Failure to model representative pipeline geometries during the design phase of new multiphase pipelineprojects can result in poor pipeline operating flexibility which could lead to deferred production andreduced ultimate hydrocarbon recovery. Detailed analyses of high resolution bathymetric data andout-of-straightness pipeline surveys have revealed that indicators can be practical flow assurance tools forthe modeling of multiphase pipeline profiles:1. The Terrain Indicator can be used to quickly quantify the roughness of pipeline topographies andto anticipate the influence of route selection on hydrodynamic phenomena such as liquid accumulationand slugging.2. When only low resolution bathymetry is available, regional regressions of roughness indicatorscan be used to create pipeline geometries that are representative of the actual seabed roughness fora better prediction of operating envelopes.3. Roughness indicators can be used to fingerprint the roughness of existing pipeline topographiesand to characterize geomorphic features of the seafloor.Reducing noise in raw survey data is essential for pertinent characterizations of the seafloor andpipeline profiles. Noise in data from seabed and out-of-straightness surveys can be reduced through asmoothing technique combining a moving average and a linear least squares fit. According to highresolution survey data, the span of this moving average should be equivalent to the length of one pipejoint; i.e. 40 feet or 12.2 meters. Before the completion of onerous Finite Element simulations foron-bottom roughness analyses, the same smoothing technique can be applied to the transformation ofbathymetric data into representative pipeline geometry. The span of the moving average required for thistransformation appears to be equivalent to the length of one double pipe joint.Two examples are presented to illustrate the application of flow assurance indicators to the design oflong subsea tiebacks.
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