Behemoth oilseeker docks in Walvis Bay harbour after sortie in South Atlantic
Of the more than 2000 vessels that docked in the ports at Walvis Bay and Lüderitz over the past year, none came close to the behemoth that sailed into the Walvis Bay harbour during the previous weekend.
The harbour staff was on high alert when the world’s largest 3D seismic survey ship, the Ramform Atlas was carefully moved into position along the quay covering several berths. At 104 metres long and 70 metres across the beam at her stern, she chose Walvis Bay to demobilise after completing a seismic survey in the South Atlantic Ocean. She falls in the ultra-high capacity Titan Class weighing over 2000 tonnes.
The ship has extraordinary length and width measurements for a marine vessel, the ratio indicating that the Ramform design is based on a very wide stern compared to its total length. The ship’s dimensions result in a stable platform which is a requirement for handling streamers. Despite her bulk, the ship is designed to sail in shallower waters with a design draft of a mere 6.4 metres.
The Ramform Atlas’ choice of Walvis Bay was entirely discretionary. There was actually no need, other than to restock on provisions, to visit Walvis Bay since she has an enormous fuel holding which enables her to sail 150 days without docking. With her onboard fuel, she can circumnavigate the globe twice before docking. When fully laden on fuel she holds an impressive 6 million litres of marine diesel.
The Ramform Atlas belongs to Petroleum Geo Services who operates a fleet of nine Ramform vessels. Built by Mitsubishi in Japan, the Ramform Atlas is number two in the fleet. She was commissioned in January 2014.
Seismic survey ships tow behind them so-called streamers. These long lines carry the equipment that picks up the returning magnetic pulses emitted by a sender unit on the ship, very similar to a magnetic resonance image. From this data, powerful computers then assemble a likeness of the rock morphology below the bottom of the ocean, indicating denser and less dense areas. Geologists in the oil industry rely on these images to identify pockets where there is the potential for oil-bearing rock. The Ramform Atlas can tow 24 streamers simultaneously.
The Ramform Atlas’ design and capacity enables her to survey large areas of the sea in a relatively short time. When first redeployed in January this year, she completed more than 113,000 metres of streamer in just over two days off the West African coast.