The EnQuest Magnus (previously BP Magnus) was one of BP’s most recognisable assets on the UKCS and has enjoyed a long production life from the field and asset. In addition to hydrocarbon production from the field, the Magnus also serves as an origin for the Northern Leg Gas Pipeline (NGLP) with gas exports from other nearby installations feeding into the network for transmission onshore to St Fergus via the Brent’s.
One of the dead-weight supports of the NLGP riser had failed and, although the line remained operational, any further dead-weight support failures would require the line to be shut down with substantial financial implications for several operators. A previous attempt to construct traditional scaffolding access at the location had failed due to the length of time to install and the subsequent risk of wave contact rising due to this.
Scope of work
Following the earlier unsuccessful attempt using traditional scaffolding, Cape PLC contracted Span Access Solutions to design, engineer, and install a suitable access solution for the repair works.
The key requirement in this project was the speed of the installation, as the previous attempt to provide access to the repair location failed primarily due to the lengthy installation time and the likelihood of high swells in such an exposed location damaging the access.
Span Access Solutions (now a HAKI company) specified the use of the HAKISPAN suspended access platform and provided client access with a suspended staircase. Developed in partnership with HAKI, this system was deemed the most suitable as it offered the fastest installation time with enough capacity for the required work scope. Span’s own TechniSpan suspension components were utilised for the solution, integrating entirely with the HAKI system.
Our team mobilised to Magnus and removed the remains of the wave damaged scaffolding using rope access techniques, before installing the platform.
A welding habitat was then constructed from the platform allowing for the new steelwork to be lifted into position and the hot works aspect to be carried out in suitable conditions. All the repairs took place just 9m above sea level.
The solution was fully installed during a 21-day mobilisation with 14 shifts of productive time available to the team.
All as-built requirements were documented offshore and continually fed back onshore for approval therefore eliminating downtime for as built checks.
The repair work scope was fully inboard and less affected by the prevalent weather conditions and was successfully completed in the summer weather window. This allowed the NGLP to remain fully operational during the repair works and this gave a substantial commercial benefit to the various stakeholders in the line.
The successful repair contributed to a smooth handover of ownership from BP to EnQuest.
Hakitec, Weather Protection2020