The GTI and 2s’ DMPTs ease construction and interface with the vessel because they can be built in Huisman’s Schiedam fabrication hall and then skidded on the quayside, where it can be tested, before a single lift onto the vessel, says Huisman.
Each DMPT has dual drum drawworks with a winch at either side of the drill lines, which means should one winch fail, the other can still operate the travelling block at full load. The two blocks are also splittable (under patent), with push button reeving change to increase block speed under light loads. Both well centers can also operate from the two setback drums, which means the system can still operate if one pipe racker fails.
Stands of pipe at 135ft formed from three 45ft sections can be constructed on the construction side, then brought around to the well center using carousels (capable of holding 252 drill pipes of 135ft each and 70 casings of 135ft—about 34,000ft and 9500ft in total respectively) on either side of the tower, with automated handling of both stands and risers.
The tower also enables equipment to be stored away from the elements. The top drive garage means that top drive maintenance can be carried out inside and with room inside the MPT for proper access. Maintenance can be carried out safely and effectively. When the topdrive is stored for maintenance; tripping, casing running can be continued. The riser tensioner system is underneath the drill floor inside the hull.