Finite Element Analysis of a Steel Catenary Riser Transporting Gas-Liquid Slug Flow

Resumo

Steel catenary risers (SCRs) are main offshore structures that transport produced oil and gas from the seabed to floating units such as floating production storage and offloading (FPSO) units. This work analyzes the dynamic behavior of a steel catenary riser transporting internally a gas-liquid slug flow. A finite element formulation for computing elastic large displacement in planar and spatial frames, with consistent numerical implementation, is presented using Updated and Total Lagrangian approaches. To account for geometric changes as external forces are applied, the nonlinear solution is linearized in steps, each representing a load or time step. However, nonlinear terms are included to calculate the stiffness matrix due to the presence of large deformations. The Newmark numerical integrator was used, coupled with the Newton-Raphson method. The two-phase slug flow is model as a homogeneous mixture with timewise and spatially varying density. Numerical results are in good agreement with available experimental data in literature. The effects of the slug flow parameters on the dynamic behavior of the steel catenary riser are investigated.