The light well intervention and dive support vessel MSV Seawell has returned to service after a US$74.5 million (£60 million) investment by its owners, Aberdeen-based Helix Well Ops (UK), a UK subsidiary of international offshore energy service company Helix Energy Solutions Group.
Launched in 1986, some 30 years ago, at the Pallion yard in Sunderland by North East Shipbuilders, MSV Seawell was described as the world’s most sophisticated offshore support vessel when it entered service in 1987.
The 114m-long (374ft) vessel was the first in a series of vessels to feature electrical propulsion and set a benchmark for multifunctional offshore support vessels, certified as a stand-by and rescue ship, and equipped as an anchor-handler.
MSV Seawell has been at the forefront of the light well intervention market since it undertook its first such project in the Magnus field, north-east of Shetland, in July 1987. In November 1995, it carried out the first subsea tree replacement from a monohull vessel anywhere in the world.
In October 1998, the North Sea’s Arkwright field was the location of another historic first for the vessel, when the world’s first wireline intervention on a horizontal subsea tree was completed.
The range of projects that MSV Seawell has undertaken has been diverse. Alongside intervention, well maintenance, production enhancement, diving and abandonment work, it has also recovered a ditched Harrier jet from the Bristol Channel.
This diversity reflects the vessel’s specification, which includes a 7m x 5m moon pool, a twin bell saturation diving system rated to 300m with a capacity for up to an 18-man dive team and work and observation class ROVs.
The vessel’s multi-million pound upgrade was carried out at the Damen yard in Vlissingen in the Netherlands, taking around eight and a half months, and was followed by extensive sea trials. Improving the efficiency and capability of MSV Seawell were set as key outcomes of the project.
Six new Rolls Royce Bergen C25:33L8ACD generator sets have replaced obsolete Hedemora generators, which had powered the vessel since it was built. The dynamic positioning (DP) thrusters and azimuths have been upgraded to DP3 class. This improves the station keeping performance of the popular vessel and the safety of wells being worked on, particularly in challenging weather.
Electrically the vessel is completely new, as all electrical systems and cabling have been replaced and upgraded. Onboard accommodation has been improved, enhancing the work and living spaces for MSV Seawell’s 122 crew members. The vessel’s dive system and bells have been refurbished, while its lifeboats have also been upgraded to comply with new North Sea performance standards.
The modifications have changed the distinctive silhouette of MSV Seawell. A new 50-tonne crane with active heave compensation and a multi-purpose tower have replaced the existing twin 65-tonne cranes aft and separate derrick that provided its characteristic profile.
Designed by Royal IHC, the new tower allows the vessel to deploy Helix Well Ops’ 73/8in SIL (subsea intervention lubricator) in addition to its 51/8in SIL. It can also stack the complete SIL and deploy it to the seabed in a single run. The ability to deploy the 73/8in SIL brings it into line with its sister vessels, Well Enhancer and Skandi Constructor.
Steve Nairn, Helix Well Ops (UK) vice president, said: “MSV Seawell has provided an important and invaluable contribution to the North Sea oil and gas industry over the past three decades. It was the first vessel of its kind and has delivered many firsts throughout its career.
“The light well intervention sector has evolved in line with this reliable and popular vessel. Its specification and capabilities have helped the vessel become respected in the North Sea, and more recently further afield. Time and again, MSV Seawell has demonstrated the cost-effectiveness of utilising a vessel to deliver light well intervention services compared to a rig.
“Refitting MSV Seawell has been a major undertaking and one that underlines Helix Well Ops’ commitment to the North Sea marketplace, and having a robust and capable fleet of vessels, which includes Well Enhancer and Skandi Constructor, to service it. The investment ensures this iconic vessel will continue to pioneer a market it has helped shape.”
Having already entered more than 650 wells, decommissioned over 150 live and suspended wells, including 15 subsea fields, this refit extends the lifespan of MSV Seawell and ensures it remains at the forefront of the light well intervention market for a further 15 or more years.
Launched in 1986, MSV Seawell was a pioneer of the light well intervention market and completed its first wireline subsea well intervention project in 1987. In 2009, Helix Well Ops (UK) expanded its fleet with the launch of Well Enhancer, a 132m (433ft) long DP3 well intervention and saturation diving vessel.
Helix Well Ops (UK) increased its deepwater capabilities in 2013, when the 120m (393ft) long DP3 well intervention vessel Skandi Constructor joined the fleet as a charter. The company employs around 400 people between its onshore and offshore operations.
Image: Seawell in Aberdeen harbor. Image from Helix Well Ops (UK)