Development of an LNG Tandem Offloading System Using Floating Cryogenic Hoses - Breaking the Boundaries of LNG Transfer in Open Seas

Author(s):  
Benjamin Mauriès ◽  
François Lirola
Keyword(s):  
Author(s):  
Jean Pierre F. Queau ◽  
Giorgio E. Torre

In 2005, SBM Offshore recognized that in future offshore Floating LNG Production Units, key enabling technologies would be required to ensure the safe and reliable tandem offloading to LNG Carriers. The foundation was thus laid down for the development of the COOL™ Hose: A cryogenic marine floating hose that would enable the tandem offloading between two vessels offshore. This paper presents, after an introduction to the COOL™ Hose design (Hose in Hose concept-HiH), the different steps in the qualification process following the EN1474-2 [1] guidelines and recommendations for design and testing of LNG transfer hoses. This qualification process has been endorsed by two Classification Societies ABS and DNV and has resulted in a Certificate of Fitness for Service from DNV and a Product Design Assessment Certificate from ABS making the SBM COOL™ Hose, the first EN1474-2 qualified LNG floating hose.


Author(s):  
Haibo Chen ◽  
Torgeir Moan ◽  
Sverre Haver ◽  
Kjell Larsen

Tandem offloading safety between FPSO and shuttle tanker is under concern. A few collisions between the two vessels have happened in the North Sea in recent years. In these incidents, excessive relative motions (termed as surging and yawing in this paper) between FPSO and tanker are identified as “failure prone situations” which have contributed to the initiation of most collision incidents. To quantitatively assess the probability of surging and yawing events, and more importantly, to effectively reduce their occurrence in tandem offloading operation, we present a simulation-based approach in this paper, which is carried out by a state-of-the-art time-domain simulation code SIMO. The SIMO simulation models are setup and calibrated for a typical North Sea purpose-built FPSO and a DP shuttle tanker. This 2-vessel system motion in tandem offloading is simulated. The simulated relative distance and relative heading between FPSO and tanker are analyzed by fitting their extreme values into statistical models. This gives out probabilities of surging and yawing events. Sensitivity studies are performed to analyze contributions from various technical and operational factors. Measures to minimize the occurrence of surging and yawing from design and operational point of view are proposed.


Author(s):  
Zhibin Zhong ◽  
Yong Luo ◽  
Dusan Curic

Mooring design for F(P)SOs in West of Africa offshore environment is in many cases governed by the squall driven condition. In the past, the squall condition was typically analyzed by using the peak wind speed with associated wind direction. However, due to its inherent transient nature, the squall event formulated in the time history with varying wind speed and direction is more appropriate and could be potentially more critical for the mooring system design. This approach has been adopted in the design and analysis of recent F(P)SO mooring systems. The F(P)SOs are turret-moored in various water depths in offshore West of Africa. A series of squall time histories have been applied to predict the global responses of the F(P)SO in the time domain. Each squall time history, which provides a unique combination of wind speed and direction variations, is analyzed in five nominal directions covering a sector of 90 degrees from East to West. Squall time histories are also applied to analyze the tandem offloading operation. The results are compared with those of the conventional constant wind speed approach and a few interesting observations are made. The paper also provides some insights into the F(P)SO yaw motions, as well as their relations to the changing wind direction. Analysis results demonstrate that using the squall time series with changing wind speed and direction is more critical than the conventional constant wind speed approach in the tandem offloading scenario. It is therefore recommended that mooring analysis using squall time series should at least be used for the tandem offloading simulations.


Author(s):  
Kazuhiro Yukawa ◽  
Takayuki Asanuma ◽  
Hiroshi Sato ◽  
Shunji Kato ◽  
Tatsuya Takaoki ◽  
...  
Keyword(s):  

Author(s):  
Wei Gao ◽  
Xiaoliang Qi ◽  
Jin Wang

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.


2015 ◽  
Author(s):  
Xiaochuan Yu ◽  
Liqing Huang

Squalls are intense, low-level winds associated with storms, and they always begin suddenly and last for minutes. They are characterized by large variation of wind speeds. Squalls control the design wind condition for floating production, storage and offloading systems (FPSOs) off the coast of West Africa. In this paper, an internal turret mooring system is designed to study the effects of squalls on the prediction of extreme tensions and offsets, which will be compared with the results from the way of using constant wind speed. Various statistic values of extreme tensions will be calculated and applied in the design. The differences between these values will also be discussed. Finally, the tandem offloading analysis is also performed in order to calculate the extreme hawser loads for the purpose of hawser line design.


2003 ◽  
Vol 126 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Haibo Chen ◽  
Torgeir Moan ◽  
Sverre Haver ◽  
Kjell Larsen

Excessive relative motions between Floating Production Storage Offloading Unit (FPSO), and tanker, which are termed as excessive surging and yawing events, are identified as the “failure prone situation” in tandem offloading. These events have contributed to the initiation of tanker drive-off in most collision incidents that happened in the North Sea in recent years. To estimate and reduce the probability of excessive surging and yawing events in tandem offloading, a simulation-based approach, which is based on a state-of-the-art time-domain simulation code SIMO, is presented in this paper. A typical North Sea FPSO and a DP shuttle tanker simulation models are setup in SIMO and calibrated by full-scale measurements. The simulated relative distance and relative heading between FPSO and tanker are analyzed by fitting their extreme values into statistical models which give out probabilities of excessive surging and yawing events. Sensitivity studies are performed to pinpoint contributions from various technical and operational factors. Measures to minimize the occurrence of excessive surging and yawing events are identified in design and operational perspectives.


1992 ◽  
Author(s):  
G.J. Feikema ◽  
R.H.M. Huijsmans ◽  
A.B. Aalbers

Author(s):  
Jaap de Wilde ◽  
Jorrit-Jan Serraris ◽  
Erik-Jan de Ridder ◽  
Marie-Laure Be´cel ◽  
Jean-Robert Fournier

LNG FPSOs are being developed for production and processing of gas in remote offshore locations. The floating production unit is positioned over the reservoir and replaces the offshore platform, the pipeline to shore, the onshore LNG plant and the jetty. Alternatively, the LNG FPSO can be utilized to liquefy and export the associated gas, produced by one or several production units. Side-by-side offloading and stern-to-bow (tandem) offloading are the main options for the direct transfer of the cryogenic product from the FPSO to the LNG shuttle tanker. For stern-to-bow we can further distinguish between a hawser mooring (passive) or a dynamic positioned shuttle tanker (active). Experience suggests that the side-by-side operation is limited to relative benign metocean conditions, whereas a stern-to-bow arrangement allows for offloading in more severe sea states in which larger maneuverability area and large capacity mooring equipments are required. This paper discusses a first investigation of LNG stern-to-bow offloading with dynamic positioned shuttle tankers, based on a basin model test program. The shuttle tanker was controlled by a full closed loop DP system which is largely identical to real DP systems, including extended Kalman filtering, PID control and thruster allocation. The modeling of the azimuthing thrusters, rudder and main propeller is discussed in the paper, as well as the modeling of the relative position between the two ships. Some results of the model test program are presented.


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