Self-short-circuit safety explosion-proof detonator for oil and gas well and detonating method

Abstract

The application discloses a self-short-circuit safety explosion-proof detonator for oil and gas wells and a detonating method, and relates to the technical field of safety detonation of oil and gas well perforation. The application comprises a metal shell, a reset spring, a guide block, a contact type detonator and an explosion-proof assembly. The explosion-proof assembly, the guide block, the reset spring and the contact type detonator are sequentially arranged from inside to outside in the metal shell. The contact type detonator comprises a detonator positive pole, a detonator negative pole, an insulating pad and an outer shell containing an ignition head and a basic detonator. The insulating pad is inserted into the detonator positive pole and the detonator negative pole. The outer shell is connected with the detonator negative pole and inserted into the inner hole of the guide block. The reset spring is sleeved on the outer shell and connected with the guide block and the detonator negative pole at both ends. The detonator negative pole is sequentially connected with the reset spring, the guide block, the explosion-proof assembly and the metal shell to form an electrical connection. The essential safety of the electric detonator for oil and gas wells during transportation, assembly, well drilling, waiting for detonation and detonation is improved, and the risk of personal injury and equipment loss caused by misdetonation and mispropagation is reduced.

Description

Technical Field

[0001] This invention relates to the field of safety technology for perforation initiation of oil and gas wells, specifically to a self-short-circuit safety explosion-proof detonator and initiation method for oil and gas wells. Background Technology

[0002] In oil and gas well perforation operations, electric detonators are typically used to detonate perforation gun strings. However, conventional electric detonators in existing technology pose a risk of accidental detonation during transportation, handling, loading, unloading, and wellhead standby due to factors such as static electricity from the human body, stray currents, electromagnetic induction, and radio frequency interference. Accidental detonation can not only cause personnel casualties but also trigger a chain reaction of detonations in the perforation gun string, resulting in significant equipment damage and well site accidents.

[0003] In addition, existing detonators usually do not have the ability to automatically switch safety states according to the downhole environment. Especially in different stages such as assembly above ground, running down the well, waiting to fire, and retrieval, there is a lack of a structural solution that can maintain safety explosion isolation and self-short circuit above ground, and automatically release safety protection and restore normal detonation transmission capability after the predetermined pressure is reached downhole.

[0004] Therefore, existing technologies need to be improved. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned defects in the prior art and provide a self-short-circuit safety explosion-proof detonator for oil and gas wells, so as to improve the inherent safety of electric detonators for oil and gas wells during transportation, assembly, well installation, waiting for detonation and retrieval, and reduce the risk of personal injury and equipment loss caused by accidental detonation and accidental detonation transmission.

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

[0007] In a first aspect, the present invention provides a self-short-circuit safety explosion-proof detonator for oil and gas wells, comprising a metal shell, a return spring, a guide block, a contact-type detonator, and an explosion-proof assembly; the explosion-proof assembly, the guide block, the return spring, and the contact-type detonator are arranged sequentially from the inside to the outside inside the metal shell.

[0008] The contact-type detonator includes a detonator positive electrode, a detonator negative electrode, an insulating pad, and an outer shell containing an ignition head and a base detonator. The insulating pad is inserted between the detonator positive electrode and the detonator negative electrode. The outer shell is connected to the detonator negative electrode and inserted into the inner hole of the guide block. The reset spring is sleeved on the outside of the outer shell and connected at both ends to the guide block and the detonator negative electrode.

[0009] The negative terminal of the detonator is electrically connected to the reset spring, the guide block, the explosion-proof assembly, and the metal shell in sequence.

[0010] In the initial state, the positive electrode of the detonator is in contact with the metal casing, causing a self-short circuit between the positive and negative electrodes through the metal casing. Under normal conditions, the explosion-proof assembly blocks the transmission of detonation waves, and the contact-type detonator can be unlocked when it undergoes axial displacement. When the well fluid pressure reaches a set value, the contact-type detonator moves axially, the positive electrode of the detonator separates from the metal casing and is insulated from the negative electrode of the detonator through the insulating pad to release the self-short circuit, and at the same time pushes the explosion-proof assembly to the unlocked position to restore detonation transmission. When the pressure drops below the reset value, the reset spring drives the contact-type detonator to reset, and the explosion-proof assembly automatically returns to its original position, re-establishing the self-short circuit and explosion-proof.

[0011] Furthermore, in this invention, the explosion-proof assembly described above includes a gasket and an explosion-proof plate, wherein the explosion-proof plate has a slit.

[0012] Furthermore, in this invention, the aforementioned gap is configured as a cross-shaped gap or a Y-shaped gap.

[0013] Furthermore, in this invention, the explosion-proof assembly described above also includes a metal plate and a torsion spring for driving its reset, wherein the metal plate is provided with a rotating shaft connected to the metal housing;

[0014] Under normal conditions, the metal plate is located in the detonation transmission path to achieve explosion isolation. When the contact detonator is displaced, it pushes the metal plate to rotate around the shaft to the avoidance position to release the explosion isolation. After the pressure is released, the torsion spring drives the metal plate back to its original position.

[0015] Furthermore, in this invention, the explosion-proof plate described above is configured as elastic rubber or a multilayer composite material.

[0016] Furthermore, in this invention, the unlocking pressure is determined by the spring force of the reset spring and the parameters of the explosion-proof component, and the unlocking pressure is greater than 3 MPa.

[0017] Furthermore, in this invention, the aforementioned metal casing, the guide block, and the internal gap together constitute a detonation attenuation path that reduces the risk of lateral damage and splash during accidental detonation.

[0018] Furthermore, in this invention, the explosion-proof assembly, the guide block, the reset spring, and the contact detonator are fixed by the rolled edge of the metal housing.

[0019] Furthermore, in this invention, the aforementioned guide block covers the outside of the contact-type detonator to provide axial guidance and limiting, thereby promoting smooth movement of the contact-type detonator.

[0020] Secondly, the present invention also provides an initiation method, which includes the aforementioned self-short-circuit safety explosion-proof detonator for oil and gas wells.

[0021] S1: When the detonator is not subjected to downhole pressure or the well fluid pressure is lower than the unlocking pressure, the positive electrode of the detonator contacts the metal casing to form a self-short circuit, and the explosion-proof component is in the explosion-proof position, blocking the transmission of the detonation wave.

[0022] S2: After the well fluid pressure reaches the set unlocking pressure, the external contact pushes the contact-type detonator to move axially, the positive electrode of the detonator separates from the metal shell and releases the self-short circuit. At the same time, the contact-type detonator pushes the explosion-proof component away from the detonation transmission path, releases the explosion-proof state, and restores the detonation transmission path.

[0023] S3: The ignition current is connected to the positive terminal of the detonator, the ignition head ignites the base detonator, and the detonation wave is transmitted normally through the unlocked explosion-proof component to complete the perforation initiation.

[0024] S4: When the gun string is pulled out, the well fluid pressure drops below the reset pressure. The reset spring drives the contact detonator to reset in the reverse direction. The explosion-proof assembly automatically returns to the explosion-proof position. The positive electrode of the detonator re-contacts the metal shell to form a self-short circuit and restores the safe explosion-proof state.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] This invention enhances the safety of the entire perforation initiation process in oil and gas wells through its self-short-circuit, explosion-proof, pressure-unlocking, and automatic reset design. After assembly, the detonator automatically forms a positive and negative self-short circuit, effectively dissipating static electricity from the human body, stray currents, radio frequency interference, and electromagnetic induction energy. This eliminates the risk of accidental detonation at the wellhead from an electrical perspective, significantly reducing safety hazards during transportation, assembly, gun loading, and wellhead standby. The built-in explosion-proof components reliably block the transmission of detonation waves under normal conditions; even if the detonator accidentally ignites, it cannot detonate the perforation gun string, preventing the accident from escalating.

[0027] Furthermore, this invention employs well fluid pressure-driven automatic unlocking, only releasing the self-short circuit and explosion-proof state when the downhole pressure reaches a set threshold. This achieves automatic switching between surface safety and downhole operations, eliminating the need for manual adjustments, making operation simple and highly reliable. When retrieving the gun string, a pressure drop triggers the reset spring and explosion-proof components to automatically reset, re-establishing self-short circuit and explosion-proof protection. No additional operations such as power outages or gun disassembly are required throughout the process, enhancing the safety of retrieval operations.

[0028] The guide block, metal shell, and internal gaps form a multi-stage detonation attenuation structure. In the event of accidental detonation, energy is released axially and directionally, the shell remains intact, and there is no lateral splashing, significantly reducing the risk of personnel injury. The device residue is easy to clean after detonation, and the explosion-proof safety components are reusable, effectively reducing operating costs. The overall structure is compact and robustly assembled, adaptable to complex downhole environments such as high temperature, high pressure, and high corrosion. It also features functions such as preventing accidental detonation, preventing detonation propagation, automatic unlocking, and automatic reset, fully meeting the high safety and high reliability requirements of oil and gas well cable perforation. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0030] Figure 1 This is a schematic diagram of the internal structure of the self-short-circuit safety explosion-proof detonator for oil and gas wells according to the present invention;

[0031] Figure 2 This is a schematic diagram of the contact-type detonator of the present invention;

[0032] Figure 3 This is a schematic diagram of the explosion-proof assembly of the present invention;

[0033] Figure 4 This is a schematic diagram of the explosion-proof plate of the present invention;

[0034] Figure 5 This is a schematic diagram illustrating the release of the self-short circuit state under the action of well fluid pressure according to the present invention;

[0035] Figure 6 This is a schematic diagram illustrating the release of the explosion-proof state after the well fluid pressure is further increased according to the present invention.

[0036] Figure 7 This is a schematic diagram of the overall structure of the self-short-circuit safety explosion-proof detonator for oil and gas wells according to the present invention;

[0037] Figure 8 This is a schematic diagram of the structure for removing the explosion-proof state according to the present invention.

[0038] The markings and corresponding component names in the attached diagram are as follows: 1-Metal housing; 2-Reset spring; 3-Guide block; 4-Contact detonator; 41-Positive detonator electrode; 42-Negative detonator electrode; 43-Insulating pad; 44-Outer housing; 5-Explosion-proof assembly; 51-Washer; 52-Explosion-proof plate; 53-Metal plate; 54-Torsion spring; 55-Rotating shaft; 6-External contact. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. 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. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0040] It should be noted that similar reference numerals 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. In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] Example 1

[0042] This embodiment 1 provides a self-short-circuit safety explosion-proof detonator for oil and gas wells, including a metal shell 1, a return spring 2, a guide block 3, a contact detonator 4, and an explosion-proof assembly 5. An axial mounting cavity is formed inside the metal shell 1, and the explosion-proof assembly 5, guide block 3, return spring 2, and contact detonator 4 are arranged sequentially from the inside to the outside of its inner hole. Each component is fixed inside the metal shell 1 by a rolled edge closing method.

[0043] like Figure 2 As shown, the contact-type detonator 4 includes a positive electrode 41, a negative electrode 42, an insulating pad 43, and an outer casing 44 containing an ignition head and a base detonator. The outer casing 44 is fitted into the inner hole of the guide block 3 and can move axially relative to the guide block 3 under external force. The negative electrode 42 contacts the return spring 2, the guide block 3, the explosion-proof assembly 5, and the metal casing 1, thereby forming a stable negative grounding circuit. The positive electrode 41 is in contact with the metal casing 1 in the initial state, so the positive electrode 41 and the negative electrode 42 are in a conductive state through the metal casing 1, i.e., a self-short-circuit state. This self-short-circuit structure makes it difficult for the detonator to form an effective ignition circuit before entering the downhole working conditions, even if it is subjected to human static electricity, stray current, or radio frequency induction, thereby avoiding accidental detonation.

[0044] like Figures 3-4 As shown, the explosion-proof assembly 5 may include a gasket 51 and an explosion-proof plate 52. The explosion-proof plate 52 may be made of high-temperature resistant elastic materials such as rubber, or a multi-layer composite explosion-proof structure may be adopted according to actual working conditions. By adjusting the height of the gasket 51 and the thickness of the explosion-proof plate 52, the attenuation of the detonation wave in the event of accidental detonation of the detonator can be controlled, so that the shock wave generated by the accidental detonation is blocked or significantly weakened before reaching the perforating gun, thereby preventing the accidental detonation from detonating the perforating gun.

[0045] Preferably, the explosion-proof plate 52 is made of an elastic material with high impact resistance and low hardness, so that it can be penetrated by the contact detonator 4 during normal unlocking, while effectively absorbing and dissipating energy in the event of accidental detonation. More preferably, the explosion-proof plate 52 is provided with a cross-shaped slot or a Y-shaped slot.

[0046] like Figure 5 As shown, the detonator of this invention can be installed in a safety explosion-proof device. After being lowered into the well, under the pressure of the well fluid, the external contact 6 gradually presses against the positive electrode 41 of the detonator and compresses the return spring 2, causing the contact-type detonator 4 to move inward along the axial direction of the metal casing 1. As the displacement increases, the positive electrode 41 of the detonator first detaches from the metal casing 1 and is insulated from the negative electrode 42 of the detonator through the insulating pad 43. At this point, the short circuit is released, and the positive electrode 41 of the detonator can be connected to the ignition wire through the external contact 6, while the negative electrode 42 of the detonator is grounded through the metal casing 1, establishing a ready-to-fire circuit.

[0047] like Figure 6 As shown, as the perforating gun string continues to penetrate deeper into the well, the well fluid pressure further increases, and the external contact 6 continues to push the contact detonator 4 forward. The contact detonator 4, through penetration, rotation, flipping, or other mechanical means, releases the explosion-proof assembly 5 from its explosion-proof state. When the contact detonator 4 reaches the predetermined position, the explosion-proof assembly 5's blocking effect on the detonation wave is released, and the detonator regains its normal detonation transmission capability. At this point, energizing the wellhead allows for normal detonation of the perforating gun.

[0048] In this invention, the spring force parameter of the return spring 2 and the structural parameters of the explosion-proof assembly 5 jointly determine the well fluid pressure required for detonator unlocking. Preferably, the well fluid pressure required to release the explosion-proof barrier and restore the detonation transmission capability is set to greater than 3 MPa. This ensures that the detonator is only allowed to enter the detonation transmission state when the perforating gun string is fully lowered into the wellbore and reaches the predetermined well fluid pressure, thus avoiding accidental locking on the surface, in shallow well sections, or under abnormal operating conditions.

[0049] When the detonator is lowered into the well but not detonated, and the detonator string needs to be retrieved, the well fluid pressure gradually decreases as the string is lifted, reducing the pushing force of the external contact 6 on the contact-type detonator 4. Preferably, when the well fluid pressure is below 1 MPa, the return spring 2 pushes the contact-type detonator 4 to reset in the opposite direction. The explosion-proof assembly 5 re-establishes the explosion-proof state through its elastic recovery structure, torsion spring 54, or other return mechanism. Simultaneously, the positive electrode 41 of the detonator re-contacts the metal casing 1, forming a self-short circuit again with the negative electrode 42 of the detonator through the metal casing 1. Thus, the detonator can automatically restore its safe protection state during retrieval.

[0050] Because the guide block 3 is located outside the basic detonator and forms a multi-level buffer, attenuation, and constraint structure with the metal casing 1 and the internal air gap, even if the contact-type detonator 4 accidentally detonates under abnormal operating conditions, the explosion energy is mainly released along the axial direction, the lateral impact is significantly reduced, the metal casing 1 is not easily damaged, and there is no obvious lateral spatter. Thus, even if an accidental detonation occurs when the operator holds the detonator, injury to personnel outside the output direction can be minimized. After normal downhole detonation, the device remains can be removed without significant residue, and the safety explosion-proof device can be reused.

[0051] Example 2

[0052] like Figure 7 and Figure 8 As shown, the overall structure of this embodiment is basically the same as that of Embodiment 1. The difference is that the explosion-proof assembly 5 is composed of a metal plate 53 and a torsion spring 54.

[0053] The metal plate 53 is rotatably mounted inside the metal housing 1 or on the mounting base of the explosion-proof assembly 5. One end of the plate is connected via a rotating shaft 55 or a pivot point. A torsion spring 54 is fitted onto the rotating shaft 55 or the pivot point, or connected to both the metal plate 53 and the mounting base, to apply a restoring force to the metal plate 53 toward the explosion-proof position. In its normal state, the metal plate 53 is located between the contact-type detonator 4 and the external detonation path, thereby blocking or interrupting the propagation path of the detonation wave and forming an explosion-proof state.

[0054] When the detonator 4 is assembled, transported, awaiting detonation, or before the unlocking pressure is reached at the wellhead, the contact-type detonator 4 is in its initial position, and the metal plate 53 is held in the explosion-proof position by the torsion spring 54. At this time, even if the contact-type detonator 4 is accidentally detonated, the metal plate 53 can mechanically block the detonation wave or high-temperature and high-pressure products, thereby reducing or blocking the risk of detonation transmission to the subsequent perforating gun.

[0055] After being lowered into the well, under the pressure of the well fluid, the external contact 6 pushes the contact-type detonator 4 to move axially. As the contact-type detonator 4 continues to move forward, its front end, sidewall, or the pushing part connected to it contacts the metal plate 53 and applies a thrust to the metal plate 53, causing the metal plate 53 to rotate around the pivot 55 or the pivot point, overcoming the restoring force of the torsion spring 54. As the rotation angle increases, the metal plate 53 gradually moves away from the detonation transmission path. When the metal plate 53 rotates to the predetermined avoidance position, the explosion-proof assembly 5 releases the explosion-proof state, and the contact-type detonator 4 resumes its normal detonation transmission capability. The metal plate 53 can be made of steel, stainless steel, or other metal materials with sufficient strength and impact resistance.

[0056] When the well fluid pressure drops, especially during the process of retrieving the detonator string without detonation, the contact-type detonator 4 returns to its original position in the opposite direction under the action of the return spring 2, no longer continuously pushing the metal plate 53. At this time, the metal plate 53 automatically rotates in the opposite direction under the action of the torsion spring 54, returning to the detonation transmission path and restoring the explosion-proof state. At the same time, the positive electrode 41 of the detonator re-contacts the metal casing 1, re-forming a self-short circuit. Therefore, this embodiment can not only achieve automatic unlocking downhole, but also automatic reset after depressurization, further improving the intrinsic safety during the return process.

[0057] In this embodiment, the shape of the metal plate 53 can be sheet-like, arc-shaped, fan-shaped, or other structures that can cover the detonation transmission path; the torque of the torsion spring 54 can be designed according to the displacement thrust, unlocking pressure, and desired reset speed of the contact detonator 4; the metal plate 53 and the contact detonator 4 can be driven by direct contact, or the force can be transmitted through a cam surface, inclined surface, lever, or linkage mechanism.

[0058] Example 3

[0059] This invention provides a blasting method, which uses the self-short-circuit safety explosion-proof detonator for oil and gas wells as described in Example 1 or Example 2. The specific method is as follows.

[0060] When the detonator is in transport, assembly, or wellhead standby state, it is not subjected to well fluid pressure or the well fluid pressure is lower than the 3MPa unlocking pressure. At this time, the positive electrode 41 of the detonator is in close contact with the inner wall of the metal shell 1, forming a self-short circuit through the metal shell 1 and the negative electrode 42 of the detonator; static electricity, stray current, and radio frequency interference are all discharged by short circuit, and the ignition head cannot be triggered; the explosion-proof component 5 is in the explosion-proof position, completely blocking the detonation wave transmission path; even if the detonator accidentally ignites, it cannot ignite the subsequent perforation gun string, achieving intrinsic safety on the well.

[0061] The downhole pressure is automatically unlocked, and the detonator is lowered into the wellbore along with the perforation gun string. The well fluid pressure gradually increases: when the pressure reaches the unlocking threshold, the external contact 6 pushes the positive electrode 41 of the detonator under the action of hydraulic pressure; the contact-type detonator 4 moves inward along the axial compression return spring 2; the positive electrode 41 of the detonator separates from the metal shell 1, and is electrically insulated from the negative electrode 42 of the detonator through the insulating pad 43, thus releasing the short circuit; the contact-type detonator 4 continues to move forward, pushing the explosion-proof assembly 5 to move: the elastic explosion-proof plate 52 is squeezed / penetrated, releasing the explosion-proof; or the metal plate 53 rotates around the rotating shaft 55, leaving the detonation transmission path; the detonation passage is fully opened, and the detonator enters the ready-to-fire state.

[0062] In normal detonation operations, after the short circuit is released and the explosion-proof barrier is unlocked: the positive electrode 41 of the detonator is connected to the ignition wire through the external contact 6; the negative electrode 42 of the detonator forms a grounding circuit through the reset spring 2, guide block 3, explosion-proof component 5, and metal shell 1; the detonation current is applied at the wellhead, and the current ignites the base detonator through the ignition head. The detonation wave is output normally along the detonation transmission path after unlocking, detonating the perforation gun string and completing the perforation operation of the oil and gas well.

[0063] The system automatically resets upon retrieval. If detonation fails, the detonator string must be retrieved, and the well fluid pressure decreases as the retrieval depth increases. When the pressure drops below 1 MPa, the thrust of the reset spring 2 exceeds the fluid pressure, pushing the contact-type detonator 4 to reverse axial reset. The positive electrode 41 of the detonator re-contacts the metal casing 1, forming a self-short circuit again. The explosion-proof assembly 5 resets synchronously: the elastic explosion-proof plate 52 restores its explosion-proof state based on its own elasticity; the metal plate 53 rotates to the detonation path under the action of the torsion spring 54, re-isolating the explosion-proof state. The detonator automatically returns to a safe state throughout the entire process, with no risk of accidental detonation or false detonation transmission during retrieval.

[0064] This embodiment requires no manual operation throughout the entire process. Pressure drives automatic unlocking and automatic reset; it is always protected against short circuits and explosions on the surface, and the detonation capability is only enabled downhole; the safety is automatically restored during the retrieval process, which significantly improves the overall safety of cable perforation operations.

[0065] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-short-circuit safety explosion-proof detonator for oil and gas wells, characterized in that, It includes a metal housing (1), a return spring (2), a guide block (3), a contact detonator (4), and an explosion-proof assembly (5); the explosion-proof assembly (5), the guide block (3), the return spring (2), and the contact detonator (4) are arranged sequentially from the inside to the outside inside the metal housing (1). The contact-type detonator (4) includes a detonator positive electrode (41), a detonator negative electrode (42), an insulating pad (43), and an outer shell (44) containing an ignition head and a base detonator. The insulating pad (43) is inserted between the detonator positive electrode (41) and the detonator negative electrode (42). The outer shell (44) is connected to the detonator negative electrode (42) and inserted into the inner hole of the guide block (3). The reset spring (2) is sleeved on the outside of the outer shell (44) and connected at both ends to the guide block (3) and the detonator negative electrode (42). The negative electrode (42) of the detonator is electrically connected to the reset spring (2), the guide block (3), the explosion-proof assembly (5), and the metal shell (1) in sequence. In the initial state, the positive electrode (41) of the detonator is in contact with the metal shell (1), so that the positive and negative electrodes form a self-short circuit through the metal shell (1); the explosion-proof component (5) normally blocks the transmission of detonation wave, and the contact detonator (4) can be pushed to unlock when it is axially displaced; when the well fluid pressure reaches the set value, the contact detonator (4) moves axially, the positive electrode (41) of the detonator is separated from the metal shell (1) and is insulated from the negative electrode (42) of the detonator through the insulating pad (43) to release the self-short circuit, and at the same time pushes the explosion-proof component (5) to the unlocked position to restore the detonation transmission; when the pressure drops below the reset value, the reset spring (2) drives the contact detonator (4) to reset, and the explosion-proof component (5) automatically returns to its original position, and the self-short circuit and explosion-proof are re-formed.

2. The self-short-circuit safety explosion-proof detonator for oil and gas wells according to claim 1, characterized in that, The explosion-proof assembly (5) includes a gasket (51) and an explosion-proof plate (52), the explosion-proof plate (52) having a slit.

3. The self-short-circuit safety explosion-proof detonator for oil and gas wells according to claim 2, characterized in that, The gap is configured as a cross-shaped gap or a Y-shaped gap.

4. The self-short-circuit safety explosion-proof detonator for oil and gas wells according to claim 2, characterized in that, The explosion-proof assembly (5) also includes a metal plate (53) and a torsion spring (54) for driving its reset. The metal plate (53) is provided with a rotating shaft (55) connected to the metal housing (1). Under normal conditions, the metal plate (53) is located in the detonation transmission path to achieve explosion isolation. When the contact detonator (4) is displaced, it pushes the metal plate (53) to rotate around the rotating shaft (55) to the avoidance position to release the explosion isolation. After the pressure is released, the torsion spring (54) drives the metal plate (53) to return to its original position.

5. The self-short-circuit safety explosion-proof detonator for oil and gas wells according to claim 2, characterized in that, The explosion-proof plate (52) is configured as elastic rubber or multilayer composite material.

6. The self-short-circuit safety explosion-proof detonator for oil and gas wells according to claim 1, characterized in that, The unlocking pressure is determined by the elastic force of the reset spring (2) and the parameters of the explosion-proof component (5), and the unlocking pressure is greater than 3 MPa.

7. The self-short-circuit safety explosion-proof detonator for oil and gas wells according to claim 1, characterized in that, The metal casing (1), the guide block (3), and the internal gap together constitute a detonation attenuation path that reduces the risk of lateral damage and splash during accidental detonation.

8. The self-short-circuit safety explosion-proof detonator for oil and gas wells according to claim 1, characterized in that, The explosion-proof assembly (5), the guide block (3), the reset spring (2) and the contact detonator (4) are fixed by the rolled edge of the metal housing (1).

9. The self-short-circuit safety explosion-proof detonator for oil and gas wells according to claim 1, characterized in that, The guide block (3) covers the outside of the contact detonator (4) to provide axial guidance and limiting, so as to make the contact detonator (4) move smoothly.

10. A method for initiating detonation, characterized in that, Including the self-short-circuit safety explosion-proof detonator for oil and gas wells as described in any one of claims 1-9, S1: When the detonator is not subjected to downhole pressure or the well fluid pressure is lower than the unlocking pressure, the positive electrode (41) of the detonator contacts the metal shell (1) to form a self-short circuit, and the explosion-proof component (5) is in the explosion-proof position, blocking the transmission of the detonation wave. S2: After the well fluid pressure reaches the set unlocking pressure, the external contact (6) pushes the contact detonator (4) to move axially, the positive electrode (41) of the detonator separates from the metal shell (1) and releases the self-short circuit. At the same time, the contact detonator (4) pushes the explosion-proof component (5) away from the detonation transmission path, releases the explosion-proof state, and restores the detonation transmission path. S3: The positive electrode (41) of the detonator is connected to the ignition current, the ignition head ignites the basic detonator, and the detonation wave is transmitted normally through the unlocked explosion-proof component (5) to complete the perforation initiation. S4: When the gun string is pulled out, the well fluid pressure drops below the reset pressure. The reset spring (2) drives the contact detonator (4) to reset in the reverse direction. The explosion-proof assembly (5) automatically returns to the explosion-proof position. The positive electrode (41) of the detonator re-contacts the metal shell (1) to form a self-short circuit and restore the safe explosion-proof state.

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