Heading for the deeps

Saipem's new pipelay giant Castorone, currently under construction at Keppel shipyard in Singapore, will replace the veteran Castoro Sei as the contractor's flagship vessel for laying large diameter pipelines and serving the growing deep- and ultra-deepwater markets. Meg Chesshyre takes an early look.

Expected to be ready for operations in 2013, Castorone will build on a long track record in the offshore pipelay sector. Past successes for Saipem include water depth records set by the Saipem 7000 with the Blue Stream project (OE September 2002) and further back by the Castoro Sei on the Transmed pipeline project in the late 1970s.

The new vessel has already secured an impressive four pipeline installation assignments, three of them in the deepwater Gulf of Mexico and the other a large trunkline offshore Australia. 

The Gulf of Mexico projects comprise Amberjack Pipeline's Walker Ridge export pipeline. To be constructed and operated for Amberjack by Chevron Pipe Line, this 219km, 24in line will run from Chevron's deepwater Jack and St Malo oilfields in 2140m of water to a Shell-owned and operated platform in Green Canyon block 19.

Saipem also has transportation and installation contracts for the 20in, 60km long Big Foot lateral export pipeline for Enbridge in 2200m maximum water depth, and for the 20in, 350km long Keathley Canyon gas export pipeline for Williams (Discovery), in water depths ranging from 100 to 2100m, both to be laid by Castorone next year.

In Australia, Saipem signed an EPCI contract with operator Inpex this January for the 42in gas export pipeline on the Ichthys LNG project (OE May 2011). The contractor's scope of work covers the engineering, procurement, construction and installation of the 889km-long trunkline, in water depths of up to 275m, which will connect the Ichthys central processing platform to the onshore processing facility in Darwin. Offshore activities will be carried out by the Castorone from 2014. The recently upgraded Semac 1 pipelay barge will be employed for the shallow water section.

Armando FaviArmando Favi, VP E&C business development with Saipem, says: ‘The trunkline and large flowline market – conventionally, offshore pipelines longer than 80km and larger than 16in diameter – is expanding in the deepwater sector, with projects in excess of 500m water depth bound to reach at least 25% of the overall 21,000km market expected in the next four years. Other projects in the same period, for example the Shtokman gas export pipeline in the Russian Barents Sea, will challenge the industry in terms of project size and harsh environment.'

Potential projects being targeted by Saipem include the future Mediterranean and Black Sea crossings, as well as several large export trunklines or deepwater field developments in the Gulf of Mexico, South Atlantic, Asia Pacific and Russia. ‘This market scenario is the driver behind Saipem's decision to invest in the Castorone pipelayer,' he notes, adding that the new vessel will have ‘extremely high productivity in a very broad range of scenarios, allowing shorter laying schedules and therefore better project economics'.

According to Favi, the fully dynamically positioned (class DP3) Castorone is designed to meet the challenges of the present and future market, ranging from S-lay of large trunklines even in Arctic conditions and steep S-lay of sealines in very deep waters over 2000m, to the J-lay of sealines in ultra-deep waters over 3000m.

The new vessel's triple joint prefabrication area. The Ice class A0 (IA Baltic) vessel will have a transit speed of 13 knots and accommodation for 702 personnel. Storage capacity is around 20,000t and there is the possibility to upgrade to unmanned loading and offloading of pipe joints. It will be capable of S-laying in DP mode pipes up to 60in diameter and prefabricating pipe strings 36m long, with the capability of joining two 18m long pipes as an alternative to three 12m conventional joints.

‘This is a unique feature,' claims Favi. ‘The stinger is specifically designed for any pipe diameter and water depth, through a continuous control of the overbend stresses in the pipe. It is composed of three articulated adjustable sections allowing to be configured from shallow to ultra-deep water without abandoning the pipe, another unique feature. Seven welding stations are used for shallow water laying. The pulling capacity is 750t (975t holding capacity), while the holding capacity for the flooded case is 1500t.'

Click for larger image. How Castorone will compare in size with predecessor Castoro Sei.

Castorone will have an overall length of 330m excluding ramp/stinger and helideck and a moulded breadth of 39m. The vessel's minimum operational draft will be 7m (maximum 10m), with a transit draft of about 8m and displacement of 100,000t at maximum operational draft. Main crane lift capacity will be 600t @ 30m, 350t @ 46m, and there will be two 52t @ 35m pipe handling cranes and a 30t @ 30m pedestal crane.

The new pipelayer already has work lined up in US and Australian waters. Favi says the design of the Castorone also allows for the future installation of a fixed tower for triple joint J-lay in excess of 3000m water depth. ‘In such cases a fast switch will be possible offshore from S-lay to J-lay during operations within the same project to best fit route and water depth requirements with minimum time losses,' he notes. With the J-lay tower in vertical position the vessel will have full weathervaning capabilities. The new vessel also has above water tie-in (AWTI) potential, being designed for future installation of up to 10 AWTI davits for easy completion of shore-to-shore trunklines. OE

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