Global elastic stability of marine risers

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6073033

Kokkinis, T

Marine risers are slender tubular columns connecting the well at the seabed to the drill structure at the ocean surface. They are prone to global static instability under the combined action of their weight, tension applied at their top and fluid static pressure forces from the water and the fluid inside them. A nonlinear mathematical model consisting of a second order equation with integral boundary terms and end rotation conditions is developed and discretized by the finite element method. It can be reduced to the equations of the classical stability theory by linearization. The stability boundaries in the space of the riser's dimensionless effective weight and dimensionless lower end effective tension are studied for the purpose of determining the effect of internal and external pressure, bending rigidity and boundary conditions. It is shown that risers may buckle globally even when they are in tension over their entire length due to internal pressure. The phenomenon of buckling in tension may occur even for relatively short risers and moderate values of the density of the fluid inside the riser. Lateral load and structural imperfections may cause the actual buckling tension to be higher than that predicted theoretically in the case of unstable postbuckling behavior. The actual buckling tension is determined by locating the limit point on the equilibrium path of riser.

• OSTI ID: 6073033
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300* -- Petroleum-- Drilling & Production
42 ENGINEERING
423000 -- Engineering-- Marine Engineering-- (1980-)
DEFORMATION
FAILURES
FINITE ELEMENT METHOD
MARINE RISERS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
NUMERICAL SOLUTION
OFFSHORE PLATFORMS
OIL WELLS
PIPES
STABILITY
TENSILE PROPERTIES
WELLS