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Shunfeng Gong - One of the best experts on this subject based on the ideXlab platform.

  • Numerical Investigation of Deepwater S-Lay Pipeline Under Freak Waves
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2020
    Co-Authors: Pu Xu, Shunfeng Gong
    Abstract:

    Abstract Freak wave is an extreme sea state with unexpected and huge wave height, which becomes a potential risk for lay barge and offshore pipeline during deepwater installation. In order to investigate the dynamic responses of deepwater S-lay pipeline induced by freak waves, this study developed a comprehensive numerical model with the particular consideration of the freak wave effect. An enhanced superposition method of combined transient wave trains and random wave trains was presented, and a series of freak wave trains were generated. The induced Pipelay Vessel motions were simulated by the use of displacement response amplitude operators (RAOs). The pipe–stinger roller interactions in the overbend and the cyclic contacts between the pipeline and seabed soil in the touchdown zone (TDZ) were fully taken into consideration. The developed S-lay model was subsequently utilized to calculate the dynamic responses of the Pipelay Vessel and offshore pipeline under random waves and freak waves for a comparison. The results illustrated the remarkable influence of freak waves on the systematic behaviors of deepwater S-laying pipeline, which offer a significant theoretical basis for the pipe structure design and Pipelay operation safety.

  • Numerical Investigation into Freak Wave Effects on Deepwater Pipeline Installation
    Journal of Marine Science and Engineering, 2020
    Co-Authors: Pu Xu, Zhixin Du, Shunfeng Gong
    Abstract:

    Freak waves are an extreme marine environment factor in offshore structure design and become a potential risk, particularly for laying oil-gas pipelines in deep waters. The objective of this study was to reveal the freak wave effects on dynamic behaviors of offshore pipelines for deepwater installation. Thus, a dedicated finite element model (FEM) for deepwater pipeline installation by the S-lay method was developed with special consideration of freak waves. The FEM also took Pipelay Vessel motions, pipe–stinger roller interactions, and the cyclic contacts between the pipeline and seabed soil into account. Real Vessel and stinger data from an actual engineering project in the South China Sea were collected to obtain an accurate simulation. Moreover, an effective superposition approach of combined transient wave trains and random wave trains was introduced, and various types of freak wave trains were simulated. Extensive numerical analyses of a 12 inch gas pipeline being installed into a water depth of 1500 m were implemented under various freak wave conditions. The noticeable influences of freak waves on the pipeline and seabed responses were identified, which provides significant awareness of offshore pipelines for deepwater installation design and field operation monitoring.

  • Numerical simulation on dynamic behaviour of deepwater J-lay systems
    Ocean Engineering, 2020
    Co-Authors: Shunfeng Gong, Tao Zhang, Xipeng Wang
    Abstract:

    Abstract The J-lay method is a comparatively feasible way to install offshore pipelines with larger diameter and heavier submerged weight in deepwater and ultra-deepwater area. In this paper, a full finite element model (FEM) for deepwater J-lay systems was established using the software OrcaFlex to study the actual dynamic Pipelay effects, which are mainly caused by hydrodynamic forces and Pipelay Vessel motions. Meanwhile, a nonlinear hysteretic soil model was employed to characterise the vertical pipe-seabed interactions, and the modified Coulomb friction model was applied to simulate the lateral pipe-seabed interactions. An explanatory example about a steel pipeline being installed to the seabed of 1500 m water depth in the LW3-1 gas field of South China Sea was introduced to carry out the numerical analysis. The dynamic behaviour of the J-lay pipeline in terms of top effective tension, bending moment, seabed resistance and pipeline embedment in the touchdown zone (TDZ) was quantitatively evaluated. The comparisons between static and dynamic results of J-lay pipelines and between J-lay and S-lay dynamic results with identical Pipelay conditions except for the departure points were carried out, respectively, in which the more noticeable dynamic effects are observed for deepwater J-lay pipelines.

  • Parametric Study on Dynamic Tension Behaviour of Offshore Pipeline for Deepwater S-lay Operation
    E3S Web of Conferences, 2018
    Co-Authors: Pu Xu, Shunfeng Gong, Ting Zhang, Cheng Chen
    Abstract:

    In recent years, higher demands for offshore pipeline design of deepwater installation are put forward. This paper mainly aims to investigate the influence of Pipelay parameters on dynamic tension behaviour of deepwater S-lay pipeline to optimize the design of pipe structure and tensioner. A full finite element model for deepwater S-lay systems is developed to simulate the dynamic response of offshore pipeline from the Pipelay Vessel via stinger to the seabed. The influences of water depth, outer diameter and submerged self-weight of the pipe, and stinger length on the dynamic tension behaviour of the pipeline have been quantitatively studied. A strong relevance between the axial tension of offshore pipeline and Pipelay parameters is observed, which offers very intuitive evidences for the design of pipe structure and tensioners.

  • Influences of pipe–soil interaction on dynamic behaviour of deepwater S-lay pipeline under random sea states
    Ships and Offshore Structures, 2016
    Co-Authors: Shunfeng Gong, Pu Xu
    Abstract:

    ABSTRACTThe pipe–soil interactions have an important influence on the dynamic behaviour of offshore pipelines in the touchdown zone (TDZ) during deepwater S-lay. This paper mainly aims to reveal the dynamic behaviour of the pipeline in the TDZ, and its actual dynamic lay effects. A full finite element model for deepwater S-lay systems is primarily developed to simulate the dynamic responses of offshore pipeline from the Pipelay Vessel via the stinger to the seabed, in which Pipelay Vessel motions, pipeline hydrodynamics, clashing contacts between the pipeline and the stinger rollers and pipe–seabed interactions are considered particularly. The numerical analysis of an illustrative case for a gas export pipeline being installed to a water depth of 1500 m in the South China Sea is carried out in the time domain using the commercial computer code OrcaFlex. The influences of seabed soil models, soil characteristics, submerged self-weight of the pipe, surface waves, and Pipelay Vessel motions on the dynamic be...

Pu Xu - One of the best experts on this subject based on the ideXlab platform.

  • Numerical Investigation of Deepwater S-Lay Pipeline Under Freak Waves
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2020
    Co-Authors: Pu Xu, Shunfeng Gong
    Abstract:

    Abstract Freak wave is an extreme sea state with unexpected and huge wave height, which becomes a potential risk for lay barge and offshore pipeline during deepwater installation. In order to investigate the dynamic responses of deepwater S-lay pipeline induced by freak waves, this study developed a comprehensive numerical model with the particular consideration of the freak wave effect. An enhanced superposition method of combined transient wave trains and random wave trains was presented, and a series of freak wave trains were generated. The induced Pipelay Vessel motions were simulated by the use of displacement response amplitude operators (RAOs). The pipe–stinger roller interactions in the overbend and the cyclic contacts between the pipeline and seabed soil in the touchdown zone (TDZ) were fully taken into consideration. The developed S-lay model was subsequently utilized to calculate the dynamic responses of the Pipelay Vessel and offshore pipeline under random waves and freak waves for a comparison. The results illustrated the remarkable influence of freak waves on the systematic behaviors of deepwater S-laying pipeline, which offer a significant theoretical basis for the pipe structure design and Pipelay operation safety.

  • Numerical Investigation into Freak Wave Effects on Deepwater Pipeline Installation
    Journal of Marine Science and Engineering, 2020
    Co-Authors: Pu Xu, Zhixin Du, Shunfeng Gong
    Abstract:

    Freak waves are an extreme marine environment factor in offshore structure design and become a potential risk, particularly for laying oil-gas pipelines in deep waters. The objective of this study was to reveal the freak wave effects on dynamic behaviors of offshore pipelines for deepwater installation. Thus, a dedicated finite element model (FEM) for deepwater pipeline installation by the S-lay method was developed with special consideration of freak waves. The FEM also took Pipelay Vessel motions, pipe–stinger roller interactions, and the cyclic contacts between the pipeline and seabed soil into account. Real Vessel and stinger data from an actual engineering project in the South China Sea were collected to obtain an accurate simulation. Moreover, an effective superposition approach of combined transient wave trains and random wave trains was introduced, and various types of freak wave trains were simulated. Extensive numerical analyses of a 12 inch gas pipeline being installed into a water depth of 1500 m were implemented under various freak wave conditions. The noticeable influences of freak waves on the pipeline and seabed responses were identified, which provides significant awareness of offshore pipelines for deepwater installation design and field operation monitoring.

  • Parametric Study on Dynamic Tension Behaviour of Offshore Pipeline for Deepwater S-lay Operation
    E3S Web of Conferences, 2018
    Co-Authors: Pu Xu, Shunfeng Gong, Ting Zhang, Cheng Chen
    Abstract:

    In recent years, higher demands for offshore pipeline design of deepwater installation are put forward. This paper mainly aims to investigate the influence of Pipelay parameters on dynamic tension behaviour of deepwater S-lay pipeline to optimize the design of pipe structure and tensioner. A full finite element model for deepwater S-lay systems is developed to simulate the dynamic response of offshore pipeline from the Pipelay Vessel via stinger to the seabed. The influences of water depth, outer diameter and submerged self-weight of the pipe, and stinger length on the dynamic tension behaviour of the pipeline have been quantitatively studied. A strong relevance between the axial tension of offshore pipeline and Pipelay parameters is observed, which offers very intuitive evidences for the design of pipe structure and tensioners.

  • Influences of pipe–soil interaction on dynamic behaviour of deepwater S-lay pipeline under random sea states
    Ships and Offshore Structures, 2016
    Co-Authors: Shunfeng Gong, Pu Xu
    Abstract:

    ABSTRACTThe pipe–soil interactions have an important influence on the dynamic behaviour of offshore pipelines in the touchdown zone (TDZ) during deepwater S-lay. This paper mainly aims to reveal the dynamic behaviour of the pipeline in the TDZ, and its actual dynamic lay effects. A full finite element model for deepwater S-lay systems is primarily developed to simulate the dynamic responses of offshore pipeline from the Pipelay Vessel via the stinger to the seabed, in which Pipelay Vessel motions, pipeline hydrodynamics, clashing contacts between the pipeline and the stinger rollers and pipe–seabed interactions are considered particularly. The numerical analysis of an illustrative case for a gas export pipeline being installed to a water depth of 1500 m in the South China Sea is carried out in the time domain using the commercial computer code OrcaFlex. The influences of seabed soil models, soil characteristics, submerged self-weight of the pipe, surface waves, and Pipelay Vessel motions on the dynamic be...

  • The influence of sea state on dynamic behaviour of offshore pipelines for deepwater S-lay
    Ocean Engineering, 2016
    Co-Authors: Shunfeng Gong, Pu Xu
    Abstract:

    The dynamic response of offshore pipelines induced by deepwater S-lay is highly noticeable, and directly dominates the design of such structures and the installation feasibility in practice. A comprehensive finite element model for deepwater S-lay systems using the software OrcaFlex is specially developed to explore the influences of sea state on the pipeline dynamic responses, considering surface waves, ocean currents, Pipelay Vessel motions, clashing contact between the pipeline and rollers. Meanwhile, a non-linear hysteretic soil model is applied to simulate the vertical pipe–seabed interaction, and the modified Coulomb friction model is used to model the lateral pipe–seabed interaction. The numerical model is then used to carry out an illustrative example analysis of a 12-in. gas export pipeline being laid onto the seabed with a water depth of 1500 m using the HYSY 201 Pipelay Vessel in the LW3-1 gas field in the South China Sea under various sea states. The influences of sea state on the pipeline dynamic behaviour on aspects of configuration, lateral displacement, axial tension, bending moment, stress and strain as well as pipeline embedment are estimated quantitatively. The findings show that a strong relevance exists between surface wave and resulting Pipelay Vessel motions, and pipeline dynamic responses.

Gullik A. Jensen - One of the best experts on this subject based on the ideXlab platform.

  • A nonlinear PDE formulation for offshore Vessel pipeline installation
    Ocean Engineering, 2010
    Co-Authors: Gullik A. Jensen, Niklas Safstrom, Tu Duc Nguyen, Thor I. Fossen
    Abstract:

    Abstract In this paper a nonlinear dynamic PDE formulation for a pipe string suspended from a Pipelay Vessel to the seabed in a Pipelay operation is developed. This model extends a three-dimensional beam model capable of undergoing finite extension, shearing, twist and bending, to apply for marine applications by adding the effects of restoring forces, hydrodynamic drag and seabed interaction. The model is validated against the natural catenary equation and the FEM code RIFLEX. The model is extended to include the Pipelay Vessel dynamics by applying a potential theory formulation of a surface Vessel, suited for dynamic positioning and low speed maneuvering, as a boundary condition for the PDE. This system is found to be input–output passive and stable. Pipeline installation applications where the presented model is suited are e.g., analysis and simulation of the installation operation, operability analysis, hardware-in-the-loop (HIL) testing for Vessel control systems, and automation of the Pipelay operation.

  • Mathematical Models for Model-Based Control in Offshore Pipelay Operations
    Volume 3: Pipeline and Riser Technology, 2009
    Co-Authors: Gullik A. Jensen, Thor I. Fossen
    Abstract:

    This paper considers mathematical models for model-based controller design in offshore Pipelay operations. Three classes of models for control design are discussed, real-world models suitable for controller design verification, controller and observer models which are used on-line in the control system implementation. The control application place requirements on the model with respect to the computational time, dynamic behavior, stability and accuracy. Models such as the beam model, two catenary models, as well as general finite element (FE) models obtained from computer programs were not able to meet all of the requirements, and two recent dynamic models designed for control are presented, which bridge the gap between the simple analytical and more complex FE models. For completeness, modeling of the Pipelay Vessel, stinger and roller interaction, soil and seabed interaction and environmental loads are discussed.Copyright © 2009 by ASME

  • Modelling and Control of Offshore Marine Pipeline during Pipelay
    IFAC Proceedings Volumes, 2008
    Co-Authors: Gullik A. Jensen, Aksel Andreas Transeth, Tu Duc Nguyen
    Abstract:

    Abstract A model suited for control tasks is developed for a submerged offshore pipe during the Pipelay operation. The pipe is fixed in the touchdown point at the seabed in one end and attached to a Pipelay Vessel in the other end. The developed model is discrete and is on the form of the robot equation with minimal coordinates. Thus the methods of controller synthesis and stability analysis can be applied directly. The model constitutes a hyper redundant system and it is shown that this system is passive. A PID-controller has been suggested. The simulation results are in agreement with the theoretical results.

Jeremy Beckman - One of the best experts on this subject based on the ideXlab platform.

E P Heerema - One of the best experts on this subject based on the ideXlab platform.

  • major deepwater Pipelay Vessel starts work in north sea
    Oil & Gas Journal, 1998
    Co-Authors: E P Heerema
    Abstract:

    Industry`s deepwater Pipelaying capability has received a boost this year with the entry into the world`s fleet of Solitaire, a dynamically positioned Pipelay Vessel of about 350 m including stinger. The converted bulk carrier, formerly the Trentwood, will arrive on station in the North Sea and begin laying pipe this month on Statoil`s Europipe II project, a 600-km, 42-in. OD gas pipeline from Norway to Germany. Next year, the Vessel will install pipe for the Exxon U.S.A.`s Gulf of Mexico South Diana development (East Breaks Block 945) in a water depth of 1,643 m and for Mobil Oil Canada as part of the Sable Island Offshore and Energy Project offshore Nova Scotia. Using the S-lay mode, Solitaire is particularly well-suited for laying large lines economically, including the deepwater projects anticipated for the US Gulf of Mexico. Table 1 presents Solitaire`s technical specifications. The design, construction, Pipelaying, and justification for building Vessels such as the Solitaire are discussed.