A bilateral opening cabin type negative pressure air gun source and a method for exciting the same

Abstract

The application provides a double-side opening cabin type negative pressure air gun source and a firing method thereof, and belongs to the field of marine seismic exploration.The application comprises two upper and lower symmetrical firing units on the basis of the existing negative pressure air gun source and the single-side negative pressure air gun source, the firing cabin is surrounded by the firing cabin housings of the two firing units, each firing unit comprises a pushing cabin and a returning cabin, the pushing cabin is in a high pressure state, the returning cabin is in a vacuum state, the differential pressure makes the firing unit realize the effect of rapid opening of the cabin, and the implosion energy can be fully released.In addition, the two firing units of the application are synchronously fired, the opening speed can be further improved, the stress during the opening process is uniform, and the shaking of the cabin body is reduced.The double-side opening cabin mode can improve the consistency of the wavelet and improve the quality of the seismic data.

Description

Technical Field

[0001] This invention belongs to the field of marine seismic exploration source design, specifically involving a double-sided open-chamber negative pressure air gun source and its excitation method; wherein, negative pressure means that during excitation, the gas pressure in the air gun excitation chamber is less than the surrounding water pressure at the excitation location. Background Technology

[0002] Traditional high-pressure air guns generate a pulsed source wavelet by instantaneously releasing pressurized high-pressure gas (e.g., 2000 PSI ≈ 13.8 MPa) into seawater. However, their performance is limited by factors such as their structural design and external excitation environment. For example: 1) The bubbles formed after the gas is released into the water oscillate periodically due to changes in internal and external pressure during expansion and contraction, resulting in residual bubble oscillations, which reduce the resolution of the wavelet and cause low-frequency jitter in the frequency domain; 2) For construction safety considerations, the operating pressure of air guns is generally below 3000 PSI. As the depth of the air gun increases, the hydrostatic pressure increases, and the energy that can be excited decreases sharply. Currently, the depth of air guns is mostly shallower than 20 meters; 3) The presence of the sea surface-air reflection interface generates a ghost wave that follows the first wave, causing a notch in the frequency domain and greatly compressing the effective bandwidth of the wavelet; 4) Affected by factors such as sea surface fluctuations, ocean current impacts, ignition delay, and changes in gas supply pressure, the consistency of the excitation wavelet, especially the ghost wave portion, is low due to the influence of factors such as sea surface fluctuations, ocean current impacts, ignition delay, and changes in gas supply pressure.

[0003] In light of this, researchers have proposed a negative pressure airgun seismic source scheme (CN202310520514.9). The negative pressure airgun seismic source utilizes negative pressure air supply; "negative pressure" refers to the gas pressure inside the airgun being lower than the surrounding water pressure at the excitation location during activation, thus creating negative pressure. During activation, the negative pressure airgun in the ocean, due to the lower air pressure inside its chamber compared to the surrounding water pressure, allows seawater to enter the chamber, compressing the gas and causing an implosion, generating a source wavelet. The negative pressure airgun seismic source can overcome conventional water depth limitations, enabling excitation in deep-water environments. Therefore, it can reduce and delay the interference of source ghost waves, effectively improving the imaging effect of seabed structures (especially shallow structures). Simulation comparisons show that the residual bubble oscillation of the negative pressure airgun seismic source is significantly weaker than that of traditional high-pressure airguns, thus significantly improving the wavelet resolution capability.

[0004] The wavelet characteristics excited by the negative pressure air gun source are directly related to the opening speed and method of the excitation chamber. Traditional single-sided opening speed is too slow, and due to uneven force, it will cause violent shaking of the chamber, affecting the excitation of the source wavelet. In addition, single-sided opening is prone to wavelet asymmetry problems, increasing the difficulty of subsequent data processing. Summary of the Invention

[0005] To address the problems in existing technologies, this invention proposes a dual-sided opening-type negative pressure air gun vibrator and its excitation method. This invention, by simultaneously opening both sides and adding an initial slide rail, increases the initial opening velocity, effectively reduces the opening time, and improves the consistency of the wavelet.

[0006] The technical solution of the present invention is as follows:

[0007] This invention first provides a dual-sided open-chamber type negative pressure air gun vibrator, including a top cover, a base, a gun body support, and an upper excitation unit and a lower excitation unit located between the top cover and the base; the top cover and the base are connected by the gun body support;

[0008] Both the upper and lower excitation units include a control cabin, an excitation cabin shell, a return capsule shell, and a return capsule propulsion device; wherein, the bottom of the control cabin and the bottom of the return capsule shell of the upper excitation unit are fixedly connected to the top cover, and the bottom of the control cabin and the bottom of the return capsule shell of the lower excitation unit are fixedly connected to the base.

[0009] Two excitation units are arranged symmetrically, one above the other. Within each excitation unit, the excitation chamber shell is fitted over the control chamber and can slide vertically relative to it. The top of the control chamber is equipped with an excitation chamber propulsion device that can move up and down and slides in a sealed manner against the inner wall of the excitation chamber shell. When both excitation chamber shells are at their maximum travel positions, they contact and seal, forming a sealed excitation chamber surrounded by the two shells and the two propulsion devices. A distance is maintained between the inner wall of the excitation chamber shell and the outer wall of the control chamber. A propulsion chamber base plate is fixedly connected to the bottom of the excitation chamber shell and slides in a sealed manner against the outer wall of the control chamber. The propulsion device, the excitation chamber shell, the propulsion chamber base plate, and the outer wall of the control chamber together form the propulsion chamber. The return capsule shell is fitted over the control chamber, with its inner wall in close contact with the outer wall of the excitation chamber shell, allowing for a slidable seal. The propulsion chamber base plate, the outer wall of the control chamber, and the return capsule shell together form the return capsule. The return capsule propulsion device is located at the bottom of the return capsule and can move up and down.

[0010] The outer surface of the control cabin is provided with several excitation control mechanisms, which are used to lock the outer shell of the excitation cabin when it is at the upper limit of its stroke; the inside of the control cabin is provided with a high-pressure air passage that connects to the propulsion cabin.

[0011] According to a preferred embodiment of the present invention, the control cabin further includes an excitation control system and a power unit; the power unit is connected to the excitation cabin propulsion device for driving the excitation cabin propulsion device to move up and down; the excitation control system is located inside the control cabin and is used to control the power unit, the return capsule propulsion device, and the excitation control mechanism; the return capsule propulsion device is used to drive the excitation cabin shell to move.

[0012] According to a preferred embodiment of the present invention, the tops of the upper and lower excitation chamber shells are provided with mutually cooperating annular stepped surfaces, and the vertical portions of the annular stepped surfaces of the two excitation chamber shells are in close contact with each other; the vertical portions of the annular stepped surfaces constitute the initial slides of the two excitation chamber shells. When the excitation chamber shells are within the initial slides, the excitation chambers remain sealed; the excitation chambers open only when the two excitation chamber shells detach from the initial slides. The control chambers, return capsule shells, and return capsule propulsion devices of the upper and lower excitation units have identical structures and are arranged symmetrically vertically. The initial slides allow the excitation chambers to maintain a short period of sealing after the excitation control mechanism is unlocked. During this period, the excitation chambers continuously accelerate, and when they slide away from the initial slides (the instant the excitation chambers open), the excitation chamber shells already possess an initial opening velocity, thereby enabling the excitation chambers to open more rapidly and avoiding the influence of the excitation chamber shell movement delay on the source wavelet.

[0013] The present invention also provides an excitation method based on the aforementioned dual-sided open-chamber negative pressure air gun vibrator, which includes the following steps:

[0014] 1) Inject high-pressure gas into the two propulsion chambers using the high-pressure gas line, and close the high-pressure gas line after the set pressure is reached;

[0015] 2) Before activation, the double-sided open-chamber negative pressure air gun vibrator is positioned underwater at the desired activation location; the activation chamber propulsion device and return chamber propulsion device of the upper and lower activation units are controlled to work synchronously to move towards the center. The two return chamber propulsion devices drive the outer shells of the upper and lower activation chambers to move towards the center. When the activation chamber propulsion devices are fully in contact, they stop working, while the return chamber propulsion devices continue to advance until the outer shells of the two activation chambers are completely in contact and sealed. At this time, the activation control mechanism controls the fixing pin to lock the outer shell of the activation chamber, and the activation chamber is in the closed state; then, the activation chamber propulsion devices and return chamber propulsion devices of the upper and lower activation units return to their original positions on both sides. At this time, the activation chamber and return chamber are evacuated, and the propulsion chamber is in a high-pressure state, and the negative pressure air gun is in the ready-to-activate state;

[0016] 3) During activation, the activation command is sent synchronously to the control cabins of the upper and lower activation units through the ship's control center. The control cabins open the fixed locking pins to unlock the outer shell of the activation chamber. Under the pressure of high-pressure gas, the bottom plates of the push cabins of the upper and lower activation units drive the outer shells of the two activation chambers to move to both sides until the activation chambers are fully opened. Water enters the activation chamber and causes an implosion, forming a source wavelet.

[0017] 4) After the excitation is complete, return to step 2) and wait for the next excitation.

[0018] Compared to existing negative pressure air guns, this invention achieves full release of implosion energy by evacuating the excitation chamber, increasing the pressure difference between the inside and outside of the chamber, and avoiding interference from subsequent residual bubble oscillations. This invention adds a propulsion chamber and a return chamber. In the pre-excitation state, the propulsion chamber is under high pressure, its main function being to provide the power for rapid opening of the excitation chamber. The return chamber is under vacuum, and in conjunction with the propulsion chamber, it also avoids water resistance during the opening of the excitation chamber. A pressure-reducing plate is fixed to the inner wall of the propulsion chamber. Its main function is to reduce the area of ​​high-pressure gas in the propulsion chamber acting on the base of the excitation chamber, thereby reducing the downward initial force. This correspondingly reduces the force requirements of the excitation control device (such as the fixed locking pin in this example), facilitating the efficient and synchronous implementation of the excitation command.

[0019] Compared to single-sided opening negative pressure air guns (where the opening speed is too slow and uneven force distribution causes violent shaking of the chamber, reducing the excitation performance of the seismic source), the double-sided opening air gun of this invention can reduce the opening time. Furthermore, by introducing an annular stepped initial slide, the sealing of the excitation chamber can be improved, and the initial opening speed can be significantly increased, thereby further reducing the opening time. Simultaneously, the double-sided opening method can improve the consistency of wavelets and enhance the quality of seismic data. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a double-sided open-chamber negative pressure air gun (in the state of being ready to be fired);

[0021] Figure 2 To activate the double-sided open-chamber negative pressure air gun;

[0022] Figure 3 A schematic diagram showing the working state of the excitation chamber propulsion device and the return chamber propulsion device when they are waiting to return to their original positions, in order to ensure that the outer shells of the excitation chamber are in contact and sealed with each other;

[0023] Figure 4 Comparison of wave field cloud images of the double-sided (a) and single-sided (b) opening of the chamber in this invention;

[0024] Figure 5 Comparison of wavelet variations with incident angle in the near field (1m) of double-sided (a) and single-sided (b) open-cell configurations;

[0025] Figure 6 The results show the comparison of wavelets excited by single-sided and double-sided open-chamber negative pressure air guns at incident angles of 0°(a), 90°(b), and 180°(c).

[0026] Among them, 1 is the air gun top cover, 2 is the air gun support, 3 is the upper excitation chamber shell, 4 is the excitation chamber shell support, 5 is the excitation chamber, 6 is the excitation chamber propulsion device, 7 is the propulsion chamber bottom plate, 8 is the return chamber, 9 is the high-pressure air passage, 10 is the base, 11 is the control chamber, 12 is the return chamber propulsion device, 13 is the fixing pin, 14 is the propulsion chamber, 15 is the one-way drainage channel, 16 is the sliding pin, 17 is the pressure reducing plate, 18 is the return chamber shell, 19 is the buffer pad, 20 is the lower excitation chamber shell, and 21 is the initial slide. Detailed Implementation

[0027] The present invention will be further described and illustrated below with reference to specific embodiments. The embodiments described are merely examples of the content of this disclosure and do not limit the scope of the invention. The technical features of each embodiment in the present invention can be combined accordingly, provided that there is no mutual conflict.

[0028] like Figures 1-3 As shown, the double-sided opening negative pressure air gun provided by the present invention includes a top cover 1, a base 10, a gun body support 2, an upper excitation unit and a lower excitation unit;

[0029] The only structural difference between the upper and lower excitation units lies in the slight difference in the top portion of the excitation chamber shell. In this invention, the tops of the upper and lower excitation chamber shells are provided with mutually cooperating annular stepped surfaces, and the vertical portions of the annular stepped surfaces of the two excitation chamber shells are in close contact with each other. The vertical portions of the annular stepped surfaces constitute the initial slide rails of the two excitation chamber shells. When the excitation chamber shells are within the initial slide rails, the excitation chamber remains sealed. The excitation chamber opens only when the two excitation chamber shells are disengaged from the initial slide rails. In one embodiment of this invention, the top of the upper excitation chamber shell 3 has an annular stepped surface structure that is longer on the outside and shorter on the inside, with a one-way drainage channel 15 inside. The top of the lower excitation chamber shell 20 has an annular stepped surface structure that is shorter on the outside and longer on the inside. The height of the vertical portion of the annular stepped surface can generally be 10-30mm. The two annular stepped surfaces are in close contact, and this design provides a basis for the initial slide rail 21 for opening the excitation chamber, enabling rapid opening.

[0030] like Figures 1-3 As shown, the upper excitation unit and the lower excitation unit are the same in other parts and are arranged symmetrically. Each excitation unit includes a control cabin 11, an excitation cabin shell, a return capsule shell 18, and a return capsule propulsion device 12. The bottom of the control cabin and the bottom of the return capsule shell of the upper excitation unit are fixedly connected to the top cover 1, and the bottom of the control cabin and the bottom of the return capsule shell of the lower excitation unit are fixedly connected to the base 10.

[0031] The excitation chamber outer shell 3 / 20 is fitted outside the control chamber 11 and can slide up and down relative to the control chamber 11; the top of the control chamber 11 is equipped with an excitation chamber pushing device 6 that can be raised and lowered and slides and seals against the inner wall of the excitation chamber outer shell; when both the upper excitation chamber outer shell 3 and the lower excitation chamber outer shell 20 are at their maximum stroke positions, the two excitation chamber outer shells contact and seal (the annular stepped surfaces cooperate with each other, and a sealing ring can be further set at the annular stepped surface to improve the sealing level), at this time the two excitation chamber outer shells and the upper and lower excitation chamber pushing devices surround and form a sealed excitation chamber 5; a distance is provided between the inner wall of the excitation chamber outer shell and the outer wall of the control chamber, and the excitation chamber outer shell 3 / 20... The bottom of the 0 is fixedly connected to a propulsion chamber bottom plate 7 (horizontally arranged), and the propulsion chamber bottom plate 7 is slidably sealed to the outer wall of the control chamber 11; the excitation chamber propulsion device 6, the excitation chamber shell, the propulsion chamber bottom plate 7, and the outer wall of the control chamber surround to form a propulsion chamber 14; the return capsule shell 18 is sleeved on the outside of the control chamber, and the inner wall of the return capsule shell 18 is in close contact with the outer wall of the excitation chamber shell, and the two are slidably sealed; the propulsion chamber bottom plate 7, the outer wall of the control chamber, and the return capsule shell 18 surround to form a return capsule 8; the return capsule propulsion device 12 is set at the bottom of the return capsule 8, and it can be raised and lowered. In this embodiment, the return capsule propulsion device 12 is an electric push rod.

[0032] The top cover 1 and the base 10 are connected by a gun body bracket 2. Several excitation control mechanisms are provided on the outer surface of the control chamber. These mechanisms are used to lock the excitation chamber shell when it is at its upper limit of travel. In this embodiment, the excitation control mechanism is a locking pin, whose installation height corresponds to the position of the push chamber bottom plate when the excitation chamber shell is at its lower limit of travel. The locking pin is installed on the control chamber. When it is necessary to lock the excitation chamber shell, the locking pin extends out of the control chamber wall and blocks the push chamber bottom plate. When it is necessary to unlock the excitation chamber shell, the locking pin retracts, allowing the excitation chamber shell to move under the pressure differential.

[0033] The control cabin is equipped with a high-pressure air passage 9 that connects to the propulsion cabin. The propulsion cabin can be filled with high-pressure gas to a preset pressure value using a high-pressure air pump and then shut off.

[0034] The control cabin of the present invention also includes an excitation control system and a power unit; the power unit is connected to the excitation cabin propulsion device 6 and is used to drive the excitation cabin propulsion device to move up and down; the excitation control system is located inside the control cabin and is used to control the power unit, the return capsule propulsion device 12, and the excitation control mechanism; the return capsule propulsion device 12 is used to drive the excitation cabin outer shell 3 / 20 to move. In this embodiment, the excitation cabin propulsion device 6 is a piston, and the power unit can be an electric push rod, a hydraulic rod, or a pneumatic push rod, which is used to drive the piston to move up and down.

[0035] A pressure-reducing plate 17 is fixedly installed inside the propulsion chamber. The pressure-reducing plate 17 is fixedly connected to the outer wall of the control chamber. Both the pressure-reducing plate and the bottom plate 7 of the propulsion chamber are arranged laterally. When the outer shell of the excitation chamber is at the upper limit of the stroke, the pressure-reducing plate 17 is close to the bottom plate 7 of the propulsion chamber to reduce the area of ​​action of the gas in the propulsion chamber on the lower bottom plate, thereby reducing the initial downward force. This can reduce the initial locking force of the excitation control mechanism, facilitate the lightweight design of the device, and improve the efficiency of the simultaneous implementation of the excitation command.

[0036] Assuming the area of ​​the bottom plate 7 of the propulsion chamber remains constant, the initial downward pressure can be altered by adjusting the area of ​​the decompression plate 17. When the area of ​​the decompression plate is close to that of the bottom plate, the initial downward pressure approaches zero. However, a low initial downward pressure leads to a lower initial speed at which the excitation chamber opens downward, thus affecting the overall opening speed. Therefore, during the design process, a balance needs to be struck between lightweight design and maximizing the opening speed. For example, the opening speed can be increased by appropriately increasing the air pressure inside the propulsion chamber.

[0037] like Figures 1-3 As shown, a buffer pad 19 is provided on the top of the return capsule propulsion device to buffer the impact on the outer shell of the excitation capsule and reduce the noise caused by the impact during the excitation process.

[0038] like Figures 1-3 As shown, the gun body bracket 2 maintains a set distance between the top cover 1 and the base 10 at all times; the gun body bracket 1 includes multiple vertically arranged support rods, the hollow interior of which can be used for cable routing; the outer walls of the upper and lower excitation chamber shells are connected to the excitation chamber shell brackets 4, which are slidably connected to the support rods via sliding pins 16. The design of the excitation chamber shell brackets 4 and the sliding pins 16 makes the movement of the two excitation chamber shells more stable, and at the same time guides the two excitation chamber shells during their mutual contact.

[0039] Furthermore, a sealing ring is provided between the propulsion chamber bottom plate 7 and the outer wall of the control chamber to achieve sealing during relative sliding; a sealing ring is provided between the excitation chamber outer shell and the return chamber outer shell to achieve sealing during relative sliding.

[0040] The dual-sided open-chamber negative pressure air gun vibrator is mounted on the hull. When in use, high-pressure gas is first injected into the upper and lower propulsion chambers through the high-pressure air path. After the set pressure is reached, the high-pressure air path is closed. The return chamber 8 is in a vacuum state.

[0041] Before activation, the double-sided open-chamber negative pressure air gun vibrator is positioned underwater at the desired activation location. The activation chamber propulsion device 6 and return chamber propulsion device 12 of the upper and lower activation units are controlled to work synchronously and move towards the center. The two return chamber propulsion devices 12 drive the outer shells of the upper and lower activation chambers to move towards the center. When the activation chamber propulsion device 6 is fully closed, the activation chamber propulsion device stops working, while the return chamber propulsion device continues to drive the propulsion until the outer shells of the two activation chambers are completely in contact and sealed. At this time, the activation control mechanism locks the outer shell of the activation chamber, and the activation chamber is in a closed state. Then, the activation chamber propulsion device and return chamber propulsion device of the upper and lower activation units return to their original positions on both sides. At this time, the activation chamber and return chamber are evacuated, and the propulsion chamber is in a high-pressure state. The negative pressure air gun is in a ready-to-activate state.

[0042] During activation, the activation command is simultaneously sent from the ship's control center to the control cabins of the upper and lower activation units. The control cabins control the activation control mechanisms to unlock the outer shell of the activation cabin. Under the pressure of high-pressure gas, the bottom plates of the upper and lower activation units drive the outer shells of the two activation cabins to move to both sides until the activation cabins are fully opened. Water enters the activation cabins and causes an implosion, forming a seismic source wavelet.

[0043] After activation, the upper and lower activation chamber propulsion devices 6 and 12 move synchronously towards the center. Once the activation chamber propulsion device 6 is fully closed, it stops working, while the 12 continues to advance until the initial slide 21 is completely closed. At this point, the water in the initial slide is discharged through the one-way drainage channel 15, and the locking pin 13 locks the bottom plate 7 of the propulsion chamber. Then, the activation chamber propulsion device and the 12 open to the sides to the preset positions. At this time, the activation chamber and the 12 are evacuated, and the negative pressure air gun is in a ready-to-activate state, waiting for the next activation command.

[0044] Figure 4 The wave field cloud diagrams of the negative pressure air guns with double-sided and single-sided opening were compared at the same moment after excitation. The red part in the figure represents the peak main pulse of the wavelet, the light blue area outside the main pulse represents the negative sidelobe part, and the inside of the main pulse represents the residual oscillation. The comparison shows that the wavelet obtained by double-sided opening is more symmetrical along the measurement line and has better wavelet consistency. The residual oscillation of single-sided opening has obvious directionality with the change of incident angle. Figure 5 Comparing the waveforms of the wavelet obtained from simulations using the two opening methods with varying incident angles, it can be seen that the waveforms are more consistent with those obtained from dual-sided opening. The above conclusions can be further validated by analyzing the time-domain waveforms (...). Figure 6 The comparison is intuitive. Figure 6The results compare the wavelets excited by single-sided and double-sided open-chamber negative pressure air guns at incident angles of 0°(a), 90°(b), and 180°(c). The double-sided open-chamber wavelet exhibits superior peak pulse stability and waveform consistency compared to the single-sided open-chamber wavelet. Furthermore, the single-sided open-chamber wavelet shows significant wake oscillations after the main pulse (most pronounced at 180°), affecting wavelet consistency and increasing the difficulty of subsequent data processing. Therefore, compared to a single-sided open-chamber negative pressure air gun, a double-sided open-chamber air gun can obtain cleaner wavelet data, improving the quality of seismic data. In addition, introducing an initial slide rail can significantly increase the initial opening speed, thereby further reducing the opening time.

[0045] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A double-sided open-chamber type negative pressure air gun vibrator, comprising a top cover (1), a base (10), and a gun body support (2), wherein the top cover and the base are connected by the gun body support; Its features are, It also includes an upper excitation unit and a lower excitation unit located between the top cover and the base, with the two excitation units arranged symmetrically in the upper and lower positions; both the upper excitation unit and the lower excitation unit include a control cabin (11), an excitation cabin shell, a return capsule shell (18), and a return capsule propulsion device (12); wherein, the bottom of the control cabin and the bottom of the return capsule shell of the upper excitation unit are fixedly connected to the top cover, and the bottom of the control cabin and the bottom of the return capsule shell of the lower excitation unit are fixedly connected to the base; Within the two excitation units, the excitation chamber shell is fitted outside the control chamber and can slide up and down relative to the control chamber; the top of the control chamber is equipped with an excitation chamber pushing device (6) that can be raised and lowered and slides and seals against the inner wall of the excitation chamber shell; when the excitation chamber shells of both excitation units are at the upper limit of their stroke, the two excitation chamber shells contact and seal, and at this time the two excitation chamber shells and the upper and lower excitation chamber pushing devices surround and form a sealed excitation chamber (5); there is a distance between the inner wall of the excitation chamber shell and the outer wall of the control chamber, and the bottom of the excitation chamber shell is fixedly connected to the bottom of the pushing chamber. The plate (7) is slidably sealed to the outer wall of the control cabin by pushing the bottom plate of the cabin; the excitation cabin propulsion device, the excitation cabin shell, the propulsion cabin bottom plate and the outer wall of the control cabin surround to form the propulsion cabin (14); the return cabin shell (18) is fitted on the outside of the control cabin, and the inner wall of the return cabin shell is in close contact with the outer wall of the excitation cabin shell, and the two are slidably sealed; the propulsion cabin bottom plate, the outer wall of the control cabin and the return cabin shell surround to form the return cabin (8); the return cabin propulsion device (12) is set at the bottom of the return cabin (8), and it can move up and down inside the return cabin (8); The tops of the upper and lower excitation chamber shells are provided with mutually cooperating annular stepped surfaces, and the vertical portions of the annular stepped surfaces of the two excitation chamber shells are in close contact with each other; the vertical portions of the annular stepped surfaces form the initial slides of the two excitation chamber shells. When the excitation chamber shells are in the initial slides, the excitation chambers remain sealed. The excitation chambers open only when the two excitation chamber shells are removed from the initial slides; the control cabins, return capsule shells, and return capsule propulsion devices of the upper and lower excitation units have identical structures and are arranged symmetrically in the upper and lower sections; the vertical portions of the annular stepped surfaces have a set height, and at least one of the annular stepped surfaces of the excitation chamber shells is provided with a one-way drainage channel, which is used to drain the water in the initial slides; The outer surface of the control cabin is provided with several excitation control mechanisms, which are used to lock the outer shell of the excitation cabin when it is at the upper limit of its stroke; the inside of the control cabin is provided with a high-pressure air passage that connects to the propulsion cabin.

2. The dual-sided open-chamber negative pressure air gun vibrator source according to claim 1, characterized in that, The control cabin also includes an excitation control system and a power unit; the power unit is connected to the excitation cabin propulsion device (6) and is used to propel the excitation cabin propulsion device up and down; the excitation control system is located inside the control cabin and is used to control the power unit, the return capsule propulsion device and the excitation control mechanism; the return capsule propulsion device is used to propel the excitation cabin shell.

3. The dual-sided open-chamber negative pressure air gun vibrator source according to claim 1, characterized in that, The excitation control mechanism is a locking pin; the excitation chamber propulsion device (6) is a piston.

4. The dual-sided open-chamber negative pressure air gun vibrator source according to claim 1, characterized in that, A pressure-reducing plate is fixedly installed inside the propulsion chamber and is fixedly connected to the outer wall of the control chamber. Both the pressure-reducing plate and the bottom plate of the propulsion chamber are arranged laterally. When the outer shell of the excitation chamber is at the upper limit of its stroke, the pressure-reducing plate is in close contact with the lower bottom plate, thereby reducing the area of ​​the gas inside the propulsion chamber acting on the bottom plate of the propulsion chamber.

5. The dual-sided open-chamber negative pressure air gun vibrator source according to claim 1, characterized in that, The top of the return capsule propulsion device is provided with a buffer pad (19).

6. The dual-sided open-chamber negative pressure air gun vibrator source according to claim 1, characterized in that, The gun body bracket maintains a set distance between the top cover and the base at all times; the gun body bracket includes multiple vertically arranged support rods, the support rods are hollow inside and can be used to run cables; the outer walls of the upper and lower excitation chamber shells are connected to the excitation chamber shell brackets (4), and the excitation chamber shell brackets are slidably connected to the support rods through sliding pins (16).

7. The dual-sided open-chamber negative pressure air gun vibrator source according to claim 1, characterized in that, A sealing ring is provided between the bottom plate (7) of the propulsion chamber and the outer wall of the control chamber to achieve sealing when they slide relative to each other; a sealing ring is provided between the outer shell of the excitation chamber and the outer shell of the return chamber to achieve sealing when they slide relative to each other.

8. A method for exciting a double-sided open-chamber negative pressure air gun vibrator as described in claim 1, characterized in that, Includes the following steps: 1) Inject high-pressure gas into the two propulsion chambers using the high-pressure gas line, and close the high-pressure gas line after the set pressure is reached; 2) Before activation, the double-sided open-chamber negative pressure air gun source is placed at the required activation position underwater; the activation chamber propulsion device (6) and return chamber propulsion device (12) of the upper and lower activation units are controlled to work synchronously to move towards the middle. The two return chamber propulsion devices (12) respectively drive the upper and lower activation chamber shells to move towards the middle. When the activation chamber propulsion device (6) is completely close, the activation chamber propulsion device stops working, while the return chamber propulsion device continues to drive the propulsion until the two activation chamber shells are completely in contact and sealed. At this time, the activation control mechanism locks the activation chamber shell, and the activation chamber is in a closed state. Then, the activation chamber propulsion device and return chamber propulsion device of the upper and lower activation units return to their original positions on both sides. At this time, the activation chamber and return chamber are evacuated, and the propulsion chamber is in a high-pressure state. The negative pressure air gun is in a ready-to-activate state. 3) During activation, the activation command is sent synchronously from the ship's control center to the control cabins of the upper and lower activation units. The control cabins control the activation control mechanisms to unlock the outer shell of the activation cabin. Under the pressure of high-pressure gas, the bottom plates of the push cabins of the upper and lower activation units drive the outer shells of the two activation cabins to move to both sides until the activation cabins are fully opened. Water enters the activation cabins and causes an implosion, forming a seismic source wavelet. 4) After the excitation is complete, return to step 2) and wait for the next excitation.

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