China Merchants Heavy Industry (Jiangsu) Co., Ltd (CMHI) and DNV GL signed a Letter of Intent (LoI) for the classification of two multi-activity jack-up units at the Offshore Technology Conference (OTC) in Houston last week.

Ordered by OOS Energy BV, which is affiliated with Netherlands-based Overdulve Offshore Services (OOS) International, these 96 m long units will be purpose-built for the decommissioning market. Construction is scheduled to start at CMHI later this year. For OOS Energy, these will be the first of the company’s units to be classed by DNV GL.

2400 Tons of Lifting Capacity

The two identical 4-legged, self-elevating multi-activity units (MAUs) will be used in decommissioning operations.

'This means that the MAUs will be equipped for light drilling operations to close wells. In addition, they can deconstruct the top side of an oil rig’s structure, and remove the jacket structure which goes right down to the sea floor,' explains Bas Veerman, Business Development Manager Benelux at DNV GL – Maritime.

Two cranes, one with a maximum hook height of 92 m and one with a maximum hook height of 122 m above deck and a combined lifting capacity of 2400 tons, can work in tandem to dismantle decommissioned offshore structures, lifting parts onto the MAU’s own deck, before transporting them back to shore. The unit is also equipped to install next generation wind turbines.

Technical Features MAUs

The MAUs will be able to operate in 55 m water depth in harsh conditions such as those found in the North Sea. In benign circumstances the units can operate in 80 m of water depth.

The units will be self-propelled by four steerable thrusters, and are also equipped with a dynamic positioning system (DP2 system), ensuring safe positioning near the platform.

Four dual fuel main generators, located in two separate engine rooms, provide power for propulsion, cranes, the drilling package and all auxiliary functions.

Specifications

  • Jack-up type: self-propelled, DP2
  • Length x breadth: 96 x 58 m
  • Transit draft: 5 m
  • Main engines: 4 x 3800 kW
  • Main generators: 4 x 3500 ekW
  • Thrusters: 4 x 2350 kW
  • Cranes, max hook height above deck: 92 m/122 m
  • Cranes, lifting capacity each: 1200 mt