Simulating an Offshore Capping Stack Using CONVERGE

Capping stacks are an essential component of containment systems to mitigate the consequences of oil spills or other subsea chemical disturbances. A capping stack’s primary purpose is to temporarily block the flow from the blowout preventer, providing engineers an opportunity to permanently seal the well head. CONVERGE’s volume of fluid (VOF) and fluid-structure interaction (FSI) modeling allow engineers to capture the real-world physics of offshore capping stack placement. Additionally, its fully autonomous meshing eliminates user meshing time for complex geometries and easily accommodates moving boundaries.

In this simulation, we used CONVERGE to model the placement of a capping stack. You can clearly see the different parts of this containment system, including the mooring cable, blowout preventer, and capping stack. We employed CONVERGE’s species-based VOF solver to simulate the oil and gas jet leaking out into the surrounding water. The mooring cable model enabled us to simulate the tethering cable, and we used CONVERGE’s rigid-body FSI to assess the interaction between the oil/gas jet and the capping stack.

The first view (0:00) shows a realistic rendering of the simulation geometry. The second view (0:17) depicts the capping stack and blowout preventer from a zoomed-in perspective. The isosurface of hydrocarbons exiting the faulty well head is colored by velocity with a rainbow color scheme. The final view (0:32) displays a vertical slice colored by velocity with the mesh overlaid. Fixed embedding is applied on the capping stack, and Adaptive Mesh Refinement is applied based on velocity, species, and void fraction.

Convergent Science's CONVERGE is an innovative computational fluid dynamics (CFD) software that eliminates the grid generation bottleneck from the simulation process through autonomous meshing.