Assessment of SYMS Survival Limit for “Peng Bo” FPSO During Installation

2010 ◽  
Author(s):  
Amal C. Phadke ◽  
Shihwei Liao ◽  
Donghui Chen
Keyword(s):  
Storm Event ◽  
Bohai Bay ◽  
Mooring System ◽  
Main Bearing ◽  
Restoring Force ◽  
Analysis Methodology ◽  
Rigid Frame ◽  
Bearing Load ◽  
Temporary Support ◽  
Ballast Tanks

The ConocoPhillips “Peng Bo” FPSO in Bohai Bay, China, is one of the largest FPSOs in the world. It was installed in early 2009 and first oil was achieved in May 2009. The FPSO is moored to a jacket platform in about 27m water depth via a Soft Yoke Mooring System (SYMS). The mooring system consists of two yoke arms (port and starboard) connected at the jacket end to a turn-table that sits on a main bearing at the top of the jacket. The other ends of the yoke arms are integrated with two large ballast tanks which are attached to two pendulums supported by a rigid frame mounted on the forward end of the FPSO. The ballast weights give rise to the necessary system surge restoring force while the turntable and bearing allow the FPSO to weathervane. The yoke arms and ballast tanks are pre-installed with empty ballast tanks mounted on two temporary support barges while awaiting the arrival of the FPSO. Upon arrival, the ballast tanks are attached to the pendulums from the FPSO side. The tanks are then filled with solid concrete ballast to achieve the design weight. Before the tanks are completely filled, the SYMS may not have sufficient restoring force in partially filled condition to prevent excessive pitching of the yoke arms and severe bearing load on the jacket beyond the design limit due to large FPSO offset in the event of an unforeseen storm event. An analysis was carried out to estimate the maximum bearing load and yoke arm pitch angle when the ballast tanks were 0%, 25%, 50%, and 75% full for 10-year and 100-year return period events. This paper describes the analysis methodology and results from the analysis. The overall project and installation experience are also discussed.

Research on the Static and Dynamics Characteristics of Soft Yoke Mooring System Based on Multi-Rigid Body Interaction

2020 ◽  
Author(s):  
Hongwei Wang ◽  
Zizhao Zhang ◽  
Gang Ma ◽  
Rongtai Ma ◽  
Jie Yang
Keyword(s):  
Time Domain ◽  
Rigid Bodies ◽  
Coupled Analysis ◽  
Mooring System ◽  
Accurate Analysis ◽  
Restoring Force ◽  
Stiffness Characteristics ◽  
The Time Domain ◽  
Multi Body ◽  
Good Agreement

Abstract Select the common mooring system-soft yoke mooring system as the research object. The soft yoke mooring system is regarded as a structure composed of multiple rigid bodies, and the theoretical analysis of multi-body dynamics is used to discuss the interaction of multi-rigid bodies. The classical HYSY113 FPSO is selected as an example, for the soft yoke mooring system, the stiffness characteristics and static restoring force curved compared with those of software OrcaFlex, and they are in good agreement, which verify the reliability of the formula derived, and it is a prerequisite for the accurate simulations in further steps. Coupled analysis to the whole system in time domain is also carried out both in OrcaFlex and AQWA, and the representative response of the FPSO under different environmental conditions is compared, the results are consistent well with each other. It is a good reference for the future study in this field. Good static characteristics are a prerequisite for accurate analysis of time-domain motion. By comparing the results in the time domain, it is found that under the same working conditions, the analysis results calculated by different commercial software (AQWA and OrcaFlex) may be different. We need to perform design analysis based on the characteristics of the software.

Stability Analysis of Two-Point Mooring System in Surge Oscillation

2010 ◽  
Vol 5 (2) ◽  
Author(s):  
A. K. Banik ◽  
T. K. Datta
Keyword(s):  
Harmonic Wave ◽  
Period Doubling ◽  
Mooring System ◽  
Restoring Force ◽  
Incremental Harmonic Balance ◽  
Cubic Polynomial ◽  
Motion Characteristics ◽  
The Stability ◽  
Continuation Technique ◽  
Amplitude Versus

Nonlinear surge response behavior of a multipoint mooring system under harmonic wave excitation is analyzed to investigate various instability phenomena such as bifurcation, period-doubling, and subharmonic and chaotic responses. The nonlinearity of the system arises due to nonlinear restoring force, which is modeled as a cubic polynomial. In order to trace different branches at the bifurcation point on the response curve (amplitude versus frequency of excitation plot), an arc-length continuation technique along with the incremental harmonic balance (IHBC) method is employed. The stability of the solution is investigated by the Floquet theory using Hsu’s scheme. The period-one and subharmonic solutions obtained by the IHBC method are compared with those obtained by the numerical integration of the equation of motion. Characteristics of solutions from stable to unstable zones, chaotic motion, nT solutions, etc., are identified with the help of phase plots and Poincaré map sections.

Study on Hysteretic Model and Damage Model of Multi-Ribbed Composite Wall

2006 ◽  
Vol 302-303 ◽  
pp. 644-650
Author(s):  
Quan Yuan ◽  
Qian Feng Yao ◽  
Ying Jie Jia
Keyword(s):  
Seismic Behavior ◽  
Structural Engineering ◽  
Damage Model ◽  
Hysteretic Model ◽  
Main Bearing ◽  
Seismic Properties ◽  
Concrete Members ◽  
Bearing Load ◽  
Composite Wall ◽  
Composite Walls

The use of composite materials in structural engineering is recent, and researchers need to investigate their behavior features. A new unit of multi-ribbed composite wall is introduced. A multi-ribbed composite wall is the main bearing-load member in multi-ribbed slab structures (MRSS). The bearing-load characteristics and seismic properties of the wall are different from those of other ordinary concrete members In order to study seismic behavior and durability of Multi-ribbed composite walls, experiments of 26 pieces of composite walls under cyclic loading were carried out, and then the hysteretic model of shear force–shear deformation is established. The hysteretic curves of typical composite walls are calculated. The calculated curves agree well with the experimental ones. The damage model is quantified. This study introduces a quantitative analysis means for evaluating seismic behavior aspects of damage and durability of multi-ribbed composite walls.

Statically Indeterminate Main Bearing Load Calculation in Frequency Domain for Usage in Early Concept Phase

2012 ◽  
Author(s):  
Tigran Parikyan ◽  
Thomas Resch
Keyword(s):  
Frequency Domain ◽  
Combustion Engine ◽  
Main Bearing ◽  
Engine Model ◽  
Bearing Load ◽  
3D Engine ◽  
Bearing Loads ◽  
And Performance ◽  
Engine Development ◽  
Early Concept Phase

The paper discusses the importance of a numerical method for fast and accurate prediction of main bearing loads of inner combustion engine and its place in the concept phase of engine development process. An approach based on linear dynamic analysis of 3D engine model in frequency domain is presented. Implemented within a separate module of AVL software package EXCITE Designer, it delivers a combination of accuracy and performance suitable for this task. An application example illustrates the method.

Design and Comparison of Catenary and Taut Mooring Systems for New Concept FPSO IQFP in Shallow Waters

2013 ◽  
Vol 353-356 ◽  
pp. 2670-2675 ◽  
Author(s):  
Tian Ying Wang ◽  
Li Jun Yang ◽  
Zhi Gang Xu ◽  
Jin Kun Liu
Keyword(s):  
Static Analysis ◽  
Time Domain ◽  
Horizontal Displacement ◽  
Static Characteristic ◽  
Lead Author ◽  
Shallow Waters ◽  
Mooring System ◽  
Characteristic Parameters ◽  
Restoring Force ◽  
Practical Experiences

In order to design an effective and economical multi-point mooring system for the new concept FPSO IQFP (fillet inverted quadrangular frustum pyramid shaped FPSO, presented by the lead author), the effects of the mooring parameters on the performance of catenary mooring system and taut mooring system were investigated according to the initial design plans given in advance according to the steady environment forces and practical experiences. Then, the optimal mooring systems were developed on the basis of the static analysis results combined with the coupled calculations in time domain. Finally, the merits and demerits of the two mooring schemes were compared based on the mooring and static characteristic parameters as well as the curves of restoring force against horizontal displacement of the catenary and taut mooring systems respectively. The results verify that the taut mooring system is preferable to the catenary mooring system for IQFP deployed in shallow waters.

Prediction of Hydrodynamic Damping of Moored Offshore Structures Using CFD

2019 ◽  
Author(s):  
Changqing Jiang ◽  
Ould el Moctar ◽  
Thomas E. Schellin
Keyword(s):  
Offshore Structures ◽  
Least Square ◽  
Navier Stokes ◽  
Coupled Analysis ◽  
Total System ◽  
Mooring System ◽  
Restoring Force ◽  
Hydrodynamic Damping ◽  
Restoring Forces ◽  
Decay Tests

Abstract Usually, mooring system restoring forces acting on floating offshore structures are obtained from a quasi-static mooring model alone or from a coupled analysis based on potential flow solvers that do not always consider nonlinear mooring-induced phenomena or fluid-structure interactions and the associated viscous damping effects. By assuming that only the mooring system influences the restoring force characteristics, the contribution of mooring-induced damping to total system damping is neglected. This paper presents a technique to predict hydrodynamic damping of moored structures based on coupling the dynamic mooring model with a Reynolds-averaged Navier-Stokes (RANS) equations solver. We obtained hydrodynamic damping coefficients using a least-square algorithm to fit the time trace of decay tests. We analyzed a moored offshore buoy and validated our predictions against experimental measurements. The mooring system consisted of three catenary chains. The analyzed response comprised the decaying oscillating buoy motions, the natural periods, and the associated linear and quadratic damping characteristics. Predicted motions, natural periods, and hydrodynamic damping generally well agreed to comparable experimental data.

Sign in / Sign up

Export Citation Format

Share Document