Analysis of Dynamic Stress Propagation in Subsea Pipeline and Flow Line Systems

Abstract

Offshore pipeline and flow line systems define a variety of subsea architectures associated with Floating Production Storage and Offloading units (FPSOs) or Floating Storage and Offloading units (FSOs) that are usually employed for oil and gas production in deep and ultra deep waters. The design of such transmission facilities, must satisfactorily account for various phenomena such as hydrodynamic wave loading, fluid transport velocity, operating pressure and temperature of the internal fluid as well as limitations imposed by the seabed subsoil layer geotechnical properties. In fact the transverse and longitudinal dynamic responses of these pipeline and flow line systems are strongly modulated by these effects. In this paper, the effect of transverse and longitudinal vibrations on the dynamic stresses induced by the fluid flow, is studied with special reference to onset of buckling or bursting of such pipes. For this purpose, an offshore pipeline is idealized as a fluid conveying elastic beam on an elastic foundation. In particular, by employing integral transforms, an analytic solution for the induced stresses is computed and simulated for design applications while comparison with corresponding formulae currently in use in the field is also carried out.