Fundamental Analysis for the SWING Motion of Single Moored FPSO in South China Sea

2012 ◽  
Author(s):  
Yu Ma ◽  
Zhiqiang Hu ◽  
Yan Qu
Keyword(s):  
South China Sea ◽  
Model Test ◽  
South China ◽  
Hydrodynamic Model ◽  
Low Frequency ◽  
Full Scale ◽  
Mooring System ◽  
Fundamental Analysis ◽  
China Sea ◽  
Short Period

FPSO moored by STP mooring system plays a dominate role in oil and gas production in South China Sea. To study its hydrodynamic characters, a joint industry project on full scale measurement for Fenjin FPSO, headed by Shanghai Jiao Tong University and sponsored by CNOOC, was initiated in October 2007 and lasted for 25 months. During the project, a special phenomenon, named as SWING, was noticed. When a SWING happened, the FPSO’s heading angle would change greatly within a relatively short period, beyond the normal range of the weather-vane effect. Due to the large low-frequency motion, the tension forces of mooring system would increase greatly. Also, it may lead to positioning failure during the tandem offloading operation. So, the SWING motion is a great threat to the safety of FPSOs. A preliminary prediction for its cause as well as a fundamental analysis of its hydrodynamic mechanism is completed in this paper. According to the statistical results of the SWING based on the Fenjin’s motion data during the full scale measurement as well as the corresponding wind wave and current data in the same period, a plausible prediction for its cause is provided. It is pointed out that the change of direction and velocity of the current within a short time might be the cause of SWING. The research for the mechanism of the SWING is carried out through both the methods of analytical analysis and the model test. A hydrodynamic model is built to simulate the low-frequency motions of FPSO in time domain. And an in-house MATLAB program is written on the basis of the hydrodynamic model, to do the calculation. Analysis results are compared with the full-scale measured data, to prove the cause prediction. Furthermore, on purpose of validating the program, a model test was conducted in Deepwater Offshore Basin in Shanghai Jiao Tong University. Several different current velocities were chosen in the test. The program results show a good agreement with both the data of full scale measurement and the model test results, which indicates that the hydrodynamic model and the code are both credible.

Observation and inversion of very-low-frequency seismo-acoustic fields in the South China Sea

2020 ◽  
Vol 148 (6) ◽  
pp. 3992-4001
Author(s):  
Shuyuan Du ◽  
Jingpu Cao ◽  
Shihong Zhou ◽  
Yubo Qi ◽  
Lei Jiang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Low Frequency ◽  
The South China Sea ◽  
Acoustic Fields ◽  
The South ◽  
Very Low Frequency ◽  
China Sea ◽  
And Inversion

Low frequency ambient noise modeling and comparison with field measurements in the South China Sea

2019 ◽  
Vol 148 ◽  
pp. 34-39 ◽  
Author(s):  
JianBo Zhou ◽  
Minhui Zhang ◽  
ShengChun Piao ◽  
Kashif Iqbal ◽  
Ke Qu ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Ambient Noise ◽  
Low Frequency ◽  
Field Measurements ◽  
The South China Sea ◽  
The South ◽  
Noise Modeling ◽  
China Sea

Study of Tandem Offloading System for a New Concept Spar FPSO

2014 ◽  
Author(s):  
Wei Gao ◽  
Xiaoliang Qi ◽  
Jin Wang
Keyword(s):  
South China Sea ◽  
Numerical Simulations ◽  
Model Test ◽  
South China ◽  
Time Domain ◽  
Oil Field ◽  
Hydrodynamic Performance ◽  
China Sea ◽  
Oil Storage ◽  
Tandem Offloading

A new concept Spar FPSO (Floating Production Storage and Offloading) is proposed for South China Sea deepwater oil field development integrating the advantages of the deep-draft Spar concept whose excellent stability and global performance enables dry-tree drilling and production, and the conventional ship-shaped FPSO for oil storage and offloading. This paper presents a study of the tandem offloading system for the new concept Spar FPSO. The paper will first give an overview of various offloading configurations and their characteristics for deepwater development; then a tandem offloading system similar to conventional ship-shaped FPSO is recommended for further investigation considering operational experience, safety and economical benefits. As the offloading operations are generally weather-limited, offloading environmental conditions for the study are selected based on API, ABS and South China Sea offshore operation practices. For a case study, hydrodynamic performance of the Spar FPSO in tandem offloading configuration with a shuttle tanker in 1500m water depth was investigated numerically and experimentally. Numerical simulations were conducted by means of fully coupled nonlinear time-domain analysis. The distance between the shuttle tanker and the Spar FPSO is optimized based on the relative motions of the two floaters and the hawser tension requirement of the shuttle tanker. Experimental results from model test are presented and compared with analytical time-domain simulation results. It is shown that the results of numerical simulations are consistent with the model test. The tandem offloading system demonstrates robust performance and cost-effectiveness for the proposed Spar FPSO concept.

Research and Design on Internal Turret Mooring System of FPSO in South China Sea

2014 ◽  
Author(s):  
Liu Huaxiang ◽  
Li Da ◽  
Bai Xueping ◽  
Wang Jianping ◽  
Zhang Baolei
Keyword(s):  
South China Sea ◽  
System Design ◽  
South China ◽  
Design Procedure ◽  
Design Parameters ◽  
Design Criteria ◽  
Mooring System ◽  
Environmental Condition ◽  
China Sea ◽  
Research And Design

This paper mainly introduced the research and design procedure, method and conclusion for internal turret mooring system of FPSO in South China Sea. According to the environmental condition characteristic and operating experience of FPSO in South China Sea and other reasons, the permanent internal turret mooring system with disconnected function is recommended as the final scenario after comparison with the other internal turret systems including disconnected system in typhoon condition and permanent system without disconnected function. For the gradually bad environmental conditions such as wind, wave and current in South China Sea, 500-year return typhoon condition is required as the extreme design condition of mooring system. According to the environmental condition distribution and classification requirement, the design standards, rules and corresponding design parameters for 500-year return condition are determined as the basis of mooring system design. The mooring system is very difficult to design because of very shallow water for catenary system and 500-year return typhoon environmental condition in South China Sea. For the problems appeared because of 500-year return extreme design condition and other parameters, a reliable solution was proposed from the aspect of wave characteristics research and got approval from classification society. The new design criteria for mooring system of FPSO in South China Sea is updated and the mooring system design is completed based on the updated design criteria. The research and design procedure and method for internal turret mooring system of FPSO in South China Sea are summarized too. This paper can be helpful to the similar projects in South China Sea.

scholarly journals Size-resolved aerosol and cloud condensation nuclei (CCN) properties in the remote marine South China Sea – Part 1: Observations and source classification

2017 ◽  
Vol 17 (2) ◽  
pp. 1105-1123 ◽  
Author(s):  
Samuel A. Atwood ◽  
Jeffrey S. Reid ◽  
Sonia M. Kreidenweis ◽  
Donald R. Blake ◽  
Haflidi H. Jonsson ◽  
...  
Keyword(s):  
South China Sea ◽  
Biomass Burning ◽  
South China ◽  
Cloud Condensation Nuclei ◽  
Marine Aerosol ◽  
Condensation Nuclei ◽  
Accumulation Mode ◽  
China Sea ◽  
Population Type ◽  
Short Period

Abstract. Ship-based measurements of aerosol and cloud condensation nuclei (CCN) properties are presented for 2 weeks of observations in remote marine regions of the South China Sea/East Sea during the southwestern monsoon (SWM) season. Smoke from extensive biomass burning throughout the Maritime Continent advected into this region during the SWM, where it was mixed with anthropogenic continental pollution and emissions from heavy shipping activities. Eight aerosol types were identified using a k-means cluster analysis with data from a size-resolved CCN characterization system. Interpretation of the clusters was supplemented by additional onboard aerosol and meteorological measurements, satellite, and model products for the region. A typical bimodal marine boundary layer background aerosol population was identified and observed mixing with accumulation mode aerosol from other sources, primarily smoke from fires in Borneo and Sumatra. Hygroscopicity was assessed using the κ parameter and was found to average 0.40 for samples dominated by aged accumulation mode smoke; 0.65 for accumulation mode marine aerosol; 0.60 in an anthropogenic aerosol plume; and 0.22 during a short period that was characterized by elevated levels of volatile organic compounds not associated with biomass burning impacts. As a special subset of the background marine aerosol, clean air masses substantially scrubbed of particles were observed following heavy precipitation or the passage of squall lines, with changes in observed aerosol properties occurring on the order of minutes. Average CN number concentrations, size distributions, and κ values are reported for each population type, along with CCN number concentrations for particles that activated at supersaturations between 0.14 and 0.85 %.

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