the pipeline end termination (PLET) structure and its connection to the suction piles that restrain the pipeline (these simulations provide the highly nonlinear force-deflection curves for use as the boundary conditions in the global pipeline thermal buckling simulation); cavity radiation simulations of the heat transfer between multiple flowlines/umbilicals in the turret of floating production platforms; thermal management simulations to ensure that the pipeline insulation design will maintain hydrocarbon temperatures during long shut-down conditions; and impact simulations to ensure that subsea structures can survive dropped object events.


2. Components of Deepwater Pipeline Systems


Unlike an onshore pipeline, a deepwater pipeline usually consists of more than just steel pipe, some valves and several compressor stations. A general layout of a deepwater pipeline system is shown in Figure 1. A deepwater pipeline is often attached at each end to a structure called a PLET (“Pipeline End Termination”). The PLET is connected to other components of the subsea development, such as a wellhead manifold, subsea tree or a riser base, by a secondary pipe structure called a jumper. The pipeline, often referred to as a flowline, may be a either a flexible composite structure or a rigid steel pipe. All of the examples discussed here in this paper are steel pipeline designs. The maintenance of the hydrocarbon fluid temperature is an important design consideration for deepwater pipeline systems. Various types of insulation designs are used to mitigate heat loss to the very cold ocean water. Umbilicals, which are not shown in Figure 1, are another important component of the deepwater production system. Umbilicals provide hydraulic fluid, electric power, chemical injection and data transmission to the subsea trees, pipelines, valves, sensors and other control instruments in the system.


2.1 The Flowline


Deepwater flowlines often have low diameter to wall thickness (D/t) ratios to meet the pressure containment requirements and collapse loads. The D/t ratios for deepwater flowlines range from 20 down to l0 or less. Given this D/t range most steel flowlines are manufactured from seamless pipe.


Figure 1. Schematic of deepwater pipeline system components. 2 2009 SIMULIA Customer Conference


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