Enpro Subsea’s F-Decom System Enables Safe Removal of ‘Attic’ Oil

Hunting Energy Services, Subsea Technologies division supporting DeepOcean has successfully completed another campaign in the North Sea using Enpro Subsea’s proven Field Decommissioning (F-Decom) system.

The recent campaign on Shell UK Limited (Shell) Brent Bravo concrete structure was completed with no safety incidents, ahead of schedule and within budget.  

Enpro’s patented technology enabled the safe access and removal of ‘attic’ oil from concrete storage cells at the base of the Brent Bravo platform in 140m water depth. The system, which on previous campaigns had been deployed direct from platform topsides, was this time deployed from a DeepOcean construction vessel, leading to a significant reduction in operating days per cell.  

The F-Decom system is the only field proven system for securely accessing fluids within gravity-based structures (GBS) concrete cells assisting operators to safely meet their decommissioning regulatory obligations to protect Europe’s marine environment.

The project involved Enpro’s offshore engineers and onshore support teams working alongside DeepOcean’s operations and subsea teams onboard the construction vessel, the Maersk Forza. Enpro Subsea’s proprietary solution centers around their patented 'anchor hub' technology which mechanically locks into the concrete cell cap and allows a suite of tooling (i.e. drilling, sampling, wireline, pumping) to be compact and lighter, thereby enabling it to be easily installed and operated using work class ROVs and operate within a broad weather window.

This is the fourth such campaign the company has undertaken for Shell to support its ongoing decommissioning program in the Brent field, located north-east of the Shetland Islands.

Enpro Subsea engineering director Neil Rogerson said: “The system is well proven, and Shell have previously deployed our F-Decom technology on both their Brent Bravo and Brent Delta platforms. For the 2020 Bravo project, our collaboration with DeepOcean has allowed us to optimize this same low risk system, specifically for working from a vessel, yielding significant operational efficiencies, and increasing value to our client. As a result, we now have extended the track record of the only field proven system, which can be configured to suit a variety AOR (Attic Oil Recovery) decommissioning programs.” 

Roy Nilsen, DeepOcean project manager said. “The attic oil recovery project on Shell’s Brent Bravo platform was a great project for DeepOcean and its success comes from the combination of Enpro Subsea’s F-Decom system and DeepOcean’s expert subsea engineering and WROV capabilities as well as the good collaboration between all parties involved.”