Optimization method and observation system of active seismic source excitation for submarine cable monitoring

Abstract

The present application relates to the technical field of seismic exploration, and discloses a method for active seismic source excitation optimization facing cable monitoring and an observation system. The method comprises the following steps: collecting cable state data and marine environment data; establishing a prediction model of seismic source excitation effect based on the data; determining optimal seismic source excitation parameters based on the prediction model, with the optimization of expected signal-to-noise ratio as the target and the expected vibration amplitude not exceeding the safety threshold as the constraint; controlling the active seismic source to excite according to the optimal seismic source excitation parameters; receiving seismic wave signals, determining the actual signal-to-noise ratio and the actual vibration amplitude; and updating the prediction model based on the actual signal-to-noise ratio and the actual vibration amplitude. The present application can dynamically optimize the seismic source excitation parameters according to the real-time state of the cable and the marine environment, improve the quality of the seismic signals under the premise of ensuring the safety of the cable structure, and make the prediction model continuously approach the real working condition through a closed-loop feedback mechanism.

Description

Technical Field

[0001] This invention relates to the field of seismic exploration technology, and in particular to an active source excitation optimization method and observation system for submarine cable monitoring. Background Technology

[0002] Existing submarine cable monitoring systems typically employ active seismic sources to generate seismic wave signals, which are then received by a distributed fiber-optic acoustic sensing system embedded within the cable to monitor the surrounding geological environment. However, current technologies often rely on manual experience or fixed presets for setting seismic source excitation parameters, failing to adequately consider the real-time status of the submarine cable and the dynamic changes in the marine environment. When using fixed excitation parameters, excessively strong excitation energy may cause the cable to experience excessive vibration stress, endangering its structural safety; conversely, insufficient excitation energy results in an inadequate signal-to-noise ratio for the seismic wave signal, making it difficult to meet monitoring accuracy requirements.

[0003] Current technologies lack a closed-loop evaluation and feedback mechanism for excitation effects, making it impossible to adaptively adjust excitation parameters based on actual monitoring results. This leads to poor signal quality stability during long-term operation. Therefore, how to dynamically optimize the source excitation parameters based on the real-time status of the submarine cable and the marine environment, while ensuring the structural safety of the submarine cable, and how to establish a closed-loop adaptive adjustment mechanism for the excitation parameters to improve the stability and reliability of submarine cable monitoring signals, has become an urgent problem to be solved. Summary of the Invention

[0004] This invention provides an active source excitation optimization method and observation system for submarine cable monitoring to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides an active source excitation optimization method for submarine cable monitoring, comprising:

[0006] S1, acquire submarine cable status data and marine environment data in the submarine cable monitoring area;

[0007] S2, Based on the submarine cable status data and the marine environment data, establish a prediction model for the seismic source excitation effect;

[0008] S3. Based on the prediction model, with the goal of optimizing the expected quality index of the seismic signal and the constraint that the expected vibration index of the submarine cable does not exceed the safety threshold, determine the optimal source excitation parameters.

[0009] S4, control the active source to excite according to the optimal source excitation parameters, and simultaneously collect the seismic wave signals generated by the excitation;

[0010] S5, receive the seismic wave signal generated by excitation, and determine the actual seismic signal quality index and the actual submarine cable vibration index based on the seismic wave signal;

[0011] S6. Update the prediction model based on the actual seismic signal quality index and the actual submarine cable vibration index.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. This invention establishes a predictive model for seismic source excitation effects by collecting submarine cable status data and marine environmental data. It solves for the optimal seismic source excitation parameters by maximizing the expected signal-to-noise ratio as the optimization objective and ensuring that the expected vibration amplitude does not exceed a safety threshold. This transforms the process from fixed preset parameters to real-time adaptive optimization of the seismic source excitation parameters. This method significantly improves the signal-to-noise ratio of seismic signals while ensuring the safety of the submarine cable structure, resolving the contradiction between excitation intensity and submarine cable safety in traditional methods.

[0014] 2. This invention constructs a closed-loop feedback architecture of "acquisition-prediction-optimization-excitation-evaluation-update" by comparing the quality and vibration indicators of the actually received seismic signals with the expected indicators of the prediction model, and then correcting and updating the key parameters of the prediction model based on the comparison results. This architecture enables the prediction model to continuously approximate the actual working conditions as the condition of the submarine cable and the marine environment change, improving the robustness and long-term operational stability of the system in complex and variable marine environments, and avoiding the problems of excitation parameter mismatch and signal quality degradation caused by environmental changes. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating an active seismic source excitation optimization method for submarine cable monitoring, provided in an embodiment of the present invention.

[0016] Figure 2 This is a functional block diagram of an active source excitation optimization observation system for submarine cable monitoring provided in an embodiment of the present invention;

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] This application provides an active source excitation optimization method for submarine cable monitoring. The execution entity of the active source excitation optimization method for submarine cable monitoring includes, but is not limited to, at least one of the following electronic devices that can be configured to execute the method provided in this application: a server, a terminal, etc. In other words, the active source excitation optimization method for submarine cable monitoring can be executed by software or hardware installed on a terminal device or a server device. The server includes, but is not limited to, a single server, a server cluster, a cloud server, or a cloud server cluster. The server can be an independent server or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (CDN), and big data and artificial intelligence platforms.

[0020] Reference Figure 1 The diagram shown is a flowchart illustrating an active seismic source excitation optimization method for submarine cable monitoring according to an embodiment of the present invention. In this embodiment, the active seismic source excitation optimization method and observation system for submarine cable monitoring include:

[0021] S1, acquire submarine cable status data and marine environment data in the submarine cable monitoring area;

[0022] In this embodiment of the invention, acquiring submarine cable status data and marine environment data of the submarine cable monitoring area includes:

[0023] The vibration response time-series data of the submarine cable at the current monitoring moment is collected in real time by the distributed fiber optic acoustic sensing device built into the submarine cable, which serves as the first submarine cable status data.

[0024] The burial depth data of the submarine cable at the current monitoring time is obtained through the depth sensing unit built into the submarine cable, and used as the second submarine cable status data.

[0025] Ocean current speed, tidal height, and background noise level are acquired using marine environmental monitoring equipment deployed in the submarine cable monitoring area, and are used as the marine environmental data.

[0026] It should be noted that the distributed fiber optic acoustic sensing device uses the optical fiber inside the submarine cable as a sensing unit. By emitting laser pulses into the optical fiber and receiving changes in the backscattered light signal, it senses the disturbance of the optical fiber caused by external vibration. When the submarine cable is subjected to seismic waves, the optical fiber will produce a slight strain change, causing a change in the phase of the backscattered light. By performing phase demodulation processing on the phase change, time-series data reflecting the vibration state of the submarine cable can be obtained. The vibration response time-series data is recorded in the form of a time series, with each sampling point corresponding to the vibration amplitude value at a certain moment.

[0027] Furthermore, the laser pulse width of the distributed fiber optic acoustic sensing device is set to 50 nanoseconds, corresponding to a spatial resolution of 5 meters. The sampling frequency is set to 10 kHz, corresponding to a maximum detectable vibration signal frequency of 5 kHz. The values ​​of the pulse width and sampling frequency are based on the following: the required spacing between monitoring points along the submarine cable in this monitoring scenario is 5 meters, so the spatial resolution is set to 5 meters; the frequency range of seismic wave signals in submarine cable monitoring is mainly concentrated between 0.1 Hz and 1 kHz, so the sampling frequency is set to 10 kHz to meet the requirements of the Nyquist sampling theorem and to completely restore the frequency domain characteristics of the signal.

[0028] The acquisition process of the vibration response time-series data is as follows: the distributed fiber optic acoustic sensing device continuously emits laser pulses along the entire submarine cable using laser pulse width and sampling frequency, receives backscattered light signals, and obtains the time-series change data of vibration amplitude at each monitoring location along the submarine cable by performing phase demodulation on the backscattered light signals. Each frame of data contains the vibration amplitude values ​​of all monitoring locations within a complete scan cycle, and the time length of the complete scan cycle is 1 second.

[0029] It should be noted that the depth sensing unit is a water pressure sensor integrated inside the submarine cable. The water pressure sensor has a range of 0 to 100 meters of water column and a measurement accuracy of 0.1% of full scale. The water pressure sensor measures the water pressure at the location of the submarine cable in real time at a sampling frequency of 1 Hz. The burial depth data is obtained through a formula. The water pressure value measured by the water pressure sensor is converted into the burial depth data of the submarine cable, wherein, This indicates the burial depth data of the submarine cable. This indicates the water pressure value measured by the water pressure sensor. Indicates the density of seawater. Represents gravitational acceleration. The reference value for seawater depth indicates the location of the submarine cable. The reference value for seawater depth is obtained by measuring the depth using a sonar depth sounder during the laying of the submarine cable and is stored in advance.

[0030] Furthermore, when the submarine cable is laid on the seabed surface, the calculated burial depth data is negative or close to zero, indicating that the cable is not buried. When the submarine cable is buried below the seabed, the calculated burial depth data is positive, indicating the burial depth of the cable. The burial depth data is an important parameter affecting the degree of energy attenuation of seismic waves propagating to the submarine cable. The greater the burial depth, the longer the seismic wave propagation path, the more significant the energy attenuation, and the lower the expected vibration amplitude at the submarine cable.

[0031] Finally, ocean current speed, tidal height, and background noise level are obtained using marine environmental monitoring equipment deployed in the submarine cable monitoring area, serving as the marine environmental data.

[0032] It should be noted that the marine environmental monitoring equipment includes a current meter, a tide gauge, and a hydrophone. The current meter is an acoustic Doppler current profiler, deployed on the seabed surface at the center of the submarine cable monitoring area, with a measurement range of 0 to 5 meters per second, a measurement accuracy of 0.01 meters per second, and a data output frequency of 1 Hz. The tide gauge is a pressure-type tide gauge, deployed on a coastal base in the submarine cable monitoring area, with a measurement range of -10 meters to 10 meters relative to the mean sea level, a measurement accuracy of 0.01 meters, and a data output frequency of 0.01 Hz, outputting data once every 100 seconds. The hydrophone is a piezoelectric hydrophone, deployed in the water at the center of the submarine cable monitoring area, 2 meters from the seabed, with a measurement frequency range of 10 Hz to 10 kHz, a sensitivity of -190 dB (reference value 1 volt per micropascal), and a data output frequency of 20 kHz. The background noise level is taken as the average of the effective sound pressure levels of the hydrophone within a 1-second time window.

[0033] S2, Based on the submarine cable status data and the marine environment data, establish a prediction model for the seismic source excitation effect;

[0034] In this embodiment of the invention, establishing a predictive model for the source excitation effect based on the submarine cable status data and the marine environment data includes:

[0035] The theoretical propagation attenuation of seismic waves at the point of propagation to the submarine cable is determined based on submarine cable burial depth data.

[0036] The signal-to-noise ratio correction factor for signal detection is determined based on the background noise level and the ocean current velocity.

[0037] By establishing the mapping relationship between the source excitation parameters and the expected signal-to-noise ratio, and the mapping relationship between the source excitation parameters and the expected vibration amplitude, the first prediction sub-model and the second prediction sub-model are obtained respectively.

[0038] The first prediction sub-model and the second prediction sub-model are combined to generate a prediction model for the source excitation effect.

[0039] It should be noted that during the propagation of seismic waves from the active hypocenter to the submarine cable monitoring location, the waves pass through the strata and seawater in sequence. Depending on the different values ​​of the submarine cable burial depth data, the propagation path of the seismic waves can be categorized into two cases.

[0040] Scenario 1: When the burial depth of the submarine cable is less than or equal to zero, it means that the submarine cable is laid on the seabed surface. The propagation path of the seismic waves is as follows: starting from the source, the waves first propagate through the strata to the seabed surface, and then through the seawater layer to the submarine cable.

[0041] Scenario 2: When the burial depth data of the submarine cable is greater than zero, it means that the submarine cable is buried below the seabed, and the propagation path of the seismic waves is: starting from the source, propagating through the strata to the submarine cable.

[0042] It should be noted that the calculation method for the theoretical propagation attenuation is as follows:

[0043]

[0044]

[0045]

[0046]

[0047]

[0048] In the formula, This represents the theoretical propagation attenuation. This indicates the amount of seismic wave attenuation during propagation within the Earth's strata. This indicates the amount of seismic wave attenuation during propagation within the seawater layer. This indicates the additional attenuation introduced by the depth of the submarine cable burial. This represents the attenuation coefficient of seismic waves in the strata. This represents the projected length of the horizontal distance from the active seismic source to the submarine cable monitoring location within the geological strata. This represents the attenuation coefficient of seismic waves in seawater, and its value is based on the sound absorption coefficient of seawater. This represents the excitation frequency of the seismic source, ranging from 0.01 kHz to 0.5 kHz. The relaxation frequency of seawater is represented by a value of 1 kHz, and the constant term 0.01 represents the energy attenuation caused by seawater scattering. This indicates the distance that seismic waves travel in the seawater layer. This represents the depth attenuation coefficient, with a value of 0.8 dB per meter. This value is determined based on the absorption characteristics of seabed sediments for P-waves. This indicates the burial depth data of the submarine cable;

[0049] When the burial depth data of the submarine cable is less than or equal to zero ;

[0050] The attenuation coefficient of seismic waves in the strata is set at 0.5 dB per meter, which is determined based on the median of the typical P-wave attenuation coefficient range of 0.3 to 0.8 dB per meter for seafloor sediments.

[0051] Furthermore, the projected length of the horizontal distance from the active seismic source to the submarine cable monitoring location in the strata is calculated through the following steps:

[0052] First, obtain the coordinates of the active seismic source deployment location and the coordinates of the submarine cable monitoring location, where the coordinates are both latitude and longitude coordinates;

[0053] Secondly, the latitude and longitude coordinates are converted from degrees to radians by multiplying the degree of longitude or latitude by pi and then dividing by 180.

[0054] Then, the horizontal distance between the two points is calculated. The specific calculation process is as follows: First, calculate the radian values ​​of the longitude difference and latitude difference between the two locations, taking half of the longitude difference and half of the latitude difference respectively; calculate the square of the sine of half the latitude difference; calculate the sine of half the longitude difference multiplied by the cosine of the latitude of the active seismic source and then multiplied by the cosine of the latitude of the submarine cable monitoring location; add the above two items to obtain the intermediate variable; calculate the square root of the intermediate variable; calculate the square root of the difference between 1 and the intermediate variable; perform arctangent operation on the above two square roots in four quadrants to obtain the radian distance between the two points; multiply the radian distance by the average radius of the Earth to obtain the horizontal distance between the two points, where the average radius of the Earth is taken as 6,371,000 meters.

[0055] Finally, the projection length of the horizontal distance from the active seismic source to the submarine cable monitoring location in the stratum is taken as the horizontal distance calculated above. The basis for this setting is: the active seismic source is placed on the seabed surface, and the seismic waves propagate downward into the stratum after starting from the seismic source. The incident point at the seabed is located directly below the seismic source. Subsequently, the seismic waves propagate horizontally in the stratum to directly below the submarine cable monitoring location, and then propagate upward to the submarine cable. Therefore, the horizontal propagation distance in the stratum is equal to the horizontal distance from the seismic source to the submarine cable monitoring point.

[0056] Furthermore, the propagation distance of the seismic wave in the seawater layer is calculated through the following steps:

[0057] First, the deployment depth of the active seismic source in the seawater is obtained, and the value is set to 10 meters. The deployment depth is set based on the fact that the active seismic source is deployed 10 meters below the sea surface, which can avoid the interference of sea waves on the seismic source, and at the same time ensure that the propagation path length of the seismic wave signal in the seawater is moderate. Similarly, the horizontal distance between the active seismic source and the monitoring position of the submarine cable is calculated.

[0058] Then, the propagation distance of the seismic wave in the seawater layer is calculated by adding the square of the horizontal distance to the square of the deployment depth, and then taking the square root of the sum.

[0059] Furthermore, when calculating the propagation distance of the seismic wave in the seawater layer for the purpose of calculating the attenuation of the seawater layer propagation, the unit needs to be converted from meters to kilometers, i.e., divided by 1000.

[0060] It should be noted that the signal-to-noise ratio correction factor is used to characterize the influence of background noise and ocean currents in the marine environment on the signal-to-noise ratio of seismic signal detection. The signal-to-noise ratio correction factor is calculated using the following formula:

[0061]

[0062] in, This represents the signal-to-noise ratio correction factor. This indicates the background noise level, with a reference value of 1 micropascal sound pressure level. This represents the influence factor of ocean current noise, with a value of 0.5 dB per (meter per second). This indicates the speed of the ocean current.

[0063] Furthermore, the negative signal-to-noise ratio correction factor indicates that the presence of background noise and ocean currents will reduce the actual achievable signal-to-noise ratio level. The lower the value of the signal-to-noise ratio correction factor, the greater the compensation required for the excitation energy of the seismic source.

[0064] It should be noted that the first and second prediction sub-models are combined to obtain the prediction model for the source excitation effect. The input parameters of the prediction model include: excitation energy, excitation frequency, and excitation interval; the output parameters include: expected signal-to-noise ratio and expected vibration amplitude. The prediction model is represented by the following mapping relationship:

[0065]

[0066] in, Indicates to stimulating energy Excitation frequency and excitation interval When the input is a signal-to-noise ratio, the prediction result set output by the prediction model includes two output components: the expected signal-to-noise ratio and the expected vibration amplitude. Indicates that the purpose is to stimulate energy. Excitation frequency is Excitation interval is When the combination of these factors is used for excitation, the expected signal-to-noise ratio at the submarine cable is [value missing]. Indicates that the energy is stimulated. Excitation frequency is Excitation interval is When the combination of these is used for excitation, the expected vibration amplitude at the submarine cable;

[0067] The prediction model is used to represent the mapping relationship between the source excitation parameters and the expected quality indicators of the seismic signal and the expected vibration indicators of the submarine cable.

[0068] In this embodiment of the invention, the step of establishing a mapping relationship between the source excitation parameters and the expected signal-to-noise ratio, and a mapping relationship between the source excitation parameters and the expected vibration amplitude, to obtain the first prediction sub-model and the second prediction sub-model respectively, includes:

[0069] Based on the theoretical propagation attenuation, the signal-to-noise ratio correction factor, and the preset source excitation parameters, a mapping relationship between the source excitation parameters and the expected signal-to-noise ratio is established as the first prediction sub-model.

[0070] Based on the theoretical propagation attenuation, the submarine cable burial depth data, the ocean current velocity, and the preset source excitation parameters, a mapping relationship between the source excitation parameters and the expected vibration amplitude is established as the second prediction sub-model.

[0071] It should be noted that the source excitation parameters include excitation energy, excitation frequency, and excitation interval. The first prediction sub-model is established using the following formula:

[0072]

[0073] In the formula, Indicates that the energy is stimulated. Excitation frequency is Excitation interval is When the combination of these factors is used for excitation, the expected signal-to-noise ratio at the submarine cable is [value missing]. The excitation energy is indicated. The corresponding source sound level, with a reference value of 1 micropascal per meter, and the excitation energy... The value ranges from 1 kJ to 100 kJ;

[0074] Stimulate energy The corresponding source sound level Convert using the following formula:

[0075]

[0076] Where 200 represents the reference sound source level at 1 kilojoule energy. It indicates the stimulation of energy. This represents the theoretical propagation attenuation. This represents the signal-to-noise ratio correction factor. The value represents the sensor noise floor level of the distributed fiber optic acoustic sensing system, and is set to 30 dB. This value is determined based on the typical noise floor power spectral density of a commercial distributed fiber optic acoustic sensing system (0.1 Pascals per root hertz converted to a 1 Hz bandwidth).

[0077] Furthermore, in submarine cable monitoring applications, seismic waves in the 10 Hz to 500 Hz frequency range can penetrate the seabed strata and carry information about the cable structure's condition; an excitation interval of 5 to 60 seconds ensures that the signals from two adjacent excitations do not overlap in time, while also meeting the time resolution requirements for monitoring. Therefore, the excitation frequency... The value ranges from 10 Hz to 500 Hz, and discretization is performed in steps of 5 Hz; excitation interval The value ranges from 5 seconds to 60 seconds, and discretization is performed with a step size of 5 seconds.

[0078] It should be noted that the second prediction sub-model is used to characterize the expected vibration amplitude at the submarine cable under different source excitation parameters, and the second prediction sub-model is established by the following formula:

[0079]

[0080]

[0081]

[0082]

[0083] in, Indicates that the energy is stimulated. Excitation frequency is Excitation interval is When the combination of these factors is used for excitation, the expected vibration amplitude at the submarine cable is... This represents the reference vibration amplitude coefficient, with a value of 0.01 micrometers per kilojoule. It indicates the stimulation of energy. Represents the frequency response coefficient. Indicates the burial depth attenuation coefficient. This represents the attenuation rate coefficient based on burial depth, with a value of 0.3 per meter. This indicates the burial depth data of the submarine cable. Represents the natural constant. Indicates the influence coefficient of ocean currents. This indicates the speed of the ocean current. This represents the amplification factor of the vibration amplitude caused by the ocean current, with a value of 0.2 per (meter per second). This represents the cutoff frequency of the submarine cable-seabed coupling system, with a default value of 100 Hz. When the excitation frequency is lower than the cutoff frequency, the submarine cable vibration response is stronger, and when the excitation frequency is higher than the cutoff frequency, the submarine cable vibration response gradually decreases.

[0084] S3. Based on the prediction model, with the goal of optimizing the expected quality index of the seismic signal and the constraint that the expected vibration index of the submarine cable does not exceed the safety threshold, determine the optimal source excitation parameters.

[0085] In this embodiment of the invention, the step of determining the optimal source excitation parameters based on the prediction model, with the goal of optimizing the expected quality index of the seismic signal and the constraint that the expected vibration index of the submarine cable does not exceed a safety threshold, includes:

[0086] The expected signal-to-noise ratio and expected vibration amplitude output by the prediction model are obtained as the target parameters and constraint parameters to be optimized. The discretized set of the source excitation parameters within their respective value ranges is obtained to generate the parameter combination space.

[0087] Traverse each set of source excitation parameter combinations in the parameter combination space, calculate the corresponding expected signal-to-noise ratio and expected vibration amplitude through the prediction model, and screen out all parameter combinations whose expected vibration amplitude does not exceed the preset submarine cable vibration safety threshold to form a feasible parameter combination set;

[0088] From the set of feasible parameter combinations, the parameter combination with the highest expected signal-to-noise ratio is selected as the optimal source excitation parameter.

[0089] It should be noted that the expected signal-to-noise ratio (SNR) characterizes the quality of the seismic wave signal. The higher the expected SNR, the easier it is for the seismic wave signal received at the submarine cable to be distinguished from the background noise, and the better the signal quality. Therefore, the expected SNR is used as the target parameter for optimization. The expected vibration amplitude characterizes the intensity of the vibration of the submarine cable caused by the seismic wave. The larger the expected vibration amplitude, the greater the mechanical stress on the submarine cable. Therefore, the expected vibration amplitude is used as a constraint parameter to limit it from exceeding the safety threshold in order to protect the safety of the submarine cable structure.

[0090] It should be noted that the source excitation parameters include parameters in three dimensions: excitation energy, excitation frequency, and excitation interval. The value range and discretization step size of each parameter are as follows:

[0091] The excitation energy ranges from 1 kJ to 100 kJ, and is discretized in steps of 5 kJ to obtain 20 discrete values: 1 kJ, 5 kJ, 10 kJ, 15 kJ, 20 kJ, 25 kJ, 30 kJ, 35 kJ, 40 kJ, 45 kJ, 50 kJ, 55 kJ, 60 kJ, 65 kJ, 70 kJ, 75 kJ, 80 kJ, 85 kJ, 90 kJ, 95 kJ, and 100 kJ.

[0092] The excitation frequency ranges from 10 Hz to 500 Hz, and is discretized in steps of 10 Hz to obtain 50 discrete values: 10 Hz, 20 Hz, 30 Hz...500 Hz.

[0093] The excitation interval ranges from 10 seconds to 120 seconds. It is discretized in 10-second increments to obtain 12 discrete values: 10 seconds, 20 seconds, 30 seconds...120 seconds.

[0094] The parameter range and step size are set based on the following: When the excitation energy is below 1 kJ, the seismic wave signal is too weak to penetrate the strata and propagate to the submarine cable monitoring area; when it is above 100 kJ, the energy output limit of the source equipment cannot support it. When the excitation frequency is below 10 Hz, the seismic wave wavelength is too long, resulting in insufficient spatial resolution; when it is above 500 Hz, the seismic wave attenuates too quickly in the strata and cannot propagate effectively. When the excitation interval is less than 10 seconds, the signals from two adjacent excitations are prone to aliasing in time; when it is above 120 seconds, the monitoring temporal resolution is insufficient, making it impossible to detect changes in the submarine cable status in a timely manner.

[0095] The parameter combination space is obtained by performing a Cartesian product operation on the discrete values ​​of the above three dimensions. The total number of parameter combinations is 20 multiplied by 50 multiplied by 12, totaling 12,000 parameter combinations.

[0096] It should be noted that the traversal process follows a three-level nested loop in the order of excitation energy, excitation frequency, and excitation interval. For each set of parameters, the expected signal-to-noise ratio is calculated by the first prediction sub-model, and the expected vibration amplitude is calculated by the second prediction sub-model.

[0097] Specifically, for the first The set of parameters is combined, and its excitation energy is set to... Excitation frequency is Excitation interval is The corresponding expected signal-to-noise ratio Calculated using the following formula:

[0098]

[0099] In the formula, Indicates the first The expected signal-to-noise ratio of the parameter combination. Indicates the stimulation of energy The corresponding source sound level, This represents the theoretical propagation attenuation. This represents the signal-to-noise ratio correction factor. This indicates the sensor's noise floor level, with a value of 30 dB.

[0100] The corresponding expected vibration amplitude is calculated using the following formula:

[0101]

[0102] In the formula, Indicates the first The expected vibration amplitude of the parameter combination This represents the reference vibration amplitude coefficient, with a value of 0.01 micrometers per kilojoule. Indicates the first Frequency response coefficient of the combination of parameters This indicates the cutoff frequency of the submarine cable-seabed coupling system; the default value is 100 Hz. No. The combination of parameters represents the burial depth attenuation coefficient. Indicates the influence coefficient of ocean currents. This indicates the speed of the ocean current;

[0103] After traversal, a one-to-one correspondence between the expected signal-to-noise ratio and the expected vibration amplitude is obtained for 12,000 sets of parameter combinations.

[0104] The screening process is as follows: for each of the 12,000 parameter combinations obtained through iterative calculation, the expected vibration amplitude corresponding to each parameter combination is determined one by one. Is it less than or equal to the submarine cable vibration safety threshold of 80 micrometers? If, then the parameter combination is retained; if If the parameter combination fails to meet the condition, it is eliminated. Ultimately, all parameter combinations that satisfy the conditions constitute the set of feasible parameter combinations.

[0105] It should be noted that all parameter combinations in the feasible parameter combination set have satisfied the submarine cable vibration safety constraints. Based on this, the parameter combination with the highest expected signal-to-noise ratio is selected from the feasible parameter combination set. The excitation energy, excitation frequency, and excitation interval corresponding to this parameter combination are the optimal source excitation parameters.

[0106] The specific selection method is as follows: compare the expected signal-to-noise ratios of each parameter combination in the feasible parameter combination set. The numerical value, select The parameter combination with the highest value is selected. If multiple parameter combinations have the same expected signal-to-noise ratio and are all at their maximum values, the parameter combination with the lowest excitation energy is selected as the final optimal source excitation parameter to reduce the energy consumption of the source equipment.

[0107] The optimal source excitation parameters include three components: optimal excitation energy. Optimal excitation frequency and optimal excitation interval It is used to control the active seismic source for excitation in subsequent steps.

[0108] It should be noted that for communication submarine cables, the vibration safety threshold is 50 micrometers; for power transmission submarine cables, the vibration safety threshold is 100 micrometers; and for monitoring composite submarine cables, the vibration safety threshold is 80 micrometers.

[0109] The vibration safety threshold for submarine cables is determined based on the type and operating status of the cable. The values ​​are set according to the following criteria: Communication submarine cables contain precision optical fiber communication components and are highly sensitive to vibration. Excessive vibration may lead to increased attenuation of optical fiber signals or loosening of connectors; Power transmission submarine cables mainly carry power transmission functions, have high structural strength, and are more resistant to vibration; Monitoring composite submarine cables integrate communication, power, and sensing functions, and their vibration resistance is between the two. Taking monitoring composite submarine cables as an example, the vibration safety threshold is set at 80 micrometers.

[0110] S4, control the active source to excite according to the optimal source excitation parameters, and simultaneously collect the seismic wave signals generated by the excitation;

[0111] In this embodiment of the invention, the step of controlling the active seismic source to excite according to the optimal source excitation parameters and synchronously acquiring the seismic wave signals generated by the excitation includes:

[0112] The optimal excitation energy, optimal excitation frequency, and optimal excitation interval from the optimal source excitation parameters are transmitted to the active source controller, which controls the active source to perform excitation operations at the predetermined excitation position according to the optimal excitation energy, the optimal excitation frequency as the center frequency of the excitation pulse, and the optimal excitation interval as the time interval between two adjacent excitations.

[0113] While the active seismic source is performing the excitation operation, the distributed fiber optic acoustic sensing device is activated to receive seismic wave signals with preset acquisition parameters. The seismic wave signals are acoustic signals generated by the active seismic source and propagated through the strata and seawater to the submarine cable.

[0114] It should be noted that the active vibration source is an electromagnetic controllable vibration source or an air gun vibration source. Taking an electromagnetic controllable vibration source as an example, after the active vibration source controller receives the optimal excitation energy, optimal excitation frequency and optimal excitation interval, it generates a corresponding driving signal to drive the vibration source exciter to generate a vibration signal with specified parameters.

[0115] The active source works as follows: The active source controller converts the optimal excitation energy into the amplitude of the driving current. The amplitude of the driving current is proportional to the square root of the optimal excitation energy. Specifically, the conversion relationship is: the amplitude of the driving current is equal to 0.5 amperes multiplied by the square root of the optimal excitation energy, where the square root of 0.5 amperes per kilojoule is the current-energy conversion coefficient of the source driver. This coefficient is determined by the rated power of the source driver and the electro-electric conversion efficiency of the exciter.

[0116] The active source controller uses the optimal excitation frequency as the frequency of the sinusoidal drive signal, and the generated drive signal is: ,in, Indicates time The driving current value, in amperes. Indicates the magnitude of the drive current. This indicates the optimal excitation frequency. Indicates time, The value is 3.14159;

[0117] The active seismic source cyclically performs the excitation operation according to the optimal excitation interval. Specifically: at time... After the first excitation, wait for the optimal excitation interval, at time [time missing]. Perform the second activation, and so on, where The value represents the optimal excitation interval, expressed in seconds.

[0118] The predetermined excitation location is a pre-set location for the seismic source near the submarine cable monitoring area. The specific location is determined by the operator based on the marine environmental conditions of the monitoring area and the submarine cable laying path.

[0119] Furthermore, it should be noted that the amplitude of the driving current is obtained through the following conversion relationship:

[0120] First, obtain the optimal excitation energy, and then calculate the square root value of the optimal excitation energy;

[0121] Finally, the square root of the optimal excitation energy is multiplied by the current-energy conversion coefficient to obtain the amplitude of the driving current, wherein the current-energy conversion coefficient is 0.5 amperes per kilojoule square root.

[0122] The current-to-energy conversion coefficient is determined as follows: In an electromagnetic controllable vibratory source, the driving force of the vibratory source exciter is proportional to the driving current, and the output energy of the vibratory source is proportional to the square of the driving force amplitude. Therefore, the amplitude of the driving current is proportional to the square root of the output energy of the vibratory source. The conversion coefficient is 0.5 amperes per kilojoule square root, which is determined by the rated power of the vibratory source driver (10 kW) and the electro-power conversion efficiency of the exciter (0.8). The specific derivation process is as follows: The maximum current that the vibratory source driver can output under rated voltage is 5 amperes, and the corresponding maximum vibratory source output energy is 100 kilojoules. Therefore, the conversion coefficient is the square root of 5 amperes divided by 100 kilojoules.

[0123] When the optimal excitation energy is 25 kJ, its square root value is 5. Multiplying this by the conversion factor of 0.5 amperes per kJ square root, the amplitude of the driving current is 2.5 amperes.

[0124] It should be noted that the distributed fiber optic acoustic sensing system is synchronously triggered at the start of each excitation operation to ensure that the acquisition time window covers the complete time period from the seismic source to the submarine cable.

[0125] The preset acquisition parameters include: acquisition duration set to 10 seconds, sampling frequency set to 10 kHz, and spatial resolution set to 5 meters.

[0126] The acquisition parameters were set as follows: The speed of seismic waves from the epicenter to the submarine cable is approximately 1500 to 2500 meters per second in the strata and approximately 1500 meters per second in the seawater. Therefore, the time required for the seismic waves to reach the submarine cable is approximately 0.2 to 0.4 seconds. The acquisition duration was set to 10 seconds to fully record the arrival process of the seismic waves after the epicenter was excited, as well as possible multi-wave reflection signals. At the same time, it provides sufficient time-domain data length for subsequent signal processing. The sampling frequency was set to 10 kHz, corresponding to a Nyquist frequency of 5 kHz, which can fully cover the main frequency band of seismic wave signals from 10 Hz to 500 Hz. The spatial resolution was set to 5 meters to meet the spacing requirements of monitoring points along the submarine cable.

[0127] The data acquisition process of the distributed fiber optic acoustic sensing device is as follows: at the excitation time of the active seismic source, a laser pulse with a pulse width of 50 nanoseconds is emitted into the submarine cable optical fiber, the backscattered light signal is received, the backscattered light signal is sampled at a sampling frequency of 10 kHz, and the sampled data is segmented according to a spatial resolution of 5 meters to obtain the seismic wave signal data at each monitoring location along the submarine cable.

[0128] Furthermore, the seismic wave signal data obtained from each excitation is stored in the form of data frames. Each data frame contains the seismic wave signal amplitude values ​​of all time sampling points and all spatial monitoring locations within a complete acquisition duration. The data dimension is the number of time sampling points multiplied by the number of spatial monitoring points. The number of time sampling points is 10 seconds multiplied by 10 kHz, i.e., 100,000 time sampling points. The number of spatial monitoring points is determined according to the length of the submarine cable monitoring. For example, when the length of the submarine cable monitoring is 10 kilometers, the number of spatial monitoring points is 10,000 meters, with a spatial resolution of 5 meters, i.e., 2,000 spatial monitoring points.

[0129] S5, receive the seismic wave signal generated by excitation, and determine the actual seismic signal quality index and the actual submarine cable vibration index based on the seismic wave signal;

[0130] In this embodiment of the invention, receiving the generated seismic wave signal and determining the actual seismic signal quality index and the actual submarine cable vibration index based on the seismic wave signal includes:

[0131] The distributed fiber optic acoustic sensing device receives seismic wave signals generated by an active seismic source and propagating to the submarine cable, and obtains raw vibration time series data.

[0132] Effective signal segments and background noise segments are extracted from the original vibration time series data. Based on the effective signal segments and the background noise segments, the actual signal-to-noise ratio is calculated as the actual seismic signal quality index.

[0133] The actual vibration amplitude is determined based on the maximum vibration amplitude in the effective signal segment.

[0134] It should be noted that the distributed fiber optic acoustic sensing system continuously collects backscattered light signals at various monitoring locations along the submarine cable within a 10-second acquisition period after the active source excitation, using sampling parameters of 10 kHz and spatial resolution of 5 meters. The light signals are then converted into raw vibration time-series data reflecting the vibration amplitude of the submarine cable through phase demodulation processing.

[0135] The original vibration time series data is a three-dimensional data structure, with the three dimensions being time sampling points, spatial monitoring locations, and vibration amplitude, respectively. The total number of time sampling points is 10 seconds multiplied by 10 kHz, i.e., 100,000 time sampling points; the number of spatial monitoring points is the total length of the submarine cable being monitored divided by 5 meters. Let the total length of the submarine cable being monitored be L meters, then the number of spatial monitoring points is L divided by 5.

[0136] It should be noted that the effective signal segment refers to the data segment corresponding to the time period when the seismic wave signal reaches the submarine cable and causes the cable to vibrate, while the background noise segment refers to the environmental vibration data segment at the submarine cable before the seismic wave signal arrives.

[0137] The methods for extracting the effective signal segment and the background noise segment are as follows:

[0138] First, determine the theoretical arrival time range of seismic waves from the active seismic source to the submarine cable. For example, if the horizontal distance between the active seismic source and the monitoring point on the submarine cable is 500 meters, the propagation speed of seismic waves in the strata is taken as 2000 meters per second, and the propagation speed in seawater is taken as 1500 meters per second, based on these parameters, the shortest theoretical propagation time of seismic waves to the submarine cable is 500 meters divided by 2000 meters per second, which is 0.25 seconds; the longest theoretical propagation time is 500 meters divided by 1500 meters per second, which is 0.33 seconds. Therefore, the theoretical arrival time range is 0.25 seconds to 0.33 seconds after excitation.

[0139] Secondly, the start time of the effective signal segment is set to 0.20 seconds after excitation, and the end time is set to 1.00 seconds after excitation. The start time of 0.20 seconds is 0.05 seconds earlier than the earliest time of 0.25 seconds in the theoretical arrival time range, which is used to include the small amplitude changes before the arrival of the seismic wave as a buffer for signal detection. The end time of 1.00 seconds is 0.67 seconds longer than the latest time of 0.33 seconds in the theoretical arrival time range, which is used to completely record the arrival of the main wave of the seismic wave as well as the subsequent reflected waves and aftershock signals. The duration of the effective signal segment is 1.00 seconds minus 0.20 seconds, which is 0.80 seconds. The corresponding number of time sampling points is 0.80 seconds multiplied by 10 kHz, which is 8000 time sampling points.

[0140] Secondly, the start time of the background noise segment is set to 1.00 seconds before excitation and the end time is the excitation time. The background noise segment takes the time domain data before excitation, which can represent the vibration level of the submarine cable environment when it is not affected by the excitation of the seismic source. The duration of the background noise segment is 1.00 seconds, and the corresponding number of time sampling points is 1.00 seconds multiplied by 10 kHz, that is, 10,000 time sampling points.

[0141] Finally, from the original vibration time series data, corresponding data segments are extracted according to the start time and the end time to obtain the effective signal segment and the background noise segment.

[0142] It should be noted that the actual vibration amplitude is used to represent the maximum amplitude of the submarine cable vibration caused by this seismic source excitation, and is used to compare with the expected vibration amplitude output by the prediction model to assess the level of mechanical stress on the submarine cable during this excitation.

[0143] The actual vibration amplitude is determined by iterating through the vibration amplitudes of all time sampling points within the effective signal segment, finding the maximum value among them, and using it as the actual vibration amplitude. The algorithm is expressed as follows:

[0144]

[0145] In the formula, This represents the actual vibration amplitude. to The table shows the vibration amplitude sequence of all time sampling points within the effective signal segment.

[0146] Furthermore, to eliminate potential spike noise interference from single sampling points, median filtering is performed on the vibration amplitude sequence within the effective signal segment before taking the maximum value. The filtering window length is set to 5 time sampling points. The specific operation of median filtering is as follows: for the vibration amplitude sequence... The amplitude of the sampling point is taken as the first sampling point. The first to the second The median of the amplitude at a total of 5 sampling points was used to replace the original value. The amplitude values ​​of each sampling point, and the filtered vibration amplitude sequence, are then used to calculate the actual vibration amplitude.

[0147] In this embodiment of the invention, calculating the actual signal-to-noise ratio as a quality indicator of the actual seismic signal includes:

[0148] The actual signal-to-noise ratio is calculated using the following formula:

[0149] ;

[0150] In the formula, This represents the actual signal-to-noise ratio. This represents the average power of the vibration amplitude within the effective signal segment. This represents the average power of the vibration amplitude within the background noise range. This represents the total number of time sampling points within the valid signal segment, with a value of 8000. Indicates the first valid signal segment Vibration amplitude at each time sampling point This represents the total number of time sampling points within the background noise segment, with a value of 10000. Indicates the first segment within the background noise range Vibration amplitude at each time sampling point.

[0151] It should be noted that a higher actual signal-to-noise ratio indicates that the seismic wave signal is more distinguishable from the background noise, and the signal quality is better.

[0152] S6. Update the prediction model based on the actual seismic signal quality index and the actual submarine cable vibration index.

[0153] In this embodiment of the invention, updating the prediction model based on the actual seismic signal quality index and the actual submarine cable vibration index includes:

[0154] Calculate the signal-to-noise ratio deviation between the actual signal-to-noise ratio and the expected signal-to-noise ratio, and the vibration amplitude deviation between the actual vibration amplitude and the expected vibration amplitude;

[0155] Determine whether the absolute value of the signal-to-noise ratio deviation exceeds a preset signal-to-noise ratio deviation threshold, and whether the absolute value of the vibration amplitude deviation exceeds a preset vibration amplitude deviation threshold;

[0156] When the absolute value of the signal-to-noise ratio deviation exceeds the signal-to-noise ratio deviation threshold, or when the absolute value of the vibration amplitude deviation exceeds the vibration amplitude deviation threshold, the parameters in the prediction model are corrected and updated to obtain the updated prediction model.

[0157] It should be noted that the signal-to-noise ratio deviation value is obtained by subtracting the expected signal-to-noise ratio from the actual signal-to-noise ratio, and the vibration amplitude deviation value is obtained by subtracting the expected vibration amplitude from the actual vibration amplitude.

[0158] It should be noted that the signal-to-noise ratio (SNR) deviation threshold is set at 3 dB. The SNR deviation threshold is set based on the following: In the actual marine monitoring environment, SNR fluctuations within 3 dB are within the normal measurement error range, caused by random fluctuations in marine environmental noise, sensor measurement noise, and other factors. When the absolute value of the SNR deviation exceeds 3 dB, it indicates that there is a significant deviation between the output of the prediction model and the actual measurement results, and the prediction model needs to be updated and corrected.

[0159] The vibration amplitude deviation threshold is set at 5 micrometers. The threshold is set based on the following: the vibration amplitude measurement accuracy of the distributed fiber optic acoustic sensing system is about 1 to 2 micrometers. Considering the measurement fluctuations caused by environmental factors, 5 micrometers is taken as the threshold for judging whether the deviation is significant. When the absolute value of the vibration amplitude deviation exceeds 5 micrometers, it indicates that the prediction model's estimation of the submarine cable vibration response deviates significantly from the actual measurement results, and the prediction model needs to be updated and corrected.

[0160] Furthermore, if the absolute value of the signal-to-noise ratio deviation is greater than 3 dB, then the first prediction sub-model of the prediction model is determined to need to be updated.

[0161] If the absolute value of the vibration amplitude deviation is greater than 5 micrometers, the second prediction sub-model of the prediction model needs to be updated.

[0162] If the absolute value of the signal-to-noise ratio deviation is no greater than 3 dB and the absolute value of the vibration amplitude deviation is no greater than 5 micrometers, then the prediction model is determined to be unnecessary to update, and the parameters of the current model are used for the optimization solution of the source excitation parameters in the next round.

[0163] It should be noted that, based on the judgment results, the key parameters in the first prediction sub-model and the second prediction sub-model are corrected and updated respectively.

[0164] When the absolute value of the signal-to-noise ratio deviation exceeds the signal-to-noise ratio deviation threshold, the formation attenuation coefficient in the first prediction sub-model is affected. Make corrections and updates.

[0165] The formation attenuation coefficient The correction method is as follows: the signal-to-noise ratio deviation value is... Proportionally allocated to the formation attenuation coefficient The correction formula for the amount of correction is as follows:

[0166]

[0167] In the formula, This represents the formation attenuation coefficient before correction, with a value of 0.5 dB per meter. This represents the corrected formation attenuation coefficient. This represents the signal-to-noise ratio deviation value. This represents the projected length of the horizontal distance from the active seismic source to the submarine cable monitoring location within the geological strata.

[0168] A positive signal-to-noise ratio (SNR) deviation indicates that the actual SNR is higher than expected, meaning that the actual propagation attenuation is less than the model estimate, and the attenuation coefficient needs to be reduced. A negative SNR deviation indicates that the actual SNR is lower than expected, meaning that the actual propagation attenuation is greater than the model estimate, and the attenuation coefficient needs to be increased.

[0169] Furthermore, the range of the corrected formation attenuation coefficient is limited to 0.1 dB per meter to 1.0 dB per meter. If the corrected calculation result exceeds this range, the boundary value is taken.

[0170] When the absolute value of the vibration amplitude deviation exceeds the vibration amplitude deviation threshold, the burial depth attenuation rate coefficient in the second prediction sub-model is affected. Make corrections and updates.

[0171] The burial depth attenuation rate coefficient The correction method is as follows: adjust the vibration amplitude deviation value. The correction amount is converted into the attenuation rate coefficient of the burial depth, and the correction formula is as follows:

[0172]

[0173] In the formula, This represents the original burial depth attenuation rate coefficient, with a value of 0.3 per meter. This represents the corrected attenuation rate coefficient for the burial depth. This indicates the deviation value of the vibration amplitude. This represents the reference vibration amplitude coefficient, with a value of 0.01 micrometers per kilojoule. This indicates the energy generated, measured in kilojoules. Represents the frequency response coefficient. Indicates the influence coefficient of ocean currents. This indicates the burial depth data of the submarine cable;

[0174] A positive vibration amplitude deviation indicates that the actual vibration amplitude is higher than expected, meaning that the burial depth has a weaker attenuation effect on the vibration than the model estimate, and the attenuation rate coefficient needs to be reduced. A negative vibration amplitude deviation indicates that the actual vibration amplitude is lower than expected, meaning that the burial depth has a stronger attenuation effect on the vibration than the model estimate, and the attenuation rate coefficient needs to be increased.

[0175] Furthermore, the corrected burial depth attenuation rate coefficient The value range is limited to 0.05 per meter to 0.8 per meter. If the corrected calculation result exceeds this range, the boundary value is taken.

[0176] When the absolute value of the signal-to-noise ratio deviation exceeds the signal-to-noise ratio deviation threshold, and the absolute value of the vibration amplitude deviation exceeds the vibration amplitude deviation threshold, the correction operations for the above two parameters are performed simultaneously.

[0177] The corrected formation attenuation coefficient and burial depth attenuation rate coefficient are substituted into the corresponding positions in the first prediction sub-model and the second prediction sub-model, respectively, to replace the original parameter values, thereby obtaining the updated prediction model. The updated prediction model is used for data calculation in the next round of source excitation parameter optimization solution.

[0178] like Figure 2 The diagram shown is a functional block diagram of an active source excitation optimization observation system for submarine cable monitoring provided in an embodiment of the present invention.

[0179] The active source excitation optimization observation system 100 for submarine cable monitoring described in this invention can be installed in an electronic device. Depending on the functions implemented, the active source excitation optimization observation system 100 for submarine cable monitoring may include a data acquisition module 101, a prediction model construction module 102, a parameter optimization module 103, an excitation control module 104, a signal receiving module 105, and a model update module 106. The module described in this invention can also be called a unit, referring to a series of computer program segments that can be executed by the processor of an electronic device and can perform a fixed function, stored in the memory of the electronic device.

[0180] In this embodiment, the functions of each module / unit are as follows:

[0181] The data acquisition module is used to acquire submarine cable status data and marine environment data in the submarine cable monitoring area;

[0182] The prediction model construction module is used to establish a prediction model of the seismic source excitation effect based on the submarine cable status data and the marine environment data.

[0183] The parameter optimization module is used to determine the optimal source excitation parameters based on the prediction model, with the goal of optimizing the expected quality index of the seismic signal and the constraint that the expected vibration index of the submarine cable does not exceed the safety threshold.

[0184] The excitation control module is used to control the active source to excite according to the optimal source excitation parameters and to simultaneously acquire the seismic wave signals generated by the excitation.

[0185] The signal receiving module is used to receive the seismic wave signal generated by the excitation, and to determine the actual seismic signal quality index and the actual submarine cable vibration index based on the seismic wave signal.

[0186] The model update module is used to update the prediction model based on the actual seismic signal quality index and the actual submarine cable vibration index.

[0187] In the several embodiments provided by this invention, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and other division methods may be used in actual implementation.

[0188] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0189] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or in the form of hardware plus software functional modules.

[0190] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0191] The embodiments of this application can acquire and process relevant data based on artificial intelligence technology. Artificial intelligence is the theory, method, technology, and application system that uses digital computers or machines controlled by digital computers to simulate, extend, and expand human intelligence, perceive the environment, acquire knowledge, and use that knowledge to obtain optimal results.

[0192] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An optimization method for active source excitation for submarine cable monitoring, characterized in that, The method includes: S1, acquire submarine cable status data and marine environment data in the submarine cable monitoring area; S2, Based on the submarine cable status data and the marine environment data, establish a prediction model for the seismic source excitation effect; S3. Based on the prediction model, with the goal of optimizing the expected quality index of the seismic signal and the constraint that the expected vibration index of the submarine cable does not exceed the safety threshold, determine the optimal source excitation parameters. S4, control the active source to excite according to the optimal source excitation parameters, and simultaneously collect the seismic wave signals generated by the excitation; S5, receive the seismic wave signal generated by excitation, and determine the actual seismic signal quality index and the actual submarine cable vibration index based on the seismic wave signal; S6. Update the prediction model based on the actual seismic signal quality index and the actual submarine cable vibration index.

2. The active source excitation optimization method for submarine cable monitoring as described in claim 1, characterized in that, Acquire submarine cable status data and marine environmental data for the submarine cable monitoring area, including: The vibration response time-series data of the submarine cable at the current monitoring moment is collected in real time by the distributed fiber optic acoustic sensing device built into the submarine cable, which serves as the first submarine cable status data. The burial depth data of the submarine cable at the current monitoring time is obtained through the depth sensing unit built into the submarine cable, and used as the second submarine cable status data. Ocean current speed, tidal height, and background noise level are acquired using marine environmental monitoring equipment deployed in the submarine cable monitoring area, and are used as the marine environmental data.

3. The active source excitation optimization method for submarine cable monitoring as described in claim 2, characterized in that, Based on the submarine cable status data and the marine environment data, a predictive model for the source excitation effect is established, including: The theoretical propagation attenuation of seismic waves at the point of propagation to the submarine cable is determined based on submarine cable burial depth data. The signal-to-noise ratio correction factor for signal detection is determined based on the background noise level and the ocean current velocity. By establishing the mapping relationship between the source excitation parameters and the expected signal-to-noise ratio, and the mapping relationship between the source excitation parameters and the expected vibration amplitude, the first prediction sub-model and the second prediction sub-model are obtained respectively. The first prediction sub-model and the second prediction sub-model are combined to generate a prediction model for the source excitation effect.

4. The active source excitation optimization method for submarine cable monitoring as described in claim 3, characterized in that, By establishing the mapping relationships between the source excitation parameters and the expected signal-to-noise ratio, and between the source excitation parameters and the expected vibration amplitude, the first prediction sub-model and the second prediction sub-model are obtained, including: Based on the theoretical propagation attenuation, the signal-to-noise ratio correction factor, and the preset source excitation parameters, a mapping relationship between the source excitation parameters and the expected signal-to-noise ratio is established as the first prediction sub-model. Based on the theoretical propagation attenuation, the submarine cable burial depth data, the ocean current velocity, and the preset source excitation parameters, a mapping relationship between the source excitation parameters and the expected vibration amplitude is established as the second prediction sub-model.

5. The active source excitation optimization method for submarine cable monitoring as described in claim 1, characterized in that, Based on the aforementioned prediction model, with the objective of optimizing the expected quality index of the seismic signal and the constraint that the expected vibration index of the submarine cable does not exceed a safety threshold, the optimal source excitation parameters are determined, including: The expected signal-to-noise ratio and expected vibration amplitude output by the prediction model are obtained as the target parameters and constraint parameters to be optimized. The discretized set of the source excitation parameters within their respective value ranges is obtained to generate the parameter combination space. Traverse each set of source excitation parameter combinations in the parameter combination space, calculate the corresponding expected signal-to-noise ratio and expected vibration amplitude through the prediction model, and screen out all parameter combinations whose expected vibration amplitude does not exceed the preset submarine cable vibration safety threshold to form a feasible parameter combination set; From the set of feasible parameter combinations, the parameter combination with the highest expected signal-to-noise ratio is selected as the optimal source excitation parameter.

6. The active source excitation optimization method for submarine cable monitoring as described in claim 2, characterized in that, The active source is controlled to generate seismic waves according to the optimal source excitation parameters, and the generated seismic wave signals are acquired simultaneously, including: The optimal excitation energy, optimal excitation frequency, and optimal excitation interval from the optimal source excitation parameters are transmitted to the active source controller, which controls the active source to perform excitation operations at the predetermined excitation position according to the optimal excitation energy, the optimal excitation frequency as the center frequency of the excitation pulse, and the optimal excitation interval as the time interval between two adjacent excitations. While the active seismic source is performing the excitation operation, the distributed fiber optic acoustic sensing device is activated to receive seismic wave signals with preset acquisition parameters. The seismic wave signals are acoustic signals generated by the active seismic source and propagated through the strata and seawater to the submarine cable.

7. The active source excitation optimization method for submarine cable monitoring as described in claim 2, characterized in that, Receive the seismic wave signal generated by the excitation, and determine the actual seismic signal quality index and the actual submarine cable vibration index based on the seismic wave signal, including: The distributed fiber optic acoustic sensing device receives seismic wave signals generated by an active seismic source and propagating to the submarine cable, and obtains raw vibration time series data. Effective signal segments and background noise segments are extracted from the original vibration time series data. Based on the effective signal segments and the background noise segments, the actual signal-to-noise ratio is calculated as the actual seismic signal quality index. The actual vibration amplitude is determined based on the maximum vibration amplitude in the effective signal segment.

8. The active source excitation optimization method for submarine cable monitoring as described in claim 7, characterized in that, Calculating the actual signal-to-noise ratio as a quality indicator of actual seismic signals includes: The actual signal-to-noise ratio is calculated using the following formula: ； In the formula, This represents the actual signal-to-noise ratio. This represents the average power of the vibration amplitude within the effective signal segment. This represents the average power of the vibration amplitude within the background noise range. This represents the total number of time sampling points within the valid signal segment, with a value of 8000. Indicates the first valid signal segment Vibration amplitude at each time sampling point This represents the total number of time sampling points within the background noise segment, with a value of 10000. Indicates the first segment within the background noise range Vibration amplitude at each time sampling point.

9. The active source excitation optimization method for submarine cable monitoring as described in claim 8, characterized in that, The prediction model is updated based on the actual seismic signal quality index and the actual submarine cable vibration index, including: Calculate the signal-to-noise ratio deviation between the actual signal-to-noise ratio and the expected signal-to-noise ratio, and the vibration amplitude deviation between the actual vibration amplitude and the expected vibration amplitude; Determine whether the absolute value of the signal-to-noise ratio deviation exceeds a preset signal-to-noise ratio deviation threshold, and whether the absolute value of the vibration amplitude deviation exceeds a preset vibration amplitude deviation threshold; When the absolute value of the signal-to-noise ratio deviation exceeds the signal-to-noise ratio deviation threshold, or when the absolute value of the vibration amplitude deviation exceeds the vibration amplitude deviation threshold, the parameters in the prediction model are corrected and updated to obtain the updated prediction model.

10. An active source excitation optimization observation system for submarine cable monitoring, used to implement the active source excitation optimization method for submarine cable monitoring as described in any one of claims 1-9, characterized in that, The system includes: The data acquisition module is used to acquire submarine cable status data and marine environmental data in the submarine cable monitoring area; The prediction model building module is used to establish a prediction model of the seismic source excitation effect based on the submarine cable status data and the marine environment data. The parameter optimization module is used to determine the optimal source excitation parameters based on the prediction model, with the goal of optimizing the expected quality index of the seismic signal and the constraint that the expected vibration index of the submarine cable does not exceed the safety threshold. The excitation control module is used to control the active source to excite according to the optimal source excitation parameters and to synchronously acquire the seismic wave signals generated by the excitation. The signal receiving module is used to receive the seismic wave signal generated by excitation, and to determine the actual seismic signal quality index and the actual submarine cable vibration index based on the seismic wave signal. The model update module is used to update the prediction model based on the actual seismic signal quality index and the actual submarine cable vibration index.

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