The dual system is capable of drilling two complete wells at the same time. In practice, in an exploration situation, the dual activity capability enables the auxiliary drilling system to be used to drill the top-hole section while the primary system is running the blowout preventer (BOP) and riser ready to land on the wellhead as soon as the 20in casing is cemented. Consequently the second rotary can be used to pick up and standback tubulars prior to running by the primary system. In a templatedrilling situation, the auxiliary rotary can batch set top-hole sections while the primary rig drills the wells to the total depth.
“The DISCOVERER ENTERPRISE drilling package features a single tubular derrick equipped
with two rotary tables, two draw-works and two top drives.”