A three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing

Abstract

The present invention relates to the field of marine engineering observation technology, and more specifically to a three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing, comprising the following steps: Step S1: Acquiring spatial characteristics of gas leakage based on sonar data; Step S2: Integrating and constructing a three-dimensional gas leakage model based on sensor data: Spatiotemporally coupling the bubble rise velocity, height, layer, position, and intensity data measured by Step S1 with the S2 data to generate a three-dimensional spatial distribution model of gas leakage; Rotating and correcting the position and velocity of each data point 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: Transmitting real-time monitoring data to a monitoring platform via wired or wireless communication to provide real-time alerts. The present invention can detect the three-dimensional characteristics of submarine gas release in real time based on sonar data, locate gas leaks, and obtain key parameters such as leak intensity and height, thereby achieving precise monitoring of gas leakage areas.

Description

Technical Field

[0001] The present invention relates to the field of marine engineering observation technology, and in particular to a three-dimensional time-series monitoring method for seabed gas leakage based on acoustic sensing. Background Art

[0002] Submarine gas seepage refers to the release of gases from the seabed into the ocean. This process reflects geochemical processes deep within the seabed and the development and evolution of submarine geological hazards, while also altering the topography of the seabed. Therefore, determining the scale and characteristics of submarine gas seepage, including bubble size, velocity, and concentration, is crucial.

[0003] Currently, there are two main methods for measuring submarine gas seepage: one uses in-situ bottom-mounted observation equipment to conduct long-term measurements of multiple seabed parameters (e.g., Chinese utility model patent CN214334779U); the other uses survey vessels or underwater robots for underway surveys (e.g., Chinese invention patent CN108931777A). However, the former cannot easily change the observation position after deployment, so it can only measure a single gas seepage vent, failing to reflect the overall situation of the submarine gas seepage area. It also lacks real-time data acquisition, making it difficult to effectively conduct gas seepage monitoring. The latter only allows for single surveys and cannot provide continuous, long-term observations of submarine gas seepage. Both of these methods suffer from limitations in terms of observation range, continuous observation time, and data real-time availability, making them inadequate for practical applications such as submarine carbon dioxide storage, submarine methane seepage monitoring, and submarine natural gas hydrate extraction. Clearly, the methods disclosed in these applications for measuring submarine gas seepage still have drawbacks in complex and volatile marine environments, failing to meet current practical application needs. This is an urgent issue that needs to be addressed. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing. It can detect the three-dimensional characteristics of submarine gas release in real time based on horizontal sonar and vertical sonar data, and can locate gas leaks and obtain key parameters such as leakage intensity and height. Through three-dimensional detection, accurate monitoring of gas leakage areas can be achieved.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for three-dimensional time-series monitoring of submarine gas leakage based on acoustic sensing is provided, comprising the following steps:

[0007] Step S1: Obtaining the spatial characteristics of gas leakage based on sonar data:

[0008] S11. Using vertical sonar to receive sound waves reflected from bubbles on the seabed, obtain bubble propagation information in the depth direction. By analyzing time delay and sound wave intensity, calculate the rising speed and height of the bubbles and their distribution at different depths, and determine the release height, layer, and gas release intensity of the gas leakage;

[0009] S12. Use horizontal sonar to receive reflected signals, rotate 360 ​​degrees to collect horizontal detection information of the gas release source, and combine it with the flow rate and temperature data in the seawater to determine the location of the gas and its expansion range on the seabed.

[0010] Step S2: Integrate and construct a three-dimensional gas leakage model based on sensor data:

[0011] The monitoring area is divided into multiple small cubic grid cells, each of which contains various gas leakage parameters. Kriging interpolation or inverse distance weighted method is used to interpolate and calculate the gas leakage parameters in each grid cell based on vertical sonar, horizontal sonar, methane concentration, pressure and flow rate data;

[0012] The time series interpolation method is used to combine the time data of each sensor to generate a continuous time-varying model.

[0013] The bubble rising speed, height, layer, position and intensity data measured in step S1 are spatiotemporally coupled with the sensor data in S2 to generate a three-dimensional spatial distribution model of gas leakage. The position and velocity 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.

[0014] 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 the changes in the gas release.

[0015] Furthermore, in step S2, before measurement, the timestamps of the data of the pressure meter, Doppler flow meter, and methane sensor are aligned to achieve sampling timing synchronization. The specific steps are as follows:

[0016] 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.

[0017] 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, setting the sensor X Timestamp tx and sample values X ( t ), then the interpolation formula is:

[0018] ;

[0019] in, t0 and t1 It is a known point in time that is approaching. tallied The base timestamp.

[0020] 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 using quadratic or cubic spline methods:

[0021] ;

[0022] in, S ( t ) is a smooth curve obtained by spline interpolation.

[0023] Step 3: Set a time difference limit. When the difference between the sensor's timestamp and the reference timestamp exceeds a certain set threshold, the data is discarded or smoothed using a sliding window method.

[0024] By synchronizing sensor sampling timing, we ensure the consistency of data from multiple sensors during submarine gas leak monitoring. This ensures the time alignment of data from pressure gauges, Doppler flow meters, methane sensors, and other sensors. Through timestamp alignment, interpolation, and data filtering, we ensure that all sensor data can be analyzed and modeled using a unified time base, providing reliable data support for the accurate construction of three-dimensional gas leak models.

[0025] Furthermore, in step S1, because the horizontal rotation angle of the sonar i ( t ) is time-varying, and the correction factor can be calculated by modeling the change in sonar rotation angle;

[0026] Define a basic angle correction factor f ( i ), and the current rotation angle i It is related to the sound wave propagation path, and it varies with the sound wave propagation path. The correction coefficient of the rotation angle is a linear function:

[0027] ;

[0028] in, α It is a correction factor that represents the effect of the rotation angle on the propagation of sound waves.

[0029] The angular velocity of the sonar rotation is i ( t ), correction factor f ( i ( t )) should change over time, combining angular velocity with time for real-time correction; the sonar's rotation angle increases linearly with time:

[0030] ;

[0031] The calculation formula of the correction coefficient is expressed as:

[0032] ;

[0033] in, i 0 is the initial angle, is the angular velocity of the sonar.

[0034] Further, the correction of sound wave time delay:

[0035] 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:

[0036] ;

[0037] Δt is the propagation time of sound waves in water.

[0038] Correction of propagation distance:

[0039] For horizontal sonar, rotation affects the length of the sound wave propagation path, and the corrected propagation distance drot It can be expressed as:

[0040] ;

[0041] in, d is the original distance the sound wave travels, f ( i ( t )) is the correction factor caused by rotation.

[0042] Signal strength correction:

[0043] Correction factor for signal strength A ( i ( t )) can be calculated as follows:

[0044] ;

[0045] in, A0 is the raw signal strength of the sonar sensor, and δ is a coefficient related to the sonar design and water conditions, which represents the effect of rotation on the signal strength.

[0046] Taking into account the rotation effect of sonar, the correction coefficient f total( i ( t )) can be expressed as:

[0047] ;

[0048] f distance( i ( t )) is the distance correction coefficient, f time( i ( t )) is the time delay correction coefficient, f intensity( i ( t )) is the signal strength correction factor.

[0049] Furthermore, in step S11,

[0050] Calculation of bubble rising speed:

[0051] The rotation angle of the vertical sonar probe i ( t ) and time delay △t Synchronous adjustment, the time it takes for the sound wave to return will be affected by the rotation angle. The formula for calculating the rising speed of the bubble is:

[0052] ;

[0053] in: f ( i ( t )) represents the coefficient corrected according to the current rotation angle.

[0054] Bubble height calculation:

[0055] Bubble height h ( t ) should be calculated according to the rotation angle, the calculation formula is:

[0056] ;

[0057] in, △t is the time delay of the sound wave returning, c is the speed of sound, i ( t ) is the rotation angle of the sonar probe.

[0058] Furthermore, in step S12, the gas release source is positioned horizontally:

[0059] The positioning formula of the gas release source in the horizontal direction is:

[0060] ;

[0061] in, △t is the echo time delay, horizontal is the speed of sound waves in the horizontal direction, i (t) is the current rotation angle of the sonar.

[0062] The formula for gas expansion rate is:

[0063] ;

[0064] in, vbase is the basic velocity of gas expansion, It is a correction function based on sonar rotation, used to compensate for the effect of rotation on expansion speed.

[0065] In step S2, the sonar rotation information needs to be considered when performing 3D modeling and introduced into the spatial coordinate transformation. In order to accurately map the 2D data measured by the sonar to the 3D spatial coordinate system, the following transformations need to be performed:

[0066] For horizontal sonar, position data ( x , y ) will change with the change of rotation angle, so the rotation matrix needs to be used to adjust the position data;

[0067] Rotation Matrix R ( i ) acts on the horizontal position data:

[0068] ;

[0069] in, R ( i ( t )) is a two-dimensional rotation matrix, i ( t ) is the current rotation angle;

[0070] 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.

[0071] Furthermore, the gas release intensity is calculated using the pressure gauge data:

[0072] Qgas = △P / R ;

[0073] Qgas is the gas release intensity, △P is the pressure change, R are the relevant parameters of the measurement area;

[0074] Calculate gas diffusion velocity using acoustic Doppler velocimeter data:

[0075] vdisp = vup + vcurrent ;

[0076] in, vdisp is the actual diffusion velocity of the gas, vup is the bubble rising speed, vcurrent is the seawater flow velocity.

[0077] Calculate the methane gas release intensity using a methane sensor:

[0078] Qmethane=Cmethane · A · vdisp ;

[0079] 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.

[0080] 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 i , the horizontal position of the gas leakage source ( x , y ) is calculated as:

[0081] x=x 0 +d · cos(θ) ;

[0082] y= y 0 + d · sin(θ) ;

[0083] d=c · t / 2 ;

[0084] in: d is the propagation distance of the sound wave, cis the speed of sound waves in water, t is the echo propagation time.

[0085] Furthermore, the depth of the gas release point is determined by measuring the echo time using vertical sonar. d vert ;

[0086] ;

[0087] in, t vert is the propagation time of the vertical echo, c is the speed of sound wave propagation.

[0088] Sonar echo strength I echo Reflection area of ​​the bubble A Proportional,

[0089] ;

[0090] in: I 0 is the signal strength of the sonar transmission, r o is the reference distance, r The actual measured distance.

[0091] According to the echo intensity and bubble volume V bubble , the gas release strength can be obtained I release :

[0092] ;

[0093] in: V bubble is the volume of the bubble, usually estimated by the intensity of the sonar echo and the number of bubbles.

[0094] Furthermore, the leakage rate is calculated by combining the volume of the bubble and the bubble rising rate. Q leak :

[0095] Q leak =V bubble · v bubble ;

[0096] in: V bubble is the volume of the bubble, v bubble is the rising velocity of the bubble.

[0097] Calculation of total leakage: Based on leakage rate Q leak and time t total , the total amount of gas leaked Q total for

[0098] Q total =Q leak · t total ;

[0099] By measuring the change in the reflection intensity of the bubble through sonar, the diffusion radius of the bubble can be calculated:

[0100] ;

[0101] in r diff is the diffusion radius of the bubble, I echo is the echo intensity, I 0 is the initial strength, r 0 is the reference radius.

[0102] 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:

[0103] A diff =π · r diff ² .

[0104] Furthermore, the rotation angle of the sonar will affect the propagation path of the echo, causing the signal strength to vary with angle and direction, and the echo intensity has different attenuation coefficients at different angles. α ( i ), echo intensity I echo ( t ) is a function of the rotation angle:

[0105] ;

[0106] in: r ( t ) is the distance from the sonar to the gas release point, α ( i ( t)) is the attenuation coefficient related to the rotation angle.

[0107] Furthermore, the vertical sonar rotation angle is i vert ( t ), echo time t vert Depth of gas release point d vert The relationship is:

[0108] d vert =c · t vert / 2;

[0109] The corrected echo strength is:

[0110] ;

[0111] in: αvert(θvert(t)) is the correction factor for the rotation effect.

[0112] Furthermore, the horizontal velocity of the gas release source at different angles detected by the horizontal sonar head during 360-degree rotation needs to be synthesized based on the measurement results in different directions.

[0113] horizontal speed v horizontal ( t ): The measured position at different angles (times) by sonar equipment ( x ( t ), y ( t ), we can calculate:

[0114] ;

[0115] in x ( t )and y ( t ) are the gas release sources at time t The horizontal coordinate of △t is the time interval.

[0116] vertical speed v vertical ( t ): The vertical position of the gas release source changes with time, and the echo time t vert ( t ) and depth d vert ( t)calculate:

[0117] .

[0118] Furthermore, consider the rotation angle of the sonar i ( t ), gas release at different angles Q leak ( i ) may be different. Based on the gas release amount at multiple angles, the total gas leakage can be calculated by weighted average method:

[0119] ;

[0120] in: w(θ) is the angle weight, adjusted according to the coverage of the sonar rotation and the spatial distribution of the bubbles.

[0121] Beneficial effects of the present invention:

[0122] This invention, by coupling time-series observation data from horizontal and vertical seafloor profiling sonars, has for the first time achieved the measurement of three-dimensional spatiotemporal variations in seafloor gas seepage. The 360-degree rotation of the horizontal seafloor profiling sonar enables wide-scale, multi-point monitoring of seafloor gas seepage. The vertical beam of the vertical seafloor profiling sonar enables wide-scale monitoring of the vertical movement and horizontal diffusion of seafloor gas seepage. Connecting to a surface platform or seafloor observation network via a coaxial cable, the system offers high stability, enabling real-time transmission of observation data and high-definition seafloor imagery, enabling comprehensive analysis of changes in seafloor gas seepage.

[0123] High-precision positioning and dynamic monitoring: Through the coupled application of vertical and horizontal sonar, combined with flow rate, temperature and other data, it is possible to accurately locate the source of gas leakage in real time and capture its expansion process.

[0124] Three-dimensional gas leakage spatial distribution and dynamic change analysis: This invention generates a three-dimensional gas leakage model through a time-space coupled data processing method, and displays the spatial distribution and dynamic changes of gas leakage in real time, providing comprehensive monitoring capabilities.

[0125] Multi-sensor data fusion and optimization: Combining data from methane concentration sensors, pressure gauges, and flow meters, multi-dimensional information fusion is performed to make gas leakage monitoring more accurate and comprehensive.

[0126] This method achieves large-scale three-dimensional spatial detection by placing a horizontally rotating sonar. The horizontal and vertical measurement results are coupled to create a three-dimensional distribution model. This involves calculating and correcting various parameters, but the challenge lies in processing and interpreting the horizontal sonar data. By combining vertical and horizontal sonar data, this method enables three-dimensional monitoring of deep-sea gas leaks, accurately determining key parameters such as the location, intensity, and height of the leak source. This monitoring method boasts high precision, high reliability, and strong real-time performance, making it suitable for use in a variety of fields, including deep-sea oil and gas fields and mineral resource extraction, and provides effective support for environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0127] Figure 1 This is a schematic diagram of the inversion results of the horizontal sonar in the present invention.

[0128] Figure 2 It is a schematic diagram of the inversion structure of the vertical sonar in the present invention. DETAILED DESCRIPTION

[0129] In order to clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods.

[0130] A three-dimensional time-series monitoring method for submarine gas leakage based on acoustic sensing includes the following steps:

[0131] Step S1: Obtaining the spatial characteristics of gas leakage based on sonar data:

[0132] S11. Use vertical sonar to receive sound waves reflected from bubbles on the seabed to obtain information on the propagation of bubbles in the depth direction. By analyzing the time delay and sound wave intensity, calculate the rising speed and height of the bubbles and their distribution at different depths, and determine the release height, layer and gas release intensity of the gas leakage.

[0133] S12. Use horizontal sonar to receive reflected signals, rotate 360 ​​degrees to collect horizontal detection information of the gas release source, and combine it with the flow rate and temperature data in the seawater to determine the location of the gas and its expansion range on the seabed.

[0134] Step S2: Integrate and construct a three-dimensional gas leakage model based on sensor data.

[0135] The monitoring area is divided into multiple small cubic grid cells, each of which contains various gas leakage parameters. Kriging interpolation or inverse distance weighted method is used to interpolate and calculate the gas leakage parameters in each grid cell based on vertical sonar, horizontal sonar, methane concentration, pressure and flow rate data.

[0136] The time series interpolation method is used to combine the time data of each sensor to generate a continuous time-varying model.

[0137] The bubble rising speed, height, layer, position and intensity data measured in step S1 are spatiotemporally coupled with the sensor data in S2 to generate a three-dimensional spatial distribution model of gas leakage. The position and velocity 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.

[0138] 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 the changes in the gas release.

[0139] Before measurement, the timestamps of the data from the pressure gauge, Doppler flow meter, and methane sensor are aligned to achieve sampling timing synchronization. The specific steps are as follows:

[0140] 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;

[0141] 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, setting the sensor X Timestamp t x and sample values X ( t ), then the interpolation formula is:

[0142] ;

[0143] in, t0 and t1 It is a known point in time that is approaching. tallied The base timestamp.

[0144] 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 using quadratic or cubic spline methods:

[0145] ;

[0146] in, S ( t ) is a smooth curve obtained by spline interpolation.

[0147] Step 3: Set a time difference limit. When the difference between the sensor's timestamp and the reference timestamp exceeds a certain set threshold, the data is discarded or smoothed using a sliding window method.

[0148] In step S1, because the horizontal sonar rotation angle i ( t ) is time-varying, and the correction factor can be calculated by modeling the change in sonar rotation angle;

[0149] Define a basic angle correction factor f ( i ), and the current rotation angle i It is related to the sound wave propagation path, and it varies with the sound wave propagation path. The correction coefficient of the rotation angle is a linear function:

[0150] ;

[0151] in, α It is a correction factor that represents the effect of the rotation angle on the propagation of sound waves.

[0152] The angular velocity of the sonar rotation is i ( t ), correction factor f ( i ( t )) should change over time, combining angular velocity with time for real-time correction; the sonar's rotation angle increases linearly with time:

[0153] ;

[0154] The calculation formula of the correction coefficient is expressed as:

[0155] ;

[0156] in, i 0 is the initial angle, is the angular velocity of the sonar.

[0157] Correction of sound wave time delay:

[0158] 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:

[0159] ;

[0160] Δt is the propagation time of sound waves in water.

[0161] Correction of propagation distance:

[0162] For horizontal sonar, rotation affects the length of the sound wave propagation path, and the corrected propagation distance drot It can be expressed as:

[0163] ;

[0164] in, d is the original distance the sound wave travels, f ( i ( t )) is the correction factor caused by rotation.

[0165] Signal strength correction:

[0166] Correction factor for signal strength A ( i ( t )) can be calculated as follows:

[0167] ;

[0168] in, A 0 is the raw signal strength of the sonar sensor, and δ is a coefficient related to the sonar design and water conditions, which represents the effect of rotation on the signal strength.

[0169] Taking into account the rotation effect of sonar, the correction coefficient f total( i ( t )) can be expressed as:

[0170] ;

[0171] f distance( i ( t )) is the distance correction coefficient, f time( i ( t )) is the time delay correction coefficient, f intensity( i ( t )) is the signal strength correction factor.

[0172] Calculation of bubble rising speed:

[0173] The rotation angle of the vertical sonar probe i ( t ) and time delay △t Synchronous adjustment, the time it takes for the sound wave to return will be affected by the rotation angle. The formula for calculating the rising speed of the bubble is:

[0174] ;

[0175] in: f ( i ( t )) represents the coefficient corrected according to the current rotation angle.

[0176] Bubble height calculation:

[0177] Bubble height h ( t ) should be calculated according to the rotation angle, the calculation formula is:

[0178] ;

[0179] in, △t is the time delay of the sound wave returning, c is the speed of sound, i ( t ) is the rotation angle of the sonar probe.

[0180] Horizontal positioning of the gas release source:

[0181] The positioning formula of the gas release source in the horizontal direction is:

[0182] ;

[0183] in, △t is the echo time delay, horizontal is the speed of sound waves in the horizontal direction, i (t) is the current rotation angle of the sonar.

[0184] The formula for gas expansion rate is:

[0185] ;

[0186] in, vbase is the basic velocity of gas expansion, It is a correction function based on sonar rotation, used to compensate for the effect of rotation on expansion speed.

[0187] When performing 3D modeling, it is necessary to consider the sonar rotation information and introduce it into the spatial coordinate transformation. In order to accurately map the 2D data measured by the sonar to the 3D spatial coordinate system, the following transformations are required:

[0188] For horizontal sonar, position data ( x , y ) will change with the change of rotation angle, so the position data needs to be adjusted using the rotation matrix.

[0189] Rotation Matrix R ( i) acts on the horizontal position data:

[0190] ;

[0191] in, R ( i ( t )) is a two-dimensional rotation matrix, i ( t ) is the current rotation angle.

[0192] 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.

[0193] Calculate the gas release intensity using the pressure gauge data:

[0194] Qgas = △P / R ;

[0195] Qgas is the gas release intensity, △P is the pressure change, R are the relevant parameters of the measurement area.

[0196] Calculate gas diffusion velocity using acoustic Doppler velocimeter data:

[0197] vdisp = vup + vcurrent ;

[0198] in, vdisp is the actual diffusion velocity of the gas, vup is the bubble rising speed, vcurrent is the seawater flow velocity.

[0199] Calculate the methane gas release intensity using a methane sensor:

[0200] Qmethane=Cmethane · A · vdisp ;

[0201] 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.

[0202] 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 i , the horizontal position of the gas leakage source ( x , y ) is calculated as:

[0203] x=x 0 +d · cos(θ) ;

[0204] y= y 0 + d · sin(θ) ;

[0205] d=c · t / 2 ;

[0206] 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.

[0207] Determine the depth of the gas release point by measuring the echo time using vertical sonar d vert ;

[0208] ;

[0209] in, t vert is the propagation time of the vertical echo, c is the speed of sound wave propagation.

[0210] Sonar echo strength I echo Reflection area of ​​the bubble A Proportional,

[0211] ;

[0212] in: I 0 is the signal strength of the sonar transmission, r o is the reference distance, r The actual measured distance.

[0213] According to the echo intensity and bubble volume V bubble , the gas release strength can be obtained I release :

[0214] ;

[0215] inV bubble is the volume of the bubble, usually estimated by the intensity of the sonar echo and the number of bubbles.

[0216] The leak rate is calculated by combining the volume of the bubble and the bubble rise rate. Q leak :

[0217] Q leak =V bubble · v bubble ;

[0218] in: V bubble is the volume of the bubble, v bubble is the rising velocity of the bubble.

[0219] Calculation of total leakage: Based on leakage rate Q leak and time t total , the total amount of gas leaked Q total for

[0220] Q total =Q leak · t total ;

[0221] By measuring the change in the reflection intensity of the bubble through sonar, the diffusion radius of the bubble can be calculated:

[0222] ;

[0223] in r diff is the diffusion radius of the bubble, I echo is the echo intensity, I 0 is the initial strength, r 0 is the reference radius.

[0224] 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:

[0225] A diff =π · r diff² .

[0226] 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 ( i ), echo intensity I echo ( t ) is a function of the rotation angle:

[0227] ;

[0228] in: r ( t ) is the distance from the sonar to the gas release point, α ( i ( t )) is the attenuation coefficient related to the rotation angle.

[0229] If the vertical sonar head rotates, the effect of the sonar head's rotation angle on the echo needs to be considered when calculating the depth of the gas release point. The vertical sonar rotation angle is i vert ( t ), echo time t vert Depth of gas release point d vert The relationship is:

[0230] d vert =c · t vert / 2;

[0231] The corrected echo strength is:

[0232] ;

[0233] in: αvert(θvert(t)) is the correction factor for the rotation effect.

[0234] The horizontal velocity of the gas release source needs to be synthesized based on the measurement results in different directions according to the different angles detected by the horizontal sonar head when it rotates 360 degrees.

[0235] horizontal speed v horizontal ( t ): The measured position at different angles (times) by sonar equipment ( x ( t ), y ( t), we can calculate:

[0236] ;

[0237] in x ( t )and y ( t ) are the gas release sources at time t The horizontal coordinate of △t is the time interval.

[0238] vertical speed v vertical ( t ): The vertical position of the gas release source changes with time, and the echo time t vert ( t ) and depth d vert ( t )calculate:

[0239] .

[0240] Consider the sonar's rotation angle i ( t ), gas release at different angles Q leak ( i ) may be different. Based on the gas release amount at multiple angles, the total gas leakage can be calculated by weighted average method:

[0241] ;

[0242] in: w(θ) is the angle weight, adjusted according to the coverage of the sonar rotation and the spatial distribution of the bubbles.

[0243] Of course, the above description is not limited to the above examples. Technical features not described in the present invention can be achieved by or by adopting existing technologies, which will not be described here. The above embodiments and drawings are only used to illustrate the technical solutions of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation methods. Ordinary technicians in this field should understand that changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not depart from the purpose of the present invention and should also fall within the scope of protection 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 by: 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 bubble propagation information in the depth direction. By analyzing time delay and sound wave intensity, calculate the rising speed and height of the bubbles and their distribution at different depths, and determine the release height, layer, and gas release intensity of the gas leakage; S12. Use horizontal sonar to receive reflected signals, rotate 360 ​​degrees to collect horizontal detection information of the gas release source, and combine it with the flow rate and temperature data in the seawater to determine the location of the gas and its extension range on the seabed; Because the horizontal sonar's rotation angle θ ( t ) is time-varying, and the correction factor can be calculated by modeling the change in sonar rotation angle; Define a basic angle correction factor f ( θ ), and the current rotation angle θ It is related to the sound wave propagation path, and it varies with the sound wave propagation path. 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 over time, combining angular velocity with time for real-time correction; the sonar's rotation angle 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; 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, which represents 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 coefficient, f time( θ ( t )) is the time delay correction coefficient, f intensity( θ ( t )) is the signal strength correction factor; 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 velocity 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 calculated: ； in r diff is the diffusion radius of the bubble, I echo is the echo intensity, 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 intensity 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; 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 gas leakage parameters. Kriging interpolation or inverse distance weighted method is used to interpolate and calculate the gas leakage parameters in each grid cell based on vertical sonar, horizontal sonar, methane concentration, pressure and flow rate data; The time series interpolation method is used to combine the time data of each sensor to generate a continuous time variation model; The bubble rise velocity, height, layer, position, and intensity data measured in step S1 are spatiotemporally coupled with the sensor data in step S2 to generate a three-dimensional spatial distribution model of gas leakage. The position and velocity of each data point are rotated and corrected to dynamically update the three-dimensional gas leakage model, which is then visualized 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 the changes in the gas release.

2. The method for three-dimensional time-series monitoring of 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 from the pressure gauge, Doppler flow meter, and methane sensor are aligned 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, setting the sensor X Timestamp t x and sample values X ( t ), then the interpolation formula is: ； in, t0 and t1 It 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 using 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's timestamp and the reference timestamp exceeds a certain set threshold, the data is discarded or smoothed using a sliding window method.

3. The method for three-dimensional time-series monitoring of submarine gas leakage based on acoustic sensing according to claim 1 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 it takes for the sound wave to return will be affected by the rotation angle. 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: Bubble height h ( t ) should be calculated according to the rotation angle, the calculation formula is: ； in, △t is the time delay of the sound wave returning, c is the speed of sound, θ ( t ) is the rotation angle of the sonar probe.

4. The method for three-dimensional time-series monitoring of submarine gas leakage based on acoustic sensing according to claim 1 is characterized in that: In step S12, the gas release source is positioned horizontally: 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 waves 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 velocity of gas expansion, It is a correction function based on sonar rotation, used to compensate for the effect of rotation on expansion speed.

5. The method for three-dimensional time-series monitoring of submarine gas leakage based on acoustic sensing according to claim 1 is characterized in that: In step S2, the sonar rotation information needs to be considered when performing 3D modeling and introduced into the spatial coordinate transformation. In order to accurately map the 2D data measured by the sonar to the 3D spatial coordinate system, the following transformations need to be performed: For horizontal sonar, position data ( x , y ) will change with the change of rotation angle, so the rotation matrix needs to be used 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.

6. The method for three-dimensional time-series monitoring of submarine gas leakage based on acoustic sensing according to claim 1 is characterized in that: 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 velocimeter 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.

7. The method for three-dimensional time-series monitoring of 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.

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