Nexen – EPC/operator collaboration successfully changes out single point failure equipment on Buzzard

Submitted by Nexen


  • Nexen Petroleum U.K. Limited in collaboration with Amec Foster Wheeler successfully changed out one of the largest shell and tube reboiler heat exchanger bundle on the Buzzard installation during the 2016 Turnaround (TAR).
  • This was the first time this bundle, a single point failure for the processing facilities, was changed out since the Buzzard field was constructed in 2007.
  • The change-out workscope required engineering of movement corridor, the removal method and detailed sequencing of the removal c/w complex lift plans.
  • Plant clashes were resolved outwith the Buzzard TAR period, and the main bundle change out was managed during the TAR period with no detrimental impact to TAR duration.

Description of Best Practice

In line with vessel integrity inspection requirements, Nexen set out to a complete inspection of the amine reboiler shell vessel during the Buzzard 2016 TAR.

To ensure a best in class inspection was carried out, it was determined that the reboiler bundle would be withdrawn from the shell. Given the single point failure status of the unit operation, the bundle would be subsequently replaced with new equipment on reinstatement.

Driven by the duty of the exchanger, this was one of the largest bundles on the Buzzard installation at  16.4T, 1.7m diameter x 7.3m length, however it was located in a challenging position on a mezzanine deck within the process facilities deck. The weight of the bundle (with movement and lift cradles) approaches the capacity of the platform crane at minimum radius.

As this was is the first time the bundle had been changed within Buzzard production life, it was necessary to identify the extraction route and sequencing of the bundle movements to ensure no detrimental impact to the TAR duration.

This involved close collaboration between Nexen and the AmecFW team in engineering the extraction route, methodology and sequencing to minimise the impact on pre-work and shutdown duration, whilst offering the most stringent level of safety mitigations. Significant benefits were realised through this collaborative approach, with a strong focus during the scoping phase on the various methods available for such a complex activity.

The execution strategy was then confirmed by a  full onshore mockup trial that recreated offshore deck plan and validated the selection of air skates as the motive solution. The onshore trial also identified further safety and operational enhancements which were then incorporated into the final execution strategy.

Execution of the change out was completed and successfully managed within the planned TAR period.

Contact: Tracey Miller