Global to Local Model Interface for Deepwater Top Tension Risers

The water depths from which oil and gas are being produced are reaching several thousand feet. Deep water risers are pipe structures that extend from the floating vessels to the bottom of the sea. In order to capture the time dependent, geometrically non-linear response of the global system with the complex multicomponent response of local details and properly analyze the riser and its interaction with subsea equipment and vessels it is necessary to use several different models. A global model is used to analyze the global response of the riser to various environmental conditions and local models to analyze the interface between the riser components. Global models usually employ finite elements such as nonlinear (large deflection) beam or pipe elements with highly simplified boundary conditions (fixed, pinned, springs, etc.) Local models are usually built of 3D solid elements with much more detailed boundary conditions, often using contact elements, to realistically predict local response of the particular components. In this paper the methodology of analytical interfacing and data transmission between the local and global models is described. The example of the interface between the global and local model for the deep water top tension risers is included.

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