Numerical Modeling of Suction and Trench Formation at the Touchdown Zone of Steel Catenary Riser

Abstract

Steel catenary risers (SCR) are widely used in deepwater oil and gas production. The riser–seabed–water interaction near the touchdown zone is one of the main concerns in the design of fatigue life of SCR. During upward displacement, suction develops under the riser and a trench might be formed when it separates from the seabed near the touchdown point. In the subsequent downward movement, the riser penetrates through this trench to the seabed. Therefore, modeling of suction and trench formation is very important. In the existing models available in the literature for uplift resistance, these factors are incorporated using empirical relationships. It is also recognized that the available finite-element (FE) modeling techniques for this large-deformation problem are computationally very expensive, although penetration behavior can be simulated. In the present research program, both penetration and uplift behavior are simulated using FE and computational fluid dynamics (CFD) approaches. The simulation results for penetration are presented in Hawlader et al. (