Simulations of subsea Risers/Conductors/Jumpers

Subsea Risers/Conductors analyses including multi-risers interference effects is performed whilst considering the combined effects of direct Fluid Structure Interactions (FSI) and Vortex Induced Vibrations (VIV) which we mitigate with the design of riser strakes and overall optimisation. We then assess the Inflow and Cross flow responses and the remaining fatigue lives.

Artificial Neural networks (ANNs) are excellent in the prediction, damage detection, online monitoring and controlling in offshore structures especially in cases where the formal Finite Element Analysis (FEA) is complicated and time consuming. Geanti uses state-of-the-art Artificial Neural Networks methodology for structural fatigue assessment and structural life extensions. From our experience as well as from several literature studies/surveys it has been proven that ANNs provide fairly accurate results compared to conventional FE methods in terms of fatigue life. Furthermore, long term erosion and corrosion experienced in such structures require complex analyses when using conventional FE Analysis techniques. ANNs are comparatively faster, reliable as well as computationally inexpensive and thus reduce the overall cost of life extension studies.

Geanti has the capability the following types of subsea analyses:

Pipelines (risers/flowlines) and subsea cables installation using Orcaflex.

Subsea structures installations such as PLET/PLEM.

FE analysis for Subsea Pipelines’ and Jumpers’ VIV using direct Fluid-Structure Interactions (FSI) and coupled Soil-Structure interactions.

Flow forces inside/outside the pipe, deflections/ stresses/vibrations, Inflow and Cross flow responses and Fatigue Life calculations due to VIV.

Jumper VIV fatigue analysis using DNV FatFree when the current direction has conservatively been presumed to be perpendicular to the M-shaped jumper span. The natural frequencies and unit diameter stresses for the VIV analysis are calculated using ABAQUS. Stress Concentration Factors (SCF) are calculated based on API Spec 5L with the weld misalignment value obtained from API 1104 also included in the SCF calculations