Structural Response Analysis Of Subsea Jumper Under Seismic Loads

In subsea oil/gas production system, a subsea jumper is a short pipe connector used to transport production fluid between two subsea components, for example, tree and manifold, manifold and manifold, or manifold and export sled. It may also connect other subsea structures such as PLEM/PLETS (Pipeline End Manifold/ Pipeline EndTerminations) and riser bases. In addition to production fluid, it can also be a pipe by which water/chemicals are injected into the well. In the analysis of the ultimate strength due to boundary displacement of subsea jumper, Ultimate strength of subsea jumper caused by different degrees of the boundary displacement are discussed. With the results of different displacement degrees lead to different parts of jumper reaching ultimate strength, hereafter three degrees are chosen to draw the ultimate strength envelop of the three degree displacements.Dynamic responses of the subsea jumper in subsea production facility under earthquake are analyzed. Seismic waves are input into subsea jumper in both horizontal and vertical direction, the nonlinear springs are used to simulate the soil- jumper interaction, and hydrodynamic forces due to earthquake are considered. Different models are analyzed and compared. It shows that vertical earthquake has more magnificent effect on the horizontal frequency of jumper dynamic response than the magnitude, the soil- jumper interaction increases the magnitude and stimulates higher modals, and hydrodynamic forces have great influence on magnitude. In conclusion, the proposed approach provides strategy to the subsea jumper design and safety assessment.As the subsea jumper is a particular structure, the lowest part of the jumper probably interacts with sea-bed. Three different interaction models due to P-y curve are compared, which are linear spring element, nonlinear spring element and PSI element, based on the different dynamic response, advantages disadvantages of different models are analyzed.