Numerical Simulations of Dynamic Pipeline-Vessel Response on a Deepwater S-Laying Vessel

Abstract

The dynamic action induced on offshore pipelines by deepwater S-laying is significant, and directly determines how the pipeline structures are designed and installed. Existing research has not fully investigated the benefits of coupling models of pipeline and pipelaying vessel motions. Therefore, this paper presents a coupled time-domain numerical model for examining the effect of coupled dynamic reactions. The coupled model takes into account the motion of the pipelaying vessel, surface waves, ocean currents, wind forces, pipeline dynamics, and contact between the rollers and the pipeline. A proportional, integral, derivative (PID) controller was used for simulating the control of the pipelaying vessel. The hydrodynamic forces that the pipeline experiences were modeled using the Morison equation. The model was solved using Newmark's method and verified using OrcaFlex software. The model was then used to analyze practical operations: the laying of a 22" gas export pipeline on the seabed by the pipelaying vessel HYSY201 in the Pingbei-Huangyan gas fields in the East China Sea. The effects of coupled factors on pipelaying vessel motions and pipeline dynamics were approximated. These effects included configurations, axial tensions, and bending moments. The results show a significant connection between the dynamic responses of the pipelines and pipelaying vessel motions.S-laying method, the pipeline is supported using a stinger and passes over a regular roller sequence forming an S-shaped trajectory before landing on the seabed, as illustrated in Figure 1. The upper curved S-shaped parts that rest on stingers are called overbends and are followed by inflection points where the pipeline curvature is zero. Before approaching the seafloor, the pipeline is reversed into a sagbend. Horizontal tension in the pipeline is maintained by mounted tensioner devices on the top of the pipeline. Consequently, S-laying operations depend on roller configuration and stinger radius. Large plastic deformation occurs when pipes pass over stingers. The plastic deformation is caused by the combined effects of the pipelaying vessel motion, roller reaction forces, axial tensions, and bending moments [5,6].Processes 2018, 6, x FOR PEER REVIEW 2 of 22 the S-laying method, the pipeline is supported using a stinger and passes over a regular roller sequence forming an S-shaped trajectory before landing on the seabed, as illustrated in Figure 1. The upper curved S-shaped parts that rest on stingers are called overbends and are followed by inflection points where the pipeline curvature is zero. Before approaching the seafloor, the pipeline is reversed into a sagbend. Horizontal tension in the pipeline is maintained by mounted tensioner devices on the top of the pipeline. Consequently, S-laying operations depend on roller configuration and stinger radius. Large plastic deformation occurs when pipes pass over stingers. The plastic deformation is caused by the combined effects of the pipelaying vessel motion, roller reaction forces, axial tensions, an...

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