Well-Safe semi-sub rig sports saturation diving system

Aberdeen-based decommissioning services provider Well-Safe Solutions has installed a saturation diving system on board its semi-submersible rig, which is now said to be the only one of its type in the North Sea with this capability.

The custom-built dive spread installed on Well-Safe Guardian has a capacity for up to 15 persons and enables access to legacy subsea wellhead and Christmas tree systems from the 1970s onwards which were originally designed for diver intervention.

The manufacture, transport and fitment of the dive spread were carried out at Burntisland, Rosyth and Methil ports on the east coast of Scotland.

Equipped with an environmentally-friendly electric bell-handling system and two hyperbaric lifeboats, the system is designed to enable diving operations to be carried out in support of well decommissioning.

Typical operations supported include cleaning, deconstruction, barrier testing, manual tree cap removal, reconfiguration of hydraulic controls and flowline removal, Well-Safe said.

“The dive spread system installed on the Well-Safe Guardian is a cost-effective, flexible alternative to the industry standard, which typically sees a light well intervention vessel (LWIV) used to plug and lubricate the well before completing decommissioning operations with a standard semi-submersible mobile offshore drilling unit (MODU),” said Phil Milton, CEO at Well-Safe Solutions.

“Our ‘single asset solution’ offers an alternative to the conventional approach and does not require multiple vessel mobilisations and demobilisations. This results in lower operating costs, minimises the risk of weather-related disruption and boosts overall project efficiency.”

According to Well-Safe, the dive spread system is designed to work in tandem with the Trendsetter Trident well intervention system that the company announced last year.

Following further systems integration and testing, Well-Safe Guardian will mobilize early in the summer, returning to the Buchan field operated by Repsol Sinopec Resources UK to plug and abandon (P&A) nine wells using the saturation dive system, the Trident well intervention system and the blow-out preventer.

UK-based RockSalt Subsea will support Well-Safe Solutions with diving services and personnel during all saturated diving operations from the rig.

Well-Safe bought the semi-submersible rig Ocean Guardian from Diamond Offshore back in 2019 with plans to convert it into a bespoke P&A unit, renaming it into Well-Safe Guardian.

The rig was mobilized for its first job in the UK North Sea in January 2022.

The addition of the saturation dive spread follows news of a contract win with BP to decommission two wells in the Kate field of the North Sea in March, as well as the mobilization of the Well-Safe Defender in April.