge housing, and a tail end, all connected by threads in sequence. The charge housing contains a propellant charge, which serves as the charge space, penetrating the interior of the charge housing. This invention, through a redesign of the charge housing structure, significantly improves the pressure-bearing capacity of the charge housing. The novel multi-groove structure further enhances the explosive loosening performance, thereby improving the loosening effect of small-diameter explosive loosening devices and reducing downhole debris after loosening.

[0006] However, the existing technology still has the following shortcomings: 1) The temperature and pressure resistance is low, which cannot meet the requirements of explosive loosening of drill pipe in deep and ultra-deep wells; 2) The mechanism of explosive loosening of drill pipe in deep and ultra-deep wells is unclear, and the amount of explosive used depends entirely on human experience, resulting in a low success rate. Summary of the Invention

[0007] This invention provides an explosive loosening device and method that utilizes axial shaped jet and explosive impact, solving the problems of unclear explosive loosening mechanism of drill pipe in deep and ultra-deep wells, the dependence of the amount of explosive used on manual experience, and the low success rate of one attempt.

[0008] To achieve the above objectives, the present invention provides the following technical solution: An explosive release device utilizing axial shaped jet and explosive impact includes a connector, a loading tube, an explosive rod, and an induction cone connected in sequence. An electric detonator is installed inside the connector. A detonating tube, a first detonating cord, and a perforating projectile are connected in sequence inside the loading tube. A pressurizing device is connected to the detonating tube, the first detonating cord, and the perforating projectile. A second detonating cord is connected to the explosive rod.

[0009] Preferably, the upper end of the connector is connected to a cable and a magnetic locator.

[0010] Preferably, the electric detonator adopts a multi-segment enhanced detonating charge structure, the explosive in the electric detonator is subjected to explosive grain optimization treatment, and the electric detonator can withstand a maximum temperature of 230°C.

[0011] Preferably, the detonation tube includes a high-temperature explosive and an aluminum alloy shell. The explosive undergoes explosive grain optimization treatment and can withstand a maximum temperature of 260°C. It is used to receive the detonation output energy of the electric detonator and transfer it to the perforating projectile through a first detonating cord.

[0012] Preferably, the first detonating cord comprises a high-temperature plastic shell and a high-temperature explosive. Through optimization of the explosive grains, the high-temperature plastic shell and the high-temperature explosive can withstand a maximum temperature of 260°C, which is used to transfer detonation energy and detonate the perforated projectile.

[0013] Preferably, the loading tube can withstand a maximum pressure of 175 MPa, and the second detonating cord can withstand a maximum temperature of 230°C and a maximum pressure of 180 MPa.

[0014] A method for explosive unfastening using axial shaped jet and explosive impact, comprising: A finite element model was established based on the working conditions of the well, and the parameters of the finite element model were set to conduct a simulation of the explosion response with prestress. The amount of explosive charge is determined based on the simulation results and the criteria for judging the loosening of the explosive charge. The installation length of the second detonating cord is determined based on the amount of explosive charge. Assemble the explosive release device and lower it into the predetermined position; Electric ignition is used for detonation.

[0015] Preferably, the steps for conducting explosion response simulation with prestress are as follows: Based on the finite element model with the parameters set, static analysis is used to obtain the stress state of the finite element model. Then, explicit dynamic analysis is performed to obtain the explosive loading conditions; Obtain the response mechanism of the threaded structure in the finite element model under explosive impact; The vibration characteristics of the threaded connection are obtained based on the stress state of the finite element model, the explosive loading conditions, and the response mechanism of the threaded structure of the finite element model under explosive impact. The dynamic response law of the perforated pipe string under explosive load was obtained based on the vibration characteristics.

[0016] Preferably, the finite element model parameters are the material, elastic modulus, and Poisson's ratio of the finite element model, as well as the yield strength and ultimate tensile strength parameters.

[0017] Preferably, the stress state of the finite element model is obtained by static analysis based on the downhole depth, the weight of the tubing string, the tension preload, and the constraint state of the gun catch.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an explosive release device utilizing axial shaped jet and explosive impact, comprising a connector, a loading tube, an explosive rod, and a guide cone connected in sequence, realizing the basic function of explosive release. An electric detonator is installed in the connector, and a detonating tube, a first detonating cord, and a perforating projectile are installed in the loading tube connected in sequence. The electric detonator, the detonating tube, the first detonating cord, the perforating projectile, and the second detonating cord jointly output explosive impact energy to provide a power source for releasing the drill rod. The explosive rod and guide cone provide support and protection. The pressurizing device is used to fix the detonating cord and the perforating projectile. The explosive release principle is clearly defined from the device design, ensuring the success rate of explosive release.

[0019] Furthermore, the method of embedding electric detonators and using perforated jets to detonate the detonating cord effectively solves the problem of the traditional method where the detonator is exposed in the well fluid. This method greatly improves the pressure resistance of the detonation release. At the same time, the method of using perforated jets to detonate high-temperature and high-pressure detonating cords to provide the explosive impact power source is conducive to improving the overall pressure resistance.

[0020] This invention also provides an explosive loosening method using axial shaped jet and explosive impact. By establishing a finite element model and simulating the response to the explosion, it provides a reference for recommending accurate explosive dosage for deep and ultra-deep wells, thereby improving the success rate of explosive loosening operations in one go. Furthermore, the mechanical state preloading before the explosion was achieved under static and quasi-static conditions; then, through dynamic relaxation, the quasi-static conditions were extended to the finite element method for explicit dynamic calculations. This enabled the simulation of the explosion response with prestress. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the upper part of the structure of an explosive unfastening device utilizing axial focused jet and explosive impact according to the present invention. Figure 2 This is a schematic diagram of the lower part of the structure of an explosive unfastening device utilizing axial focused jet and explosive impact according to the present invention; Figure 3 This is a flowchart of an explosive unfastening method using axial focused jet and explosive impact according to the present invention. Figure 4 This is a simulation flowchart of the explosion response of an explosion release method utilizing axial focused jet and explosive impact according to the present invention. Figure 5 This is a diagram illustrating the criteria for judging whether an explosion has loosened the fastener according to the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0025] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] like Figure 1As shown, this embodiment of the invention provides an explosive release device that utilizes axial shaped jet and explosive impact, including a connector 1, a loading cylinder 6, an explosive rod 8, and an induction cone 9 connected in sequence. An electric detonator 2 is installed inside the connector 1. A detonating tube 3, a first detonating cord, and a perforating projectile 5 are connected in sequence inside the loading cylinder 6. A pressing device 4 is connected to the first detonating cord and the perforating projectile 5. A second detonating cord 7 is connected to the explosive rod 8.

[0027] The method of using an internal electric detonator 2 and a perforating projectile 5 to detonate the detonating cord effectively solves the problem of the traditional method where the detonator is exposed in the well fluid. This method greatly improves the pressure resistance of the detonation release. At the same time, the method of using the perforating projectile 5 to detonate the high-temperature and high-pressure detonating cord to provide the explosive impact power source is also conducive to improving the overall pressure resistance.

[0028] Another embodiment of the present invention provides an explosive release device utilizing axial shaped jet and explosive impact, comprising a connector 1, a loading cylinder 6, an explosive rod 8, and an induction cone 9 connected in sequence. An electric detonator 2 is disposed inside the connector 1. A detonating tube 3, a first detonating cord, and a perforating projectile 5 are disposed inside the loading cylinder 6 connected in sequence. A pressing device 4 is connected to the first detonating cord and the perforating projectile 5. A second detonating cord 7 is connected to the explosive rod 8.

[0029] The upper end of connector 1 is connected to a cable and a magnetic locator. Connector 1 is a quick-connect coupling, a conventional quick-connect coupling for oil and gas wells, primarily serving the functions of connection and power transmission. This allows the device to be positioned more accurately at the target location and facilitates remote control and monitoring via cable. The magnetic locator also helps determine the device's location in complex or difficult-to-observe environments, improving operational accuracy and safety.

[0030] Another embodiment of the present invention provides an explosive release device utilizing axial shaped jet and explosive impact, comprising a connector 1, a loading cylinder 6, an explosive rod 8, and an induction cone 9 connected in sequence. An electric detonator 2 is disposed inside the connector 1. A detonating tube 3, a first detonating cord, and a perforating projectile 5 are disposed inside the loading cylinder 6 connected in sequence. A pressing device 4 is connected to the first detonating cord and the perforating projectile 5. A second detonating cord 7 is connected to the explosive rod 8.

[0031] The electric detonator 2 adopts a multi-segment enhanced detonation charge structure, and the explosive in the electric detonator is subjected to explosive grain optimization treatment. The maximum temperature that the electric detonator 2 can withstand is 230℃.

[0032] The device employs a multi-stage enhanced detonating charge structure and optimizes explosive grains, thereby improving detonation reliability and explosive energy release efficiency. Furthermore, the electric detonator 2 can withstand a maximum temperature of 230℃, ensuring normal operation even in high-temperature environments and broadening its application range.

[0033] Another embodiment of the present invention provides an explosive release device utilizing axial shaped jet and explosive impact, comprising a connector 1, a loading cylinder 6, an explosive rod 8, and an induction cone 9 connected in sequence. An electric detonator 2 is disposed inside the connector 1. A detonating tube 3, a first detonating cord, and a perforating projectile 5 are disposed inside the loading cylinder 6 connected in sequence. A pressing device 4 is connected to the first detonating cord and the perforating projectile 5. A second detonating cord 7 is connected to the explosive rod 8.

[0034] The detonation tube 3 includes a high-temperature explosive and an aluminum alloy shell. The explosive undergoes explosive grain optimization treatment and can withstand a maximum temperature of 260°C. It is used to receive the detonation output energy of the electric detonator 2 and transmit it to the perforating projectile 5 through the first detonating cord.

[0035] The detonation tube 3 comprises a high-temperature explosive and an aluminum alloy shell. The explosive has undergone optimized treatment to improve the transfer efficiency and stability of detonation energy. Its maximum withstand temperature is 260℃, enabling the device to maintain stable performance in extreme high-temperature environments and ensuring the smooth execution of the detonation release process.

[0036] Another embodiment of the present invention provides an explosive release device utilizing axial shaped jet and explosive impact, comprising a connector 1, a loading cylinder 6, an explosive rod 8, and an induction cone 9 connected in sequence. An electric detonator 2 is disposed inside the connector 1. A detonating tube 3, a first detonating cord, and a perforating projectile 5 are disposed inside the loading cylinder 6 connected in sequence. A pressing device 4 is connected to the first detonating cord and the perforating projectile 5. A second detonating cord 7 is connected to the explosive rod 8.

[0037] The first detonating cord consists of a high-temperature plastic shell and a high-temperature explosive. Through optimization of the explosive grains, the high-temperature plastic shell and the high-temperature explosive can withstand a maximum temperature of 260°C, which is used to transfer detonation energy and detonate the perforated projectile 5.

[0038] The first detonating cord consists of a high-temperature plastic shell and high-temperature explosive, and its high-temperature and pressure resistance has been improved through explosive grain optimization treatment. This allows the detonating cord to stably transmit detonation energy in harsh environments and reliably detonate the perforated projectile 5, thus ensuring the effectiveness of the detonation release.

[0039] Another embodiment of the present invention provides an explosive release device utilizing axial shaped jet and explosive impact, comprising a connector 1, a loading cylinder 6, an explosive rod 8, and an induction cone 9 connected in sequence. An electric detonator 2 is disposed inside the connector 1. A detonating tube 3, a first detonating cord, and a perforating projectile 5 are disposed inside the loading cylinder 6 connected in sequence. A pressing device 4 is connected to the first detonating cord and the perforating projectile 5. A second detonating cord 7 is connected to the explosive rod 8.

[0040] The loading tube 6 has a maximum pressure resistance of 175 MPa, and the second detonating cord 7 has a maximum temperature resistance of 230°C and a maximum pressure resistance of 180 MPa.

[0041] The loading tube 6 has a pressure resistance of up to 175 MPa, ensuring stability even under high pressure. The second detonating cord 7 has a maximum temperature resistance of 230°C and a pressure resistance of 180 MPa, enabling it to operate normally in high-temperature and high-pressure environments, further improving the reliability and applicability of the device.

[0042] Another embodiment of the present invention provides an explosive release device utilizing axial shaped jet and explosive impact, comprising a connector 1, a loading cylinder 6, an explosive rod 8, and an induction cone 9 connected in sequence. An electric detonator 2 is disposed inside the connector 1. A detonating tube 3, a first detonating cord, and a perforating projectile 5 are disposed inside the loading cylinder 6 connected in sequence. A pressing device 4 is connected to the first detonating cord and the perforating projectile 5. A second detonating cord 7 is connected to the explosive rod 8.

[0043] The connector 1 is a quick connector, which is a conventional quick connector for oil and gas wells. Its upper end is connected to a cable and a magnetic locator. It mainly serves the functions of connection and power transmission.

[0044] The electric detonator 2 is a high-temperature electric detonator, which employs a multi-segment enhanced detonating charge structure. Through optimization of explosive grains, the maximum temperature can reach 230℃. The high-temperature electric detonator is installed inside the quick connector.

[0045] The detonation tube 3 is a high-temperature detonation tube, which uses high-temperature explosives and an aluminum alloy shell. Through optimization of the explosive grains, the maximum temperature can reach 260℃. It is used to receive the detonation output energy of the high-temperature electric detonator and transfer it to the perforating projectile through the detonating cord.

[0046] The pressurizing device is used to support the detonating tube 3, the high-temperature detonating cord, and the perforating projectile 5.

[0047] The first detonating cord consists of a high-temperature plastic shell and a high-temperature explosive. Through optimization of the explosive grains, the maximum temperature can reach 260°C. It is used to transfer detonation energy and reliably detonate the perforating projectile.

[0048] The perforating projectile 5 is made of high-temperature resistant explosive, and through optimization of explosive grains, the maximum temperature can reach 260°C. The perforating projectile 5 is installed inside the loading tube 6. After the first detonating cord detonates the perforating projectile 5, the resulting high-speed metal jet penetrates the loading tube 6 and detonates the next stage second detonating cord 7.

[0049] The loading tube 6 is used to install perforating projectiles 5, etc., and serves to isolate the wellbore fluid. It has a high pressure resistance and a maximum temperature resistance of 175MPa. Compared with the traditional solution where the electric detonator is exposed in the well fluid, this solution greatly improves the pressure resistance of the explosive release mechanism.

[0050] The second detonating cord 7 consists of a high-temperature plastic shell and high-temperature explosive, possessing both temperature and pressure resistance, with a maximum pressure resistance of 180 MPa and a maximum temperature resistance of 230°C. After the perforation projectile jet detonates the main detonating cord, the main detonating cord detonates multiple detonating cords that are intertwined. The combined explosive impact energy provides the power source for loosening the drill pipe.

[0051] like Figure 2 As shown, the explosive rod 8 and the guide cone 9 are composed of conventional oil and gas well explosive rods and guide cones, which serve to provide support and protection.

[0052] like Figure 3 As shown, the present invention also provides an explosive loosening method utilizing axial shaped jet and explosive impact, comprising: S101 establishes a finite element model based on the working conditions of the well, sets the parameters of the finite element model, and conducts a simulation of the explosion response with prestress. S102 determines the amount of explosive charge based on simulation results and the judgment criteria for loosening the explosive charge. S103 determines the installation length of the second detonating cord 7 based on the amount of explosive charge; S104 assembles the explosive release device and lowers it into the predetermined position; S105 is initiated by electric ignition.

[0053] The detailed steps are as follows: A finite element model was established based on the working conditions of the well. The material properties, elastic modulus, Poisson's ratio, yield strength, and ultimate tensile strength parameters of the finite element model were set. Simulations of the explosion response with prestress were then conducted. Details are as follows: 1. The explosive load caused a change in the stress state of the thread meshing interface. The preload generated under static load could not resist the instantaneous impact of the explosion. The meshing area was affected by vibration and underwent a slight displacement. At the same time, the stable stress state changed. 2. Assuming that the explosive load dissipates immediately after being applied to the interface, the redistributed stress state can provide new frictional force, and the contact interface becomes relatively stationary again.

[0054] 3. In reality, the explosive load will not dissipate immediately after the first application. Instead, it will be affected by the discontinuous characteristics of the connection surfaces of each level of the pipe string system in the well. It will oscillate in the connection interfaces of each level in various forms such as dissipation and reflection, causing small displacements multiple times and continuously giving the meshing surface a new stress balance state and positional relationship. After repeated accumulation of the minute displacements described in point 4, complete separation of the meshing interface may occur, causing the preload to decrease to a low level or even zero. This allows the applied torsional lifting torque to successfully release the engagement.

[0055] Based on the simulation results of the explosion response, combined with Figure 3 The explosion loosening judgment criterion determines the charge amount, and uses simulation calculation to obtain the contact surface strain curve dissipation and zeroing judgment benchmark for thread loosening.

[0056] The installation length of the high-temperature and high-pressure detonating cord 7 is determined based on the amount of explosive charge.

[0057] The assembled explosive release device is lowered into the predetermined position. Then, a suitable position is selected for electric ignition to detonate the high-temperature electric detonator 2, the high-temperature detonating tube 3, the high-temperature detonating cord, and the perforating projectile 5.

[0058] The perforating projectile 5 generates a high-speed metal jet that detonates the high-temperature and high-pressure detonating cord 7, thereby providing an impact vibration power source for the drill pipe to be sent out of the lock.

[0059] By establishing a finite element model and simulating the response to explosion, a reference is provided for recommending the precise amount of explosives for loosening loose connections in deep and ultra-deep wells, thereby improving the success rate of one-time loosening operations. like Figure 4 As shown, the specific steps for conducting a simulation of the explosion response with prestress are as follows: Based on the finite element model with the parameters set, static analysis is used to obtain the stress state of the finite element model. Then, explicit dynamic analysis is performed to obtain the explosive loading conditions; Obtain the response mechanism of the threaded structure in the finite element model under explosive impact; The vibration characteristics of the threaded connection are obtained based on the stress state of the finite element model, the explosive loading conditions, and the response mechanism of the threaded structure of the finite element model under explosive impact. The dynamic response law of the perforated pipe string under explosive load was obtained based on the vibration characteristics.

[0060] The mechanical state preloading before the explosion was achieved under static and quasi-static conditions; then, through dynamic relaxation, the quasi-static conditions were extended to the finite element method for explicit dynamic calculations. This enabled the simulation of the explosion response with prestress.

[0061] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the specification, can make many other modifications without departing from the scope of the claims of the present invention, and all of these modifications are within the scope of protection of the present invention.

Claims

1. An explosive release device utilizing axial shaped jet and explosive impact, characterized in that, It includes a connector (1), a loading tube (6), an explosive rod (8) and an induction cone (9) connected in sequence. An electric detonator (2) is installed inside the connector (1). A detonating tube (3), a first detonating cord and a perforating projectile (5) are connected in sequence inside the loading tube (6). A projectile pressing device (4) is connected to the detonating tube (3), the first detonating cord and the perforating projectile (5). A second detonating cord (7) is connected to the explosive rod (8).

2. The explosive loosening device utilizing axial focused jet and explosive impact according to claim 1, characterized in that, The upper end of the connector (1) is connected to a cable and a magnetic locator.

3. The explosive loosening device utilizing axial focused jet and explosive impact according to claim 1, characterized in that, The electric detonator (2) adopts a multi-segment enhanced detonation charge structure. The explosive in the electric detonator is subjected to explosive grain optimization treatment. The electric detonator (2) can withstand a maximum temperature of 230℃.

4. The explosive loosening device utilizing axial focused jet and explosive impact according to claim 1, characterized in that, The detonation tube (3) includes a high-temperature explosive and an aluminum alloy shell. The explosive is subjected to explosive grain optimization treatment and the maximum temperature that the explosive can withstand is 260°C. It is used to receive the detonation output energy of the electric detonator (2) and transmit it to the perforating projectile (5) through the first detonating cord.

5. The explosive loosening device utilizing axial focused jet and explosive impact according to claim 1, characterized in that, The first detonating cord consists of a high-temperature plastic shell and a high-temperature explosive. Through optimization of the explosive grains, the high-temperature plastic shell and the high-temperature explosive can withstand a maximum temperature of 260°C, which is used to transfer detonation energy and detonate the perforating projectile (5).

6. The explosive release device utilizing axial focused jet and explosive impact according to claim 1, characterized in that, The loading tube (6) has a maximum pressure resistance of 175 MPa, and the second detonating cord (7) has a maximum temperature resistance of 230°C and a maximum pressure resistance of 180 MPa.

7. A method for explosive loosening using axial shaped jet and explosive impact, characterized in that, include A finite element model was established based on the working conditions of the well, and the parameters of the finite element model were set to conduct a simulation of the explosion response with prestress. The amount of explosive charge is determined based on the simulation results and the criteria for judging the loosening of the explosive charge. The installation length of the second detonating cord (7) is determined based on the amount of explosive charge; Assemble the explosive release device and lower it into the predetermined position; Electric ignition is used for detonation.

8. The explosive loosening method using axial shaped jet and explosive impact according to claim 7, characterized in that, The specific steps for conducting explosion response simulation with prestress are as follows: Based on the finite element model with the parameters set, static analysis is used to obtain the stress state of the finite element model. Then, explicit dynamic analysis is performed to obtain the explosive loading conditions; Obtain the response mechanism of the threaded structure in the finite element model under explosive impact; The vibration characteristics of the threaded connection are obtained based on the stress state of the finite element model, the explosive loading conditions, and the response mechanism of the threaded structure of the finite element model under explosive impact. The dynamic response law of the perforated pipe string under explosive load was obtained based on the vibration characteristics.

9. The explosive loosening method using axial shaped jet and explosive impact according to claim 7, characterized in that, The parameters of the finite element model are the material, elastic modulus, and Poisson's ratio of the finite element model, as well as the yield strength and ultimate strength parameters.

10. The explosive loosening method using axial shaped jet and explosive impact according to claim 7, characterized in that, The stress state of the finite element model is obtained by static analysis based on the downhole depth, the weight of the tubing string, the tension preload, and the constraint state of the gun.

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