UK-based Ineos has submitted its decommissioning plans for the Windermere field located in the Southern North Sea to the UK authorities.
The decommissioning programs are for the Windermere platform and the Windermere pipelines (PL1273 and PL1273.1 to PL1273.3).
The Ineos-operated Windermere field, located in the Southern Basin of the UK continental shelf in license block 49/9b, was discovered in 1989 and in 35m water depth.
The Windermere facilities comprise a normally unattended platform installation, wells, Windermere export pipeline, which is 6.8km long, and a 7 km long umbilical between Windermere and the ST-1 platform.
The platform was installed in November 1996 and is a small topside minimum facilities structure, fixed on a three-legged tripod jacket.
Production from the field started in April 1997 and cased in April 2016.
In 2017, the pipeline and umbilical between Windermere and ST-1 were cleaned and flushed and left in a flooded condition. The two wells on Windermere were shut-in and all topsides pipeline cleaned and disconnected. The helideck, crane, and lifeboat on Windermere were taken out of service and walk-to-work docking stations installed in order to allow a once-per-year interventions to be undertaken on Windermere. Due to power previously being received from ST-1 no longer being available, solar powered NAVAIDS and new platform signs were installed on the platform whilst it remains in this ‘hydrocarbon safe mode’ prior to decommissioning.
Following public, stakeholder, and regulatory consultation, Ineos submitted the decommissioning programs. The company’s plan entails the plugging and abandonment of wells, removal of topsides and jackets to be recycled or disposed onshore.
Furthermore, the gas export pipeline will be partially removed, the exposed sections adjacent to the platforms will be removed and recycled or disposed onshore. The exposed ends will be lowered to achieve adequate depth of coverage. The existing buried sections of umbilical will be left in situ. All concrete mattresses and grout bags will be recovered to shore for reuse, recycling or disposal.
Further according to the plan, the umbilical will be partially removed. The exposed sections adjacent to the platforms will be removed and recycled or disposed onshore. The exposed ends will be lowered to achieve adequate depth of coverage. The existing buried sections of umbilical will be left in situ; and on completion of the decommissioning programs a seabed survey will be undertaken to identify and recover debris within the platform 500m zone and a 100m wide corridor along each pipeline route.
Offshore Energy Today Staff