Which rigs usually utilize a subsea blowout control system?

• A. Drill ships only
• B. Floating production storage and offloading
• C. Jackups and drillships
• D. Drilling ships and semisubmersibles

Answer: (D)

Subsea blowout control systems sit on the seabed and are controlled from the surface, allowing control of the well when a riser connects a moving vessel to the well. This arrangement is essential for floating drilling units, where the rig remains above the water while the wellbore and subsea components stay fixed to the seabed. Drilling ships and semisubmersibles are the floating rigs that routinely drill with a riser connected to the seabed, so they typically use a subsea BOP stack controlled from the rig via hydraulic lines and ROVs. Jackups, being fixed to the seabed in shallower waters, usually employ surface BOPs mounted on the rig rather than subsea systems. Floating production units aren’t drilling in the same way, so subsea BOPs are associated with drilling operations on floating rigs. Therefore, drilling ships and semisubmersibles are the rigs that usually utilize a subsea blowout control system.