A suspended sand diffusion analysis method for submarine cable pipeline construction period of offshore oil and gas engineering

Abstract

The present invention discloses a method for analyzing suspended sand diffusion during the construction period of submarine cable pipelines in marine oil and gas engineering, which relates to the technical field of marine oil and gas engineering, and comprises the following steps: collecting marine environmental data in the construction area, and formulating an observation plan according to the construction characteristics and prediction requirements, obtaining representative points for calculating the source strength of suspended sand diffusion, wherein the marine environmental data includes historical data and real-time data, extracting relevant features based on the collected marine environmental data and the representative points for calculating the source strength of suspended sand diffusion, and establishing a suspended sand diffusion prediction model, and calculating each representative point for calculating the source strength of suspended sand diffusion. The present invention sets the representative points for calculating the source strength of suspended sand diffusion in the suspended sand diffusion prediction model, and dynamically adjusts the representative points involved in the calculation based on the actual construction progress, thereby ensuring the validity and representativeness of each calculation point, and simultaneously adopts the spatial interpolation technology to integrate the maximum suspended sand diffusion influence envelope of each representative point, effectively eliminating the errors of human understanding and judgment, and improving the accuracy of the prediction results.

Description

Technical Field

[0001] The invention relates to the technical field of marine oil and gas engineering, and in particular to a method for analyzing suspended sand diffusion during the construction period of a submarine cable pipeline of a marine oil and gas engineering project. Background Art

[0002] Submarine cables and pipelines are an important part of marine oil and gas projects. They are responsible for signal transmission, data transmission, power supply, and the transportation of crude oil, natural gas, water and other materials between platforms. They are crucial to ensuring the smooth progress of marine oil and gas exploitation activities. Any engineering activities that may affect the marine environment require an environmental impact assessment. During the construction of submarine cables and pipelines, due to excavation, laying and other activities, seabed sediments may be disturbed, resulting in the diffusion of suspended sand, which in turn poses a potential threat to the water quality environment and benthic organisms. The diffusion of suspended sand may not only affect water quality and increase water turbidity, but may also affect the growth and habitat of marine organisms, causing adverse effects on the marine ecosystem. Therefore, accurately predicting the impact range of suspended sand diffusion during the construction period is of great significance for formulating effective environmental protection measures.

[0003] At present, the suspended sand diffusion during the construction period of submarine cables and pipelines in marine oil and gas projects is generally calculated by numerical model calculation methods. The usual practice is to set representative points for suspended sand diffusion calculation one by one at the turning points of the submarine cable and pipeline routes. After the source strength of the suspended sand diffusion is given, the influence range of the suspended sand diffusion of the representative points is calculated within 24 hours. By connecting the maximum influence envelope ranges of multiple representative points, the maximum influence envelope range of suspended sand during the construction period of the submarine cable and pipeline is obtained.

[0004] In the prior art, the traditional suspended sediment diffusion prediction method usually adopts numerical model calculation and sets the calculation representative point at the turning point of the submarine cable pipeline route. However, in actual construction, the overall construction time of the submarine cable pipeline may be several months, and the daily construction progress is also different. Therefore, the above numerical prediction method is easy to cause different calculators to have different understandings of the maximum diffusion influence envelope range of suspended sediment. The shapes of the maximum influence envelope range obtained are often different, and the values ​​of the maximum influence envelope area obtained are also different, which in turn affects the accuracy of the prediction results. In addition, the suspended sediment diffusion is affected by the dynamic changes of natural factors such as water flow and tide, such as water flow velocity, sediment characteristics, etc., which leads to deviations in the prediction results. Therefore, reducing the impact of dynamic changes of natural factors and improving the accuracy of prediction results are the problems we need to solve now. Summary of the invention

[0005] The present invention aims to provide a method for analyzing the diffusion of suspended sand during the construction period of a submarine cable pipeline in an offshore oil and gas project, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for analyzing suspended sand diffusion during the construction period of a submarine cable pipeline in an offshore oil and gas project comprises the following steps:

[0008] Step 1: Collect marine environmental data in the construction area, formulate an observation plan based on construction characteristics and forecast requirements, and obtain representative points for suspended sediment diffusion source intensity calculation, where the marine environmental data includes historical data and real-time data;

[0009] Step 2: Based on the collected marine environment data and representative points of suspended sediment diffusion source strength calculation, relevant features are extracted and a suspended sediment diffusion prediction model is established;

[0010] Step 3, calculating each suspended sediment diffusion source strength calculation representative point, and evaluating the maximum suspended sediment diffusion influence envelope range of each suspended sediment diffusion source strength calculation representative point;

[0011] Step 4, predicting the maximum diffusion impact envelope of suspended sediment during the construction period of the entire submarine cable pipeline, obtaining the prediction results, obtaining the water flow velocity index and sediment index, and analyzing the potential impact on the water quality environment and benthic organisms;

[0012] Step 5: Based on the prediction results, obtain the error value of the maximum diffusion impact envelope range, identify the main source of the error, and make targeted adjustments.

[0013] A further improvement of the technical solution of the present invention is that the process of obtaining representative points for calculating the suspended sediment diffusion source strength is as follows:

[0014] Step 101, clarify the specific sea area location, boundary and scope of the construction, and determine the longitude and latitude coordinates of the construction sea area, boundary line, construction start and end time, total length and route of the submarine cable pipeline, and suspended sediment source generated during the construction activities according to the construction design documents of the submarine cable pipeline;

[0015] Step 102, through ocean observation stations, satellite remote sensing and deployment of wave buoy equipment, real-time monitoring and collection of marine environmental data, such as flow velocity, flow direction, etc., and obtaining historical water depth and topographic data, historical hydrological data, historical wave data and historical water quality and bottom quality data of the construction area through the database, wherein the historical water depth and topographic data include historical water depth maps and topographic maps, the historical hydrological data include historical tidal and ocean current data, the historical wave data include historical wave statistics, and the historical water quality and bottom quality data include historical water quality monitoring data and bottom quality survey reports;

[0016] Step 103: According to the construction characteristics and forecast requirements, as well as the length of the submarine cable pipeline, a representative point for calculating the suspended sediment diffusion source strength is set at intervals of 10 m on the route of the submarine cable pipeline. The point locations should cover areas with different water depths, flow directions, and flow velocities to fully reflect the situation of suspended sediment diffusion, and key periods during the construction period are selected for observation, such as the peak construction period and the period of significant tidal changes;

[0017] Step 104, establish a data record table to record the time, location, environmental conditions, such as wind speed, wind direction, water flow velocity, etc., and observation results, such as suspended sediment concentration, water flow velocity, etc., of each observation.

[0018] A further improvement of the technical solution of the present invention is that the construction process of the suspended sediment diffusion prediction model is:

[0019] Step 201, cleaning and preprocessing the collected real-time data and historical data, and extracting features related to representative points for suspended sediment diffusion source intensity calculation, to obtain water flow velocity features, water flow direction features, wave features, water depth features and terrain features;

[0020] Step 202, integrating water velocity characteristics, water flow direction characteristics, wave characteristics, water depth characteristics and terrain characteristics to form a unified data set, and establishing a suspended sediment diffusion prediction model;

[0021] Step 203, dividing the integrated data set into a training set, a validation set and a test set, using the training set data to train the suspended sediment diffusion prediction model, and using the validation set and the test set data to verify the trained suspended sediment diffusion prediction model, and evaluating the performance of the suspended sediment diffusion prediction model;

[0022] Step 204 , using the trained suspended sediment diffusion prediction model, reflects the main impact of construction activities on suspended sediment diffusion, and analyzes the suspended sediment diffusion source strength of each representative point.

[0023] A further improvement of the technical solution of the present invention is that the process of obtaining the maximum suspended sediment diffusion influence envelope range is:

[0024] Step 301, setting the running time of the suspended sediment diffusion prediction model to the start and end time of the submarine cable pipeline construction, and configuring it according to the construction design schedule;

[0025] Step 302, using the trained suspended sediment diffusion prediction model, calculate the suspended sediment diffusion situation of each suspended sediment diffusion source strength calculation representative point, and obtain the calculation result;

[0026] Step 303, extracting the suspended sediment diffusion influence envelope of each suspended sediment diffusion source strength calculation representative point from the calculation results, including diffusion distance and diffusion area, which is usually a regional range containing the maximum suspended sediment concentration, and analyzing the maximum suspended sediment diffusion influence envelope of each sand diffusion source strength calculation representative point to determine its maximum influence range, maximum concentration value and influence direction;

[0027] Step 304, based on the calculation results, draw isoconcentration lines of suspended sediment concentration, and analyze the impact of the construction activities on the marine environment according to the calculation results of the suspended sediment diffusion source strength.

[0028] A further improvement of the technical solution of the present invention is that the process of obtaining the water flow velocity index and the sediment index is as follows:

[0029] Step 401, based on each suspended sediment diffusion source strength calculated previously, the maximum suspended sediment diffusion influence envelope of the representative point is calculated, and the discrete suspended sediment diffusion source strength calculation representative point results are integrated into a continuous suspended sediment diffusion influence envelope range map through spatial interpolation, such as Kriging interpolation, inverse distance weighted interpolation, etc.;

[0030] Step 402, using the suspended sediment diffusion prediction model, analyze the flow velocity characteristics of the water flow during and before and after the construction, as well as the water depth characteristics and terrain characteristics of the construction area, obtain the flow velocity index and sediment index, analyze the impact of different water flow velocities on the suspended sediment diffusion, high-speed water flow may accelerate the diffusion of suspended sediment; while low-speed water flow may make the suspended sediment deposit faster, and high-concentration suspended sediment has a greater impact, and evaluate the direct impact of suspended sediment diffusion on the sediment cover layer and benthic habitat. The cover of suspended sand will change the living environment of benthic organisms and affect their breathing, foraging and other behaviors;

[0031] Step 403, combining the suspended sediment diffusion impact envelope, water flow velocity index and sediment index, assessing the impact of suspended sediment diffusion on the water quality environment, such as turbidity increase, dissolved oxygen change, etc., and analyzing the potential impact of suspended sediment diffusion on benthic population structure, diversity and ecological function, and obtaining a risk assessment coefficient;

[0032] Step 404, based on the risk assessment coefficient, divide the risk levels of different areas and match the corresponding risk assessment thresholds to provide a basis for formulating environmental protection measures, and formulate corresponding environmental protection measures, such as adjusting the construction time, reducing the construction intensity, setting up protective facilities, etc., to reduce the impact of submarine cable and pipeline construction on the water quality environment and benthic organisms.

[0033] A further improvement of the technical solution of the present invention is that the calculation formula of the water flow velocity index is:

[0034] ;

[0035] in, is the water flow velocity index, v is the current water flow velocity, is the reference flow rate, is the reference flow rate, is the maximum observed flow velocity, is the average flow velocity, where the unit of flow velocity is ;

[0036] The calculation formula of the sediment index is:

[0037] ;

[0038] in, is the sediment index, is the concentration of a pollutant in the sediment, is the standard concentration limit of the pollutant, is the maximum particle size in the sediment, is the average particle size in the sediment, S is the sediment coverage area, A is the total area of ​​the study area, and the concentration unit is , particle size unit is mm, area unit is .

[0039] A further improvement of the technical solution of the present invention is that the calculation formula of the risk assessment coefficient is:

[0040] ;

[0041] Among them, R is the risk assessment coefficient, is the water velocity index, The threshold value of the water velocity index that has a significant impact on benthic ecology is is the standard value of the water velocity index, is the sediment index, is the threshold value of the sediment index for benthic ecology, is the standard value of the sediment index, is the uncertainty measure of the water velocity index, is the uncertainty measure of the sediment index, It is a measure of uncertainty in the ecological characteristics of benthic organisms, such as population structure and diversity. is the distance between benthic organisms and the source of suspended sediment diffusion, It is the critical distance for suspended sediment diffusion to affect benthic organisms.

[0042] A further improvement of the technical solution of the present invention is that: the multiple risk levels correspond to multiple risk assessment thresholds, wherein the risk assessment thresholds include an upper threshold and a lower threshold;

[0043] The multiple risk levels and the multiple risk assessment thresholds satisfy the following relationship:

[0044] Low risk level: ;

[0045] Medium risk level: ;

[0046] High risk level: ;

[0047] Among them, R is the risk assessment coefficient, is the upper threshold corresponding to the low risk level and the lower threshold corresponding to the medium risk level, The upper threshold corresponding to the medium risk level and the lower threshold corresponding to the high risk level.

[0048] A further improvement of the technical solution of the present invention is that the process of obtaining the error value is:

[0049] Step 501 inputs the characteristic data of water velocity characteristics, water flow direction characteristics, wave characteristics, water depth characteristics and terrain characteristics in the pre-processed historical data into the suspended sediment diffusion prediction model, calculates the water velocity index and sediment index respectively, and evaluates the accuracy and completeness of the historical data;

[0050] Step 502, based on the pre-processed historical data, the predicted maximum diffusion impact envelope range is compared with the water flow velocity index and the sediment index to obtain an error value and obtain an error analysis table;

[0051] Step 503, adjusting the suspended sediment diffusion prediction model according to the error analysis table to cope with the dynamic changes of environmental factors. For extreme weather or sea conditions, measures such as suspending construction can be taken to reduce the impact on the environment.

[0052] A further improvement of the technical solution of the present invention is that the calculation formula of the error value is:

[0053] ;

[0054] in, is the error value, is the predicted maximum diffusion impact envelope area, is the maximum diffusion impact envelope area actually observed, is the predicted water flow velocity index, The actual observed water flow velocity index, is the predicted sediment index, is the actual observed sediment index, is the standard value of the sediment index, Forecast area The standard deviation of The observation area The standard deviation of along with and The increase in the difference between the predicted area and the actual observed area directly reflects the mismatch between the predicted area and the actual observed area. Water velocity index and sediment index The difference between the predicted and observed values ​​is amplified by the square operation, and the error increases further when both deviate from their standard values. The term takes into account the relative size of the uncertainty in the predicted area and the observed area. When the uncertainty in the prediction is much larger than the uncertainty in the observation, the value of this term will increase, further increasing the error.

[0055] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0056] The present invention provides a suspended sand diffusion analysis method during the construction period of submarine cables and pipelines in marine oil and gas projects. Representative points for suspended sand diffusion source strength calculation are accurately set in a suspended sand diffusion prediction model, and the representative points involved in the calculation are dynamically adjusted based on the actual construction progress, thereby ensuring the effectiveness and representativeness of each calculation point. At the same time, spatial interpolation technology is used to integrate the maximum suspended sand diffusion influence envelope of each representative point, thereby effectively eliminating errors in human understanding and judgment, and greatly improving the accuracy of the prediction results.

[0057] The present invention provides a suspended sand diffusion analysis method during the construction period of submarine cables and pipelines in marine oil and gas projects. By integrating a high-precision numerical model with a real-time environmental monitoring system, a refined simulation of the suspended sand diffusion process is achieved. The numerical model not only takes into account the complex interaction of natural factors such as water flow and tide, but also introduces key parameters such as sediment characteristics and seabed topography changes, so that the simulation results are closer to reality. At the same time, the system can dynamically adjust the model parameters according to real-time monitored water flow speed, direction and other data to ensure that the accuracy of the prediction can be maintained even in a complex and changeable marine environment, effectively reducing the impact of dynamic changes in natural factors on the prediction results, and improving the timeliness and reliability of the prediction.

[0058] The present invention provides a method for analyzing suspended sand diffusion during the construction period of submarine cable pipelines in marine oil and gas projects. Through a built-in risk warning mechanism, the dynamic changes of suspended sand diffusion can be monitored in real time, and a warning signal can be issued in time when potential risks are found. At the same time, the system also provides an emergency response plan library, which automatically matches corresponding emergency measures and disposal processes according to the warning signals, thereby improving the safety and emergency response speed during the construction period and reducing the environmental and ecological risks caused by suspended sand diffusion.

[0059] The present invention provides a suspended sand diffusion analysis method during the construction period of a submarine cable pipeline of an offshore oil and gas project. In the method, dense and equally spaced representative points for calculating the suspended sand diffusion source strength are set, one for every 10 meters, thereby reducing the error caused by sparse or uneven selection of representative points in the prediction process. In addition, the calculation of representative points is started and terminated one by one according to the actual construction progress, thereby ensuring the synchronization of the prediction time and the construction activities, further reducing the influence of the time deviation on the prediction result, significantly reducing the prediction error of the suspended sand diffusion influence envelope range, and providing a more accurate basis for environmental impact assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0061] Figure 1 is a flow chart of the method of the present invention;

[0062] Figure 2 The flowchart of obtaining the water flow velocity index and the sediment index of the present invention;

[0063] Figure 3 This is a flow chart for obtaining the error value of the present invention. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] Embodiment 1, as Figure 1-3 As shown, the present invention provides a method for analyzing suspended sand diffusion during the construction period of a submarine cable pipeline in an offshore oil and gas project, comprising the following steps:

[0066] Step 1: Collect marine environmental data of the construction area, and formulate an observation plan based on the construction characteristics and forecast needs to obtain representative points for calculating the suspended sediment diffusion source strength, where the marine environmental data includes historical data and real-time data; the process of obtaining representative points for calculating the suspended sediment diffusion source strength is to clarify the specific sea area location, boundary and scope of the construction, and determine the latitude and longitude coordinates, boundary lines, construction start and end time, total length and route of the submarine cable pipeline, and suspended sediment sources generated during construction activities according to the construction design documents of the submarine cable pipeline. Through marine observation stations, satellite remote sensing and deployment of wave buoy equipment, real-time monitoring and collection of marine environmental data such as flow velocity and flow direction, and obtain historical water depth and topographic data, historical hydrological data, historical wave data, and historical water quality and bottom data of the construction area through the database. The historical water depth and topographic data include historical water depth maps and topographic maps, the historical hydrological data include historical tides and current data, the historical wave data include historical wave statistics, and the historical water quality and bottom quality data include historical water quality monitoring data and bottom quality survey reports. According to the construction characteristics and forecast requirements, as well as the length of the submarine cable pipeline, a representative point for suspended sediment diffusion source strength calculation is set at intervals of 10m on the route of the submarine cable pipeline. The points should cover areas with different water depths, flow directions and flow velocities to fully reflect the situation of suspended sediment diffusion. Observations should be conducted during key periods during construction, such as construction peak periods and periods with significant tidal changes. A data record sheet should be established to record the time, location, environmental conditions, such as wind speed, wind direction, water flow velocity, etc., and observation results, such as suspended sediment concentration and water flow velocity, etc.;

[0067] Step 2: Based on the collected marine environment data and representative points for suspended sediment diffusion source strength calculation, relevant features are extracted and a suspended sediment diffusion prediction model is established. The construction process of the suspended sediment diffusion prediction model is as follows: the collected real-time data and historical data are cleaned and preprocessed, and features related to representative points for suspended sediment diffusion source strength calculation are extracted to obtain water velocity features, water flow direction features, wave features, water depth features and terrain features, and the water velocity features, water flow direction features, wave features, water depth features and terrain features are integrated to form a unified data set, and a suspended sediment diffusion prediction model is established. The integrated data set is divided into a training set, a validation set and a test set, and the suspended sediment diffusion prediction model is trained using the training set data, and the trained suspended sediment diffusion prediction model is verified using the validation set and test set data, and the performance of the suspended sediment diffusion prediction model is evaluated, and the trained suspended sediment diffusion prediction model is used to reflect the main impact of construction activities on suspended sediment diffusion, and the suspended sediment diffusion source strength of each representative point is analyzed;

[0068] Step 3, calculate each representative point of suspended sediment diffusion source strength calculation, and evaluate the maximum suspended sediment diffusion influence envelope range of each representative point of suspended sediment diffusion source strength calculation; the process of obtaining the maximum suspended sediment diffusion influence envelope range is: set the running time of the suspended sediment diffusion prediction model to the start and end time of the submarine cable pipeline construction, and configure it according to the construction design schedule, use the trained suspended sediment diffusion prediction model to calculate the suspended sediment diffusion situation of each representative point of suspended sediment diffusion source strength calculation, obtain the calculation results, extract the suspended sediment diffusion influence envelope of each representative point of suspended sediment diffusion source strength calculation from the calculation results, including the diffusion distance and diffusion area, which is usually a regional range containing the maximum suspended sediment concentration, and analyze the maximum suspended sediment diffusion influence envelope of each representative point of suspended sediment diffusion source strength calculation to determine its maximum influence range, maximum concentration value and influence direction, draw the isoconcentration lines of suspended sediment concentration based on the calculation results, and analyze the impact of construction activities on the marine environment based on the calculation results of suspended sediment diffusion source strength;

[0069] Furthermore, the running time of the suspended sediment diffusion prediction model is set to the start and end time of the submarine cable pipeline construction, and is configured according to the construction design schedule. According to the construction progress, each suspended sediment diffusion source strength calculation representative point is activated in turn for calculation. The time each representative calculation point participates in the calculation corresponds to the actual construction time of the 10m long cable pipeline. Once a section of 10m cable pipeline is completed, the representative calculation point corresponding to the section exits the calculation, and the next representative calculation point starts to participate in the calculation. This cycle continues until the calculation of the entire cable pipeline is completed. According to the calculation results of the suspended sediment diffusion source strength, the impact of the construction activities on the marine environment is analyzed, including the suspended sediment concentration exceeding the standard, the diffusion range, etc.

[0070] Step 4: predict the maximum suspended sediment diffusion impact envelope range of the entire submarine cable pipeline during the construction period, obtain the prediction results, obtain the water flow velocity index and sediment index, and analyze its potential impact on the water quality environment and benthic organisms; the process of obtaining the water flow velocity index and sediment index is as follows: calculate the maximum suspended sediment diffusion impact envelope of the representative point according to each suspended sediment diffusion source strength calculated previously, and integrate the discrete suspended sediment diffusion source strength calculation representative point results into a continuous suspended sediment diffusion impact envelope range map through spatial interpolation, such as Kriging interpolation, inverse distance weighted interpolation, etc., and use the suspended sediment diffusion prediction model to analyze the water flow velocity characteristics during and before and after the construction period, as well as the water depth characteristics and terrain characteristics of the construction area, to obtain the water flow velocity index and sediment index, and analyze the impact of different water flow velocities on suspended sediment diffusion. High-speed water flow may accelerate the diffusion of suspended sediment and expand the impact range. The scope of suspended sand diffusion is the same as that of the surrounding water; while low-speed water flow may make suspended sand deposit faster and reduce the diffusion range. The direct impact of suspended sand diffusion on the sediment cover and benthic habitat is evaluated. The cover of suspended sand will change the living environment of benthic organisms and affect their breathing, foraging and other behaviors. Combined with the envelope range of suspended sand diffusion, water flow velocity index and sediment index, the impact of suspended sand diffusion on water quality environment, such as turbidity increase and dissolved oxygen change, is evaluated. The potential impact of suspended sand diffusion on benthic population structure, diversity and ecological function is analyzed to obtain the risk assessment coefficient. According to the risk assessment coefficient, the risk level of different areas is divided and the corresponding risk assessment threshold is matched to provide a basis for the formulation of environmental protection measures. Corresponding environmental protection measures are formulated, such as adjusting the construction time, reducing the construction intensity, setting up protective facilities, etc., to reduce the impact of submarine cable and pipeline construction on water quality environment and benthic organisms;

[0071] Step 5, based on the prediction results, obtain the error value of the maximum diffusion impact envelope range, identify the main source of the error, and make targeted adjustments at the same time; the error value acquisition process is: input the characteristic data of water velocity characteristics, water flow direction characteristics, wave characteristics, water depth characteristics and terrain characteristics in the pre-processed historical data into the suspended sediment diffusion prediction model, calculate the water flow velocity index and sediment index respectively, evaluate the accuracy and completeness of the historical data, compare the predicted maximum diffusion impact envelope range with the water flow velocity index and sediment index based on the pre-processed historical data, obtain the error value, obtain the error analysis table, and adjust the suspended sediment diffusion prediction model according to the error analysis table to cope with the dynamic changes of environmental factors. For extreme weather or sea conditions, measures such as suspending construction can be taken to reduce the impact on the environment.

[0072] Embodiment 2, as Figure 1-3 As shown, based on Example 1, the present invention provides a technical solution: Preferably, the calculation formula of the water flow velocity index is:

[0073] ;

[0074] in, is the water flow velocity index, v is the current water flow velocity, is the reference flow rate, is the reference flow rate, is the maximum observed flow velocity, is the average flow velocity, where the unit of flow velocity is ;

[0075] The calculation formula of sediment index is:

[0076] ;

[0077] in, is the sediment index, is the concentration of a pollutant in the sediment, is the standard concentration limit of the pollutant, is the maximum particle size in the sediment, is the average particle size in the sediment, S is the sediment coverage area, A is the total area of ​​the study area, and the concentration unit is , particle size unit is mm, area unit is ;

[0078] The calculation formula of risk assessment coefficient is:

[0079] ;

[0080] Among them, R is the risk assessment coefficient, is the water velocity index, is the threshold value of the water flow velocity index for benthic ecology, is the standard value of the water velocity index, is the sediment index, is the threshold value of the sediment index for benthic ecology, is the standard value of the sediment index, is the uncertainty measure of the water velocity index, is the uncertainty measure of the sediment index, It is a measure of uncertainty in the ecological characteristics of benthic organisms, such as population structure and diversity. is the distance between benthic organisms and the source of suspended sediment diffusion, is the critical distance for suspended sediment dispersion to affect benthic organisms;

[0081] Each risk level corresponds to a plurality of risk assessment thresholds, wherein the risk assessment thresholds include an upper threshold and a lower threshold;

[0082] Multiple risk levels and multiple risk assessment thresholds satisfy the following relationship:

[0083] Low risk level: When the comprehensive risk value of the assessed area is lower than a certain lower threshold, the area is considered to have low risk and may have little impact on the environment. No special attention or additional protective measures are required. At this risk level, the impact of suspended sediment diffusion on water quality and benthic organisms is relatively small, but monitoring is still required to ensure that construction activities meet environmental protection requirements. Water quality and benthic organism monitoring can be carried out regularly to promptly identify and deal with potential environmental problems;

[0084] Medium risk level: When the comprehensive risk value is between the lower threshold and the higher threshold, it is considered that the area has a medium risk and needs to pay attention to its impact on the environment. The frequency and accuracy of suspended sediment diffusion prediction can be increased, and more advanced prediction models and methods can be used to improve the accuracy of prediction results, such as setting up protective dikes and suspended curtains to block the spread of suspended sand. At the same time, environmental supervision during construction should be strengthened to ensure that various environmental protection measures are effectively implemented;

[0085] High risk level: When the comprehensive risk value is higher than the set higher threshold, the area is considered to have a high risk and may cause serious impact on the environment. At this time, it is necessary to immediately stop construction activities and take emergency measures to control the scope and extent of suspended sand diffusion. Further measures: Initiate emergency plans, including but not limited to increasing environmental monitoring stations, expanding the monitoring scope, and strengthening the storage and deployment of environmental emergency materials. At the same time, cooperate with environmental protection departments and relevant scientific research institutions to jointly study and formulate effective response measures to reduce the impact of suspended sand diffusion on the environment;

[0086] Among them, R is the risk assessment coefficient, is the upper threshold corresponding to the low risk level and the lower threshold corresponding to the medium risk level, The upper threshold corresponding to the medium risk level and the lower threshold corresponding to the high risk level;

[0087] The error value is calculated as follows:

[0088] ;

[0089] in, is the error value, is the predicted maximum diffusion impact envelope area, is the maximum diffusion impact envelope area actually observed, is the predicted water flow velocity index, The actual observed water flow velocity index, is the predicted sediment index, is the actual observed sediment index, is the standard value of the sediment index, Forecast area The standard deviation of The observation area The standard deviation of along with and The increase in the difference between the predicted area and the actual observed area directly reflects the mismatch between the predicted area and the actual observed area. Water velocity index and sediment index The difference between the predicted and observed values ​​is amplified by the square operation, and the error increases further when both deviate from their standard values. The term takes into account the relative size of the uncertainty in the predicted area and the observed area. When the uncertainty in the prediction is much larger than the uncertainty in the observation, the value of this term will increase, further increasing the error.

[0090] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for analyzing suspended sand diffusion during the construction period of submarine cables and pipelines in offshore oil and gas projects, characterized by: The following steps are involved: Step 1: Collect marine environmental data in the construction area, formulate an observation plan based on construction characteristics and forecast requirements, and obtain representative points for suspended sediment diffusion source intensity calculation, where the marine environmental data includes historical data and real-time data; Step 2: Based on the collected marine environment data and representative points of suspended sediment diffusion source strength calculation, relevant features are extracted and a suspended sediment diffusion prediction model is established; Step 3, calculating each suspended sediment diffusion source strength calculation representative point, and evaluating the maximum suspended sediment diffusion influence envelope range of each suspended sediment diffusion source strength calculation representative point; Step 4, predicting the maximum diffusion impact envelope of suspended sand during the construction period of the entire submarine cable pipeline, obtaining the prediction result, obtaining the water flow velocity index and the sediment index, and analyzing the potential impact on the water quality environment and benthic organisms. The process of obtaining the water flow velocity index and the sediment index is as follows: Step 401, based on the previously calculated maximum suspended sediment diffusion influence envelope of each suspended sediment diffusion source intensity representative point, the discrete suspended sediment diffusion source intensity calculation representative point results are integrated into a continuous suspended sediment diffusion influence envelope range map by spatial interpolation; Step 402, using the suspended sediment diffusion prediction model, analyzing the flow velocity characteristics of the water flow during and before and after the construction, as well as the water depth characteristics and terrain characteristics of the construction area, obtaining the flow velocity index and the sediment index, and analyzing the influence of different flow velocities on the suspended sediment diffusion; Step 403, combining the suspended sediment diffusion impact envelope, water flow velocity index and sediment index, assessing the impact of suspended sediment diffusion on the water quality environment, and analyzing the potential impact of suspended sediment diffusion on benthic organism population structure, diversity and ecological function, to obtain a risk assessment coefficient; Step 404, according to the risk assessment coefficient, the risk levels of different areas are divided, and the corresponding risk assessment thresholds are matched to provide a basis for formulating environmental protection measures, and corresponding environmental protection measures are formulated; The calculation formula of the water flow velocity index is: ； in, is the water flow velocity index, v is the current water flow velocity, is the reference flow rate, is the reference flow rate, is the maximum observed flow velocity, is the average flow velocity; The calculation formula of the sediment index is: ； in, is the sediment index, is the concentration of a pollutant in the sediment, is the standard concentration limit of the pollutant, is the maximum particle size in the sediment, is the average particle size in the sediment, S is the sediment coverage area, and A is the total area of ​​the study area; Step 5: Based on the prediction results, obtain the error value of the maximum diffusion impact envelope range, identify the main source of the error, and make targeted adjustments.

2. The method for analyzing suspended sand diffusion during the construction period of submarine cables and pipelines in marine oil and gas projects according to claim 1 is characterized by: The process of obtaining representative points for suspended sediment diffusion source strength calculation is as follows: Step 101, clarify the specific sea area location, boundary and scope of the construction, and determine the longitude and latitude coordinates of the construction sea area, boundary line, construction start and end time, total length and route of the submarine cable pipeline, and suspended sediment source generated during the construction activities according to the construction design documents of the submarine cable pipeline; Step 102, monitor and collect marine environmental data in real time through ocean observation stations, satellite remote sensing and deployment of wave buoy equipment, and obtain historical water depth and topographic data, historical hydrological data, historical wave data, and historical water quality and bottom quality data of the construction area through the database; Step 103, according to the construction characteristics and forecast requirements, as well as the length of the submarine cable pipeline, a representative point for calculating the suspended sand diffusion source strength is set every 10m on the route of the submarine cable pipeline, and a key period during the construction period is selected for observation; Step 104, establish a data record table to record the time, location, environmental conditions and observation results of each observation.

3. The method for analyzing suspended sand diffusion during the construction period of a submarine cable pipeline in an offshore oil and gas project according to claim 2 is characterized in that: The construction process of the suspended sediment diffusion prediction model is as follows: Step 201, cleaning and preprocessing the collected real-time data and historical data, and extracting features related to representative points for suspended sediment diffusion source intensity calculation, to obtain water flow velocity features, water flow direction features, wave features, water depth features and terrain features; Step 202, integrating water velocity characteristics, water flow direction characteristics, wave characteristics, water depth characteristics and terrain characteristics to form a unified data set, and establishing a suspended sediment diffusion prediction model; Step 203, dividing the integrated data set into a training set, a validation set and a test set, using the training set data to train the suspended sediment diffusion prediction model, and using the validation set and the test set data to verify the trained suspended sediment diffusion prediction model, and evaluating the performance of the suspended sediment diffusion prediction model; Step 204 , using the trained suspended sediment diffusion prediction model, reflects the main impact of construction activities on suspended sediment diffusion, and analyzes the suspended sediment diffusion source strength of each representative point.

4. The method for analyzing suspended sand diffusion during the construction period of submarine cables and pipelines in marine oil and gas projects according to claim 3 is characterized by: The process of obtaining the maximum suspended sediment diffusion impact envelope range is as follows: Step 301, setting the running time of the suspended sediment diffusion prediction model to the start and end time of the submarine cable pipeline construction, and configuring it according to the construction design schedule; Step 302, using the trained suspended sediment diffusion prediction model, calculate the suspended sediment diffusion situation of each suspended sediment diffusion source strength calculation representative point, and obtain the calculation result; Step 303, extracting the suspended sediment diffusion influence envelope of each suspended sediment diffusion source strength calculation representative point from the calculation results, including the diffusion distance and diffusion area, and analyzing the maximum suspended sediment diffusion influence envelope of each sand diffusion source strength calculation representative point to determine its maximum influence range, maximum concentration value and influence direction; Step 304, based on the calculation results, draw isoconcentration lines of suspended sediment concentration, and analyze the impact of the construction activities on the marine environment according to the calculation results of the suspended sediment diffusion source strength.

5. The method for analyzing suspended sand diffusion during the construction period of submarine cables and pipelines in marine oil and gas projects according to claim 4 is characterized by: The calculation formula of the risk assessment coefficient is: ； Among them, R is the risk assessment coefficient, is the water velocity index, is the threshold value of the water flow velocity index for benthic ecology, is the standard value of the water velocity index, is the sediment index, is the threshold value of the sediment index for benthic ecology, is the standard value of the sediment index, is the uncertainty measure of the water velocity index, is the uncertainty measure of the sediment index, For benthic ecological characteristics, is the distance between benthic organisms and the source of suspended sediment diffusion, It is the critical distance for suspended sediment diffusion to affect benthic organisms.

6. The method for analyzing suspended sand diffusion during the construction period of submarine cables and pipelines in marine oil and gas projects according to claim 5 is characterized by: The plurality of risk levels correspond to the plurality of risk assessment thresholds, wherein the risk assessment thresholds include an upper threshold and a lower threshold; The multiple risk levels and the multiple risk assessment thresholds satisfy the following relationship: Low risk level: ; Medium risk level: ; High risk level: ; Among them, R is the risk assessment coefficient, T1 is the upper threshold corresponding to the low risk level and the lower threshold corresponding to the medium risk level, and T2 is the upper threshold corresponding to the medium risk level and the lower threshold corresponding to the high risk level.

7. The method for analyzing suspended sand diffusion during the construction period of submarine cables and pipelines in marine oil and gas projects according to claim 6 is characterized by: The process of obtaining the error value is as follows: Step 501, inputting characteristic data of water velocity characteristics, water flow direction characteristics, wave characteristics, water depth characteristics and terrain characteristics in the pre-processed historical data into the suspended sediment diffusion prediction model, calculating the water velocity index and sediment index respectively, and evaluating the accuracy and completeness of the historical data; Step 502, based on the pre-processed historical data, the predicted maximum diffusion impact envelope range is compared with the water flow velocity index and the sediment index to obtain an error value and obtain an error analysis table; Step 503: adjusting the suspended sediment diffusion prediction model according to the error analysis table to cope with the dynamic changes of environmental factors.

8. The method for analyzing suspended sand diffusion during the construction period of submarine cables and pipelines in marine oil and gas projects according to claim 7 is characterized by: The calculation formula of the error value is: ； in, is the error value, is the predicted maximum diffusion impact envelope area, is the maximum diffusion impact envelope area actually observed, is the predicted water flow velocity index, The actual observed water flow velocity index, is the predicted sediment index, is the actual observed sediment index, is the standard value of the sediment index, Forecast area The standard deviation of The observation area The standard deviation of .

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