Ice-strengthened props at the ‘heart’ of new Russian AHTS vessels

While newbuild activity in the offshore oil and gas sector has slowed in 2020, it has not all together stopped, particularly for specialised vessels. Orders for 12 offshore support, two offshore supply and four offshore anchor-handling tug supply (AHTS) vessels had been placed as of mid-October 2020, according to BRL Weekly Newbuilding Contracts.

Two AHTS newbuilds under construction in Turkey are specially designed for operation in the ice-infested waters of the Caspian Sea.

Designed by Istanbul-based naval architectural firm V Denge Technology, the two AHTS newbuilds, Polar and Polus, will each be driven by three 1,740 kW Schottel SCP 65 4-XSG controllable-pitch (CP) propellers. These powerful ice-strengthened props, with a diameter of 2.1 m and an optimised hub for full feathering mode, are at the heart of the AHTS vessels. Each of the vessels will have a free-running speed of 12 knots in open waters, with a bollard pull of 70 tonnes. Steel was cut for Polar, NB 016, in February and Polus, NB 017, in June.

Including the vessels’ transverse thrusters, Germany’s Schottel is supplying a total of eight propulsion units to Turkey’s Atlas Shipyard, which is building the AHTS vessels for Russian company Polar LLC & Polus LLC, affiliates of Ark Shipping & Adamant. Both vessels are set to be completed by the end of 2021.

Complementing the newbuilds’ Schottel CP propeller systems are 400-kW Schottel transverse thruster (STT 1 FP) bow thrusters, providing full dynamic positioning to DP 1 standards.

To withstand the harsh conditions of the Caspian Sea, the CP propellers will be ice-strengthened, according to Finnish-Swedish Ice Class 1A Super. With the capability of operating in a minimum draught of 2.5 m, the CP propellers will be well suited for shallower operations in the Caspian Sea.

With a length of 73.3 m and beam of 16.9 m, the AHTS vessels will be able to haul, lay, retrieve and lift the anchors of semi-submersible drilling platforms or pipe-laying vessels. Furthermore, they will be capable of towing drilling rigs, lighters, other vessels and floating facilities, as well as serving as emergency response and rescue vessels and supply transports.

These are not the first ice-class, shallow-draught AHTS vessels built by Atlas Shipyard for Ark Shipping. In 2017, Atlas Shipyard delivered the AHTS vessel Antarctic with a Bureau Veritas ice-class 1A notation to Ark Shipping. Designed by naval architectural firm OSD-IMT, Antarctic is slightly smaller than Polar and Polus at 66.29 m long and 16.50 m wide, but is a DP 1-capable vessel, fully equipped to operate in the challenging winter conditions of the Caspian Sea, where ice formation of around 80 cm is not uncommon. Construction of the hull from special-grade steel will enable Antarctic to endure minimum temperatures of -25 to -30 C°.

Propulsion power for Antarctic is supplied by three 1,864 kW Cummins QSK60-M diesel engines that drive three Kort nozzled Caterpillar CP propellers via Reintjes LAF 873 marine gears. As a result, Antarctic can achieve a bollard pull of 70 tonnes and a free-running speed of 12 knots.

All three AHTS vessels will have their hulls protected by Ecospeed from Subsea Industries.

According to Subsea Industries’ agent in Turkey, Amat Engineering, the positive experience of Ecospeed on Antarctic made the choice for the next two vessels much easier for the owner.

“These are super ice-class vessels that require extensive hull protection for the operations they (will) undertake,” said Amat Engineering managing director Orkun Çomuoğlu.

Qatari well stimulation vessel

US-based oilfield services firm Schlumberger’s FlexSTIM platform is an offshore modular stimulation system that has been deployed on vessels in oil-producing regions around the world, including the Caspian Sea.

Under a recent agreement with Middle East maritime and logistics company Milaha, Schlumberger will be developing a Qatari-owned well stimulation vessel that will be outfitted with the well stimulation technology.

Under a memorandum of understanding (MoU), Milaha and Schlumberger will support value-building projects while jointly driving ‘Tawteen’ initiatives for Qatar, creating local content and knowledge-building. Led by Qatar Petroleum (QP), the Tawteen programme wants to increase new investment opportunities to retain in-country ‘economic value’ in Qatar.

One of the centrepieces of the five-year joint development project is a Qatar-owned, Qatar-flagged and Qatar-operated oil well stimulation vessel. Milaha said the first of these vessels would be designed and outfitted in Qatar, creating the inaugural FlexSTIM platform, which will be modified, owned and operated locally.

“The Tawteen programme wants to increase new investment opportunities to retain in-country economic value”

Schlumberger says in some cases the FlexSTIM system can be designed and implemented in less than four weeks from the order date. Its capacity can be tailored to meet specific operator needs – a standard 900-m² deck area supply vessel can be moulded for capacities up to 10,000 kW, 350 m³ of proppant storage, and 605,000 litres of concentrated acid capacity. This combination of flexibility, capacity, and rapid turnaround time is unparalleled, even for dedicated stimulation execution.