As an important part of lifeline engineering in the development and utilization of marine resources, the submarine fluid-filled pipeline is a complex coupling system which is subjected to both internal and external fl...As an important part of lifeline engineering in the development and utilization of marine resources, the submarine fluid-filled pipeline is a complex coupling system which is subjected to both internal and external flow fields. By utilizing Kennard＇s shell equations and combining with Helmholtz equations of flow field, the coupling equations of submarine fluid-filled pipeline for n=0 axisymmetrical wave motion are set up. Analytical expressions of wave speed are obtained for both s=1 and s=2 waves, which correspond to a fluid-dominated wave and an axial shell wave, respectively. The numerical results for wave speed and wave attenuation are obtained and discussed subsequently. It shows that the frequency depends on phase velocity, and the attenuation of this mode depends strongly on material parameters of the pipe and the internal and the external fluid fields. The characteristics of PVC pipe are studied for a comparison. The effects of shell thickness/radius ratio and density of the contained fluid on the model are also discussed. The study provides a theoretical basis and helps to accurately predict the situation of submarine pipelines, which also has practical application prospect in the field of pipeline leakage detection.展开更多
With the acceleration of the investigation and development of marine resources,the detection and location of submarine pipelines have become a necessary part of modern marine engineering.Submarine pipelines are a typi...With the acceleration of the investigation and development of marine resources,the detection and location of submarine pipelines have become a necessary part of modern marine engineering.Submarine pipelines are a typical weak magnetic anomaly target,and their magnetic anomaly detection can only be realized within a certain distance.At present,a towfish or an autonomous underwater vehicle(AUV)is mainly used as the platform to equip magnetometers close to the submarine pipelines for magnetic anomaly detection.However,the mother ship directly affects the towfish,thus causing control interference.The AUV cannot detect in real time,which affects the magnetic anomaly detection and creates problems regarding detection efficiency.Meanwhile,a two-part towed platform has convenient control,thus reducing the interference of the towed mother ship and real-time detection.If the platform can maintain constant altitude sailing through the controller,the data accuracy in the actual magnetic anomaly detection can be guaranteed.On the basis of a two-part towed platform,a magnetic detection system with constant altitude sailing ability for submarine pipelines was constructed in this study.In addition,experimental verification was conducted.The experimental verification research shows that the constant altitude sailing experiment of the two-part towed platform verifies that the platform has good constant altitude sailing ability in both a hydrostatic environment and the actual marine environment.Meanwhile,the offshore magnetic anomaly detection experiment of submarine pipelines verifies the stable measurement function of the magnetic field and the function of the system to detect magnetic anomaly of submarine pipelines.展开更多
海洋石油单点系泊(Single Point Mooring,SPM)系统被广泛应用于海洋油气田开发,是海上石油运输的中转终端,采用合理的检测方案以保障其安全性是海洋石油工程领域备受关注的问题。声学探测、目视检测是常用的单点系泊系统外检测技术。本...海洋石油单点系泊(Single Point Mooring,SPM)系统被广泛应用于海洋油气田开发,是海上石油运输的中转终端,采用合理的检测方案以保障其安全性是海洋石油工程领域备受关注的问题。声学探测、目视检测是常用的单点系泊系统外检测技术。本研究基于EdgeTech 6205组合式双频侧扫声呐与条带式多波束测深系统、Innomar SES 2000参量阵浅地层剖面仪、国产FIFISH PRO W6水下机器人等调查装备,介绍了声学探测技术和目视检测技术在国内某单点系泊系统外检测中的应用实例。探测结果表明,该单点系泊区域地形整体平坦,局部受侵蚀冲刷影响,区域内有6条锚链沟发育,锚链沟深度为1.0-4.5 m,锚链摆动小,浮筒稳定性较好;管道埋藏类型分为完全埋藏型、浅埋藏型、裸露型3类。通过综合分析对比,查明了锚链被大量生物附着、腐蚀速度加快的具体位置,提出了定期进行防腐蚀除锈维护的有效建议。展开更多
A new distributed optical fiber sensor system for long-distance oil pipeline leakage and external damage detection is presented. A smart and sensitive optical fiber cable is buried beneath the soil running along the o...A new distributed optical fiber sensor system for long-distance oil pipeline leakage and external damage detection is presented. A smart and sensitive optical fiber cable is buried beneath the soil running along the oil pipeline, which is sensitive to soakage of oil products and mechanical deformation and vibration caused by leaking, tampering, and mechanical impacting. The region of additional attenuation can be located based on the optical time domain reflectometry （OTDR）, and the types of external disturbances can be identified according to the characteristics of transmitted optical power. The Golay codes are utilized to improve the range-resolution performance of the OTDR sub-system and offer a method to characterize the transmitted optical power in a wide range of frequency spectrum. Theoretic analysis and simulation experiment have shown that the application of Golay codes can overcome the shortcomings of the prototype based on the conventional single-pulse OTDR.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.50905036)
文摘As an important part of lifeline engineering in the development and utilization of marine resources, the submarine fluid-filled pipeline is a complex coupling system which is subjected to both internal and external flow fields. By utilizing Kennard＇s shell equations and combining with Helmholtz equations of flow field, the coupling equations of submarine fluid-filled pipeline for n=0 axisymmetrical wave motion are set up. Analytical expressions of wave speed are obtained for both s=1 and s=2 waves, which correspond to a fluid-dominated wave and an axial shell wave, respectively. The numerical results for wave speed and wave attenuation are obtained and discussed subsequently. It shows that the frequency depends on phase velocity, and the attenuation of this mode depends strongly on material parameters of the pipe and the internal and the external fluid fields. The characteristics of PVC pipe are studied for a comparison. The effects of shell thickness/radius ratio and density of the contained fluid on the model are also discussed. The study provides a theoretical basis and helps to accurately predict the situation of submarine pipelines, which also has practical application prospect in the field of pipeline leakage detection.
基金the support of the Fund of State Key Laboratory of Ocean Engineering(GKZD010068,GKZD010074,GKZD010075).
文摘With the acceleration of the investigation and development of marine resources,the detection and location of submarine pipelines have become a necessary part of modern marine engineering.Submarine pipelines are a typical weak magnetic anomaly target,and their magnetic anomaly detection can only be realized within a certain distance.At present,a towfish or an autonomous underwater vehicle(AUV)is mainly used as the platform to equip magnetometers close to the submarine pipelines for magnetic anomaly detection.However,the mother ship directly affects the towfish,thus causing control interference.The AUV cannot detect in real time,which affects the magnetic anomaly detection and creates problems regarding detection efficiency.Meanwhile,a two-part towed platform has convenient control,thus reducing the interference of the towed mother ship and real-time detection.If the platform can maintain constant altitude sailing through the controller,the data accuracy in the actual magnetic anomaly detection can be guaranteed.On the basis of a two-part towed platform,a magnetic detection system with constant altitude sailing ability for submarine pipelines was constructed in this study.In addition,experimental verification was conducted.The experimental verification research shows that the constant altitude sailing experiment of the two-part towed platform verifies that the platform has good constant altitude sailing ability in both a hydrostatic environment and the actual marine environment.Meanwhile,the offshore magnetic anomaly detection experiment of submarine pipelines verifies the stable measurement function of the magnetic field and the function of the system to detect magnetic anomaly of submarine pipelines.
文摘海洋石油单点系泊(Single Point Mooring,SPM)系统被广泛应用于海洋油气田开发,是海上石油运输的中转终端,采用合理的检测方案以保障其安全性是海洋石油工程领域备受关注的问题。声学探测、目视检测是常用的单点系泊系统外检测技术。本研究基于EdgeTech 6205组合式双频侧扫声呐与条带式多波束测深系统、Innomar SES 2000参量阵浅地层剖面仪、国产FIFISH PRO W6水下机器人等调查装备,介绍了声学探测技术和目视检测技术在国内某单点系泊系统外检测中的应用实例。探测结果表明,该单点系泊区域地形整体平坦,局部受侵蚀冲刷影响,区域内有6条锚链沟发育,锚链沟深度为1.0-4.5 m,锚链摆动小,浮筒稳定性较好;管道埋藏类型分为完全埋藏型、浅埋藏型、裸露型3类。通过综合分析对比,查明了锚链被大量生物附着、腐蚀速度加快的具体位置,提出了定期进行防腐蚀除锈维护的有效建议。
基金This work was supported by the R&D Foundation of China National Petroleum Corporation (CNPC) (No.2001411-4)by the Natural Science Foundation of Henan Province (No. 0511052700).
文摘A new distributed optical fiber sensor system for long-distance oil pipeline leakage and external damage detection is presented. A smart and sensitive optical fiber cable is buried beneath the soil running along the oil pipeline, which is sensitive to soakage of oil products and mechanical deformation and vibration caused by leaking, tampering, and mechanical impacting. The region of additional attenuation can be located based on the optical time domain reflectometry （OTDR）, and the types of external disturbances can be identified according to the characteristics of transmitted optical power. The Golay codes are utilized to improve the range-resolution performance of the OTDR sub-system and offer a method to characterize the transmitted optical power in a wide range of frequency spectrum. Theoretic analysis and simulation experiment have shown that the application of Golay codes can overcome the shortcomings of the prototype based on the conventional single-pulse OTDR.
