Oceans of knowledge
In October 2009, the Munin sailed for Singapore’s Sembawang Shipyard to be prepared for operation at Huizhou, located 120 kilometres southeast of Hong Kong in the South China Sea, for field operator CACT (CNOOC, Agip, Chevron, Texaco). The Munin operated in the same mode as at Xijiang: on DP and external turret with a floating buoy.
In 1997, immediately after delivery, the Munin was converted by her previous owners to a Floating Production Storage and Offloading (FPSO) vessel at Jurong yard in Singapore and started operating for client Statoil at the Lufeng field in the South China Sea, an area frequently visited by typhoons. Bluewater purchased the Munin in 2001.
The Munin was built in 1996 at the Samsung ship yard (South Korea) as a so-called Multi purpose Shuttle Tanker (MST), meaning she could be employed in various modes as a Dynamically Positioned (DP) shuttle tanker and adapted to be converted to an FPSO or to a deep-water drilling vessel.
The Munin owes her versatility to the redundant DP system in combination with two different disconnectable turret systems.
The first disconnectable turret consists of a submerged buoy mooring system with riser slots and mooring lines to the seabed. The risers transport the well fluids (oil, gas and water) from subsea wells to the FPSO process plant.
The subsurface buoy is designed to fit into a specially configured compartment in the hull of the FPSO, housing the swivel and bearing around which the FPSO can rotate.
With the second turret system, the Munin is able to operate in Dynamic Positioning (DP) mode, where well fluids can be imported via risers supported by a floating disconnectable buoy and external turret system.
Both disconnectable turrets and the associated position keeping systems have been used extensively and successfully. Disconnectable turrets are particularly suited for FPSOs operating in areas prone to hurricanes and typhoons. If the FPSO is threatened by a tropical storm, ice or other phenomena, she disconnects and sails away from the affected area to seek shelter without any oil spill.
When the tropical storm has passed, the FPSO returns and hooks up in DP mode to the buoy and its subsea infrastructure and resumes oil production.
The Munin produced at the Lufeng field from late 1997 to 2009 using the submerged turret. This 12-year period was interrupted only in 2004 and 2005, when the vessel operated at the Xijiang field in Dynamic Positioning (DP) mode with the external turret and floating buoy.
In 2004 the external turret has been fitted at Sembawang yard in Singapore. Like Lufeng, the Xijiang field is located in the South China Sea and is operated by Conoco Phillips.