Coaxial follow-up perforating gun

Abstract

The invention discloses a coaxial follow-up perforating gun, and belongs to the technical field of underground soil layer perforating equipment. The perforating gun comprises a gun body and a bullet frame, a plurality of mounting holes are formed in the two sides of the bullet frame in a staggered mode, clamping holes are formed in the side, opposite to the mounting holes, of the other side of the bullet frame, front lifting bushings and perforating bullets are arranged in the mounting holes, the front lifting bushings are located between the outer walls of the perforating bullets and the inner walls of the mounting holes, and detonating bodies are arranged at one ends of the inner sides of the perforating bullets; the end part of the detonating body penetrates through the clamping hole and extends to the outside; at least two fixing clamping rings are arranged on the elastic rack and located on the outer side of the mounting hole, and adjusting hole positions are formed in the fixing clamping rings; a three-stage fixing system is formed through combination of the front lining, the rear hole and the fixing clamping ring, it is ensured that the orientation of each perforating bullet is independent and accurate through mechanical rigid positioning and dynamic adjustment, and multiple bullets do not interfere with one another during cooperative operation. The perforating gun is mainly composed of the gun body, the gun frame and the self-directional bearing, the whole perforating gun is of a simple and stable structural design, and maintenance is convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of equipment for shooting through underground soil layers, and more specifically, to a coaxial advancing perforating gun. Background Art

[0002] After the cementing process of an oil and gas well is completed, a well casing is installed in the original wellbore and cement slurry is injected to reinforce the strength of the wellbore. At this time, the wellbore and the formation are in a separated state, and it is impossible to extract oil and gas from the oil and gas reservoir beside the wellbore. At this time, a perforating gun needs to be used for perforating to open the connection between the bottom layer and the wellbore and form a channel for oil and gas transmission. As the core equipment, the structural design of the perforating gun directly affects the perforating accuracy, reliability and operation efficiency. Existing perforating guns usually include a gun body and a cartridge rack. The cartridge rack is used to install perforating charges and synchronously or sequentially detonate them through detonating cords. However, in complex well conditions, the following technical bottlenecks exist in traditional perforating guns.

[0003] The fixing methods of traditional perforating charges mostly rely on a single structure, such as a rigid clamp or simple bolt fastening, lacking a hierarchical collaborative fixing mechanism. The radial clamping force is weak, the impact resistance is poor, and displacement is likely to occur under high-frequency vibration or perforating impact, resulting in detonation failure or perforating direction deviation, seriously affecting the operation success rate. In view of this, we propose a coaxial advancing perforating gun. Summary of the Invention

[0004] The purpose of the present invention is to provide a coaxial advancing perforating gun to solve the problems raised in the above background art: To achieve the above purpose, the present invention provides the following technical solutions: A coaxial advancing perforating gun includes a gun body and a cartridge rack. A plurality of mounting holes are staggered on both sides of the cartridge rack. A positioning hole is provided on the side of the cartridge rack opposite to the mounting holes. A front supporting bushing and a perforating charge are arranged in the mounting hole. The front supporting bushing is located between the outer wall of the perforating charge and the inner wall of the mounting hole. A detonator is arranged at one end inside the perforating charge, and the end of the detonator passes through the positioning hole and extends to the outside; At least two fixing rings are arranged on the outside of the cartridge rack at the mounting holes, and adjustment holes are provided on the fixing rings.

[0005] Preferably, the front supporting bushing and the perforating charge are in interference fit.

[0006] Preferably, the front supporting bushing and the perforating charge are coaxially arranged. Grooves are provided on the outer wall of the front supporting bushing, and the grooves extend along the axial direction of the perforating charge; The fixing ring is made of elastic metal or memory alloy. A protrusion is provided at the adjustment hole position of the fixing ring, and the protrusion extends into the groove of the front supporting bushing.

[0007] Preferably, a detonating cord is spirally wound around the outer wall of the cartridge rack, and a limiting groove is provided on the detonator, and the detonating cord passes through the limiting groove.

[0008] Preferably, self-aligning bearings are provided at both ends of the cartridge rack, and the self-aligning bearings are spherical self-aligning structures.

[0009] The self-aligning bearing includes an outer ring, an inner ring and spherical rollers provided between the outer ring and the inner ring. An anti-slip coating is provided on the outer surface of the outer ring, and the inner ring is connected to the end of the cartridge rack through a keyway.

[0010] Preferably, an annular boss is provided on the cartridge rack near the self-aligning bearing. Three slots are provided on the annular boss along its circumference, and three mounting holes are provided on the gun body. A plug-in member is penetrated through the mounting holes. The plug-in member is in plug-in fit with the slots. A spring is provided on the inner wall of the gun body at the mounting hole. One end of the spring is connected to the plug-in member, and the other end of the spring is connected to the inner wall of the gun body. A pull ring is provided at the outer end of the plug-in member, and the inner end of the plug-in member is provided as a spherical structure.

[0011] Preferably, an adjusting rod is penetrated through the adjusting hole position. The adjusting rod is threadedly connected to the gun body. One end of the adjusting rod extends forward to the middle axis of the front support bushing. Multiple adjusting slots are provided on the adjusting rod along its length direction.

[0012] Preferably, the inner side wall of the adjusting hole position of the fixing snap ring is an arc groove recessed toward the convex side.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention forms a three-stage composite fixing system through the interference fit of the front support bushing, the mechanical limit of the positioning hole and the adjustment of the elastic fixing snap ring, which improves the radial clamping force of the perforating charge and enhances the axial anti-impact ability, ensuring zero displacement under high-vibration conditions; a three-stage fixing system is formed through the combination of "front bushing + rear opening + fixing snap ring". Through mechanical rigid positioning and dynamic adjustment, the orientation of each perforating charge is ensured to be independently accurate, and there is no interference during multi-projectile collaborative operation. The multi-directional adjustment slots of the adjustment hole position and the tool-assisted expansion and contraction design can adapt to various commercial perforating charges with a diameter error of ±3 mm. The perforating gun of the present invention mainly consists of three modules: the gun body, the cartridge rack and the self-aligning bearing. The overall structure design is simple and stable, and all accessories can be disassembled and replaced at will to facilitate the maintenance of the perforating gun damage in case of accidents.

[0014] (2) The present invention fixes the position of the detonating cord through the setting of the limiting groove, and the limiting groove provides an accurate spiral winding path for the detonating cord to ensure a stable spiral pitch and winding angle of the detonating cord on the outer wall of the cartridge rack. It effectively prevents the axial sliding or radial deviation of the detonating cord due to factors such as vibration and impact during transportation, storage, or firing. The fixed clamping ring has an elastic buffer design, and the protrusion is made of elastic material to avoid hard contact damage to the projectile body. When the gun body is connected to the cartridge rack, the cooperation of the plug-in part and the spring and the design of the self-aligning bearing, through the spatial misalignment layout and the rigid-flexible function partition, dynamically cooperate and compensate with each other to improve the reliability under complex working conditions, and solve the problems of no centering adjustment in the rigid connection of traditional perforating guns or easy loosening in the flexible centering adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is a schematic diagram of the cartridge rack structure of the present invention; Figure 3 is a schematic diagram of a partial structure of the cartridge rack of the present invention; Figure 4 is a front view schematic diagram of a partial structure of the cartridge rack of the present invention; Figure 5 is a schematic diagram of the structure of the front support bushing of the present invention; Figure 6 is a rear view schematic diagram of the front support bushing of the present invention.

[0016] Explanation of the reference numerals in the drawings: 1. Gun body; 2. Cartridge rack; 201. Mounting hole; 202. Positioning hole; 203. Fixed clamping ring; 204. Adjustment hole position; 3. Perforating charge; 4. Front support bushing; 5. Initiator; 6. Detonating cord; 7. Self-aligning bearing; 8. Cartridge rack detonator chamber. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0018] Embodiment: Please refer to Figure 1-6 , a coaxial follow-up perforating gun, including a gun body 1 and a cartridge rack 2. A plurality of mounting holes 201 are staggered on both sides of the cartridge rack 2. A positioning hole 202 is provided on the other side of the cartridge rack 2 opposite to the mounting hole 201. A front support bushing 4 and a perforating charge 3 are arranged in the mounting hole 201. The front support bushing 4 is located between the outer wall of the perforating charge 3 and the inner wall of the mounting hole 201. One end of the inner side of the perforating charge 3 is provided with an initiator 5, and the end of the initiator 5 passes through the positioning hole 202 and extends to the outside; the mounting hole 201 and the positioning hole 202 can be selected according to the size of the perforating charge 3.

[0019] There are at least two fixing clamping rings 203 arranged on the outside of the cartridge rack 2 at the installation hole 201, and adjustment hole positions 204 are arranged on the fixing clamping rings 203. And a special fixing clamping ring 203 is designed on the cartridge rack 2 to fix the perforating charge 3 that has been assembled with the front lifting bushing 4. A screwdriver can be used to insert into the adjustment hole position 204 of the fixing clamping ring 203 to adjust the clamping force; by inserting a tool (such as a screwdriver) into the adjustment hole position 204 and rotating, the fixing clamping ring 203 is driven to radially contract or expand, so as to adjust the clamping force on the perforating charge 3.

[0020] Among them, the fixing clamping ring 203 is made of elastic metal or shape memory alloy, and an anti-slip pattern or a rubber gasket is arranged on the side in contact with the front lifting bushing 4 to enhance the frictional fixation of the front lifting bushing 4.

[0021] The present invention forms a three-stage fixing system through the combination of "front bushing + rear opening + fixing clamping ring 203". Through mechanical rigid positioning and dynamic adjustment, the orientation of each perforating charge is ensured to be independent and accurate, and there is no interference when multiple charges operate cooperatively. This design breaks through the technical bottleneck that multiple charges in traditional perforating guns must interfere, and is the core innovation point for realizing efficient, safe and accurate perforation, especially suitable for the development of complex well types (such as horizontal wells, highly deviated wells) and high-value reservoirs.

[0022] In this application, the front lifting bushing 4 and the perforating charge 3 are in interference fit. The front lifting bushing 4 fixes the perforating charge 3 through interference fit with the perforating charge 3, and can be compatible with most perforating charges 3 on the market.

[0023] In this application, the front lifting bushing 4 and the perforating charge 3 are coaxially arranged. A groove is opened on the outer wall of the front lifting bushing 4, and the groove extends along the axis direction of the perforating charge 3; a protrusion is arranged at the adjustment hole position 204 of the fixing clamping ring 203, and the protrusion extends outward into the groove of the front lifting bushing 4. The clearance between the groove and the protrusion is ≤0.2mm, ensuring that the coaxiality deviation between the front lifting bushing and the perforating charge is ≤0.5mm. Through the arrangement of the protrusion, the position of the front lifting bushing 4 is restricted to prevent the front lifting bushing 4 from displacing in the downhole vibration or high-pressure environment.

[0024] Among them, the inner side wall of the adjustment hole position 204 of the fixing clamping ring 203 is an arc-shaped groove recessed towards the protrusion side, as Figure 4 shown; the concave surface of the arc-shaped groove is adapted to the outer shape of the protrusion, and the circumferential angle of the protrusion can be finely adjusted through surface fitting, ensuring that the clamping force of the fixing clamping ring 203 on the front lifting bushing 4 is evenly distributed in the circumferential direction of the perforating charge 3, avoiding the axis deviation of the perforating charge 3 caused by eccentric force. The concave structure of the arc-shaped groove provides a buffer space for the elastic deformation of the fixing clamping ring (made of elastic metal or shape memory alloy). When the perforation generates impact force, the inner side wall of the arc-shaped groove can absorb the radial expansion stress of the clamping ring, avoiding stress concentration caused by rigid contact between the protrusion and the edge of the adjustment hole position, and prolonging the service life of the clamping ring.

[0025] In a possible embodiment, the protrusion is made of an elastic material, which provides a buffering pressure when fixing the perforating charge 3, avoiding damage to the front support bushing 4 or the perforating charge 3 caused by rigid contact.

[0026] In the present application, a detonating fuse 6 is spirally wound around the outer wall of the cartridge rack 2. A limiting groove is provided on the detonating body 5, and the detonating fuse 6 passes through the limiting groove. The position of the detonating fuse 6 is fixed by the arrangement of the limiting groove, and the limiting groove provides an accurate spiral winding path for the detonating fuse 6, ensuring that the detonating fuse 6 maintains a stable spiral pitch and winding angle on the outer wall of the cartridge rack 2. Effectively prevent the detonating fuse 6 from generating axial sliding or radial offset due to factors such as vibration and impact during transportation, storage or launching. By fixing the relative position of the detonating fuse 6 and the detonating body 5, ensure that the detonation wave can propagate stably along the predetermined path and avoid energy loss.

[0027] In the present application, self-aligning bearings 7 are provided at both ends of the cartridge rack 2. The self-aligning bearings 7 are of a spherical self-aligning structure, and the automatic compensation for wellbore eccentricity error is ≤3°. The axis deviation between the wellbore and the cartridge rack 2 is corrected in real time through the spherical self-aligning structure, ensuring the stability of the projectile motion trajectory; the self-adaptive deflection characteristic can reduce the local contact stress caused by eccentricity and extend the service life of the bearing; it automatically adjusts within the eccentricity range of ≤3°, avoiding vibration or jamming of the cartridge rack due to wellbore deformation; compensating for assembly errors, reducing the dependence on the machining accuracy of the wellbore, and improving the system tolerance capacity. The self-aligning bearing 7 includes an outer ring, an inner ring and spherical rollers provided between the outer ring and the inner ring. An anti-slip coating is provided on the outer surface of the outer ring, and the inner ring is connected to the end of the cartridge rack 2 through a keyway. The stability of the bearing is improved through the anti-slip coating and spherical rollers.

[0028] The perforating gun of the present invention mainly consists of three modules: the gun body 1, the cartridge rack 2, and the double-end self-aligning bearing 7. The overall structure design is simple and stable, and all accessories can be disassembled and replaced at will to facilitate the maintenance of the damaged perforating gun in case of an accident.

[0029] In a possible embodiment, a ring-shaped boss is provided near the self-aligning bearing 7 on the cartridge carrier 2. Three slots are provided along the circumference of the ring-shaped boss. Three mounting holes are provided on the gun body 1. A plug is penetrated through the mounting holes. The plug is in plug-in fit with the slots. A spring is provided on the inner wall of the gun body 1 at the position of the mounting holes. One end of the spring is connected to the plug, and the other end of the spring is connected to the inner wall of the gun body 1. A pull ring is provided at the outer end of the plug. The inner end of the plug is provided with a spherical structure. The plug end of the spherical structure can adapt to the slight deviation between the ring-shaped boss and the mounting hole, ensuring the smoothness of the plugging process. The manual pulling operation of the plug is realized through the pull ring, which is convenient for the quick separation and assembly of the cartridge carrier and the gun body. Through the setting of the spring, the elastic force of the spring is used to push the plug into the slot, realizing the quick assembly of the gun body 1 and the cartridge carrier 2. At the same time, the spring provides continuous radial pressure, which not only prevents the plug from accidentally coming out under vibration conditions, but also avoids stress concentration caused by rigid connection. The three symmetrically distributed plugs work together to balance the radial load when the cartridge carrier 2 rotates. The pull ring can be made of a flexible material. When the gun body 1 and the cartridge carrier 2 are connected, the pull ring can be located in the mounting hole, without occupying the outer position of the gun body 1. At the same time, when disassembling, the pull ring can be hooked out by a tool, so as to pull the plug. Through the cooperation of the plug and the spring when the gun body and the cartridge carrier are connected and the design of the self-aligning bearing 7, through the spatial misalignment layout, the rigid-flexible function partition, and the dynamic cooperative compensation of the two, the reliability under complex working conditions is improved, and the problems of no centering adjustment for rigid connection or easy loosening for flexible centering adjustment of traditional perforating guns are solved.

[0030] In a possible embodiment, an adjusting rod is penetrated through the adjusting hole position 204. The adjusting rod is threadedly connected to the gun body 1. One end of the adjusting rod extends in the direction of the central axis of the front supporting bushing 4. A plurality of adjusting grooves are provided along the length direction of the adjusting rod. The plurality of adjusting grooves are evenly distributed in the length direction and the circumferential direction of the gun body 1. By inserting the insert piece into the adjusting groove, the adjusting rod can be driven to rotate, so that the adjusting rod pushes the adjusting hole position 204 towards the side close to the axis of the front supporting bushing 4, realizing the expansion or contraction of the adjusting hole position 204, and making the convex part of the adjusting hole position 204 in close contact with the groove of the front supporting bushing 4. The plurality of adjusting grooves are evenly distributed in the length direction and the circumferential direction of the gun body 1 to facilitate repeatedly inserting the insert piece into different adjusting grooves in a small space and repeatedly driving the adjusting rod to rotate.

[0031] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention, and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A coaxial tandem perforating gun, comprising a gun body (1) and a cartridge rack (2), characterized in that: On both sides of the cartridge rack (2), a plurality of mounting holes (201) are arranged staggeredly. On the other side of the cartridge rack (2) opposite to the mounting holes (201), a clamping hole (202) is arranged. A front lifting bushing (4) and a perforating charge (3) are arranged in the mounting hole (201). The front lifting bushing (4) is located between the outer wall of the perforating charge (3) and the inner wall of the mounting hole (201). One end of the inner side of the perforating charge (3) is provided with a detonator (5), and the end of the detonator (5) passes through the clamping hole (202) and extends to the outside; At least two fixing snap rings (203) are arranged outside the mounting hole (201) on the cartridge rack (2), and adjustment holes (204) are arranged on the fixing snap rings (203).

2. The coaxial tandem perforating gun according to claim 1, wherein: The front lifting bushing (4) is coaxially arranged with the perforating charge (3). A groove is arranged on the outer wall of the front lifting bushing (4), and the groove extends along the axial direction of the perforating charge (3); The fixing snap ring (203) is made of elastic metal or shape memory alloy. A protrusion is arranged at the adjustment hole (204) of the fixing snap ring (203), and the protrusion extends into the groove of the front lifting bushing (4).

3. A coaxial follow-up perforating gun according to claim 1, characterized in that: A detonating cord (6) is spirally wound around the outer wall of the cartridge rack (2). A limiting groove is arranged on the detonator (5), and the detonating cord (6) passes through the limiting groove.

4. A coaxial tandem perforating gun according to claim 1, wherein: Self-aligning bearings (7) are arranged at both ends of the cartridge rack (2), and the self-aligning bearings (7) are of a spherical self-aligning structure.

5. A coaxial tandem perforating gun according to claim 4, characterized in that: The self-aligning bearing (7) includes an outer ring, an inner ring and spherical rollers arranged between the outer ring and the inner ring. An anti-slip coating is arranged on the outer surface of the outer ring, and the inner ring is connected with the end of the cartridge rack (2) through a keyway.

6. The coaxial tandem perforating gun according to claim 4, wherein: A circular boss is arranged on the cartridge rack (2) near the self-aligning bearing (7). Three slots are arranged along the circumference of the circular boss. Three mounting holes are arranged on the gun body (1). A plug-in member is arranged through the mounting holes. The plug-in member is in plug-in fit with the slots. A spring is arranged on the inner wall of the gun body (1) at the mounting hole. One end of the spring is connected with the plug-in member, and the other end of the spring is connected with the inner wall of the gun body (1). A pull ring is arranged at the outer end of the plug-in member, and the inner end of the plug-in member is of a spherical structure.

7. A coaxial tandem perforating gun according to claim 1, characterized in that: An adjusting rod is arranged through the adjustment hole (204). The adjusting rod is threadedly connected with the gun body (1). One end of the adjusting rod extends towards the central axis of the front lifting bushing (4). A plurality of adjusting grooves are arranged along the length direction of the adjusting rod.

8. A coaxial tandem perforating gun according to claim 2, characterized in that: The inner side wall of the adjustment hole (204) of the fixing snap ring (203) is an arc-shaped groove recessed towards the protrusion side.

9. The coaxial tandem perforating gun according to claim 1, characterized in that: The front lifting bushing (4) is in interference fit with the perforating charge (3).

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