The BP Magnus is one of BP’s most recognisable assets on the UKCS and BP have 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, while the line remained operational, the repair of this support was a priority for the various interests associated with the line, including EnQuest who were due to assume ownership of Magnus later that year. 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.
Following the earlier unsuccessful attempt using traditional scaffolding, Cape plc contracted Span Access Solutions to design, engineers, install and commission 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 of traditional scaffold and the likelihood of high swells in such an exposed location damaging the access.
We specified the use of HAKI-Span 750 suspended access platform and provided client access with a suspended staircase. Developed in partnership with HAKI UK, this system was deemed the most suitable as it offers the fastest installation time with enough capacity for the required work scope and the structural ties available to us. Despite the availability of our own inhouse system, Span will always seek to install the most appropriate system for the project and have forged a number of successful relationships with key suppliers to offer an unrivalled portfolio of access systems allowing us to use a “square peg to fit a square hole”, proverbially speaking.
Our team mobilised to Magnus and using roped access techniques we removed the remains of the wave damaged scaffolding before installing the platform, again using rope access to start at the target and work our way back to deck level.
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 also contributed to a smooth handover of ownership from BP to EnQuest.