Feature 2 | WEST AFRICA Lion’s raw
Te delivery of the new Seadrill semi-submersible West Leo to Tullow Oil Ghana is expected to provide a major boost to drilling activities within the oil exploration company’s West Africa-based Jubilee field.
H
ailed as one of the largest semi-submersible
to date, Seadrill’s 118.56m-long
West Leo, constructed at Jurong Shipyard in Singapore, is, at time of going to press, still on schedule to undergo transit to Ghana, West Africa, before January 2012 is out. Initially, the vessel has been contracted to Tullow Oil Ghana, a local subsidiary of oil and gas exploration and production group Tullow Oil, for a period of 12 months, commencing in April, and she is set to take advantage of the raw resources currently located in Tullow Oil’s Jubilee field. According to the World Bank, Ghana’s oil
fields represent just under 2% of the country’s total gross domestic product at present, with Tullow Oil reported as predicting production in Ghana to average between 70,000-90,000 barrels per day (bpd) this year. Tis scenario, if things remain on track, should lead to a domestic growth spurt of 10% over the course of 2012, the World Bank hints. West Leo comprises Jurong Shipyard’s
eighth ultra-deepwater semi-submersible rig delivery to Seadrill, and is reportedly the second Moss Maritime CS50 MkII harsh-environment rig to be built from a six-column bare-deck hull that the yard has delivered to the drilling specialist – the first being the same-sized West Pegasus, which was delivered by Jurong in March 2011, and is currently operating in the Gulf of Mexico (see Offshore Marine Technology, 4th Quarter 2011). Te semi-submersible has been constructed to handle a wide range of extreme temperatures, making her suitable for charter to cold environments as well as the Sub-Saharan heat. Te vessel features the capacities for 192 persons, 3260m3 mud, 1500m3
of fuel, 2000m3 of drill water and 775m3
of liquid of
potable water. Eight Rolls-Royce Bergen main diesel engines, situated across four rooms, generate a combined power output of 36.8MW as well as providing back-up emergency power for her onboard systems.
West Leo (pictured right, alongside the Jurong-built Seadrill semi-submersible West Capricorn) will be deployed under a 12-month contract by Tullow Oil Ghana.
Shaffer was selected to supply West Leo’s riser system, which features 22.9m long joints and a minimum inner diameter of 476.25mm. West Leo has also been equipped with
a series of blowout prevention (BOP) and riser handling gear, comprising in total: two BOP gantry cranes, each with a capacity of 200tonnes; two riser gantry cranes, with 20tonnes capacity apiece; a 450tonne BOP skid; an 120tonne Xmas tree skid; and two Xmas tree gantry cranes, each wielding 60tonne capacity. Two Liebherr BOS 4200-100 pedestal cranes (rated at 100tonnes main block, 15tonnes whip line) and a NOV 12tonne knuckle boom crane, installed to provide for pipe-handling duties, satisfy the vessel’s liſting requirements. Classified to Dynamic Positioning
(DP) 3 DYNPOS AUTRO by Norwegian class society Det Norske Veritas, courtesy of a Kongsberg DP system, West Leo also features a helideck, capable of accommodating a Sikorsky S-92 helicopter, or equivalent. Speaking in November 2011, Seadrill president and chief executive Alf Thorkildsen commented: “[West
Offshore Marine Technology 1st Quarter 2012
Leo] will further enhance our rapidly growing fleet of modern, premium, high-specification rigs and strengthen our position in the ultra-deepwater and harsh-environment segments.” Including drillships, rigs and jack-ups under construction, Seadrill currently presides over a 63-strong fleet. OMT
TECHNICAL PARTICULARS West Leo
Length, oa .......................................118.56m Beam ....................................................72.2m Overall height (to main deck) ........38.65m Water depth .......................................3048m Maximum drilling depth .................10,600m Transit speed ...................................... 8knots Complement.............................192 persons Main engines.......... 8 x Rolls-Royce Bergen diesel engines
Total power output ...........................36.8kW Classification society and notations... DNV 1A1 Column Stabilised Drilling Unit,
DRILLING (N), DYNPOS AUTRO DP Class 3 21 types built
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32