China's Yantai CIMC Raffles Offshore Ltd. (CIMC Raffles) reported Wednesday that it has completed mating operations for the Frigstad Deepwater Rig Alfa, a 7th generation semisubmersible drilling rig ordered by Frigstad Deepwater Ltd., at its Yantai shipyard.
Using parallel construction, the lower hull (19,277 ton) and the upper deck box (18,727 ton) were completed on land while mating was successfully completed using the CIMC Raffles' TAISUN crane, the largest capacity crane of this type in the world. This is the 11th deepwater semisubmersible rig mated by using the TAISUN crane.
The Frigstad D90TM rig is the first 7th generation ultra deepwater semisubmersible drilling rig under construction, with an operating displacement of 69,800 metric tons (MT), VDL of 10,000 MT, and drilling depth capacity of 60,000 feet, making it the world's largest semisubmersible drilling rig.
Equipped with a NOV Dual Activity Rig with 2 x 1,400 short ton lifting capacity ( 2 x 1250 short ton in elevator) and two seven ram Blow Out Preventers (BOPs), this solution makes the drilling process more efficient by allowing the running of two loadpaths at the same time. A new process can be completed without interrupting the ongoing activity. To streamline the assembly of the risers, 10,200 feet out of the total 12,000 feet total capacity are stored vertically in double lengths of 110 feet. In addition, space has been allocated for vertical storage of 60,000 feet of tubulars, with drilling tubulars mounted in 135 feet lengths.
The rig is tailor-made for safe and efficient exploration. This includes open and uncluttered deck areas, providing efficiency and safety of all processes during operations and optimal living conditions for the crew. On the Frigstad D90TM, there are no air vents obstructing the open deck areas, practically no blind zones for cranes, and high comfort for the crew. The rig is equipped with 200 single cabins, each with its own window.
The clean design is also reflected in the hull structure. Four columns without diagonal bracings simplify the construction of the rig. When the rig is partly submerged, barges can enter in between the hull columns carrying heavy components (such as BOPs) for easier and safer loading and unloading. Four horizontally mounted bracings simplify the construction and reduce costs. The bracings are placed so that they are above the waterline in transit. This, together with the design of the pontoons, greatly improves the transit speed.
The efficiently designed hull moves easily in the water with reduced fuel consumption. The rig accommodates a so-called “green HPU”, which amongst others uses environmentally friendly hydraulic oil. The drill cuttings facility is designed to provide high flexibility during operation, with drill cuttings handled safely in fully integrated tanks of 21,189 cubic feet (600 cubic meters). Drill cuttings can then be pumped directly onto the supply vessel, without having to use traditional skips or deck mounted tanks and the use of cranes.
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