Method and system for optimizing deep-sea exploration coherent air gun pressure wavelets through air gun spacing and arrangement mode

Abstract

The invention discloses a method and system for optimizing deep-sea exploration coherent air gun pressure wavelets through air gun spacing and arrangement modes, and belongs to the field of deep-sea resource exploration. Establishing an interaction numerical model, and then designing parameters; obtaining pressure wavelet diagrams and sound pressure level spectrograms of three annularly arranged air gun bubble combinations and three linearly arranged air gun bubble combinations under different air gun intervals; the relation between the number of air guns and the pressure wavelet features is obtained; obtaining a change rule between the main pulse of the pressure wavelet, the bubble period, the bubble ratio and the main frequency of the sound pressure level spectrum and the air gun spacing; according to limiting conditions in practical engineering application, the number of combined air guns is increased, the distance between the air guns is kept to be about two maximum bubble radiuses, a multi-air-gun combined design method of annular arrangement is adopted, and in-phase synchronous excitation of the air guns is kept. The method is used for solving the problem that a large-volume air gun in an existing project cannot give consideration to low frequency and main pulse amplitude.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of deep-sea resource exploration, and particularly relates to a method for optimizing deep-sea exploration coherent air gun pressure wavelet through air gun spacing and arrangement mode and a system thereof. BACKGROUND

[0002] In seabed resource exploration, people hope that the air gun array produces high-amplitude and low-frequency pulses to improve the detection accuracy and depth. At present, the mainstream of air gun frequency reduction adopts a larger air gun volume. However, the larger the air gun is, the greater the impact force on the internal shuttle valve during movement, which brings great challenges to air gun manufacturing and ten-thousand-level continuous excitation. Moreover, compared with the signal excited by a large air gun with the same total volume, the main pulse of the signal excited by a plurality of small-volume air guns with the same total volume is obviously reduced. Therefore, the combination of a plurality of air guns can well optimize the pulse characteristics of the air gun pressure wavelet, achieve the purpose of reducing the main frequency of the air gun, and not excessively damage the main pulse of the air gun signal.

[0003] However, high-quality pulses cannot be obtained without the design of the air gun array and the coherent gun. The superposition of pressure wavelets under different air gun bubble combinations has obvious differences. If the reflection is not considered, the wavelet signals emitted by a single air gun are basically the same in each direction, while the wavelet signals emitted by a plurality of air gun combinations have great differences in each direction, and the energy transfer has strong directionality. When all the air guns in the array emit at the same time, the main pulse formed at the initial moment will be directly superimposed at the far-field measurement point. If each air gun bubble has a different period, the time at which the bubble pulses arrive at the far-field measurement point is different, and the superposition of the pressure wavelets of each gun will also present different results. Therefore, reasonable arrangement of a plurality of air gun combinations, appropriate adjustment of the distance, volume, depth, and time of each air gun, and different pressure wavelets obtained can meet different exploration needs.

[0004] The multi-bubble fusion problem plays a very key role in the arrangement of coherent guns and the design of multi-opening air guns. The nonlinear coupling and fusion problem of bubble groups involves a complex exchange process of mass, momentum, and energy. The present application uses the finite volume method to solve this problem. This method has local conservation and an advantage in handling gas-liquid two-phase flow problems. SUMMARY

[0005] The present application provides a method for optimizing deep-sea exploration coherent air gun pressure wavelet through air gun spacing and arrangement mode to solve the problem that large-volume air guns cannot balance low frequency and main pulse amplitude in existing engineering.

[0006] The present application is implemented by the following technical solutions: A method for optimizing deep-sea exploration coherent air gun pressure wavelet through air gun spacing and arrangement mode, the method comprising the following steps: Step one: establish a numerical model of the interaction between compressible three-dimensional multi-air gun bubbles, and then design dimensionless distance parameters and dimensionless pressure wave characteristic parameters; Step two: obtain the pressure wave pattern and sound pressure level spectrum of three annularly arranged air gun bubble combinations and three linearly arranged air gun bubble combinations under different air gun spacings; Step three: obtain the relationship between the number of air guns and pressure wave characteristics; Step four: obtain the variation law between the main pulse of the pressure wave, the bubble period, the bubble ratio, and the main frequency of the sound pressure level spectrum and the air gun spacing by combining the calculation results obtained in steps two and three; Step five: based on the limiting conditions in actual engineering applications, obtain the multi-air gun combination design method of increasing the number of combinations, keeping the air gun spacing around two maximum bubble radii, and adopting annular arrangement, and keep the air guns in phase and synchronous excitation to realize the optimization of deep-sea exploration coherent air gun pressure wave through air gun spacing and arrangement.

[0007] Further, the step one of establishing a numerical model of the interaction between compressible three-dimensional multi-air gun bubbles is specifically based on the finite volume method to process gas-liquid two-phase flow problems, and the calculation domain is discretized into individual grid cells, each fluid cell satisfying the following equations corresponding to mass conservation and momentum conservation: (1) (2) wherein, is the average fluid density in the control unit, is the flow field velocity in the control unit.

[0008] Further, the step one of designing dimensionless distance parameters is the ratio of the air gun spacing to the maximum radius of bubble pulsation, which can be quickly adjusted according to the distance parameter .

[0009] Further, the step two is specifically to design three annularly arranged air gun bubble combinations and three linearly arranged air gun bubble combinations, and adjust the distance between the air gun bubbles, and obtain the pressure wave pattern and sound pressure level spectrum of the three annularly arranged air gun bubble combinations and the three linearly arranged air gun bubble combinations under different air gun spacings through the numerical model of the interaction between compressible three-dimensional multi-air gun bubbles in step one.

[0010] Further, the step three is specifically designed four annular arrangement of air gun bubble combination and four linear arrangement of air gun bubble combination, and adjust the distance between the air gun bubble, through the compressible three-dimensional multi-air gun bubble interaction numerical model in step one, obtain four annular arrangement of air gun bubble combination and four linear arrangement of air gun bubble combination under different air gun spacing pressure subwave and sound pressure level spectrum, and compare the best pressure subwave and sound pressure level spectrum of single air gun, three air guns and four air guns working condition, obtain the relationship between the number of air gun and pressure subwave characteristics.

[0011] Further, the step two and step three are based on the compressible three-dimensional multi-air gun bubble interaction numerical model established in step one, and the dimensionless distance parameter is used to calculate the pressure subwave characteristics and sound pressure level spectrum characteristics under different air gun spacing, and the best pressure subwave and sound pressure level spectrum of single air gun, three air guns and four air guns working condition are compared, so as to obtain the relationship between the number of air gun and pressure subwave characteristics.

[0012] Further, the step four is specifically designed to integrate the calculation results obtained in step two and step three, and extract the parameter variation law of main pulse, bubble ratio, period and main frequency, and compare three bubble working condition and four bubble working condition. From the calculation results, the pressure wave characteristic parameter variation of the four arrangement schemes presents a significant common law: the main pulse amplitude and bubble ratio increase first and then decrease with the increase of air gun spacing; the bubble period continuously decreases with the increase of spacing; while the main frequency and the period are inversely proportional, and continuously increase with the increase of spacing.

[0013] Further, the step five is specifically designed to integrate the rules obtained in steps two to four, and consider the limiting conditions in actual engineering application, to obtain the best combination air gun number, air gun spacing adjustment method and air gun arrangement method; in order to obtain higher main pulse and initial bubble ratio, the best bubble critical spacing of three air guns and four air guns in annular arrangement is 2 times the maximum radius of bubble; for three guns and four guns in linear arrangement, the best bubble critical spacing is 1.5-1.75 times the maximum radius of bubble; with the same number of bubbles and bubble spacing, annular arrangement is better than linear arrangement, which can make the low frequency band lower while keeping the main pulse amplitude at a higher level.

[0014] A deep sea exploration coherent air gun pressure subwave system optimized by air gun spacing and arrangement method, the system uses the deep sea exploration coherent air gun pressure subwave method optimized by air gun spacing and arrangement method as described above, the system comprises, A numerical model establishment module for establishing a compressible three-dimensional multi-air gun bubble interaction numerical model, A parameter design module for designing dimensionless distance parameter And dimensionless pressure subwave characteristic parameter; The change rule acquisition module obtains the pressure subwave pattern and the sound pressure level spectrum of the three annularly arranged air gun bubble combinations and the three linearly arranged air gun bubble combinations under different air gun spacings; The relationship between the number of air guns and the pressure subwave characteristics is obtained. The change rule between the pressure subwave main pulse, the bubble period, the bubble ratio, and the main frequency of the sound pressure level spectrum and the air gun spacing is obtained in combination with the obtained calculation results. The coherent air gun pressure subwave optimization module obtains the multi-air gun combination design method of increasing the number of combined air guns, keeping the air gun spacing around two maximum bubble radii, and adopting annular arrangement according to the obtained rules and the restriction conditions in actual engineering application, and keeps the air guns in phase and synchronous excitation, so that the deep sea exploration coherent air gun pressure subwave is optimized through the air gun spacing and the arrangement mode.

[0015] The beneficial effects of the present application are: The present application aims to provide guidance for the application and deployment of multi-gun coherence in offshore exploration. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The present application is a method flowchart.

[0017] Figure 2 The air gun combination schematic diagram and the bubble movement condition under different arrangement modes, wherein (a) is three-bubble linear arrangement; (b) is four-bubble linear arrangement; (c) is three-bubble annular arrangement; and (d) is four-bubble annular arrangement.

[0018] Figure 3 The pressure subwave comparison diagram and the sound pressure level spectrum curve comparison diagram under the optimal distance parameter of three-air gun working conditions and four-air gun working conditions, wherein (a) is the pressure subwave curve, and (b) is the sound pressure level spectrum curve.

[0019] Figure 4 The change curve diagram of the pressure subwave characteristic parameter with the dimensionless distance parameter , wherein (a) is the change of the main pulse with the distance, and (b) is the change of the bubble ratio with the distance.

[0020] Figure 5 The deep sea exploration multi-air gun combination method for achieving the optimal pressure subwave. DETAILED DESCRIPTION

[0021] In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, devices, and circuits are omitted so as not to obscure the description of the present application with unnecessary detail.

[0022] It is to be understood that the terminology "including", when used in the present specification and in the following claims, indicates the presence of the described features, integers, steps, operations, elements, and / or components but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0023] It is also to be understood that the terminology used in the present specification and the appended claims is for the purpose of describing the particular embodiments only and is not intended to be limiting.

[0024] The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the drawings in the specification of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0025] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in other manners different from those described herein, and those skilled in the art can make similar generalizations without departing from the spirit and scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0026] Embodiment one The present embodiment provides a method for optimizing deep-sea exploration coherent air gun pressure wavelet by air gun spacing and arrangement, which comprises the following steps: Step one: a numerical model of the interaction between compressible three-dimensional multi-air gun bubbles is established by combining the finite volume method with the bubble group coupling mechanism, and dimensionless distance parameters and dimensionless pressure wavelet characteristic parameters are designed to make the rules more universal. For example, the dimensionless distance parameter is defined as follows: Figure 2 ​As shown. Step two: design three annular arrangement of air gun bubble combination and three linear arrangement of air gun bubble combination, and adjust the distance between the air gun bubbles, through the compressible three-dimensional numerical model of the interaction between multiple air gun bubbles in step one, obtain the pressure subwave and sound pressure level spectrum of three annular arrangement of air gun bubble combination and three linear arrangement of air gun bubble combination under different air gun spacing; as shown in Figure 2 、 3 As shown.

[0027] Step three: design four annular arrangement of air gun bubble combination and four linear arrangement of air gun bubble combination, and adjust the distance between the air gun bubbles, through the compressible three-dimensional numerical model of the interaction between multiple air gun bubbles in step one, obtain the pressure subwave and sound pressure level spectrum of four annular arrangement of air gun bubble combination and four linear arrangement of air gun bubble combination under different air gun spacing, and compare the best pressure subwave and sound pressure level spectrum of single air gun, three air guns and four air guns working condition, obtain the relationship between the number of air guns and the pressure subwave characteristics; as shown in Figure 2 、 3 As shown.

[0028] Step four: combine the calculation results obtained in step two and step three, extract the dimensionless pressure subwave key characteristic parameters and draw the parameter-distance variation diagram, obtain the variation law between the pressure subwave main pulse, bubble period, bubble ratio and the main frequency of sound pressure level spectrum and the air gun spacing; Step five: according to the restriction conditions in actual engineering application, obtain the design method of increasing the number of combined air guns, keeping the air gun spacing at about two maximum bubble radii and adopting annular arrangement of multiple air guns, and keeping the air guns in phase and synchronous excitation, which can make the low frequency band lower and the main pulse amplitude higher at the same time, realize the optimization of deep sea exploration coherent air gun pressure subwave through air gun spacing and arrangement.

[0029] Further, the step one of establishing the numerical model of the interaction between compressible three-dimensional multiple air gun bubbles is specifically based on the finite volume method to process the gas-liquid two-phase flow problem, and the calculation domain is discretized into a grid unit, each fluid unit satisfies the following equations corresponding to mass conservation and momentum conservation: (1) (2) Wherein, is the average fluid density in the control unit, is the flow field velocity in the control unit.

[0030] Further, the step one designs the dimensionless distance parameter The ratio of the distance between the bubbles to the maximum radius of the bubble pulse, so in engineering applications, even if the size of the air gun volume and the maximum radius of the generated bubble pulse are different, the distance parameter can be used as a reference The distance between the bubbles of the air gun is quickly adjusted.

[0031] The dimensionless distance parameter Specifically, the distance is represented by the maximum radius of the bubble n, because the maximum radius of the bubble generated by different air guns is different, the dimensionless can make the calculated numerical results not limited to a certain working condition, and can better reflect the relationship between variables.

[0032] Further, the step two is specifically designed three annular arrangement air gun bubble combinations and three linear arrangement air gun bubble combinations, and the distance between the air gun bubbles is adjusted, and the pressure subwave and the sound pressure level spectrum of the three annular arrangement air gun bubble combinations and the three linear arrangement air gun bubble combinations under different air gun distances are obtained through the compressible three-dimensional multi-air gun bubble interaction numerical model in step one.

[0033] The interaction numerical model is specifically based on the numerical model established in step one, and the initial conditions (such as air gun volume, excitation depth, working pressure, etc.) are input, and the pressure of the flow field (i.e. pressure subwave) is calculated through the numerical model, and then the pressure of the flow field is converted to sound pressure level (i.e. Fourier transform) to obtain the sound pressure level spectrum.

[0034] Further, the step three is specifically designed four annular arrangement air gun bubble combinations and four linear arrangement air gun bubble combinations, and the distance between the air gun bubbles is adjusted, and the pressure subwave and the sound pressure level spectrum of the four annular arrangement air gun bubble combinations and the four linear arrangement air gun bubble combinations under different air gun distances are obtained through the compressible three-dimensional multi-air gun bubble interaction numerical model in step one, and the best pressure subwave and sound pressure level spectrum of single air gun, three air guns and four air guns are compared, and the relationship between the number of air guns and the pressure subwave characteristics is obtained.

[0035] Further, the steps two and three are based on the compressible three-dimensional multi-air gun bubble interaction numerical model established in step one, and the dimensionless distance parameter is used as a characteristic system to calculate the pressure subwave characteristics and the sound pressure level spectrum characteristics under different air gun distances, and the best pressure subwave and sound pressure level spectrum of single air gun, three air guns and four air guns are compared, so as to obtain the relationship between the number of air guns and the pressure subwave characteristics.

[0036] The specific calculation process is: input the initial conditions, then the model starts to calculate (in openfoam), and finally the flow field pressure data at each time is obtained.

[0037] Further, the step four is specifically, the calculation results obtained by integrating step two and step three are integrated, and the variation laws of key parameters such as main pulse, bubble ratio, period and main frequency are extracted, and the three-bubble working condition and the four-bubble working condition are compared. From the calculation results, the pressure wave characteristic parameter variation of the four arrangement schemes presents a significant common law, such as Figure 4 As shown in the figure: the main pulse amplitude and the bubble ratio (the ratio of the main pulse to the bubble pulse) both increase first and then decrease with the increase of the air gun spacing; the bubble period continuously decreases with the increase of the spacing; and the main frequency and the period are inversely proportional, and continuously increase with the increase of the spacing.

[0038] Specifically, since the calculation results of all working conditions draw pressure subwave graphs and frequency spectrum graphs, these key parameters are the values of some key points in the pressure subwave graph, and after the values of the key points are extracted, the corresponding dimensionless distance The parameter-distance corresponding relationship curve is drawn.

[0039] Further, the step five is specifically, the laws obtained by integrating steps two to four are integrated, and the best combined air gun number, air gun spacing adjustment method and air gun combination arrangement method are obtained considering the limiting conditions in actual engineering application, such as Figure 4 As shown in the figure: in order to obtain higher main pulse and initial bubble ratio, the best bubble critical spacing of the three air guns and the four air guns in the ring arrangement is 2 times the maximum bubble radius; the best bubble critical spacing of the three air guns and the four air guns in the linear arrangement is 1.5-1.75 times the maximum bubble radius; the ring arrangement is better than the linear arrangement with the same bubble number and bubble spacing, which can make the low frequency band lower and the main pulse amplitude higher.

[0040] The consideration of the limiting conditions in actual engineering application is specifically, in actual engineering application, the air gun source is towed by a geophysical prospecting ship and excited in water and as far as possible excited underwater about 5-15 m; the air gun source excitation is accompanied by a strong shock wave, and the coherent guns are too close to cause structural damage.

[0041] Compared with the prior art, the large-volume air gun designed in the present application reduces the low frequency while weakening the main pulse, and the design method of the air gun array and the coherent gun is still immature. The present application based on the finite volume method proposes a method for optimizing the pressure subwave of the coherent air gun for deep sea exploration by air gun spacing and arrangement, which aims to provide guidance for the application and deployment of multi-gun coherence in offshore exploration.

[0042] Embodiment two The embodiment provides a system for optimizing the pressure subwave of the coherent air gun for deep sea exploration by air gun spacing and arrangement, which uses the method for optimizing the pressure subwave of the coherent air gun for deep sea exploration by air gun spacing and arrangement according to the embodiment one, and the system comprises, a numerical model establishing module: a numerical model of interaction among compressible three-dimensional multi-air gun bubbles is established by combining finite volume method with bubble group coupling mechanism, a parameter designing module: dimensionless distance parameters are designed and dimensionless pressure subwave characteristic parameters are designed, so that the rules are more universal; a variation rule obtaining module: three annularly arranged air gun bubble combinations and three linearly arranged air gun bubble combinations are designed, and the distance between air gun bubbles is adjusted, the pressure subwave graphs and sound pressure level spectrum graphs of the three annularly arranged air gun bubble combinations and the three linearly arranged air gun bubble combinations under different air gun spacings are obtained through the numerical model of interaction among compressible three-dimensional multi-air gun bubbles in step one; four annularly arranged air gun bubble combinations and four linearly arranged air gun bubble combinations are designed, and the distance between air gun bubbles is adjusted, the pressure subwave graphs and sound pressure level spectrum graphs of the four annularly arranged air gun bubble combinations and the four linearly arranged air gun bubble combinations under different air gun spacings are obtained through the numerical model of interaction among compressible three-dimensional multi-air gun bubbles in step one, and the relationship between the number of air guns and the pressure subwave characteristics is obtained by comparing the optimal pressure subwave and sound pressure level spectrum of single air gun, three air guns and four air guns; combining the obtained calculation results, dimensionless pressure subwave key characteristic parameters are extracted and parameter-distance variation graphs are drawn, and the variation rules between the main pulse of pressure subwave, bubble period, bubble ratio, and main frequency of sound pressure level spectrum and air gun spacing are obtained; a coherent air gun pressure subwave optimization module: according to the restriction conditions in actual engineering application, the obtained rules are comprehensively used, the design method of increasing the number of combined air guns, keeping the air gun spacing around two maximum bubble radii and adopting annular arrangement of multi-air gun combination is obtained, and the air guns are kept in phase and synchronous excitation, so that the low frequency band is kept low while the main pulse amplitude is kept at a high level, and the deep sea exploration coherent air gun pressure subwave is optimized through air gun spacing and arrangement.

[0043] Embodiment three The embodiment is applied to the field of deep sea resource exploration by optimizing deep sea exploration coherent air gun pressure subwave through air gun spacing and arrangement by a method as described in embodiment one.

[0044] Embodiment four The electronic device provided by the embodiments of the present application includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the memory is configured to store software programs and modules, and the processor is configured to execute various function applications and data processing by running the software programs and modules stored in the memory. The memory and the processor are connected through a bus. Specifically, the processor implements any of the steps in the above-mentioned embodiment I by running the above-mentioned computer program stored in the memory.

[0045] It should be understood that, in the embodiments of the present application, the processor can be a central processing unit (CPU), and the processor can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0046] The memory can include read-only memory, flash memory, and random access memory, and provide instructions and data for the processor. Part or all of the memory can also include non-volatile random access memory.

[0047] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of functional units and modules is exemplified, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, i.e. the internal structure of the above-mentioned device is divided into different functional units or modules to complete all or part of the above-mentioned functions. Each functional unit and module in the embodiments can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit, and the integrated unit can be realized in the form of hardware or software. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction, and do not limit the protection scope of the present application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the above-mentioned method embodiments, which will not be repeated here.

[0048] It should be noted that the method and its details provided by the above-mentioned embodiments can be combined into the device and equipment provided by the embodiments, and mutual reference will not be repeated.

[0049] The above embodiments are only used to illustrate the technical solutions of the present application, but not intended to limit the present application; even though the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions recorded in the foregoing embodiments, or equivalent replacements can be made to part of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method for optimizing deep-sea exploration coherent airgun pressure wavelet by airgun spacing and arrangement, characterized in that, The method comprises the following steps: Step one: Establish the numerical model of the interaction between the compressible three-dimensional multi-air gun bubbles, and redesign the dimensionless distance parameter And the dimensionless pressure wavelet characteristic parameter; Step two: obtain the pressure subwave pattern and the sound pressure level spectrum pattern of three annularly arranged air gun bubble combinations and three linearly arranged air gun bubble combinations under different air gun spacings; Step three: obtain the relationship between the number of air guns and the pressure subwave characteristics; Step four: obtain the variation law between the pressure subwave main pulse, the bubble ratio, the sound pressure level spectrum main frequency and the air gun spacing by combining the calculation results obtained in steps two and three; Step five: obtain the design method of increasing the number of combined air guns, keeping the air gun spacing at about two maximum bubble radii and adopting annular arrangement of the multi-air gun combination according to the restriction conditions in actual engineering application, and keep the air guns in phase and synchronous excitation, so as to realize the optimization of deep sea exploration coherent air gun pressure subwave through air gun spacing and arrangement mode.

2. The method of claim 1, wherein, The step one of establishing the compressible three-dimensional multi-air gun bubble interaction numerical model is specifically based on the finite volume method to process the gas-liquid two-phase flow problem, and the calculation flow field is discretized into grid units, each fluid unit satisfies the following equations corresponding to mass conservation and momentum conservation: (1) (2) wherein, is the average fluid density within the control unit, is the flow field velocity within the control unit.

3. The method of claim 1, wherein, The step one designs a dimensionless distance parameter The ratio of the bubble spacing to the maximum radius of the bubble pulsation, which can be calculated according to the distance parameter The bubble spacing of the air gun is quickly adjusted.

4. The method of claim 1, wherein, The step two is specifically to design three annularly arranged air gun bubble combinations and three linearly arranged air gun bubble combinations, adjust the distance between the air gun bubbles, and obtain the pressure subwave pattern and the sound pressure level spectrum pattern of the three annularly arranged air gun bubble combinations and the three linearly arranged air gun bubble combinations under different air gun spacings through the compressible three-dimensional multi-air gun bubble interaction numerical model in step one.

5. The method of claim 1, wherein, The step three is specifically to design four annularly arranged air gun bubble combinations and four linearly arranged air gun bubble combinations, adjust the distance between the air gun bubbles, and obtain the pressure subwave pattern and the sound pressure level spectrum pattern of the four annularly arranged air gun bubble combinations and the four linearly arranged air gun bubble combinations under different air gun spacings through the compressible three-dimensional multi-air gun bubble interaction numerical model in step one, and compare the best pressure subwave and the sound pressure level spectrum of single air gun, three air guns and four air guns working conditions to obtain the relationship between the number of air guns and the pressure subwave characteristics.

6. The method of claim 4 or 5, wherein, The steps two and three are based on the compressible three-dimensional multi-air gun bubble interaction numerical model established in step one, and the dimensionless distance parameter is used to represent the system to calculate the pressure subwave characteristics and the sound pressure level spectrum characteristics under different air gun spacings, and the best pressure subwave and the sound pressure level spectrum of single air gun, three air guns and four air guns working conditions are compared, so as to obtain the relationship between the number of air guns and the pressure subwave characteristics.

7. The method of claim 4 or 5, wherein, The step four is specifically to combine the calculation results obtained in steps two and three, extract the parameter variation law of the main pulse, the bubble ratio, the period and the main frequency, and compare the three bubble working conditions and the four bubble working conditions. From the calculation results, the pressure wave characteristic parameter variation of the four arrangement schemes presents a significant common law: the main pulse amplitude and the bubble ratio both increase first and then decrease with the increase of the air gun spacing; the bubble period continuously decreases with the increase of the spacing; and the main frequency and the period are inversely proportional, and continuously increase with the increase of the spacing.

8. The method of claim 1, wherein, The step five is specifically, the law obtained from the step two to step four is obtained, the best combination air gun number, air gun spacing adjustment method and air gun combination arrangement method; for obtaining higher main pulse and initial bubble ratio, the best bubble critical spacing of three air guns and four air guns arranged in ring is 2 times of the maximum bubble radius; for three guns and four guns arranged in line, the best bubble critical spacing is 1.5-1.75 times of the maximum bubble radius; the same bubble number and bubble spacing, the ring arrangement is better than the linear arrangement, so that the low frequency band is lower and the main pulse amplitude is kept at a high level.

9. A system for optimizing deep-sea exploration coherent airgun pressure wavelet by airgun spacing and arrangement, characterized in that, The system uses the method for optimizing deep sea exploration coherent air gun pressure subwave by air gun spacing and arrangement mode according to any one of claims 1-8, and the system comprises, a numerical model establishing module: a numerical model of three-dimensional compressible multi-air gun bubble interaction is established, Parameter design module: design dimensionless distance parameter and dimensionless pressure subwavelet characteristic parameter; a change law obtaining module: the pressure subwave figure and the sound pressure level spectrum figure of three ring arrangement air gun bubble combinations and three linear arrangement air gun bubble combinations under different air gun spacings are obtained; the relationship between the air gun number and the pressure subwave characteristics is obtained; the change law between the pressure subwave main pulse, the bubble period, the bubble ratio, the main frequency of the sound pressure level spectrum and the air gun spacing is obtained by combining the obtained calculation results; a coherent air gun pressure subwave optimization module: according to the restriction conditions in actual engineering application, the increase of the combination air gun number, the air gun spacing kept around two maximum bubble radii and the multi-air gun combination design method of ring arrangement are obtained by comprehensively considering the obtained law, and the air guns are kept in phase and synchronous excitation, so as to realize the optimization of deep sea exploration coherent air gun pressure subwave by air gun spacing and arrangement mode. 10.A method for optimizing deep sea exploration coherent air gun pressure subwave by air gun spacing and arrangement mode according to any one of claims 1-8 is applied to the field of deep sea resource exploration.

Images