Collapse Simulations of an Accidentally Dropped Drill Riser
- Brad Skinner (INPEX Australia Pty Ltd) | Hema Wadhwa (INTECSEA Pty Ltd) | Arya Majed (INTECSEA)
- Document ID
- International Society of Offshore and Polar Engineers
- The 28th International Ocean and Polar Engineering Conference, 10-15 June, Sapporo, Japan
- Publication Date
- Document Type
- Conference Paper
- 2018. International Society of Offshore and Polar Engineers
- blowout preventer, nonlinear dynamic substructuring, Dropped object, drill riser, finite element model, seabed impact zone, impact energy
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- 27 since 2007
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An accidentally dropped drill riser/blowout preventer (BOP) system can pose extreme and costly hazard to subsea facilities. High-fidelity multi-body nonlinear dynamic simulations are required to accurately predict the propagating axial compression waves along the riser due to BOP's seabed impact, the evolution of the collapse of the riser, riser impact energies, the riser seabed layout, and the resulting impact zone to better manage risks.
The nonlinear simulations must involve detailed finite element models (FEMs) to accurately capture the stiffness and mass distribution along the riser span, the asymmetrical bending stiffness/mass contribution and axial slip from the auxiliary lines, nonlinear behavior at the flex joint, and the flange/flange joint connections. These effects are critically important in the modeling the propagation of the compression waves that speed through the riser from the point of BOP impact and initiate the drill riser buckling and post-buckling dynamics/collapse.
To incorporate detailed FEM and at the same time maintain computational efficiency and accuracy, nonlinear dynamic substructuring (NDS) is utilized. NDS extends the frame work of dynamic substructuring to nonlinear problems enabling highly efficient multibody nonlinear system level simulations while maintaining the accuracy of individual FEM components. The multi-body NDS solver utilized for efficient computation of this large-order multi-physics problem enables the coupling of four physical models: (i) nonlinear dynamics, (ii) hydrodynamics, (iii) flexible body dynamics, and (iv) multi-body dynamics. Each model's response can be influenced by the other three response models’ actions and vice-versa, resulting in a complex highly coupled nonlinear simulation model.
The simulations demonstrate that for this drill riser configuration, the top unbuoyed sections play a key role in the collapse process of the drill riser. The seabed impact zone and impact energies to assess potential impact with seabed infrastructure are discussed.
High-fidelity dropped object simulations are required to better assess and manage risks during drilling operations (Majed and Cooper, 2013). This includes the accidental drop of drill joints as well as entire drill riser/blow out preventer (BOP) systems. Accurate predictions of dropped object trajectories and kinetic energies provide operators with insights into the consequences from the drop and the extent of the damage.
|File Size||1 MB||Number of Pages||8|