Submarine gas leakage three-dimensional time sequence monitoring method based on acoustic sensing

Abstract

The invention relates to the technical field of ocean engineering observation, in particular to a submarine gas leakage three-dimensional time sequence monitoring method based on acoustic sensing. Comprising the following steps: S1, acquiring spatial characteristics of gas leakage based on sonar data; S2, integrating and constructing a three-dimensional gas leakage model by combining sensor data: carrying out space-time coupling on bubble rising speed, height, hierarchy, position and intensity data measured in S1 and data in S2, and generating a spatial distribution model of three-dimensional gas leakage; performing rotation correction on the position and the speed of each data point so as to dynamically update the three-dimensional gas leakage model, and visualizing the three-dimensional gas leakage model into a dynamic change diagram and a three-dimensional distribution diagram; and S3, transmitting the real-time monitoring data to a monitoring platform in a wired or wireless manner to provide a real-time alarm. According to the invention, three-dimensional characteristics of seabed gas release can be detected in real time based on sonar data, gas leakage positioning and acquisition of key parameters such as leakage intensity and height are realized, and accurate monitoring of a gas leakage area is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of ocean engineering observation, and particularly relates to a three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing. Background Art

[0002] Submarine gas leakage refers to the process in which gas formed inside the seabed is released into seawater, reflecting the biogeochemical processes at the seabed depth and the gestation and development of submarine geological disasters. At the same time, it also transforms the submarine topography and geomorphology. Therefore, it is very important to determine the scale and characteristics of submarine gas leakage, including bubble size, velocity, concentration, etc.

[0003] Currently, the methods for measuring submarine gas leakage mainly include two types: one is to use in-situ bottom-mounted observation equipment to complete long-term measurement of multiple submarine parameters (such as Chinese Utility Model Patent CN214334779U); the other is to use a survey ship or an underwater robot for a cruising survey (such as Chinese Patent Application for Invention CN108931777A). However, the former cannot easily change the observation position after deployment, so it can only measure a single gas leakage vent, cannot reflect the overall situation of the submarine gas leakage area, and cannot obtain data in real time, making it difficult to effectively carry out gas leakage monitoring; the latter can only conduct a single survey and cannot continuously observe the situation of submarine gas leakage for a long time. The above two methods have problems in terms of observation range, continuous observation time, data real-time performance, etc., and cannot meet the actual needs of engineering activities such as submarine carbon dioxide sequestration, submarine methane leakage monitoring, and submarine natural gas hydrate exploitation. Obviously, for the complex and variable marine environment, the methods for measuring submarine gas leakage disclosed in the above applications still have defects and cannot meet the existing actual application requirements, which is an urgent problem to be solved at present. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing, which can detect the three-dimensional characteristics of submarine gas release in real time based on horizontal sonar and vertical sonar data, can realize the positioning of gas leakage, and obtain key parameters such as leakage intensity and height, and realize precise monitoring of the gas leakage area through a three-dimensional detection method.

[0005] The present invention is realized through the following technical solutions: Provide a three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing, including the following steps: Step S1: Obtain the spatial characteristics of gas leakage based on sonar data: S11. Use a vertical sonar to obtain the propagation information of bubbles in the depth direction by receiving the sound waves reflected from the seabed bubbles. By analyzing the time delay and sound wave intensity, calculate the rising speed, height of the bubbles and their distribution at different depths, and determine the release height, layer and gas release intensity of gas leakage. S12. Use a horizontal sonar to receive the reflected signals, rotate 360 degrees to collect the detection information of the gas release source in the horizontal direction, and combine the flow velocity and temperature data in the seawater to determine the position of the gas and its expansion range on the seabed.

[0006] Step S2: Integrate and construct a three-dimensional gas leakage model in combination with the sensor data: Divide the monitoring area into multiple small cubic grid cells, each grid cell contains various parameters of gas leakage, and use Kriging interpolation or inverse distance weighting method to interpolate and calculate the gas leakage parameters in each grid cell based on the vertical sonar, horizontal sonar, methane concentration, pressure and flow velocity data. Adopt a time series interpolation method, combine the time data of each sensor, and generate a continuous time variation model.

[0007] Couple the data of the bubble rising speed, height, layer, position and intensity measured in step S1 with the data of each sensor in S2 in space and time to generate a spatial distribution model of three-dimensional gas leakage; correct the rotation of the position and speed of each data point to dynamically update the three-dimensional gas leakage model, and visualize it as a dynamic change diagram and a three-dimensional distribution diagram.

[0008] Step S3: Transmit the real-time monitoring data to the monitoring platform through wired or wireless means, and provide real-time alarms according to the changes in gas release.

[0009] Further, in step S2, before measurement, align the timestamps of the data of the pressure gauge, Doppler flowmeter and methane sensor respectively to achieve sampling timing synchronization. The specific steps are as follows: Step 1: Select the data timestamp of the pressure gauge t pressure As the unified benchmark, which is used as the basis for data alignment, and align the data of other sensors to this time benchmark.

[0010] Step 2: According to the unified time benchmark selected in step 1, use the interpolation algorithm to align the data timestamps of other sensors; when the difference between the sampling time points of other sensors and the benchmark time point is small, a linear interpolation method can be used to fill in the missing timestamps. Assume the timestamp X of the sensor t x and the sampling value X ( t ), then the interpolation formula is: ; Wherein, t0 and t1 are adjacent known time points, taligned is the reference timestamp.

[0011] When the data changes greatly and higher smoothness is required, the spline interpolation method can obtain more accurate interpolation results and avoid discontinuities or excessive fluctuations. The spline interpolation can be implemented by quadratic or cubic spline methods: ; Wherein, S ( t ) is the smoothed curve obtained by spline interpolation.

[0012] Step 3: Set the time difference limit. If the difference between the timestamp of the sensor and the reference timestamp exceeds a certain set threshold, discard the data or smooth the data using the sliding window method.

[0013] By synchronizing the sampling time sequence of the sensors, ensure the time sequence consistency of the data of multiple sensors during the monitoring of submarine gas leakage, and be used to ensure the time alignment of the data of sensors such as pressure gauges, Doppler current meters, and methane sensors. Through means such as timestamp alignment, interpolation processing, and data filtering, ensure that the data of each sensor can be analyzed and modeled under a unified time reference, so as to provide reliable data support for the accurate construction of the three-dimensional gas leakage model.

[0014] Furthermore, in step S1, because the rotation angle θ ( t ) of the horizontal sonar changes with time, the correction coefficient can be calculated by modeling the change of the sonar rotation angle; Define a basic angle correction coefficient f ( θ ), which is related to the current rotation angle θ , and it changes with the different acoustic wave propagation paths. The correction coefficient of the rotation angle is a linear function: ; Wherein, α is a correction coefficient, indicating the influence of the rotation angle on the acoustic wave propagation.

[0015] The angular velocity of the sonar rotation is θ ( t ), and the correction coefficient f ( θ ( t )) should change with time. Combine the angular velocity with time for real-time correction; the rotation angle of the sonar increases linearly with time: ; The calculation formula of the correction coefficient is expressed as: ; Wherein, θ 0 is the initial angle, is the angular velocity of the sonar.

[0016] Furthermore, the correction of the acoustic wave time delay: For the vertical sonar, the rotation effect is reflected in the propagation path of the acoustic wave, and the corrected time delay Δtrot can be expressed as: ; Δt is the propagation time of the acoustic wave in water.

[0017] The correction of the propagation distance: For the horizontal sonar, the rotation affects the length of the acoustic wave propagation path, and the corrected propagation distance drot can be expressed as: ; Wherein, d is the original distance of the acoustic wave propagation, f ( θ ( t )) is the correction coefficient caused by rotation.

[0018] The correction of the signal intensity: The correction coefficient of the signal intensity A ( θ ( t )) can be calculated by the following method: ; Wherein, A 0 is the original signal intensity of the sonar sensor, and δ is a coefficient related to the sonar design and water body conditions, indicating the influence of rotation on the signal intensity.

[0019] Considering the rotation influence of the sonar comprehensively, the correction coefficient f total( θ ( t )) can be expressed as: ; f distance( θ ( t )) is the distance correction coefficient, f time( θ ( t )) is the time delay correction coefficient, fintensity( θ ( t )) is the signal intensity correction coefficient.

[0020] Furthermore, in step S11, Calculation of the bubble rising speed: The rotation angle of the vertical sonar probe θ ( t ) and the time delay △t are synchronously adjusted. The time for the sound wave to return is affected by the rotation angle. The formula for calculating the bubble rising speed is: ; Where: f ( θ ( t )) represents the coefficient corrected according to the current rotation angle.

[0021] Calculation of the bubble height: The height of the bubble h ( t ) should be calculated according to the rotation angle. The calculation formula: ; Wherein, △t is the time delay of the sound wave return, c is the speed of sound, θ ( t ) is the rotation angle of the sonar probe.

[0022] Furthermore, in step S12, horizontal positioning of the gas release source: The positioning formula for the gas release source in the horizontal direction is: ; Wherein, △t is the echo time delay, vhorizontal is the sound wave propagation speed in the horizontal direction, θ (t) is the current rotation angle of the sonar.

[0023] The gas expansion speed formula is: ; Wherein, vbase is the basic speed of gas expansion, is the correction function based on sonar rotation, used to compensate for the influence of rotation on the expansion speed.

[0024] In step S2, when performing 3D modeling, the rotation information of the sonar needs to be considered and introduced into the spatial coordinate transformation. In order to accurately map the 2D data measured by the sonar to the 3D space coordinate system, the following transformation is required: For a horizontal sonar, the position data ( x , y ) will change with the change of the rotation angle. Therefore, a rotation matrix is needed to adjust the position data; The rotation matrix R ( θ ) acts on the horizontal position data: ; Among them, R ( θ ( t )) is a two-dimensional rotation matrix, θ ( t ) is the current rotation angle; For a vertical sonar, the correction of the depth data needs to consider the influence of the rotation angle and tilt angle of the sonar, and a rotation matrix or coordinate transformation method is used to adjust.

[0025] Furthermore, the gas release intensity is calculated using the pressure gauge data: Qgas = △P / R ; Qgas is the gas release intensity, △P is the pressure change, R is the relevant parameter of the measurement area; The gas diffusion velocity is calculated using the acoustic Doppler current meter data: vdisp = vup + vcurrent ; Among them, vdisp is the actual diffusion velocity of the gas, vup is the bubble rising velocity, vcurrent is the seawater flow velocity.

[0026] The methane gas release intensity is calculated using a methane sensor: Qmethane = Cmethane · A · vdisp ; Among them, Qmethane is the release intensity of methane gas, Cmethane is the methane concentration, A is the cross-sectional area of the measurement area, vdisp is the diffusion velocity.

[0027] Furthermore, the horizontal position of the gas leakage source is determined by the echo time and rotation angle of the horizontal sonar ( x , y ), given the known position of the sonar device ( x 0 ,y 0 ) and the direction angle of the echo θ , the horizontal position of the gas leakage source ( x , y ) is calculated as: x = x 0 +d · cos(θ) ; y = y 0 + d · sin(θ) ; d = c · t / 2 ; Where: d is the propagation distance of the sound wave, c is the propagation speed of the sound wave in water, t is the propagation time of the echo.

[0028] Furthermore, the depth of the gas release point is determined by measuring the echo time with a vertical sonar d vert ; ; Wherein, t vert is the propagation time of the vertical echo, c is the propagation speed of the sound wave.

[0029] The echo intensity of the sonar I echo is proportional to the reflection area of the bubble A ; ; Where: I 0 is the signal intensity emitted by the sonar, r o is the reference distance, r is the actual measured distance.

[0030] According to the echo intensity and the bubble volume V bubble , the gas release intensity I release : ; Where: V bubble is the volume of the bubble, usually estimated by the intensity of the sonar echo and the number of bubbles.

[0031] Furthermore, by combining the volume of the bubble and the bubble rising rate, the leakage rate is calculatedQ leak : Q leak =V bubble · v bubble ; Wherein: V bubble is the volume of the bubble, v bubble is the rising speed of the bubble.

[0032] Total leakage calculation: According to the leakage rate Q leak and time t total , the total amount of gas leaked Q total is Q total =Q leak · t total ; By measuring the change in the reflection intensity of the bubble with sonar, the diffusion radius of the bubble can be deduced: ; Wherein r diff is the diffusion radius of the bubble, I echo is the echo intensity, I 0 is the initial intensity, r 0 is the reference radius.

[0033] Diffusion area calculation: The diffusion of the bubble is circular, and the area A diff of the bubble diffusion can be calculated by the following formula: A diff =π · r diff ² .

[0034] Furthermore, the rotation angle of the sonar will affect the propagation path of the echo, resulting in the signal intensity varying with the angle and direction. The echo intensity has different attenuation coefficients α ( θ ) at different angles. The echo intensity I echo ( t ) has a functional relationship with the rotation angle: ; Wherein: r ( t ) is the distance from the sonar to the gas release point, α ( θ ( t )) is the attenuation coefficient related to the rotation angle.

[0035] Furthermore, the vertical sonar rotation angle is θ vert ( t ), and the echo time t vert has the following relationship with the depth of the gas release point d vert : d vert =c · t vert / 2; The corrected echo intensity is: ; Wherein: αvert(θvert(t)) is the correction factor for the rotation effect.

[0036] Furthermore, when the horizontal sonar head rotates 360 degrees, the horizontal velocity of the gas release source needs to be synthesized according to the measurement results in different directions. The horizontal velocity v horizontal ( t ): By the measurement positions of the sonar device at different angles (times) ( x ( t ), y ( t ))), the following can be calculated: ; Wherein x ( t ) and y ( t ) are respectively the horizontal coordinates of the gas release source at time t , △t is the time interval.

[0037] The vertical velocity v vertical ( t ): The position of the gas release source in the vertical direction changes with time. Through the echo time t vert ( t ) and the depth dvert ( t ) Calculate: .

[0038] Furthermore, considering the rotation angle θ ( t ) of the sonar, the gas release amount Q leak ( θ ) at different angles may be different. According to the gas release amounts at multiple angles, the total gas leakage amount can be calculated by the method of weighted average: ; Where: w(θ) is the angle weight, which is adjusted according to the coverage range of the sonar rotation and the spatial distribution of the bubbles.

[0039] Advantages of the present invention: The present invention utilizes the coupling of time series observation data of the horizontal submarine profiler sonar and the vertical submarine profiler sonar, and for the first time realizes the measurement of the three-dimensional spatio-temporal variation of submarine gas leakage. The horizontal submarine profiler sonar rotates 360 degrees, realizing the large-range multi-point leakage monitoring of submarine gas leakage. The vertical sound beam of the vertical submarine profiler sonar realizes the large-range monitoring of the vertical movement and horizontal diffusion of submarine gas leakage. It can be connected to the sea surface platform or the submarine observation network through a coaxial cable, with high stability, and can transmit observation data and high-definition submarine images in real time, and comprehensively analyze the change situation of submarine gas leakage.

[0040] High-precision positioning and dynamic monitoring: Through the coupled application of the vertical and horizontal sonars, combined with data such as flow velocity and temperature, the gas leakage source can be accurately positioned in real time, and its expansion process can be captured.

[0041] Three-dimensional gas leakage spatial distribution and dynamic change analysis: The present invention generates a three-dimensional gas leakage model through a spatio-temporal coupling data processing method, and displays the spatial distribution and dynamic changes of gas leakage in real time, providing comprehensive monitoring capabilities.

[0042] Multi-sensor data fusion and optimization: By combining the data of methane concentration sensors, pressure gauges, and flow meters, multi-dimensional information fusion is carried out, making the gas leakage monitoring more accurate and comprehensive.

[0043] The present invention realizes large - range three - dimensional space detection by horizontally placing and rotating a sonar, couples the horizontal measurement results and the vertical measurement results, establishes a three - dimensional distribution model, involves the calculation and correction of various parameters. The difficulty lies in the data processing and interpretation of the horizontal sonar data. By combining the vertical sonar and horizontal sonar data, three - dimensional stereoscopic monitoring of deep - sea gas leakage is achieved, and important parameters such as the location, intensity, and height of the gas leakage source can be accurately determined. This monitoring method has the characteristics of high precision, high reliability, and strong real - time performance, is applicable to multiple fields such as deep - sea oil and gas fields and mineral resource exploitation, and provides effective support for environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the inversion result of the horizontal sonar in the present invention.

[0045] Figure 2 It is a schematic diagram of the inversion structure of the vertical sonar in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0046] To clearly illustrate the technical features of this solution, the following elaborates on this solution through specific embodiments.

[0047] A three - dimensional time - series monitoring method for submarine gas leakage based on acoustic sensing includes the following steps: Step S1: Obtain the spatial characteristics of gas leakage based on sonar data: S11. Use a vertical sonar to receive the sound waves reflected from the submarine bubbles, obtain the propagation information of the bubbles in the depth direction, calculate the rising speed, height, and their distribution at different depths of the bubbles by analyzing the time delay and sound wave intensity, and determine the release height, level, and gas release intensity of the gas leakage.

[0048] S12. Use a horizontal sonar to receive the reflected signals, rotate 360 degrees to collect the detection information of the gas release source in the horizontal direction, and combine the flow velocity and temperature data in the seawater to determine the position of the gas and its spread range on the seabed.

[0049] Step S2: Integrate and construct a three - dimensional gas leakage model by combining sensor data.

[0050] Divide the monitoring area into multiple small cubic grid cells, each grid cell contains various parameters of gas leakage, and use Kriging interpolation or inverse distance weighting method to interpolate and calculate the gas leakage parameters in each grid cell based on the vertical sonar, horizontal sonar, methane concentration, pressure, and flow velocity data.

[0051] Adopt a time - series interpolation method, combine the time data of each sensor, and generate a continuous time - varying model.

[0052] The data of the bubble rising speed, height, level, position and intensity measured in step S1 are coupled with the data of each sensor in S2 in space and time to generate a spatial distribution model of three-dimensional gas leakage; the position and speed of each data point are rotationally corrected to dynamically update the three-dimensional gas leakage model and visualize it as a dynamic change graph and a three-dimensional distribution graph.

[0053] Step S3: Transmit the real-time monitoring data to the monitoring platform by wire or wirelessly, and provide real-time alarms according to the changes in gas release.

[0054] Before measurement, align the timestamps of the data of the pressure gauge, Doppler flowmeter and methane sensor respectively to achieve sampling timing synchronization. The specific steps are as follows: Step 1: Select the data timestamp of the pressure gauge t pressure As a unified benchmark and the basis for data alignment, align the data of other sensors to this time benchmark; Step 2: According to the unified time benchmark selected in Step 1, use the interpolation algorithm to align the data timestamps of other sensors; when the difference between the sampling time points of other sensors and the benchmark time point is small, the linear interpolation method can be used to fill in the missing timestamps. Set the sensor X timestamp t x and sampling value X ( t ), then the interpolation formula is: ; where t0 and t1 are adjacent known time points, taligned is the benchmark timestamp.

[0055] When the data changes greatly and higher smoothness is required, using the spline interpolation method can obtain more accurate interpolation results and avoid discontinuity or excessive fluctuations. Spline interpolation can be achieved by quadratic or cubic spline methods: ; where S ( t ) is the smooth curve obtained by spline interpolation.

[0056] Step 3: Set the time difference limit. If the difference between the timestamp of the sensor and the benchmark timestamp exceeds a certain set threshold, discard the data or smooth the data using the sliding window method.

[0057] In step S1, because the rotation angle θ ( t) varies with time and the correction coefficient can be calculated by modeling the change in the sonar rotation angle; Define a basic angle correction coefficient f ( θ ) that is related to the current rotation angle θ and varies with different acoustic wave propagation paths. The correction coefficient of the rotation angle is a linear function: ; Among them, α is a correction coefficient representing the influence of the rotation angle on the acoustic wave propagation.

[0058] The angular velocity of the sonar rotation is θ ( t ) and the correction coefficient f ( θ ( t )) should vary with time. Combine the angular velocity with time for real-time correction; the rotation angle of the sonar increases linearly with time: ; The calculation formula of the correction coefficient is expressed as: ; Among them, θ 0 is the initial angle, is the angular velocity of the sonar.

[0059] Correction of the acoustic wave time delay: For the vertical sonar, the rotation influence is reflected in the acoustic wave propagation path, and the corrected time delay Δtrot can be expressed as: ; Δt is the propagation time of the acoustic wave in water.

[0060] Correction of the propagation distance: For the horizontal sonar, the rotation affects the length of the acoustic wave propagation path, and the corrected propagation distance drot can be expressed as: ; Among them, d is the original distance of the acoustic wave propagation, f ( θ ( t )) is the correction coefficient caused by rotation.

[0061] Correction of the signal intensity: The correction coefficient of the signal intensity A ( θ ( t) can be calculated as follows: ; where, A 0 is the original signal intensity of the sonar sensor, and δ is a coefficient related to sonar design and water conditions, representing the influence of rotation on the signal intensity.

[0062] Taking into account the rotational influence of the sonar, the correction coefficient f total( θ ( t ) can be expressed as: ; f distance( θ ( t ) is the distance correction coefficient, f time( θ ( t ) is the time delay correction coefficient, f intensity( θ ( t ) is the signal intensity correction coefficient.

[0063] Calculation of the bubble rising speed: By synchronously adjusting the rotation angle θ ( t ) of the vertical sonar probe and the time delay △t , the time for the sound wave to return is affected by the rotation angle, and the formula for calculating the bubble rising speed is: ; where: f ( θ ( t )) represents the coefficient corrected according to the current rotation angle.

[0064] Calculation of the bubble height: The height of the bubble h ( t ) should be calculated according to the rotation angle, and the calculation formula is: ; where, △t is the time delay for the sound wave to return, c is the speed of sound, θ ( t ) is the rotation angle of the sonar probe.

[0065] Horizontal positioning of the gas release source: The positioning formula for the gas release source in the horizontal direction is: ; Among them, △t is the echo time delay, vhorizontal is the sound wave propagation speed in the horizontal direction, θ θ(t) is the current rotation angle of the sonar.

[0066] The gas expansion speed formula is: ; Among them, vbase is the basic speed of gas expansion, is the correction function based on sonar rotation, used to compensate for the influence of rotation on the expansion speed.

[0067] When performing three-dimensional modeling, the rotation information of the sonar needs to be considered and introduced into the spatial coordinate transformation. In order to accurately map the two-dimensional data measured by the sonar to the three-dimensional space coordinate system, the following transformations are required: For the horizontal sonar, the position data ([[]] x , y ) will change with the change of the rotation angle. Therefore, a rotation matrix is needed to adjust the position data.

[0068] The rotation matrix R ( θ ) acts on the horizontal position data: ; Among them, R ( θ ( t )) is the two-dimensional rotation matrix, θ ( t ) is the current rotation angle.

[0069] For the vertical sonar, the correction of the depth data needs to consider the influence of the rotation angle and tilt angle of the sonar, and a rotation matrix or coordinate transformation method is used to adjust.

[0070] Calculate the gas release intensity using the pressure gauge data: Qgas = △P / R ; Qgas is the gas release intensity, △P is the pressure change amount, R is the relevant parameter of the measurement area.

[0071] Calculate the gas diffusion speed using the acoustic Doppler velocimeter data: vdisp = vup + vcurrent ; Among them, vdispis the actual diffusion velocity of the gas, vup is the rising velocity of the bubble, vcurrent is the seawater flow velocity.

[0072] Calculate the methane gas release intensity using a methane sensor: Qmethane = Cmethane · A · vdisp ; where, Qmethane is the release intensity of methane gas, Cmethane is the methane concentration, A is the cross-sectional area of the measurement area, vdisp is the diffusion velocity.

[0073] Determine the horizontal position of the gas leakage source through the echo time and rotation angle of the horizontal sonar ( x , y ), given the known position of the sonar device ( x 0 , y 0 ) and the direction angle of the echo θ , the horizontal position of the gas leakage source ( x , y ) is calculated as: x = x 0 +d · cos(θ) ; y = y 0 + d · sin(θ) ; d = c · t / 2 ; where: d is the propagation distance of the sound wave, c is the propagation velocity of the sound wave in water, t is the propagation time of the echo.

[0074] Determine the depth of the gas release point by measuring the echo time of the vertical sonar d vert ; ; where, t vert is the propagation time of the vertical echo, c is the propagation velocity of the sound wave.

[0075] The echo intensity of the sonar I echo is proportional to the reflection area of the bubble A and ; Wherein: I 0 is the signal intensity emitted by the sonar, r o is the reference distance, r is the actually measured distance.

[0076] According to the echo intensity and the bubble volume V bubble , the gas release intensity I release can be obtained: ; Wherein V bubble is the volume of the bubble, usually estimated by the intensity of the sonar echo and the number of bubbles.

[0077] By combining the volume of the bubble and the bubble rising rate, the leakage rate Q leak is calculated as: Q leak =V bubble · v bubble ; Wherein: V bubble is the volume of the bubble, v bubble is the rising speed of the bubble.

[0078] Total leakage calculation: According to the leakage rate Q leak and time t total , the total amount of leaked gas Q total is Q total =Q leak · t total ; By measuring the change in the reflection intensity of the bubble by sonar, the diffusion radius of the bubble can be deduced: ; Wherein r diff is the diffusion radius of the bubble, I echo is the echo intensity, I 0 is the initial intensity, r 0is the reference radius.

[0079] Diffusion area calculation: The diffusion of the bubble is circular, and the area of the bubble diffusion A diff can be calculated by the following formula: A diff =π · r diff ² .

[0080] The rotation angle of the sonar will affect the propagation path of the echo, resulting in the signal intensity varying with the angle and direction. The echo intensity has different attenuation coefficients at different angles α ( θ ), the echo intensity I echo ( t ) has a functional relationship with the rotation angle: ; where: r ( t ) is the distance from the sonar to the gas release point, α ( θ ( t )) is the attenuation coefficient related to the rotation angle.

[0081] If there is rotation at the vertical sonar head, when calculating the depth of the gas release point, the influence of the rotation angle of the sonar head on the echo needs to be considered. The vertical sonar rotation angle is θ vert ( t ), the echo time t vert and the depth of the gas release point d vert The relationship is: d vert =c · t vert / 2; The corrected echo intensity is: ; where: αvert(θvert(t)) is the correction factor for the rotation influence.

[0082] When the horizontal sonar head rotates 360 degrees, for the different angles detected, the horizontal velocity of the gas release source needs to be synthesized according to the measurement results in different directions.

[0083] Horizontal velocity v horizontal (t ) The measured positions at different angles (times) by the sonar device ( x ( t ), y ( t )) can be used to calculate: ; where x ( t ) and y ( t ) are the horizontal coordinates of the gas release source at time t , △t is the time interval.

[0084] Vertical velocity v vertical ( t ) The position of the gas release source in the vertical direction changes with time. Through the echo time t vert ( t ) and the depth d vert ( t ) are calculated as: .

[0085] Considering the rotation angle θ ( t ) of the sonar, the gas release amounts Q leak ( θ ) at different angles may be different. Based on the gas release amounts at multiple angles, the total gas leakage amount can be calculated by the method of weighted average: ; where: w(θ) is the angle weight, which is adjusted according to the coverage range of the sonar rotation and the spatial distribution of the bubbles.

[0086] Of course, the above description is not limited to the above examples. The technical features not described in the present invention can be implemented by or adopted from the prior art, and will not be elaborated here; the above embodiments and the accompanying drawings are only used to illustrate the technical solutions of the present invention and are not limitations to the present invention. The present invention has been described in detail with reference to the preferred embodiments. Those of ordinary skill in the art should understand that any changes, modifications, additions, or substitutions made by those of ordinary skill in the art within the scope of the essence of the present invention do not depart from the purpose of the present invention and should also fall within the scope of the claims of the present invention.

Claims

1. A three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing, characterized in that: The following steps are involved: Step S1: Obtaining spatial characteristics of gas leakage based on sonar data: S11. Using vertical sonar to receive sound waves reflected from bubbles on the seabed, obtain the propagation information of bubbles in the depth direction, calculate the rising speed, height and distribution of bubbles at different depths by analyzing time delay and sound wave intensity, and determine the release height, layer and gas release intensity of gas leakage; S12. Use horizontal sonar to receive reflected signals, rotate 360 ​​degrees to collect detection information of the gas release source in the horizontal direction, and combine the flow rate and temperature data in the seawater to determine the location of the gas and its extension range on the seabed; Step S2: Integrate and construct a three-dimensional gas leakage model based on sensor data: The monitoring area is divided into multiple small cubic grid cells, each of which contains various parameters of gas leakage. The gas leakage parameters in each grid cell are interpolated and calculated based on vertical sonar, horizontal sonar, methane concentration, pressure and flow rate data using Kriging interpolation or inverse distance weighted method; The time series interpolation method is used to combine the time data of each sensor to generate a continuous time variation model; The bubble rising speed, height, level, position and intensity data measured in step S1 are spatiotemporally coupled with the sensor data in step S2 to generate a three-dimensional gas leakage spatial distribution model; the position and speed of each data point are rotated and corrected to dynamically update the three-dimensional gas leakage model and visualize it as a dynamic change graph and a three-dimensional distribution graph; Step S3: The real-time monitoring data is transmitted to the monitoring platform via wired or wireless means, and a real-time alarm is provided according to changes in gas release.

2. The three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing according to claim 1 is characterized in that: In step S2, before measurement, the timestamps of the data of the pressure meter, Doppler flow meter and methane sensor are aligned respectively to achieve sampling timing synchronization. The specific steps are as follows: Step 1: Select the data timestamp of the pressure gauge t pressure To unify the benchmark, as the basis for data alignment, the data of other sensors are aligned to this time benchmark; Step 2: Based on the unified time base selected in step 1, use the interpolation algorithm to align the data timestamps of other sensors; when the difference between the sampling time points of other sensors and the reference time points is small, the linear interpolation method can be used to fill in the missing timestamps and set the sensor X Timestamp t x and sample values X ( t ), then the interpolation formula is: ； in, t0 and t1 is a known point in time that is approaching, taligned is the base timestamp; When the data varies greatly and requires higher smoothness, using spline interpolation methods can obtain more accurate interpolation results and avoid discontinuities or excessive fluctuations. Spline interpolation can be achieved through quadratic or cubic spline methods: ； in, S ( t ) is a smooth curve obtained by spline interpolation; Step 3: Set a time difference limit. When the difference between the sensor timestamp and the reference timestamp exceeds a certain set threshold, the data is discarded or smoothed using a sliding window method.

3. The three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing according to claim 1 is characterized in that: In step S1, because the horizontal rotation angle of the sonar θ ( t ) is time-varying, and the correction factor can be calculated by modeling the change in the sonar rotation angle; Define a basic angle correction factor f ( θ ), and the current rotation angle θ It is related to the rotation angle, and it varies with the different propagation paths of the sound waves. The correction coefficient of the rotation angle is a linear function: ； in, α is a correction factor that represents the effect of the rotation angle on the propagation of sound waves; The angular velocity of the sonar rotation is θ ( t ), correction factor f ( θ ( t )) should change with time, combining angular velocity with time for real-time correction; the rotation angle of the sonar increases linearly with time: ； The calculation formula of the correction coefficient is expressed as: ； in, θ 0 is the initial angle, is the angular velocity of the sonar.

4. The three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing according to claim 3 is characterized in that: Correction of sound wave time delay: For vertical sonar, the rotation effect is reflected in the propagation path of the sound wave, and the corrected time delay Δtrot It can be expressed as: ； Δt is the propagation time of sound waves in water; Correction of propagation distance: For horizontal sonar, rotation affects the length of the sound wave propagation path, and the corrected propagation distance drot It can be expressed as: ； in, d is the original distance the sound wave travels, f ( θ ( t )) is the correction factor caused by rotation; Signal strength correction: Correction factor for signal strength A ( θ ( t )) can be calculated as follows: ； in, A 0 is the raw signal strength of the sonar sensor, δ is a coefficient related to the sonar design and water conditions, representing the effect of rotation on the signal strength; Taking into account the rotation effect of sonar, the correction coefficient f total( θ ( t )) can be expressed as: ； f distance( θ ( t )) is the distance correction factor, f time( θ ( t )) is the time delay correction factor, f intensity( θ ( t )) is the signal strength correction factor.

5. The three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing according to claim 4 is characterized in that: In step S11, Calculation of bubble rising speed: The rotation angle of the vertical sonar probe θ ( t ) and time delay △t Synchronous adjustment, the time for the sound wave to return will be affected by the rotation angle, and the formula for calculating the rising speed of the bubble is: ； in: f ( θ ( t )) represents the coefficient corrected according to the current rotation angle; Bubble height calculation: Height of bubbles h ( t ) should be calculated according to the rotation angle, the calculation formula is: ； in, △t is the time delay of the return of the sound wave, c is the speed of sound, θ ( t ) is the rotation angle of the sonar probe.

6. The three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing according to claim 1 is characterized in that: In step S12, the horizontal positioning of the gas release source position: The positioning formula of the gas release source in the horizontal direction is: ； in, △t is the echo time delay, vhorizontal is the speed of sound wave propagation in the horizontal direction, θ (t) is the current rotation angle of the sonar; The formula for gas expansion rate is: ； in, vbase is the basic speed of gas expansion, It is a correction function based on sonar rotation, used to compensate for the effect of rotation on the expansion speed.

7. The three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing according to claim 1 is characterized in that: In step S2, the rotation information of the sonar needs to be considered when performing three-dimensional modeling and introduced into the spatial coordinate transformation. In order to accurately map the two-dimensional data measured by the sonar to the three-dimensional spatial coordinate system, the following transformation needs to be performed: For horizontal sonar, the position data ( x , y ) will change with the rotation angle, so the rotation matrix is ​​needed to adjust the position data; Rotation Matrix R ( θ ) acts on the horizontal position data: ； in, R ( θ ( t )) is a two-dimensional rotation matrix, θ ( t ) is the current rotation angle; For vertical sonar, the correction of depth data needs to take into account the influence of the sonar's rotation angle and tilt angle, and use rotation matrix or coordinate transformation method to adjust.

8. The three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing according to claim 1 is characterized by: Calculate the gas release intensity using the pressure gauge data: Qgas = △P / R ； Qgas is the gas release intensity, △P is the pressure change, R are the relevant parameters of the measurement area; Calculate gas diffusion velocity using acoustic Doppler anemometer data: vdisp = vup + vcurrent ； in, vdisp is the actual diffusion velocity of the gas, vup is the bubble rising speed, vcurrent is the seawater velocity; Calculate the methane gas release intensity using a methane sensor: Qmethane=Cmethane · A · vdisp ； in, Qmethane is the release intensity of methane gas, Cmethane is the methane concentration, A is the cross-sectional area of ​​the measurement area, vdisp is the diffusion rate.

9. The three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing according to claim 1 is characterized in that: The horizontal position of the gas leakage source is determined by the echo time and rotation angle of the horizontal sonar ( x , y ), given the known position of the sonar device ( x 0 , y 0 ) and the direction angle of the echo θ , the horizontal position of the gas leakage source ( x , y ) is calculated as: x=x 0 +d · cos(θ) ； y = y 0 + d · sin(θ) ； d=c · t / 2 ； in: d is the propagation distance of the sound wave, c is the speed of sound waves in water, t is the echo propagation time.

10. The three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing according to claim 1 is characterized in that: The leak rate is calculated by combining the volume of the bubble and the bubble rise rate. Q leak : Q leak =V bubble · v bubble ； in: V bubble is the volume of the bubble, v bubble is the rising speed of the bubble; Calculation of total leakage: Based on leakage rate Q leak and time t total , the total amount of gas leaked Q total for Q total =Q leak · t total ； By measuring the change in the reflection intensity of the bubble through sonar, the diffusion radius of the bubble can be inferred: ； in r diff is the diffusion radius of the bubble, I echo is the echo strength, I 0 is the initial strength, r 0 is the reference radius; Diffusion area calculation: The diffusion of bubbles is circular, and the area of ​​bubble diffusion is A diff It can be calculated by the following formula: A diff =π · r diff ² ； The rotation angle of the sonar will affect the propagation path of the echo, causing the signal strength to vary with angle and direction. The echo intensity has different attenuation coefficients at different angles. α ( θ ), echo strength I echo ( t ) is a function of the rotation angle: ； in: r ( t ) is the distance from the sonar to the gas release point, α ( θ ( t )) is the attenuation coefficient related to the rotation angle; When calculating the depth of the gas release point, it is necessary to consider the effect of the sonar head's rotation angle on the echo. The vertical sonar rotation angle is θ vert ( t ), echo time t vert Depth of gas release point d vert The relationship is: d vert =c·t vert / 2； The corrected echo strength is: ； in: αvert(θvert(t)) is the correction factor for the rotation effect.

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