A pressure relief safety gun tail and method for cable transmission perforating gun

Abstract

The present invention discloses a pressure relief safety gun tail for a cable-transmitted perforating gun, which belongs to the technical field of oil and gas well testing and exploitation. The pressure relief safety gun tail for a cable-transmitted perforating gun disclosed by the present invention is characterized in that it comprises: a gun tail shell, a through hole is provided in the middle of the gun tail shell, and the through hole extends from one end of the gun tail shell to the other end; a piston, and the piston is sealingly and slidably connected with the through hole along a direction from one end of the through hole to the other end; a pressure relief hole, one end of the pressure relief hole is located outside the gun tail shell, and the other end is located inside the through hole of the gun tail shell; a detonator protective sleeve; a tail seal; a connecting part. The present invention provides a pressure relief safety gun tail for a cable-transmitted perforating gun, which provides a pressure relief function in the abnormal perforating situation where only the detonator is detonated, introduces well fluid into the perforating gun, achieves internal and external pressure balance, and avoids dangerous accidents during disassembly due to high pressure in the gun.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas well testing and exploitation, and in particular relates to a pressure relief safety gun tail for a cable transmission perforating gun and a method. Background Art

[0002] Perforation is the finishing touch of oil and gas field exploitation and an important technical means of oil and gas field exploitation. After the perforating gun is detonated normally underground, the perforating bullet penetrates the perforating gun, casing, cement ring and rock formation to form oil holes. Under the action of formation pressure, oil and gas pass through the holes to the wellbore and are produced to the ground.

[0003] After the perforating gun is perforated normally, holes are formed on the perforating gun body to communicate the pressure inside and outside the gun. Therefore, there is no problem in disassembling the perforating gun after the well is pulled out.

[0004] In the process of implementing the embodiments of the present invention, the inventors found that the background technology has at least the following defects:

[0005] When the perforating gun is not detonated normally, the detonator may detonate but the detonating cord may explode and the perforating charge may not be detonated. Alternatively, the perforating charge may also burn without perforating. The increased pressure inside the gun cannot be released, and when the gun is disassembled after the well is lifted, it is easy for the joint to fall off and injure people. Summary of the invention

[0006] The purpose of the present invention is to provide a pressure relief safety gun tail and method for a cable transmission perforating gun, which is used to replace the common gun tail currently in use. It is to solve the problem that when the perforating gun is not detonated normally, the detonator is detonated but the detonating cord is deflagrated, and the perforating bullet cannot be detonated, or the perforating bullet is also burned without perforating, and the increased pressure in the gun cannot be released. When disassembling after lifting the well, it is easy to cause the joint to fall off and injure people.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A pressure relief safety gun tail for a cable transmission perforating gun, comprising:

[0009] A gun tail shell, wherein a through hole is provided in the middle of the gun tail shell, and the through hole extends from one end of the gun tail shell to the other end;

[0010] A piston, the piston being sealingly and slidingly connected with the through hole in a direction from one end of the through hole to the other end;

[0011] A pressure relief hole, one end of which is located outside the gun tail shell, and the other end of which is located in the through hole of the gun tail shell;

[0012] Detonator protective sleeve;

[0013] Tail seal;

[0014] Connecting part;

[0015] The side surface of one end of the gun tail shell has a connecting portion for connecting to the perforating gun, the through hole opening at the other end of the gun tail shell is sealed by a tail seal, the detonator protective sleeve and the piston are located in the through hole, one end of the detonator protective sleeve is located on one side of the connecting portion of the gun tail shell, the piston is located at the other end of the detonator protective sleeve, there is a gap between the piston and the tail seal, the piston has a first position and a second position, when the piston is in the first position, one end of the pressure relief hole is connected to the side wall of the piston, when the piston is in the second position, the pressure relief hole is connected to the through hole.

[0016] The through hole includes a first through hole, a second through hole and a third through hole which are interconnected. The detonator protective cover is located in the first through hole, the piston is located in the second through hole, and the length of the third through hole is greater than the length of the piston.

[0017] An inner diameter of the third through hole is greater than an inner diameter of the second through hole.

[0018] A side of the tail seal opposite to the through hole is provided with a concave hole, and the central axis of the concave hole is not centered.

[0019] The concave hole is a conical concave hole, and the central axis of the conical concave hole is not on the central axis of the through hole.

[0020] One end of the piston is in an asymmetric shape, and the asymmetric end of the piston is directly opposite to the tail seal.

[0021] A sealing ring is provided between the piston and the wall of the through hole in the gun tail shell, and the piston is sealed and connected to the gun tail shell through the sealing ring.

[0022] The breech block housing is provided with a connector, the middle of which is provided with a detonating cord through hole whose diameter is smaller than the inner hole of the detonator protective sleeve. The connector is located at the end of the breech block housing at one end of the connecting part, and the detonator protective sleeve is connected to the outside of the breech block housing through the detonating cord through hole of the connector.

[0023] The connector is also provided with a positioning ring, the middle of the positioning ring is provided with a fourth through hole, one end of the connector is inserted into the fourth through hole, and the other end of the connector is inserted into the detonator protective sleeve;

[0024] One end of the connecting piece is threadedly connected to the positioning ring, and the other end of the connecting piece is threadedly connected to the detonator protection sleeve.

[0025] A fifth through hole matching the shape of the connecting piece is provided at the end of the gun tail shell, and the connecting piece is embedded in the fifth through hole.

[0026] A method for depressurizing a cable-transmitted perforating gun, comprising:

[0027] Connect the detonator chamber to the inner cavity of the perforating gun using a damping hole;

[0028] A piston chamber with a pressure relief hole in a radial direction is opened outside the detonator chamber, and the piston chamber is connected with the detonator chamber, wherein the pressure relief hole is a hole connecting the piston chamber with the outside world;

[0029] The piston is installed at the pressure relief hole in the piston cavity, and the outside world is blocked from the detonator chamber by the piston. The length of the piston is shorter than the distance from the pressure relief hole in the piston cavity to the bottom of the piston cavity.

[0030] The beneficial effect of the present invention is that the present invention provides a pressure relief safety gun tail for a cable-transmitted perforating gun, which provides a pressure relief function in an abnormal perforating situation where only the detonator is detonated, introduces well fluid into the perforating gun, achieves internal and external pressure balance, and avoids dangerous accidents during disassembly caused by high pressure in the gun. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a schematic diagram of the overall structure of a pressure relief safety gun tail for a cable transmission perforating gun.

[0032] The following are marked in the figure: 1. perforating gun; 2. bomb rack; 3. positioning ring; 4. connecting piece; 5. gun tail shell; 6. detonator protective cover; 7. piston; 8. tail seal; 9. pressure relief hole. DETAILED DESCRIPTION

[0033] The pressure relief safety tail solution for a perforating gun provided by the embodiment of the present invention will be described in detail below through several specific embodiments.

[0034] Example 1

[0035] Please refer to Figure 1 , which shows a schematic diagram of the overall structure of a pressure relief safety gun tail for a cable transmission perforating gun, the pressure relief safety gun tail for the perforating gun includes:

[0036] A gun tail shell 5, wherein the middle of the gun tail shell 5 has a through hole extending from one end of the gun tail shell 5 to the other end;

[0037] A piston 7, the piston 7 is sealingly and slidably connected with the through hole in a direction from one end of the through hole to the other end;

[0038] A pressure relief hole 9, one end of which is located outside the gun tail housing 5, and the other end of which is located inside the through hole of the gun tail housing 5;

[0039] Detonator protective sleeve 6;

[0040] Tail seal 8;

[0041] Connecting part;

[0042] The side surface of one end of the gun tail shell 5 has a connecting portion for connecting to the perforating gun, and the through hole opening at the other end of the gun tail shell 5 is sealed by a tail seal 8. The detonator protective sleeve 6 and the piston 7 are located in the through hole. One end of the detonator protective sleeve 6 is located on one side of the connecting portion of the gun tail shell 5, and the piston 7 is located at the other end of the detonator protective sleeve 6. There is a gap between the piston 7 and the tail seal 8. The piston 7 has a first position and a second position. When the piston 7 is located at the first position, one end of the pressure relief hole 9 is connected to the side wall of the piston 7, and when the piston 7 is located at the second position, the pressure relief hole 9 is connected to the through hole.

[0043] In the above embodiment, in order to avoid the problem that when the perforating gun 1 is not detonated normally, the detonator is detonated but the detonating cord deflagrates and the perforating charge cannot be detonated, or the perforating charge also burns without perforating, and the pressure in the gun cannot be released, the tail connected to the tail of the perforating gun 1 is redesigned and improved, the space inside the tail is extended, and a piston 7 is added inside the tail. The connection between the tail and the outside is controlled by the piston 7. The piston 7 controls the connection with the outside by providing a plurality of pressure relief holes 9 on the side wall of the tail shell 5.

[0044] In normal conditions, the pressure relief hole 9 is blocked by the piston 7, and after the detonator in the detonator protective sleeve 6 is detonated, the thrust of the detonator can push the piston 7 to the other side. At this time, there is no piston 7 blocking the pressure relief hole 9, and the pressure relief hole 9 will be connected to the inside of the gun tail shell 5, and further the pressure relief hole 9 will be connected to the inside of the perforating gun 1. In order to facilitate the piston 7 to be pushed to the other side after the detonator explodes, and then the pressure relief hole 9 is connected to the inside of the perforating gun 1, a certain gap is reserved between the piston 7 and the tail seal 8, so that the pressure relief hole 9 is connected to the inside of the gun tail shell 5 when the piston 7 is pushed to the gap.

[0045] Through the structure of this embodiment, when the perforating gun 1 is not detonated normally, as long as the detonator is detonated, the inside of the gun will be connected with the outside.

[0046] Example 2

[0047] For further information, please refer to Figure 1 Another embodiment of a pressure relief safety gun tail for a cable-transmitted perforating gun of the present invention, the through hole includes a first through hole, a second through hole and a third through hole which are interconnected, the detonator protective cover 6 is located in the first through hole, the piston 7 is located in the second through hole, and the length of the third through hole is greater than the length of the piston 7.

[0048] In the above embodiment, the through hole inside the gun tail shell 5 can be divided into three areas, namely, a first through hole, a second through hole and a third through hole which are connected in sequence, wherein the first through hole is mainly used to set the detonator protection sleeve 6, and the detonator protection sleeve 6 is used to install the detonator, the second through hole is used to set the piston 7, and a pressure relief hole 9 is set between the second through hole and the outside of the gun tail shell 5, and the third through hole is mainly used to provide a movable space for the piston 7, so that a part or all of the piston 7 can be moved into the third through hole, and after the piston 7 moves into the third through hole, the pressure relief hole 9 is connected with the inside of the gun tail shell 5.

[0049] Example 3

[0050] For further information, please refer to Figure 1 According to another embodiment of a pressure relief safety gun tail for a cable-transmitted perforating gun of the present invention, the inner diameter of the third through hole is greater than the inner diameter of the second through hole.

[0051] In the above embodiment, since the impact force is relatively large when the detonator explodes, in order to prevent the piston 7 from being pushed against the tail seal 8 and then rebounding, thereby blocking the pressure relief hole 9, the inner diameter of the third through hole is set larger than the inner diameter of the second through hole. After the piston 7 enters the third through hole, it will be stuck by the step between the third through hole and the second through hole, ensuring that the pressure relief hole 9 will not be blocked by the piston 7 again after the detonator explodes.

[0052] Example 4

[0053] Furthermore, in another embodiment of a pressure relief safety gun tail for a cable-transmitted perforating gun of the present invention, a side of the tail seal 8 directly opposite to the through hole has a concave hole, and the central axis of the concave hole is not centered.

[0054] In the above embodiment, the inventors found during the specific implementation that, due to the large impact force of the detonator, even if the inner diameter of the third through hole is larger than the inner diameter of the second through hole, when the piston 7 is bounced onto the tail seal 8, after the piston 7 runs from the second through hole to the third through hole, there is still a chance that it will be rebounded into the second through hole again. Therefore, a surface of the tail seal 8 directly opposite the through hole is set as a concave hole with a non-centered central axis. The concave hole can form an effect similar to an inclined surface at the bottom of the tail seal. When the piston 7 contacts the tail seal 8 and is rebounded again, due to the effect of the inclined surface, the piston 7 will not rebound along the same path, but will rebound upward or downward and will be retained in the third through hole.

[0055] Furthermore, a surface of the tail seal facing the through hole is an inclined surface, and a surface of the tail seal 8 facing the piston 7 is not parallel.

[0056] Example 5

[0057] For further information, please refer to Figure 1According to another embodiment of the pressure relief safety gun tail for a cable-transmitted perforating gun of the present invention, the concave hole is a conical concave hole, and the central axis of the conical concave hole is not on the central axis of the through hole.

[0058] In the above embodiment, the concave hole is changed into a conical concave hole which does not coincide with the central axis of the through hole. On the premise that the rebound path of the piston 7 can be changed, the processing difficulty is lower and the manufacturing and production are convenient.

[0059] Example 6

[0060] For further information, please refer to Figure 1 In another embodiment of a pressure relief safety gun tail for a cable-transmitted perforating gun of the present invention, one end of the piston 7 is asymmetrically shaped, and the asymmetrical end of the piston 7 is directly opposite to the tail seal 8.

[0061] In the above embodiment, when solving the problem that the piston 7 will bounce back to the original path after hitting the tail seal 8, another solution is to change the shape of the piston 7 so that even if the piston hits a plane or a symmetrical surface, the piston 7 will deviate from the original path by its own irregular surface when hitting the tail seal 8, so that the piston 7 is left in the third through hole, thereby achieving the effect of maintaining the stable operation of the pressure relief safety tail of the perforating gun.

[0062] Example 7

[0063] For further information, please refer to Figure 1 In another embodiment of a pressure relief safety gun tail for a cable transmission perforating gun of the present invention, a sealing ring is provided between the piston 7 and the wall of the through hole in the gun tail housing 5, and the piston 7 is sealed and connected to the gun tail housing 5 through the sealing ring.

[0064] In the above embodiment, in order to ensure that the pressure relief hole 9 is disconnected from the inside of the gun tail shell 5 when the detonator is not detonated, a sealing ring is added between the piston 7 and the through hole wall in the gun tail shell 5, and the sealing ring is located on both sides of the pressure relief hole 9 to seal the pressure relief hole 9. The working stability of the pressure relief safety gun tail for the perforating gun is ensured.

[0065] There are 4 sealing rings on the piston, which are distributed on both sides of the 4 pressure relief holes 9 after installation. When the detonator is detonated, the explosion pressure pushes the piston to move and fly into the tail seal 8. Since the bottom of the tail seal 8 is an inclined surface formed by the offset conical hole, it cannot return along the original route even after the collision and will be stuck inside. In this way, the pressure relief hole is exposed, and the well fluid enters the perforating gun through the pressure relief hole to achieve pressure balance between the wellbore and the gun.

[0066] Example 8

[0067] For further information, please refer to Figure 1Another embodiment of a pressure relief safety breech block for a cable-transmitted perforating gun of the present invention comprises a connector 4 outside the breech block housing 5, a detonating cord through hole smaller than the inner diameter of a detonator protective sleeve 6 in the middle of the connector 4, the connector 4 is located at the end of the breech block housing 5 at one end of the connecting portion, and the detonator protective sleeve 6 is connected to the outside of the breech block housing 5 through the detonating cord through hole of the connector 4.

[0068] In the above embodiment, in order to ensure that the main impact force of the detonator can be concentrated on the piston 7 when the detonator explodes, a connecting piece 4 is added between the connection between the detonator protective sleeve 6 and the perforating gun. The middle part of the connecting piece 4 has a detonating cord through hole, which can ensure that the detonating cord ignited by the detonator can be correctly connected to the perforating bullet in the perforating gun, and can also ensure that the explosion pressure of the detonator in the detonator protective sleeve 6 is concentrated on the piston 7, so that the piston 7 is pushed out normally.

[0069] Example 9

[0070] For further information, please refer to Figure 1 According to another embodiment of a pressure relief safety gun tail for a cable transmission perforating gun of the present invention, the connector 4 is further provided with a positioning ring 3, the middle of the positioning ring 3 is provided with a fourth through hole, one end of the connector 4 penetrates into the fourth through hole, and the other end of the connector 4 extends into the detonator protective sleeve 6;

[0071] In the above embodiment, the positioning ring 3 is stably connected to the detonator protective sleeve 6 through the connecting piece 4, which can ensure the stability of the detonator protective sleeve 6 relative to the perforating gun.

[0072] For further information, please refer to Figure 1 In another embodiment of a pressure relief safety gun tail for a cable transmission perforating gun of the present invention, one end of a connector 4 is threadedly connected to a positioning ring 3 , and the other end of the connector 4 is threadedly connected to a detonator protective sleeve 6 .

[0073] In the above embodiment, one end of the connector 4 is threadedly connected to the positioning ring 3, and the other end of the connector 4 is threadedly connected to the detonator protective sleeve 6, making it easier and faster to install and disassemble, and facilitating the construction of operators.

[0074] Example 10

[0075] For further information, please refer to Figure 1 Another embodiment of a pressure relief safety gun tail for a cable transmission perforating gun of the present invention has a fifth through hole matching the shape of the connecting member 4 at the end of the gun tail housing 5, and the connecting member 4 is embedded in the fifth through hole.

[0076] In the above embodiment, in order to make the device more compact, a fifth through hole for accommodating the connecting member 4 is provided at the end of the breech block housing 5, and the connecting member 4 is disposed in the fifth through hole.

[0077] Preferably, this example is used for cable transmission perforating, and the purpose of this example is to prevent disassembly safety hazards caused by abnormal detonation.

[0078] Embodiment 11

[0079] A method for depressurizing a cable-transmitted perforating gun, comprising:

[0080] Connect the detonator chamber to the inner cavity of the perforating gun using a damping hole;

[0081] A piston chamber with a pressure relief hole in a radial direction is opened outside the detonator chamber, and the piston chamber is connected with the detonator chamber, wherein the pressure relief hole is a hole connecting the piston chamber with the outside world;

[0082] The piston is installed at the pressure relief hole in the piston cavity, and the outside world is blocked from the detonator chamber by the piston. The length of the piston is shorter than the distance from the pressure relief hole in the piston cavity to the bottom of the piston cavity.

[0083] In the above embodiment, in order to avoid the problem that when the perforating gun 1 is not detonated normally, the detonator is detonated but the detonating cord deflagrates and the perforating charge cannot be detonated, or the perforating charge also burns but no perforation is made, and the pressure in the gun cannot be released, the gun tail connected to the tail of the perforating gun 1 is redesigned, a piston chamber is opened outside the detonator chamber, the piston chamber has a pressure relief hole, and the pressure relief hole in the piston chamber is controlled by the piston inside the piston chamber to control the opening and closing of the pressure relief hole.

[0084] The detonator chamber is connected to the inner cavity of the perforating gun by using a damping hole, which can prevent the excessive pressure in the detonator chamber from being discharged into the inner cavity of the perforating gun when the detonator explodes, and can concentrate the energy of the detonator explosion in the piston cavity, so that when the detonator explodes, the energy can push the piston to the other side, and finally push the piston to move, so that the piston that blocks the pressure relief hole in the radial direction is pushed to the other side, thereby connecting the outside world with the detonator chamber. As long as the detonator explodes, whether the perforating gun 1 is perforated or not, the external pressure can be introduced into the perforating gun. Through the method of this embodiment, when the perforating gun 1 is not detonated normally, as long as the detonator is detonated, the inside of the gun will be connected to the outside.

[0085] It should be noted that all directional indications in this embodiment (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0086] In addition, the descriptions involving "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0087] The technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A pressure relief safety gun tail for a cable-transmitted perforating gun, characterized in that: include: A gun tail shell (5), wherein a through hole is provided in the middle of the gun tail shell (5), and the through hole extends from one end of the gun tail shell (5) to the other end; A piston (7), the piston (7) being sealingly slidably connected to the through hole in a direction from one end of the through hole to the other end; A pressure relief hole (9), one end of the pressure relief hole (9) is located outside the gun tail housing (5), and the other end is located in the through hole of the gun tail housing (5); Detonator protective sleeve (6); Tail seal (8); Connecting part; The side surface of one end of the gun tail shell (5) has a connection portion for connecting to the perforating gun, the through hole opening at the other end of the gun tail shell (5) is sealed by a tail seal (8), the detonator protection sleeve (6) and the piston (7) are located in the through hole, one end of the detonator protection sleeve (6) is located on one side of the connection portion of the gun tail shell (5), the piston (7) is located at the other end of the detonator protection sleeve (6), a gap is provided between the piston (7) and the tail seal (8), the piston (7) has a first position and a second position, when the piston (7) is located at the first position, one end of the pressure relief hole (9) is connected to the side wall of the piston (7), when the piston (7) is located at the second position, the pressure relief hole (9) is communicated with the through hole; The through hole comprises a first through hole, a second through hole and a third through hole which are interconnected, the detonator protection sleeve (6) is located in the first through hole, the piston (7) is located in the second through hole, and the length of the third through hole is greater than the length of the piston (7); The gun tail shell (5) has a connecting piece (4) outside, and a detonating cord through hole having a diameter smaller than the inner hole of the detonator protective sleeve (6) is provided in the middle of the connecting piece (4). The connecting piece (4) is located at the end of the gun tail shell (5) at one end of the connecting part, and the detonator protective sleeve (6) is connected to the outside of the connecting piece (4) through the detonating cord through hole; The connecting member (4) is further provided with a positioning ring (3) outside, the positioning ring (3) having a fourth through hole in the middle, one end of the connecting member (4) extending into the fourth through hole, and the other end of the connecting member (4) extending into the detonator protective sleeve (6); One end of the connecting piece (4) is threadedly connected to the positioning ring (3), and the other end of the connecting piece (4) is threadedly connected to the detonator protective sleeve (6).

2. A pressure relief safety gun tail for a cable-transmitted perforating gun as claimed in claim 1, characterized in that: An inner diameter of the third through hole is greater than an inner diameter of the second through hole.

3. A pressure relief safety gun tail for a cable-transmitted perforating gun as claimed in claim 1, characterized in that: A side of the tail seal (8) opposite to the through hole has a concave hole, and the central axis of the concave hole is not centered; or One end of the piston (7) is asymmetrical in shape, and the asymmetrical end of the piston (7) is directly opposite to the tail seal (8).

4. A pressure relief safety gun tail for a cable-transmitted perforating gun as claimed in claim 3, characterized in that: The concave hole is a conical concave hole, and the central axis of the conical concave hole is not on the central axis of the through hole.

5. A pressure relief safety gun tail for a cable-transmitted perforating gun as claimed in claim 1, characterized in that: A sealing ring is provided between the piston (7) and the wall of the through hole in the breech block housing (5); the piston (7) is sealedly connected to the breech block housing (5) via the sealing ring.

6. A pressure relief safety gun tail for a cable-transmitted perforating gun as claimed in claim 1, characterized in that: A fifth through hole matching the shape of the connecting piece (4) is provided at the end of the gun tail housing (5), and the connecting piece (4) is embedded in the fifth through hole.

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