Nonlinear Response of Marine Riser due to Ocean Wave and Internal Flow

A marine riser is a flexible pipe used in offshore production. The application of the marine riser is in the form of production, and flow lines. According to environmental conditions, marine risers may experience large displacement and encounter with nonlinear dynamic responses. From literature review, there are a limit of research concerning riser transporting unstable flow. This paper presents the nonlinear response of marine risers while the riser undergoes large displacement. The equation of motion is derived based on the work-energy principle. The nonlinear finite element model formulation is then developed for solving the numerical results. In this study, the nonlinear responses of the marine riser are determined by using the Newmark time integration procedure. The effects of wave amplitude, wave frequency, current speed, and internal flow on the nonlinear response of marine risers are evaluated. It found that wave frequency would affect the response of riser quite a lot both in normal and tangential displacements. However, the effects of wave amplitude and frequency of the internal fluid rarely affect the response of riser.