Norfolk, UK-based Fendercare Marine Diving Services (FMDS) has been contracted to provide significant diving services and equipment for an offshore installation in Liverpool Bay, UK.

The Liverpool Bay Development comprises four oil and gas fields, together with significant offshore and onshore facilities used for extracting, transporting and processing the oil and gas reserves.

Late last year, FMDS mobilised the DP2 DSV Seabed Worker, complete with a full air diving and nitrox surface demand diving spread, two work-class ROVs, a complete pipeline hydrographic survey facility and the James Fisher, UK, Hydro-Digger (mass flow excavator) for survey and remedial works to the assets located offshore in Liverpool Bay. The work scopes included the hydrographic surveys and mooring integrity surveys.

SENT

Offshore operations at Liverpool Bay are focused on the Douglas complex – a facility that monitors and controls the development’s three unmanned satellite platforms at Lennox, Hamilton and Hamilton North, with oil and gas from all four fields being received at Douglas. The Lennox and Douglas fields produce oil which is sent through a pipeline to the offshore storage installation before being loaded into tankers for export worldwide. Hamilton, Hamilton North and Lennox produce the gas which is part-processed on Douglas before it is sent via pipeline to the Point of Ayr gas terminal on the North Wales coast.

As part of the work conducted by FMDS, pipeline routes were surveyed and a full condition report submitted on completion. The survey team also identified the locations of the three joining links attaching the mooring chains to the anchor wires on three moorings between the CALRAM (catenary anchor leg rigid arm mooring) and its anchor buried in three metres of seabed. These links were excavated by the Hydro-Digger, raised by ROV and NDT inspected. 

Preselected areas of nine mooring chains were also cleaned and inspected between the surface and seabed by ROVs and divers, remedial works and maintenance procedures were also completed on the PLEM (pipeline end manifold) and the main safety chain in preparation for change out at a later date. 

COMPLIANCE

All of the diving and marine operations were carried out in compliance with the Offshore Approved Codes of Practice (ACoP) as defined within the HSE Diving at Work Regulations 1997 and International Marine Contractors Association recommendations.

This is not the first time that FMDS has provided support to the Liverpool Bay Development. The company has also been contracted to provide the diving facility together with associated operational procedures and risk assessments for the change out of the 24 tons of safety mooring chain with a Salentic line. For this operation FMDS was asked to operate utilising its platform-based air diving spread deployed to the offshore installation.

The work scopes included procedures for the cleaning and inspection of the main securing pad-eye attached to the buoy, located in the splash zone two metres below the surface. The pad-eye attachment welds and first three chain links were cleaned to enable inspection divers, utilising underwater magnetic particle inspection (MPI) equipment, to inspect the pad-eye attachment welds and links. On confirmation of the pad-eye integrity and fitness for purpose, the chain was rigged for removal and secured at both ends prior to being cut free from under the buoy and recovered, and a replacement Salentic line was rigged and installed.

TRAINED

FMDS director Bob MacMillan says: “We are very proud of our involvement with the Liverpool Bay Development and our work demonstrates the wide range of services and equipment we can offer our customers. All of our diving teams are trained and experienced in a wide range of techniques and procedures and safety is paramount in everything we do.”

Total recoverable reserves in Liverpool Bay are currently estimated to be in excess of 150 million barrels of oil and 1.2 trillion cubic feet of gas.

With peak oil production expected to average some 70,000 barrels per day and a peak gas capacity of 300 million cubic feet per day, the life of the development is projected to be at least 20 years.