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.

Unlocking the Potential of Complex Marginal Reservoir in Highly Mature Oil Field, XiJiang24 South China Sea

2013 ◽  
Author(s):  
Luo Donghong ◽  
Yan Zhenghe ◽  
Gao Xiaofei ◽  
Rao Zhihua ◽  
Du Ding Yu ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Oil Field ◽  
China Sea

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.

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