Steel Catenary Riser-Seabed Interaction Due to Caspian Sea Environmental Conditions

This paper investigates the integrated riser/vessel system which is subjected to random waves. Riser pipelines are the main components of the oil and gas offshore platforms. Whereas Iran country has been located on the fringes of Caspian Sea deep water, therefore study and research in this area is increasingly essential. The fluctuation of floating production causes the severe response and greatest fatigue damage near the Touchdown Point (TDP) where the Steel Catenary Riser (SCR) first touches the seabed. Therefore, analysis the response of SCRs in the TDP is very important to approximate the behavior of the riser. In this study, initially, the structural parameters (wall thickness and diameter) according to design codes due to the severe climatic conditions are obtained. In the next step, Pipe-soil interaction is modelled using a linear model in the vertical direction and Coulomb friction models in the lateral direction. Also, the significance of SCR-seabed interaction in the global response of riser pipeline at TDP when subjected to random waves on soft clay is analyzed based on the Caspian Sea environmental conditions. A fully three-dimensional non-linear time domain finite element program with a robust meshing technique has been applied to simulate the arbitrarily large deflections of the flexible from the initial configuration by using the commercial software OrcaFlex.