Session: 04-03-01 Rigid Risers

Submission Number: 180903

Lazy Wave Riser Dynamical Behavior Under Slug Flow: a Parametric Analysis 

Steel lazy-wave risers (SLWR) are commonly considered in the offshore industry as an alternative for deepwater gas and oil exploitation, as their floatation alleviates the top tension and touchdown (TDP) movements. Although there are some works on the topic, the whole understanding of their dynamic behavior under multi-phase flows is an open issue. Their particular geometric configuration is prone to accumulating gas bubbles.

Multiphase flow is a complicated phenomenon that requires complex models to be analyzed, even if the flow-structure interaction is not considered. But given the flow parameters, like density, pressure, and mass flux, one can study the effect of the multiphase flow on the SWLR dynamics in a one-way manner. There are commercial computer codes dedicated to riser analysis that can do this job.

This paper focuses on a parametric analysis of the response of a typical deepwater SLWR to slug flows, assessing the effects of such flows on the riser's structural behavior. The main flow parameters are varied realistically to study the effects of each parameter on the riser's dynamical response, considering displacements, tension, stresses, and fatigue.

The program Orcaflex™ is used to do the job. That program has more than one method to input the flow parameters, and all those methods were tested and compared.

Presenting Author: Rodrigo Provasi University of São Paulo

Presenting Author Biography: Rodrigo Provasi is currently an assistant professor in the department of Structural and Geotechnical Engineering in University of São Paulo. His background is from a graduation course in Mechatronics Engineering and PhD in Computational Mechanics, in which he focused on developing methods and tools for Offshore flexible pipes and umbilical cables analysis.
He is also part of the LMO - Offshore Mechanics Laboratory, which is well-known in the offshore industry with more than 30 years working as partner of the largest offshore players.

Authors:

Rodrigo Provasi University of São Paulo
Ramon Rangel Dos Santos University of São Paulo
Celso Pupo Pesce University of São Paulo
Clovis De Arruda Martins University of São Paulo