VESSEL REVIEW | Stena Evolution – Ultra-deepwater vessel for Stena Drilling’s Gulf of Mexico operations

Stena Drilling has taken delivery of a new drillship from South Korean shipbuilder Samsung Heavy Industries.

The ultra-deepwater capable Stena Evolution has a length of 233 metres, a beam of 42 metres, a depth of 19 metres, an operating draught of 11 metres, a displacement of 89,792 tonnes, and accommodations for up to 240 crewmembers. A Kongsberg Maritime DP3 system will enable it to operate safely in water depths of up to 3,600 metres and drill at depths up to 12,000 metres.

Designated a seventh-generation drillship, the vessel boasts a premium high specification and an optimal design that utilises riser storage in the hull to offer extensive deck space with a 24,000-tonne variable deck load. The hull also has a moonpool measuring 25.6 by 12.5 metres. The design of the hull itself is optimised to ensure enhanced fuel efficiency.

The drillship features an array of four NOV knuckle boom deck cranes, two BOP gantry cranes, and a subsea tree overhead crane as well as BOP and subsea tree trolleys. The drillfloor and the moonpool also have two-man riding basket equipped cranes supplied by Palfinger Marine.

The vessel can also be upgraded for 20,000psi well operations if needed.

Extensive storage capacities are available for diesel (7,799 cubic metres), fresh water (1,563 cubic metres), drill water (3,122 cubic metres), base oil (1,018 cubic metres), dry bulk cement (414 cubic metres), liquid mud (4,234 cubic metres), and completion fluids (1,016 cubic metres).

Power is provided by six 8,000kW, four-stroke main diesel engines while six ABB AMG 0900LS10 LS 7,400kW generators supply electricity for the various onboard systems. The main engines turn six Kongsberg Maritime UUC-455 5,500kW azimuthing thrusters housing fixed-pitch propellers via six ABB ACS6000 5.5MW variable-speed drives to enable the drillship to reach speeds of up to 12 knots in addition to being utilised for station keeping. Emergency power will be sourced from a Cummins PM734G1 1.8MW generator and an STX QSK650DMGE four-stroke engine.

The accommodation spaces include 40 one-person cabins and 100 two-person cabins. Also fitted is a flight deck that can accommodate a 12-tonne utility helicopter.

Stena Evolution is classed by the American Bureau of Shipping. The drillship recently arrived in the Gulf of Mexico for its initial contract, a five-year charter on behalf of Shell Offshore.