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21 February 2025, Volume 11 Issue 4 Previous Issue   

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Anomaly Detection of Environmental Features Based on LSTM-Reconstructed Data ZHOU Lei1, SU Xin2, ZHANG Qi2, HUANG Yi2 2024, 11 (4):  1-7.  DOI: 10.12087/oeet.2095-7297.2024.04.01 Abstract ( 123 )   PDF (5649KB) ( 38 )   With the advancement of environmental monitoring technologies， accurately identifying anomalies in data has become a crucial challenge. This study introduces a method combining Long Short-Term Memory (LSTM) networks and Random Forest models for predicting and reconstructing environmental feature data， thereby enabling effective anomaly monitoring. Initially， the LSTM model is used to forecast time series data for environmental features such as wind speed and direction. Subsequently， these forecasts are used as inputs to apply a Random Forest model for predicting axial force. The research indicates that by reconstructing features， the accuracy of axial force predictions can be significantly enhanced compared to direct anomaly detection methods. The R2 values， Mean Absolute Error (MAE)， and Root Mean Squared Error (RMSE) for data with reconstructed features surpass those for data with original features. Particularly， the improvement from an R2 value of 0.921 to 0.956 underscores a significant enhancement in the model's data fitting capability. Related Articles | Metrics

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The Development and Performance Test of Chemical Injection Metering Valve Calibration Loop JIANG Donglei1, MA Xiaowei2, 3, ZENG Chunmin1, LI Fengqing3, LI Wentuo1, ZHANG Xiaodong3, JIA Juncai1 2024, 11 (4):  8-13.  DOI: 10.12087/oeet.2095-7297.2024.04.02 Abstract ( 132 )   PDF (5181KB) ( 25 )   Chemicals such as methanol and ethylene glycol can prevent the formation of hydrates， waxing and scaling within subsea production systems， playing a crucial role in flow assurance. Subsea Chemical Injection Metering Valve (CIMV) is used to control and measure the injected chemicals into subsea production systems. It aids in achieving precise ondemand injection as well as cost reduction and efficiency increase. The structure and measurement principle of CIMV differ significantly from conventional flow meters， hence rigorous calibration is required to ensure the measurement accuracy meeting the design requirements. Based on the product characteristics of CIMV， this paper introduces the design and construction of the first domestic CIMV calibration loop， and discusses how to use this loop to study and build a selfdeveloped CIMV measurement algorithm model. The measurement accuracy of CIMV is verified on this loop， with results as good as ±3% F.S. (Full Scale). This paper provides a valuable reference for the localization of CIMV. Related Articles | Metrics

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Design and Optimization of Impeller for Underwater Helico-axial Multiphase Pump LIU Yibo1, BI Yuqin1, MA Qiang2, 3, XIAO Huaping1, LIU Shuhai1 2024, 11 (4):  14-20.  DOI: 10.12087/oeet.2095-7297.2024.04.03 Abstract ( 201 )   PDF (2410KB) ( 38 )   As a key equipment in underwater pressurization technology， the underwater helical axial flow mixing pump is widely used in the development of offshore oil and gas fields. How to further enhance its pressurization performance has attracted the attention of researchers. This study adopts a method combining orthogonal experimental design and numerical simulation to optimize 5 key structural parameters of the helical axial flow pump impeller， aiming to improve the pressurization performance of the mixing pump. Using Fluent software and the standard SST k-ω turbulence model， numerical simulations are conducted on a singlestage compression unit of a helical axial flow pump with an impeller shaft diameter of 350 mm. The influence of five different structural parameters of the impeller on the pressurization performance is studied， and the optimal parameter combination is determined. The results show that under the operating conditions of a flow rate of 500 m3/h and a speed of 4500 r/min， the pressurization performance is optimal for a compression unit with three blades， a blade wrap angle of 130°， a blade thickness of 6 mm， and inlet and outlet angles of 6°， achieving 2.02 MPa， which is a 22% improvement in pressurization compared to the initial structure. Finally， numerical simulations are carried out on the optimized threestage mixing pump impeller under different operating conditions to predict the pressurization effect. The research results provide a theoretical basis for the design and optimization of underwater helical axial flow mixing pumps. Related Articles | Metrics

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Research on Development of Suction Bucket Foundation Technology in China Based on Patent Analysis MA Tianchi1, ZHENG Yuan2, NIU Guoxu3, CAO Minghe4 2024, 11 (4):  21-28.  DOI: 10.12087/oeet.2095-7297.2024.04.04 Abstract ( 131 )   PDF (4204KB) ( 18 )   In order to fill the gap in patent analysis of suction bucket foundation technology in China， this article analyzes the overall development trend， patent types and effectiveness， technology development stages， regional distribution， innovation entities， and hot areas of patent technology by using the method of bibliometrics that based on relevant patent data. The analysis results show that the patent technology of suction bucket foundation in China is in a rapid growth stage， with a high proportion of effective patents and nearly 60% of invention patents. The patent application areas are mainly concentrated in economically developed coastal areas， and the overall trend of regional development is from north to south. The proportion of enterprises among applicants is the highest， and hot technology fields are highly concentrated. In the future， the development of patent technology in China should focus on improving patent quality， balancing regional development， improving the cooperation of industryuniversityacademy， expanding the application fields of technology， and improving the rationality of technology field layout. Related Articles | Metrics

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Design and Analysis of Mooring System for Hexagonal Floating Photovoltaic Platform SUN Jiayang, CUI Yutao, REN Tie, WANG Yihou 2024, 11 (4):  29-35.  DOI: 10.12087/oeet.2095-7297.2024.04.05 Abstract ( 157 )   PDF (9090KB) ( 37 )   Floating photovoltaic platforms， recognized as the most promising technological development direction in the industry， have advantages such as wide application scenarios and low environmental pollution. Their development is of great significance for the development and utilization of offshore solar energy. However， the research on floating photovoltaic platforms in China started relatively late and is still in the empirical stage. As a positioning system for floating photovoltaic platforms， mooring systems can ensure stable operation under extreme sea conditions. Therefore， the design and selection analysis of mooring systems have important research value. This article compares the scattering mooring and group mooring forms of a floating photovoltaic platform in the waters of China， and explores the motion response characteristics and mooring line tension characteristics of different mooring forms of photovoltaic platforms under extreme sea conditions. The research results can provide reference for the reasonable selection and design of photovoltaic platform mooring systems. Related Articles | Metrics

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Domestically Produced Transformation and Application of Expansion Compressor Rotor Assembly LI Jiucheng 2024, 11 (4):  36-40.  DOI: 10.12087/oeet.2095-7297.2024.04.06 Abstract ( 127 )   PDF (5386KB) ( 6 )   Natural gas expansion compressor is the key equipment of natural gas terminal expansion refrigeration process， which plays a vital role in the recovery rate of natural gas byproducts. At present， all natural gas processing terminals use imported expansion compressor sets， but the imported compressor sets have large investment and high maintenance and spare parts costs in the later stage due to technical constraints. Two imported expansion compressors (1.2 million cubic meters/day) that have been used for many years and have frequent failures have been reformed domestically in a onshore terminal of Bohai oil and gas field. The localization transformation of expansion compressor rotor assembly mainly includes expansion end impeller， compression end impeller， main shaft， bearing， diaphragm shaft seal， connecting key and other auxiliary parts. For the first time， the rotor assembly of the imported expansion compressor of natural gas onshore terminal in Bohai area was localized， and the spare parts of the unit did not depend on imports， which was completely independently developed and produced in China. The supply channels were smooth， and the required maintenance spare parts could be purchased in the shortest time， and the technical core parameters were controlled to shorten the maintenance cycle， saving the later maintenance time and cost. The comparison results show that the field application effect of domestic unit parts is good， the unit has been running continuously for 78，840 hours without abnormality， and its performance far exceeds the service life of imported parts， which provides a good reference for similar projects of natural gas expansion refrigeration. Related Articles | Metrics

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Overview of the Development and Design of Dynamic Cable for Floating Offshore Wind Power in China LIN Zeyin, WANG Yibing, LI Dongsheng 2024, 11 (4):  41-46.  DOI: 10.12087/oeet.2095-7297.2024.04.07 Abstract ( 139 )   PDF (2023KB) ( 161 )   In recent years, the global offshore wind power has developed rapidly. As nearshore resources become increasingly scarce, offshore wind power has gradually moved to the deeper sea. To accommodate the dynamic characteristics of floating wind turbines, floating platforms must be supported by dynamic cables. This is a comprehensive cable of transmitting electricity and control signals, with constantly changing position and force status, which can withstand the combined effect of wind, wave, current and other natural environment, to ensure the effective transmission of power and monitoring signals. Compared with foreign industries, Chinas dynamic cable industry started later, with the harsh working conditions and the lack of relevant technology. All these factors restrict the progress of the dynamic cable industry. This paper will provide a detailed introduction to the basic principles, current development status, key technologies, and challenges faced by floating wind turbine dynamic cables, summarizing the latest industry information and technology to support the development of Chinas dynamic cable industry. Related Articles | Metrics

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The Application Risk and Control Measures of S420 Ultra High Strength Steel in Deep Water Jacket WANG Huoping, LUN Yuguo, WANG Deyang, XIAO Wangsui, PENG Yijin 2024, 11 (4):  47-52.  DOI: 10.12087/oeet.2095-7297.2024.04.08 Abstract ( 144 )   PDF (2510KB) ( 13 )   n Branch, CNOOC， Shenzhen 257237， Guangzhou China) Abstract Liuhua 11-1 jacket is the deepest deepwater jacket in Asia at present. Compared with shallow water jacket， Liuhua 11-1 jacket has the characteristics of high design risk， long construction cycle， high steel production technology and difficulty in welding. This paper will study the production process of S420 super-strength steel， jacket design risk， construction risk， dynamic performance， welding quality control measures and other aspects， so as to provide reference for similar deepwater jacket project management and control in the future. Related Articles | Metrics

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Research and Application of Solid Insulated Switchgear on Offshore Platform LI Tingting, WANG Xiaozhi, WANG Aiwu, WANG Jing, LI Xialing 2024, 11 (4):  53-57.  DOI: 10.12087/oeet.2095-7297.2024.04.09 Abstract ( 88 )   PDF (4429KB) ( 7 )   According to the miniaturization requirements of medium voltage switchgear on offshore platforms， based on the solid insulated switchgear technology， a series of removable products suitable for offshore oil and gas field environment are developed. This paper introduces the technical parameters， overall scheme and key technologies of this kind of products in detail. Through type test and third-party certification， the product can fully meet the needs of offshore oil and gas fields， and provide a new mediumvoltage switchgear solution for the miniaturization and lightweight design of marginal oil fields， modified expansion platforms， deep-water floating platforms， etc. Related Articles | Metrics

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Multibody Coupled Dynamics Analysis of the Dual Vessel Float-over Method for Wind Turbine Installation System ZHANG Ningbo1, AN Chen1, ZHAO Tianfeng1, GAO Songlin1, NI Haocheng1, ZHOU Zhenyu2 2024, 11 (4):  58-66.  DOI: 10.12087/oeet.2095-7297.2024.04.10 Abstract ( 115 )   PDF (7736KB) ( 12 )   In order to deal with the vibration and stress of key components caused by ship movement when installing wind turbines on double-ship float supports， this paper proposes a rigid-flexible coupling multi-body dynamics analysis method for load transfer during wind turbine installation. A rigid-flexible coupled multi-body dynamic model for the twinbarge float-over wind turbine installation was developed， considering the elastic deformation of key components and its impact on the overall system. Dynamic analysis of the installation and docking process of the wind turbine and foundation was performed， calculating acceleration and stress curves of the wind turbine and key components under various working conditions. The dynamic stress results and vibration characteristics were investigated， revealing that changes in the twin-barge motion period significantly affect the variation pattern of the wind turbine's stress curve. This study provides a theoretical basis for the structural design of the twin-barge float-over wind turbine installation system， contributing to improved stability and safety during the installation process. Related Articles | Metrics

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Hydrodynamic Study on the Probes of Expendable Bathythermograph HUANG Heyuan1, QIU Jiangliang1, LI Zhongsheng1, LIU Jinjian2 2024, 11 (4):  67-74.  DOI: 10.12087/oeet.2095-7297.2024.04.11 Abstract ( 94 )   PDF (5707KB) ( 19 )   The expendable bathythermograph (XBT) is capable of measuring hydrological data across ocean depth profiles， so the precision of the XBT probe's operational depth is crucial to the system's accuracy. Based on nonlinear hydrodynamic theory and integrated with large-eddy simulation methods， this paper establishes a scaled three-dimensional computational fluid dynamics (CFD) numerical model and nonlinear hydrodynamic motion equations. Through numerical analysis of the probe's external flow field characteristics， the drag coefficient is extracted and utilized as a boundary condition to solve for the solution which can estimate the motion depth. Experiments conducted to verify the accuracy of the motion depth estimated. The results reveal that the error in the drag coefficient calculated by the numerical model is less than 4.39%. The drag on the XBT probe originates from the stagnation zone at the head and the adverse pressure gradient flow in the middle section. Using the drag coefficient as a boundary condition， the second-order differential motion equation， known as the nonlinear falling equation (FRE)， can be derived. The hyperbolic arctangent analytical solution of the FRE exhibits a maximum velocity deviation of 6.2% and a distance deviation of 3.2% compared to experimentally measured values. This methodology provides accurate speed and depth references for the design and engineering application of XBT probes， laying a foundation for the digital integration of this type of product and enhancing the accuracy of depth calibration. Related Articles | Metrics

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Experimental Study on Platform Vortex Induced Motion Considering Wave Current Coupling Effect TANG Qianyu 2024, 11 (4):  75-84.  DOI: 10.12087/oeet.2095-7297.2024.04.12 Abstract ( 99 )   PDF (5727KB) ( 13 )   In order to further investigate the vortex motion response of the platform under wave-current coupling， this study conducted vortex motion tests of the platform under wave-current coupling for a deepwater semi-submersible production， storage and offloading platform in the Lingshui 17-2 gas field in the northern part of the South China Sea， which is planned to be developed by the China National Offshore Oil Corporation (CNOOC). The objective of the study is to characterize and quantify the vortex-excited motion response of the semi-submersible platform under different flow velocities， flow angles， and the presence or absence of wave action， in order to provide design inputs for the fatigue analysis of risers and moorings. We fabricated a 1∶60 scaled-down model of the semi-submersible platform， simulated purely homogeneous flow and wave-coupled environmental conditions through a towed pool， and tested the static stiffness， intrinsic period， and six-degree-of-freedom kinematic response of the platform. The results show that the vortex-excited motions of the semi-submersible platform are mainly characterized by transverse and longitudinal motions in the horizontal plane and first sway， with the transverse motion response being the most significant. Under the effect of uniform flow， the amplitude of transverse motion response at 45° flow angle is larger than that at 0° flow angle， and it reaches the maximum in the interval of folding speed from 5 to 7. The additional damping device effectively reduces the kinematic response， especially at 45° flow angle. The presence of waves has a weakening effect on the vortex-excited motion amplitude， which is especially significant at folding velocities close to 7. In addition， the experiments also observed that the longitudinal and first-swing motions exhibited different characteristics from those under uniform flow. The significance of this study is to provide important engineering data and theoretical support for the design of semi-submersible platforms in deep-sea oil and gas development， which can help to optimize the design of riser and mooring systems and ensure the safe and stable operation of the platforms in complex marine environments. Related Articles | Metrics

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Research on Analysis and Application of Non-Slide Construction and Loading Technology for Offshore Platform Jacket MA Deqiang, LUO Chao, WU Binbin, WEN Cai, JIANG Lei 2024, 11 (4):  85-88.  DOI: 10.12087/oeet.2095-7297.2024.04.13 Abstract ( 105 )   PDF (3552KB) ( 15 )   The feasibility of non slide horizontal construction and loading in the construction technology of jacket is discussed. A comparative study was conducted on the processes of slide construction and non slide construction， as well as the loading of Self-Propelled Modular Transporter and towed loading. Taking a certain jacket of Panyu as an example， this paper elaborates in detail on the construction process and key technologies of jacket and loading. The paper provides standardized processes and design processes for subsequent non slide construction projects of jacket structures， to improve the utilization rate of construction sites. It will play an important role in standardizing the construction of subsequent projects and building a maritime power. Related Articles | Metrics

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Analysis of Wave Slamming Impact on the Launching of Underwater Data Cabin XU Aijin 2024, 11 (4):  89-94.  DOI: 10.12087/oeet.2095-7297.2024.04.14 Abstract ( 109 )   PDF (7319KB) ( 57 )   In the process of subsea manifold hoisting and lowering， when the ship-cable-body multi-body coupling system moves greatly due to strong nonlinear environmental load， the cables of the hoisting system will change rapidly from slack to tensioning， resulting in the instantaneous surge of mooring impact tension， which may endanger the safe operation of the system. This article simulates the launching process of the underwater data center through fully coupled dynamic time-domain simulation. It considers the motion of ships and the effects of wind， waves， currents， and wave slamming， especially the impact of waves on the underwater data center when it first enters the water. Sensitivity analysis is conducted on the key parameters of wave slamming， accurately predicting the acceleration and six degrees of freedom of the data center when it enters the water， ensuring the smooth and safe entry of the underwater data center into the water. The research results provide certain theoretical and technical references for the design and offshore installation of underwater data centers in the future. Related Articles | Metrics

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Research on AUV Path Planning Method Based on Deep Sea Multi-Target Search Mission XU Chunhui1, 2, ZHOU Shihao1, 2, 4, QI Yu1, 2, FANG Tian1, 2, 3, YANG Shilin1, 2, 3 2024, 11 (4):  95-102.  DOI: 10.12087/oeet.2095-7297.2024.04.15 Abstract ( 120 )   PDF (4652KB) ( 14 )   Autonomous underwater robots (AUVs) can perform tasks such as resource exploration and target search in deep sea areas. At offshore sites, we often face the need to quickly respond to mission deployment and conduct path planning for AUV search and mapping missions. This paper proposes an AUV multi-target search method that clusters first and then searches in the AUV multi-suspect target point search task. It performs K-means clustering on multiple target points in the large-scale sea area to be measured to form multiple target points to be tested. The measurement area reduces the search for non-target areas and ensures higher search efficiency when the AUV carries limited energy; the comb path scheme is implemented in multiple areas to be measured to form an AUV search path in multiple areas. An AUV multi-target clustering search software based on Tkinter was developed to implement the method proposed in this article through visual interactive tools, solving the problems of time-consuming and error-prone manual planning and improving the efficiency of AUV deployment. Finally, We compare the length of AUV paths between different cluster numbers to determine the feasibility and application value of this method. Related Articles | Metrics

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Influence of Sea Condition on Tracking Accuracy and Control Energy Consumption of Unmanned Surface Vessels under Straight Line Navigation YONG Jiuqin1, 2, XUE Zhentao1, 2, CHEN Li1, 2 2024, 11 (4):  103-109.  DOI: 10.12087/oeet.2095-7297.2024.04.16 Abstract ( 150 )   PDF (2226KB) ( 208 )   Adaptability to various sea conditions is vital to unmanned surface vessels (USVs). This paper aims to reveal influence of sea conditions on tracking performance. The USV controlled by PID tuned for the baseline sea condition is studied. A three degree of freedom dynamic model is built， and a new evaluation index of control energy consumption accounting for propeller propulsion and steering mechanism operation is designed other than the conventional tracking accuracy. Simulation results demonstrate the variation trend of the tracking accuracy and control energy consumption with sea conditions under the typical straight line navigation case. The performance is significantly affected under high sea conditions， with root mean square error increasing 188 times up to 158.207m and control energy consumption increasing 3 times up to 46.916 kWh. The quantification of the tracking accuracy and control energy consumption with sea conditions provides reference for the design and control of USVs. Related Articles | Metrics

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Design and Application of the End-up System for the Suction Bucket Jacket WANG Shuai, YANG Guangjuan, WANG Xiaobin, HUANG Guilang, FAN Weiwei 2024, 11 (4):  110-116.  DOI: 10.12087/oeet.2095-7297.2024.04.17 Abstract ( 116 )   PDF (8455KB) ( 41 )   In response to the rapid development of offshore wind power equipment construction， relying on the existing suction bucket jacket construction project， this paper compares and analyzes the characteristics and performance of existing jacket hoisting technology， and innovatively designs a jacket end-up system according to project requirements， which is used for the vertical work of a 1400t jacket. The article analyzes and compares the advantages and disadvantages of the flipping system with traditional cranes， and uses finite element software to analyze the overall strength and stability of the end-up system. This system has been successfully applied in practical engineering， successfully end-up 50 sets of suction bucket jacket， proving the reliability and safety of the system， and providing the latest technical reference for the construction and installation of offshore wind power suction bucket jacket. Related Articles | Metrics

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Research on Key Technology of Monpile Foundation Installation in Offshore Wind Farms ZHANG Jianxiang, SONG Yunfeng, LU peng 2024, 11 (4):  117-124.  DOI: 10.12087/oeet.2095-7297.2024.04.18 Abstract ( 137 )   PDF (9251KB) ( 17 )   In light of the rapid development of offshore wind power， more economically efficient construction techniques are required. Traditional heavy-duty maritime cranes in construction face high costs and significant risks. On the other hand， the balloon-assisted floatation technology， with its low cost， ease of operation， and ability to reduce crane loads， presents itself as a potential alternative. This article provides an in-depth exploration of the theoretical foundation， technological design， and advantages of balloon-assisted floatation technology， elucidating its potential application prospects in offshore wind turbine single pile foundation construction. Research has shown that the balloon-assisted buoyancy technology offers significant advantages in terms of enhancing construction efficiency， reducing costs， and minimizing environmental impact. It is poised for broad applications in the offshore wind sector in the future. Related Articles | Metrics

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Exploration of Underwater Storage Facilities Application Scenarios CAI Wenjuan, CAO Pengwei, ZHAO Ming, ZHOU Qi 2024, 11 (4):  125-130.  DOI: 10.12087/oeet.2095-7297.2024.04.19 Abstract ( 144 )   PDF (4331KB) ( 95 )   Underwater storage facilities， leveraging oil-water displacement technology， serve as independent storage units that provide diversified media storage at sea and are essential for the development and utilization of marine energy. This paper analyzes five potential application scenarios for future underwater storage facilities， including the development of marginal oil fields in shallow waters， underwater energy storage technology， underwater methanol and ammonia storage technology， underwater carbon dioxide storage technology， and the storage and injection technology of chemical reagents on the seabed. In marginal oil fields， a combined approach using an integrated processing platform， underwater storage facilities， and shuttle tankers can enhance cost adaptability and the flexibility of storage capacity customization. Underwater energy storage technology (underwater compressed air energy storage and underwater hydrogen storage) is provided for offshore wind platforms to ensure the stability of power transmission and reduce the limitations of storage space on the platform. Offshore wind power can also be converted into methanol and ammonia， by adopting underwater storage solutions. The storage units on the platform can be canceled， thereby reducing overall investment. By installing LCO2 storage facilities underwater instead of storing it on the injection platform， the efficiency of LCO2 storage and its environmental adaptability can be improved. The use of seabed chemical reagent storage and injection technology significantly enhances the safety， cost-effectiveness， and injection accuracy of the chemical reagent system. Related Articles | Metrics