Why does the weight and drag of the BOP stack (which hangs below the drillship via the riser) affect the vessel's DP capability and the DP model?

A. The riser acts as a mooring-like restoring force when the vessel offsets from directly above the wellhead — this is included in the DP mathematical model as a riser tension input; an incorrect riser tension setting in the DP model means the position-keeping algorithm uses wrong force balance calculations, degrading accuracy

B. The BOP weight has no effect on DP performance — it only matters for structural load calculations

C. The BOP weight is only a concern when the vessel is in water shallower than 100m

D. The BOP weight increases the vessel's natural period, which always improves DP stability

A. An LMRP disconnect occurs automatically whenever the DP system goes to joystick mode

B. The LMRP is only disconnected when drilling operations are completed for the well

C. An LMRP (Lower Marine Riser Package) disconnect is an emergency separation of the riser/BOP stack at the connector below the BOP, triggered when the vessel cannot hold position adequately to prevent riser overstress or when a drive-off/drift-off puts the riser beyond its angular tolerance — it disconnects the vessel from the wellhead before the riser is damaged or pulls the BOP off the wellhead

D. An LMRP disconnect is a planned daily procedure carried out to inspect the BOP

A. The colour zones represent thruster availability: green = all thrusters online, yellow = one thruster offline, red = two or more offline

B. Green = normal operating range (riser within safe angular limits); Yellow = advisory — riser angle approaching limits, increased monitoring required; Red = riser angle at or beyond limits — LMRP disconnect must be initiated; these limits are defined in the WSOG for the specific well and riser configuration

C. Red means the riser is fully vertical; green means it is at its maximum angle

D. The colours indicate weather severity, not riser angle