What term is used to refer to the use of thrusters to keep a semisubmersible rig over the drill hole?

• A. Riserless drilling
• B. Marine Riser
• C. Anchored mooring
• D. Dynamic Positioning

Answer: (C)

Dynamic Positioning is the term for keeping a semisubmersible rig over the drill hole using thrusters. It’s a computerized system that continuously monitors the rig’s position and automatically commands the thrusters to counteract wind, waves, and current, allowing precise, non-anchored station keeping. Anchored mooring uses fixed anchors on the seabed to hold position, which is a different method and doesn’t rely on thrusters. Riserless drilling and Marine Riser relate to whether a riser is used, not how the vessel maintains its position. So the thruster-based, over-the-well control described is Dynamic Positioning.