A Numerical Analysis of the Internal Flow Effect on the Riser’s Mechanical Behavior

Pipes are widely deployed in the offshore environment especially in the petroleum industry where rigid and flexible pipes are used for the well drilling and hydrocarbon production. Whereas during drilling, a mixture of drilling mud, rock cuttings and sometimes gas flows through the drilling riser; during production mono or multiphase (comprising oil, water and gas) flow takes place within the production system. However up till now, most of the studies on offshore pipelines and risers have been focused on the pipe structure and its interaction with hydrodynamic forces and offshore platforms. In particular for numerical computation studies and reduced scale model experiments, the pipe is usually modeled as a tensioned beam and sometimes only the internal pressure is taken into account with other effects due to its internal flow being neglected. This paper presents a study on the influence of the internal flow on the pipe’s dynamics. The mechanical behavior of the pipe is modeled using the Consistent Mass and the Finite Element Method (FEM); the effect of an inviscid internal flow is also included. Numerical simulations in time domain have been carried out. Discussion about the experimental results and numerical simulation is also featured.