Configuration analysis of deepwater S-lay pipeline

Abstract

The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline configuration has a remarkable effect on the structural behaviour of the tube. The special studies focus on the deepwater S-lay technique in the present paper. The stiffened catenary theory is applied to establish the static equilibrium governing differential equation of a pipe element, and the solution equations of the total pipeline configuration from a lay-barge over a stinger to the seabed are derived. The numerical iteration method for solving pipeline configuration is described in detail, and the corresponding program is developed to conduct the analysis of effects of various parameters such as laying water depth, pipe diameter, thickness of concrete weighted coating layer, stinger length, control strain, and axial tension on pipeline configuration. The results show that the laying water depth, the submerged weight of the pipe, and the axial tension are the critical factors influencing pipeline configuration. In addition, geometrical parameters of the stinger such as length, radius, and shape have an important effect on the pipe-laying capacity of the vessel. The validity of the program is further verified by means of a comparison with results obtained from the commercial finite element software OFFPIPE.

Numerical Investigation into Freak Wave Effects on Deepwater Pipeline Installation

“…The maximum responses occurred at the center position xp = 0 m with a peak axial tension of 4550. 13 x p =-200 m…”

“…These non-linear features could cause some difficulties for analytical approaches and experimental tests to obtain accurate and comprehensive simulations. As a consequence, numerical techniques are preferred for modeling systematical behaviors of offshore pipelines in the S-lay process [13][14][15]. Gong et al [16] and Gong and Xu [17] developed a full FEM on the basis of OrcaFlex to simulate the structural behaviors of pipeline installation and explored the influence of normal sea states on the pipeline responses.…”

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

“…In linear theory, when the motion of the pipelaying vessel and waves are assumed to be small, the hydrostatic restoring forces are linear and proportional to the respective displacements of the body, and are simply represented by f hs (t) = −Cx(t) (10) where C is the hydrostatic restoring matrix.…”

“…Brewer examined the impact of pipelaying barge motions on suspended pipelines using quasi-static procedures and an extended stiffened catenary concept [9]. In recent years, some researchers have analyzed the S-laying pipeline configuration using the stiffened catenary technique and proposed a co-rotational finite element formulation integrated with Bernoulli's beam theory for assessing offshore pipeline configurations and stresses in S-laying operations [10].…”

Mathematical Model of Pipeline Abandonment and Recovery in Deepwater

“…By the means of extensive numerical studies, Kashani and Young [7] found that in ultradeepwater pipeline laying problem the installation parameters were sensitive to pipe wall thickness. Gong et al [8,9] made a parameter sensitivity analysis of Slay technique for deepwater pipelines. The stiffened catenary theory was applied to establish the governing differential equations.…”